Native to South and Central America and the Caribbean, delicious guava fruits are the epitome of tropical flavor. But guava trees can become invasive. Are you up to the challenge?
Cousin to clove, allspice, eucalyptus, and evening primrose, guava trees (Psidium guajava) are a low maintenance, drought tolerant, highly productive tropical fruit tree. If you enjoy eating guavas, growing your own is certainly worth some thought.
Guava plant description
Guavas are an evergreen tree or shrub with shallow roots. Under ideal conditions, trees can reach 12 to 20 feet in height. Elsewhere, they remain more shrublike. Guavas grown in containers will remain small. Attractive, one inch flowers are white. Leaves are thick and fragrant. Fruits generally have green or yellow skin and white flesh, but there are cultivars with red skin, and pink or red flesh. Fruits can range in size from 2 to 5 inches in diameter.
Types of guava
There are many varieties and cultivars of guava. You may have heard of apple guava, strawberry guava, and pineapple guava. While the first two are actually guava varieties, pineapple guava is a different species altogether. In the world of guavas, plants are sorted by fruit skin and flesh color, skin thickness, and sweetness. To find the best variety for your microclimate, contact your local County Extension Office.
Guavas are extremely drought tolerant, but plants require up to 39 inches of water each year to produce a good crop. Feeding roots only go down 9 inches, so top dressing with aged compost is an excellent way to keep guava trees fed.
Guava pests and disease
Guava wood is naturally resistant to insects and fungal disease. They are, however, susceptible to attack by weevils, mites, and guava fruit flies, and they are a host to the Caribbean fruit fly. Many moth and butterfly caterpillars will also feed on guava leaves, and the Erwinia psidii bacteria can cause rot diseases.
Guavas contain a lot of pectin, so it is easy to make guava jams, jellies, and marmalades.
You’ve proba-bly never heard of proba bugs. They are another relatively new pest on the California scene. And they love artichokes.
Proba bugs (Proba californica) have been around for some time, but they used to prefer coyote brush. Coyote brush is a common native plant found along highways in agricultural areas of California. At some point (around 1997) a proba bug decided to give artichokes a try. From that moment on, proba bugs have become an increasing threat to artichoke plants. So, what do they look like?
Proba bug description
Adult proba bugs are plain brown and only 0.2 inches long. [That means you could line up 3-1/2 proba bugs across the top of a dime.] Nymphs start out looking like pale yellowish green aphids, except that they move a lot faster than aphids, due to their long legs. During the next to developmental stages (instars) they are reddish-brown, and then they develop light and dark bands on they abdominal area during the final two instars. [I couldn't find any usable photos of proba bug nymphs - sorry!]
Proba bug lifecycle
Proba bugs are active year round (just a lot slower in winter). As temperatures begin to rise, usually in March, they begin feeding and breeding in earnest. Eggs are laid on artichoke petioles (leaf stems) and hatch within 20 to 30 days. Nymphs go through five instars before reaching adulthood.
Damage caused by proba bugs
The damage caused by proba bugs is similar to that of lygus bugs, only proba bugs are more aggressive in their feeding habits. Adults and nymphs feed on young artichoke leaves and at the base of developing buds. They feed by piercing the tissue and injecting a toxin that kills plant cells. As the surrounding leaf tissue continues to grow, these punctured areas turn into brown dead spots that dry and fall off, leaving a shot hole appearance. Feeding on the base of flower buds causes the bud [the part we eat] to turn black. Not very appetizing. This phytotoxin also causes stunting and deformed flower buds. Severely affected leaves will be smaller than normal and chlorotic.
Controlling proba bugs
Until relatively recently, commercial artichoke fields were treated with organophosphates and chlorinated hydrocarbon insecticides. Use of these neurotoxins is being phased out, so proba bugs are becoming more of a problem. Infested fields can lose 20 to 30% of the harvest to proba bugs. Farmers are now removing the coyote brush near their fields and tilling the crop residue under, in a practice called stumping, to help combat this pest.
Natural predators, such as big-eyed bugs, damsel bugs, minute pirate bugs, and spiders all feed on the nymph stage of proba bugs, so avoid using broad spectrum pesticides.
You can help protect your artichoke plant by cutting the plant off at ground level, once flower production is done for the year, and monitoring for signs of infestation in March and April.
It is unusual for a new disease or pathogen to be discovered. It is even more rare when a new disease is found to be caused by a common pest. This is Fusarium dieback, and it can kill your trees.
Fusarium dieback is a fungal disease carried by invasive borers. As borers burrow into trees, they carry three different fungal pathogens with them. These fungi form colonies within a tree’s vascular system, blocking the flow of water and nutrients. Trees infected with Fusarium dieback must be destroyed and disposed of by professional arborists.
Symptoms of Fusarium dieback
Since this disease affects many different types of trees, and is caused by different fungi, it is no wonder that there are different symptoms. Infected avocado trees, for example, will exhibit sawdust-like frass (bug poop), gumming, and sugar volcanoes. Sugar volcanoes are white discharges of sugary sap. On other host trees, you may see dark, greasy looking areas on the bark, withered leaves and stem tips, and the presence of white mycelium under the bark. Mycelia are the vegetative growths of fungi.
As the infestation progresses, perfectly round, tiny borer entry and exit holes may become visible. These holes are only 0.03 inches in diameter, so you have to look very closely, usually just below areas showing symptoms of disease. Eventually, you will start seeing branches die. If you cut into an infected branch, you will see that the wood is discolored, brown or black. If you scrape the bark away from entry or exit holes, you will also see discoloration. After cutting, be sure to disinfect your tools with a 5% bleach solution or bathroom disinfectant, to avoid spreading the disease.
Once Fusarium dieback has infected a tree, the wounds and weakened condition of the tree make it susceptible to many other fungal infections and other diseases.
Originally found in Israel, Fusarium dieback was first seen in Southern California in 2003. The carrier was believed to be the tea shot hole borer, a common pest of tea plants in Sri Lanka. DNA testing, however, showed that this was an entirely new species, now named the polyphagous shot hole borer. By 2010, this borer, and the disease it carries, had become a serious threat to SoCal’s box elder trees, palm trees, black locust, and our beloved avocado trees. In 2015, a second variety of carrier, the Kuroshio shot hole borer, joined the party and started infecting the popular California palms (Washingtonia filifera). It is estimated that this disease now threatens 25% of all the trees lining Southern California’s streets.
To the naked eye, the two species of borer responsible for Fusarium dieback look identical. Female beetles are tiny and black, only 0.07 to 0.1 inches long. Males are brown and even smaller, at only 0.06 inches long. Female beetles can fly and will leave their birthplace to find other host trees to use as nurseries, carrying the disease with them when they go. Males do not fly and generally stay in the tree of their birth. These beetles are most active during summer and fall.
Fusarium dieback hosts
Shot hole borers can be found feeding on and breeding in over 200 species of woody plants. That’s a lot of potential hosts. To date, the disease has been found in more than 130 different host species.
While this disease prefers palms and ornamentals, such as maple, birch, and tulip trees, it is becoming a serious threat to avocados and California live oaks. California bay laurel, carob, chestnut, elderberries, figs, olive, peaches, persimmons, pineapple guava, pistachios, and pomegranate are also vulnerable to Fusarium dieback.
How infection occurs
This disease starts when female beetles bore into tree trunks and branches, creating galleries of tunnels. Within the tunnels, chambers are built for eggs. Female beetles have developed a symbiotic relationship with three different fungi, which they carry around in their mouths, much the way we carry around bacteria in our gut. [The fungal pathogens of Fusarium dieback are Fusarium euwallaceae, Graphium euwallaceae and Paracremonium pembeum, if you enjoy the Latin.]
The fungi that set up housekeeping within the tree end up being food for the newly hatched beetle larvae. By eating the fungi, the larvae then become carriers of the disease. These fungal colonies develop very rapidly, once they are inside a tree, and there is no known treatment at this time. Complicating matters even more, not all infected trees will show signs of infection. Some infected trees simply serve as breeding grounds, without showing any signs of disease, and we don’t yet know why.
Healthy trees are far better able to protect themselves against borers. This means selecting plants appropriate to your microclimate, irrigating and fertilizing them properly, and providing healthy soil. Also, monitor your trees regularly.
Currently, Fusarium dieback is limited to Israel and Southern California. You can see a map of the disease, as it spreads through California, here. [It’s a big file, so it make take some time loading.] While Fusarium dieback has only come as far north as San Luis Obispo, to date, that can change overnight. Research is underway, to try and identify an effective lure that can be used to trap the borers.
If you suspect Fusarium dieback on a tree, please contact your local County Extension Office. Together, we may be able to slow or stop the spread of this disease.
Jerusalem artichokes are a species of sunflower with an edible tuber.
Having nothing to do with Jerusalem and very little to do with artichokes, these members of the sunflower family are native to the eastern half of North America.
There is debate over the source of the name Jerusalem (which may be a corruption of the Italian word for sunflower, girasole), the ‘artichoke’ portion of the name comes from the flavor shared by these two plants. Other people claim these tubers taste more like chard, only sweeter. [Have you eaten Jerusalem artichokes? What do they taste like, too you? Let us know in the Comments!]
Also known as earth apples, sunroots, Canadian truffles, or sunchokes, Jerusalem artichokes (Helianthus tuberosus) have provided an attractive dietary staple to many indigenous peoples. Now naturalized in Europe, thanks to the colonists who sent tubers home, Jerusalem artichokes fell out of favor in the U.S., until recently.
Jerusalem artichoke description
Jerusalem artichokes look like their cousins, the sunflowers, reaching 6 to 15 feet in height, with somewhat smaller, bright yellow flowers. The tubers look a lot like turmeric and ginger. Long and bumpy, these tubers can range in color from brown to white, or purple to red, depending on the species and growing conditions.
Growing Jerusalem artichokes
To grow your own Jerusalem artichoke crop, begin by selecting a site. Remember, these plants are going to be around for a long time, and they can become rather tall. Unlike many other plants, sunchokes seem to enjoy being clumped together, but they should still be planted 8 to 12 inches apart. Create soil mounds over the plantings, 2 to 3 inches deep, and water regularly, allowing the soil to dry out between waterings.
Starting with a single Jerusalem artichoke tuber, you will eventually find your garden overrun with these perennials. Each plant can produce 75 to 200 tubers every year. Left unharvested, each of those will produce tubers of their own. In my book, that’s a good thing - but you may feel differently. Since tubers left in the ground for too long tend to deteriorate, and they can become invasive, Jerusalem artichokes are a good candidate for large containers or raised beds. This will facilitate crop rotation and control the number of Jerusalem artichoke plants you end up with each year. Any little piece of tuber left in the ground is likely to sprout, to plant accordingly.
Grown in containers, Jerusalem artichokes do not need to be fertilized if you start with nutrient rich potting soil mixed with aged compost. Plants will need to be watered deeply, once a week, throughout the summer. Staking may be needed to keep plants from toppling over, or you can grow them along a fence or against a building.
Harvesting Jerusalem artichokes
As the leaves, flowers, and stems begin to die back at the end of the growing season, usually around October, you can dig up the tubers and allow them to dry, unwashed, for storage. Each plant will produce approximately five pounds of tubers. Sunchoke stems can be chopped and used for mulch, while the tubers to be used for the next year’s crop are simply placed back in the growing bed, along with some aged compost, and the cycle begins again.
[Mostly] edible sunchokes
Surprisingly low in starch, Jerusalem artichokes contain a type of carbohydrate sugar, called inulin, which gives them an underlying sweet taste. While the human gut cannot digest inulin, bacteria further down can, so some people may experience a certain ‘airiness’ after eating sunchokes. If they are not bothersome to you, they also provide a lot of potassium, iron, fiber, and B vitamins.
Or, if you prefer, you can ferment your Jerusalem artichoke crop to make brandy, the way they do in Germany.
As an older native plant, sunchokes have very few pests or diseases to worry about. So, mark your calendar to start Jerusalem artichokes in March or April, and start preparing the planting space today!
How can digging both cause and correct hardpan?
Before we can answer that question, we need to know what hardpan is.
Hardpan is a layer of soil so dense that air, water, and roots can barely move through it, if at all. Think of it as a saucer under the teacup of life. Unlike compacted soil, which is a general condition of not enough macropores and micropores, hardpan is a distinct layer, usually found 4 to 40 inches below the surface, that reduces or halts drainage, roots, and gas exchanges altogether.
Acidic soils are far more likely to cause calcium and iron to form hardpan layers, than alkaline soil. Soil structure is another important factor. Clay particles are very small and already tend to become compacted. In clay soil, rain or irrigation followed by high temperatures can also create hardpan. However it occurs, plant roots don’t like it.
Do you have hardpan?
Poor drainage is the first sign of hardpan, followed by a general failure to thrive. If you have a soil tester, you can take a few 2 or 3 foot deep samples of your soil, to see if there is a hardened layer. If you have a post hole digger, you can basically do the same thing, with more soil and more effort. The important thing is to look at the layers of soil as you bring them up. If you reach a layer where all the plant roots start growing horizontally, you have hit hardpan.
Once a layer of hardpan has formed, it takes brute strength and proper soil amendments to correct the problem. Basically, you can either dig down into the hardpan layer, breaking it up, or add significant amounts of organic matter and let nature takes its course.
If you opt for the brute strength method, you will have to wait for the soil to be dry. [Digging wet soil is never a good idea.] You can use a digging fork, spade, or broadfork to break through the hardpan layer. As you do this, you will want to make sure that the subsoil is not brought up and mixed with the topsoil.
To prevent compounding the problem by even more digging, it is important to add significant amounts of organic matter, in the form of aged compost or manure, or peat, to improve the soil structure, as you dig. Earthworms and other soil dwelling creatures will, over time, break through a thin layer of hardpan, but only if enough organic material is added to the soil.
Treating acidic soil with lime can help break up the chemical bonds that hold a hardpan layer in place. This is not an option, here in the Bay Area, where our soil tends to be very alkaline. You can also top dress the area repeatedly with organic matter to treat hardpan, but it may take years before you see results.
People started growing and eating soybeans three thousand years before the invention of written language. Originally from East Asia, this high protein legume is now found practically everywhere. Soy milk, tofu, and soy sauce are just a few products made from soybeans, but what about the plants themselves? Is there a place for soybeans in your summer garden?
The soybean plant
Mature soybean plants can reach 2 to 4 feet tall, and they have trifoliate leaves. This means that each leaf is made up of three leaflets. Like other legumes, soybean roots have a symbiotic relationship with certain soil bacteria (Rhizobium) that help them use atmospheric nitrogen. They are deep rooted plants, going down 3 to 5 feet. Soybeans are photoperiodic plants. This means shortening days is what triggers them to start producing flowers. Soybean plants have small, self-fertile flowers that can be purple, pink, or white. Once flower production begins, many soybean plants drop their leaves.
Soybean fruits are 3 inch long, hairy pods that contain 2-4 seeds, called pulses. Soybean pulses can be brown, black, green, yellow, or multicolored. By 2010, 93% of soybeans grown commercially in the U.S. were genetically modified. In that same year, scientists mapped the soybean genome, the first bean to be sequenced.
Types of soybeans
There are two basic categories of soybeans: vegetable and field. Field soybeans are grown for oil production. Vegetable varieties are higher in protein, easier to cook, and taste better than field soybeans. Soybeans contain 38-45% protein and up to 19% oil.
How to grow soybeans
Soybeans (Glycine max) are an annual bean plant that loves hot, summer weather. Pulses should be planted 1 inch deep and spaced with mature sizes in mind. To provide an ongoing harvest, you may want to use succession planting, adding new plants every week or two during the growing season. Soybeans are ready to harvest within 80-120 days after planting. Pick pods while they are still green. Once they brown, the pulses lose flavor. Of course, you can always use mature pulses to plant the next season's crop! Because of their nitrogen-fixing ability, soybeans make an excellent player in crop rotation plans.
Soybean pests and diseases
Spider mites are the most destructive pest of soybeans, followed by corn earworm moths, Mexican bean beetles, bean leaf beetles, and cyst nematodes. Fungal diseases, such as stem blight, rust, and white mold can infect soybean plants, along with bean yellow mosaic and other viral diseases. But don't let that stop you!
If you have the space, give soybeans a try in your yard!
Wrapping your trees to protect against winter cold sounds like a good idea, but it probably isn’t.
For decades (centuries?) people have wrapped their trees to protect against frost cracks, winter sunscald, and other forms of cold weather damage. While this sounds like a great idea, it ends up that those wraps can actually cause more harm than good.
The theory behind tree wraps
Winter tree and plant damage can occur in several ways: flat out freezing; temporary warming, followed by freezing; and cracks caused by the water within the plant freezing, expanding, and pushing its way out. When you get down to it, it is rapidly fluctuating temperatures that cause the most damage to trees in winter.
Types of tree wraps
Tree wraps, also known as tree guards, or tree liners, can take many forms. Commercially available tree wraps include white plastic guards, white adhesive tape, foil-backed fiberglass panels, capillary mats, landscape fabric, reflective greenhouse insulation, and watering bags. DIY growers have used paper, bubble wrap, burlap, cardboard, shredded newspaper, foam, and I have a neighbor who knitted sleeves for her trees!
Problems with tree wraps
According to the International Society of Arboriculture (ISA), studies have shown that tree wraps do not actually prevent temperature fluctuations. In some cases, temperature variations are even worse with the wraps. Also, tree wraps provide protection for many wood-boring insects, wasps, and earwigs, just to name a few. This is especially true with snugly fitting wraps.
Manufacturers and many gardening sites suggest that tree tubes be left on young trees for several years, until they are well established. They claim that tree tubes insulate the trunk against winter sunscald and shade it against summer sunburn. These tubes may also prevent a tree from swaying in the breeze so much that it fails to get strong, through a process called thigmomorphogenesis. [How’s that for a cool garden word?]
Wrapped too tightly, tree wraps can interfere with normal growth, causing girdling. Depending on the material used, it may cut into the bark, causing points of entry for pests and disease.
Often bare root stock and young trees are sold with tree wraps in place. These wraps can provide protection during digging and shipping, but they can also hide injuries, insects, and improper pruning.
Wrapping your trees may reduce mechanical damage and rodent feeding, but it is more likely to result in insect damage and fungal disease. And it will not protect your trees against frost cracks or winter sunscald. Personally, I prefer whitewashing, mulch, and proper irrigation to prevent cold weather damage.
Summer sunburns hurt, but winter sunscalds are worse (for trees).
You might not think sunscald, or sunburn, could occur in winter, but it can. [Ask any of your skier friends. They know.] Unlike summer sunburns, which are much like the sunburns we get, winter sunscald occurs when it gets warm enough in the daytime for plant cells just under the bark to break dormancy.
There are several chemical changes that occur as plants enter dormancy. These changes protect plants against the cold. Warm, sunny days can trick overeager cells into breaking dormancy and losing those protections. Then they die, leaving a sunken area below the bark.
Damage caused by winter sunscald
The sunken areas created by winter sunscald normally develop a protective callus, but not always. Once the tissue is damaged, it is more likely to develop cracks during the growing season. Slugs and other pests love to hide out in the fissures created by sunscald.
Winter sunscald is rarely fatal, except to one- or two-year old trees. However, it can weaken a tree and make it susceptible to wood-boring pests and canker diseases. Nearly all fruit trees and all newly planted trees are vulnerable to winter sunscald. Thin barked trees, such as ash, beech, birch, honey locust, linden, maple, oak, white pine, and willow tend to develop winter scald, if left unprotected.
Preventing winter sunscald
There are several ways you can prevent winter sunscald from damaging your trees. First, keep your trees properly irrigated. A water stressed tree is far more likely to develop winter sunscald. Also, avoid damaging the trunk with lawnmowers, car doors, and weedwackers. Damaged trunks have a harder time protecting themselves. You can prevent mechanical injury and stabilize soil temperatures with a thick layer of mulch around the tree. Just be sure to keep the mulch from touching the trunk, which would set the stage for fungal disease.
If watering and mulching aren’t enough, whitewashing the trunk and exposed surfaces of major branches can help prevent winter sunscald. It will protect against summer sunburn, too. Some people find the paint unattractive. Personally, I like it. Just don’t whitewash your trees with enamel paint. They will suffocate. Instead, combine 1 part water with 1 part white latex paint (preferably one without extra chemical additives) and use that to paint your trees.
Traditionally, tree wrapping was recommended as a protection against winter sunscald, but we now know that those wraps can cause more harm than they prevent. Wraps allow moisture to collect, setting the stage for rot, and they provide an excellent hiding place for pests and fungal disease. Also, cracks that occur under the wraps tend to not heal as well. Bottom line: don’t wrap your trees.
If your trees tend to get winter sunscald, you can block or shade the southwest side of your trees to provide some protection against winter sunscald.
Winter sunscald care
Once damage has occurred, you can speed the healing process by smoothing the edge of the wound with a sharp, sterilized knife. Do not remove more than 1/2” of the bark. Also, resist the urge to paint tar or sealant over the wound. This usually traps moisture against the wound, increasing the chance of disease and decay.
Finally, you know that old adage about getting lost in the woods and looking for moss on the north side of trees? Well, that piece of advice is useless. Moss grows on the side of the tree with the most moisture and sun protection. What you can do, however, is look for winter sunscald, which nearly always occurs on the south or southwest sides of trees in the northern hemisphere.
Now you know.
Witch hazel. While it would be fun to imagine that the name witch hazel has something to do with Halloween and cauldrons, the words actually come from the Middle English wiche, meaning bendable or pliant, and the Germanic hæsel, which can refer to any temperate shrub or small tree. Sorry for popping your bubble, but these trees really do have plenty to offer.
During my visit to the Missouri Botanical Gardens, I saw lovely, low spreading trees that happen to provide a bonus of striking flowers. In winter! The trees I saw were tucked away under larger deciduous trees, often with a backdrop of evergreens. While generally pruned into the shape of a small tree, I have since learned that witch hazels will also grow into a many-stemmed shrub, and that there is even a weeping variety. But it is the flowers that captured my attention. These are not your garden variety roses or daisies.
Witch hazel flowers
While we generally focus on edible plants at The Daily Garden, I had to make an exception for witch hazel trees. The winter flowers of witch hazel provide color, nectar, and pollen through the lean winter months, increasing biodiversity, and improving your mood. At a time when everything else is grey, these striking flowers are visual fireworks in an otherwise drab view. Witch hazel flowers can be a buttery yellow color, or they may be a brilliant orange or red. Very often, flower petals have a red or purple base, adding depth to the color.
The witch hazel tree
The genus name for this group, Hamamelis, means “together with fruit”. This name refers to the way flowers and new stems occur while fruit from the previous year is still on the tree. Very often, flowers will start out yellow, then shift to orange, and end their lives a fiery red before falling to the ground. The fun thing about witch hazel trees, especially with the yellow flowering varieties, is that they look like sunflower trees, in the dead of winter.
There are four species of witch hazel, or winterbloom, native to North America: H. mexicana, H. ovalis, H. virginiana, and H. vernalis. Each of these varieties has a pleasant fragrance. There is also one Japanese variety, H. japonica, and one Chinese variety, H. mollis, neither of which have a fragrance. There are also several different cultivars. Pacific Horticulture has an excellent description of the many cultivars available today.
Witch hazel trees are deciduous. They can reach a height of 40’, but most of them peak out at 10 feet. Witch hazels seem to prefer a lower growth, keeping to the shadows of other, larger trees. Witch hazel trees will not perform well, left exposed to California’s scorching summer sun, but they make lovely understory trees. The fruit is a capsule that contains one or more black seeds. When the fruit is ripe, it splits explosively, ejecting seeds up to 30 feet from the parent tree. [In some areas, these trees are called Snapping Hazels because of this behavior.] Witch hazel trees have thin bark and shallow roots, so it is important to keep newly planted trees well irrigated.
How to grow witch hazel
Growing witch hazel requires patience. After they have been cold stratified, seeds take up to a year to germinate. You will want to start them in pots, where they will stay for 2 or 3 years, before they will be ready for transplanting. Flowers do not appear until plants are 6 years old. Native to the northeast and throughout the Appalachian Mountains, witch hazel prefers life on the northern side of everything: the north side of your house, on north facing slopes, that sort of thing.
Witch hazel extract
These are the trees that provide us with the popular astringent of the same name. Native Americans used witch hazel extract to treat a wide variety of conditions, including inflammations, tumors, and swellings. The Puritans adopted these practices and many medical claims are made about the effectiveness of witch hazel, some of which are true, while others are not. According to WebMD, the leaves, bark, and twigs of witch hazel contain tannins that reduce swelling, which is why it is used to treat bags under your eyes, hemorrhoids, minor bleeding, and mild skin irritations. All the other claims about witch hazel extract are unsubstantiated.
Before you go trying to make your own witch hazel extract, you need to understand that the inexpensive plastic bottle of witch hazel available at the drugstore is a distilled version of the original recipe. It’s probably not worth the trouble of trying to make your own, unless you are really into that sort of thing. Also, witch hazel can be toxic, so be careful.
Witch hazel lore
Forked witch hazel branches are the tool of choice as dowsing or divining rods. Early settlers observed the Native Americans using witch hazel branches to find underground water sources. According to the American Society of Dowsers, “The dowsing rod is a simple instrument which shows the reaction of the human nervous system to certain factors which are unknown to us at this time.” Sounds fair enough. Apparently, the flexibility of witch hazel limbs makes them particularly sensitive and responsive to those as yet unknown reactions.
If you have a shady spot in your landscape and need some winter color, witch hazel might be just what you need.
Frost cracks look strange on small twigs, but they can be devastating to tree trunks.
The first step to preventing frost cracks is to know your frost dates.
Frost dates are estimates of when the first and last frost will occur in your area. It is important to know your local frost dates. It is also important to know that those dates are only statistical averages. Frost may occur before or after those dates, so be prepared.
Plants in winter
In nature, plants protect themselves from frost cracks and winter sunscald by absorbing large amounts of water from the ground and radiant heat from the soil. Even a blanket of snow provides insulation that stabilizes soil temperatures for the roots. Once the ground freezes, plants are unable to get the water they need. Plants also go through chemical changes that help prevent death by freezing. Sometimes, those adaptations are not enough and frost cracks can occur.
How do frost cracks happen?
Frost cracks can occur two ways: the moisture held inside the plant freezes, or the outer bark cools faster than the living wood. In the first case, the water stored within the plant freezes and forces its way out of those cells. The loss of moisture causes these areas to shrink and they crack away from the larger, unfrozen plant tissue. As temperatures rise, the tissue may be able to absorb enough moisture to close the crack, but it will always be a weak spot, prone to pests and disease, and re-cracking. Repeated cracking can result in a condition known as “frost ribs”. Frost ribs are permanently damaged areas that remain susceptible to pests and disease.
These frost cracks tend to be vertical, exposing the cambium layer, and can be several feet long, though you may not actually see them until spring, when the tree resumes growing. Frost cracks are more likely to occur where injuries, such as collisions, have occurred in previous years, providing a good argument for protective tree supports in high traffic areas.
Frost cracks can also occur when the bark and underlying wood are heated during the day, causing them to expand. As temperatures drop in the evening, the bark cools faster than the internal wood, causing the bark to crack.
Frost cracks are most common on the west and southwest sides of thin, or smooth barked trees, such as apple and pear, as well as beech, crabapple, horse chestnut, linden, maple, oak, sycamore, yellow poplar, and willow. Other plants are susceptible to frost cracks and winter sunscald, as well.
Caring for frost cracks
Once a frost crack has occurred, it is likely to occur again. Caring for these injuries properly will go a long way toward protecting your tree from invading pests and diseases. First, resist the urge to paint sealant or tar over the wound. Sealants are not effective at treating these injuries. Quite the contrary, sealants tend to trap moisture against the wound, increasing the chance of decay, especially near branch collars. If a frost crack has jagged edges, you can help your tree heal by cutting a narrow strip (< 1/2”) around the wound with a sharp, sterile knife, creating smooth edges. This will speed the growth of cambium, which will develop into a protective callus.
How to prevent frost cracks
First and foremost, keeping your plants healthy and properly irrigated will help them protect themselves. Since healthy tissue and defective tissue expand and contract at different rates, maintaining healthy trees in the first place is your best insurance against frost cracks and winter sunscald. These other tips can make a big difference is how your plants weather the winter:
Temperature-sensitive plants can be protected with blankets or other coverings, just be sure to keep the covering from touching leaves and tender stems, and allow the material to hang, rather than bunching it around the trunk. This helps collect radiant heat form the surrounding soil.
Remember, it is far better for your plants to have frost and ice protections in place before they are needed.
If extrafloral nectaries are not super-sized nectarine flowers, what are they?
While most plants produce nectar in their flowers to attract pollinators, there are over 2,000 plants that produce nectar in other places, and for entirely different reasons.
What are extrafloral nectaries?
Nectar is the currency used by plants to attract beneficial insects. Nectar is manufactured in glands, called nectaries. Nectaries are usually found in flowers. When these glands occur elsewhere, usually on leaves or stems, they are called extrafloral. So, extrafloral nectaries (EFN)s) are knob-shaped, nectar-producing glands found on leaves and stems.
These glands can take many different forms. Some are very primitive in structure, while others are highly complex. Regardless of the form, the nectar produced by EFNs is surprisingly consistent across species, and around the globe. This is in direct contrast to the wide ranging differences found in the nectar produced by flowers.
Why do plants have extrafloral nectaries?
If nectar is supposed to attract pollinators, why would it occur on stems and leaves? The most popular theory asserts that extrafloral nectar attracts insects, spiders, and crustaceans that protect the plant from sap-sucking, plant nibbling, seed eating pests. There is another theory that claims extrafloral nectaries may also serve a waste elimination function, but that theory is not nearly as popular, or as appetizing. Many beneficial insects (and some not so beneficial insects) are attracted to EFNs, regardless of the reason.
Insects attracted by extrafloral nectaries
Scientists believe this structure evolved on vining plants, due to ant traffic. Ants are one of the most frequent visitors to extrafloral nectaries. Since ants frequently carry diseases from one plant to another, and they farm aphids, I don’t usually count them as beneficial insects, even though they do help aerate the soil. Recent research, however, has also shown that ants serve a valuable function to trees by feeding on nectar and harmful insects, and then pooping those nutrients onto leaves. Those nutrients are then absorbed through the leaf, providing valuable plant food, right where it is needed.
A few, full-blown pests, such as Florida’s lovebugs, also tap into this food resource. For the most part, it is beneficial insects, such as ladybugs, lacewings, praying mantids, and wasps, who are attracted to extrafloral nectaries. Some plants provide sheltered chambers, called domatia, for similar benefits.
Plants that feature extrafloral nectaries
There are over 2,000 plants that have extrafloral nectaries. All cucurbits and many members of the Prunus and legume families feature extrafloral nectaries. This means that your squash, melons and gourds have these knobby glands, as do your peach, apricot, nectarine, cherry, and plum trees. Cowpeas and elderberries do, too. Common vetch, willow, peonies, and many ferns, vines, and carnivorous plants also feature extrafloral nectaries. [Some scientists disagree with ferns being included in this list, since ferns do not produce flowers. Those scientists call these glands ‘extrasoral’.]
As more botanical research is conducted, we are learning than the food provided through extrafloral nectaries is critical to biodiversity, especially during times of drought.
Which plants in your garden have extrafloral nectaries?
Shallots are a type of onion. Slightly milder in flavor, shallots add a special touch to your cooking and, yes, cutting them up will make you cry.
Until recently, shallots were classified as their own species, but we now know that they are, in fact, members of the onion family, along with scallions, chives, leeks, and garlic.
Types of shallots
Shallots are believed to have originated in Central or Southwest Asia. There are several types of shallots, but the two most well known are the popular, red-skinned shallot (Allium cepal), and the more flavorful French Grey shallots (A. oschaninii).
How shallots grow
Shallots are a type of bulb. Rather than growing a single bulb, the way onions do, or as a single head with several cloves, the way garlic grows, shallots create clusters of identical daughter bulbs, called offsets. Covering each bulb is a protective layer of papery tissue that can range in color from golden brown of a crimson red. The flesh can be off-white, tinged with magenta or green. Shallots are very tolerant plants. They can handle bright, hot sunlight or partial shade, and they will grow in soil pH from 5.0 to 6.8. Shallots love phosphorus, so they tend to grow very well in the Bay Area. The one thing they cannot tolerate is poor drainage. Shallots that sit in soggy soil will rot.
How to grow shallots
October and November are the best times of year to plant shallots in the Bay Area. You can start with seeds, but I urge you to try using those offshoots, commonly called “starts” for faster results. Prepare the bed by top dressing with aged compost. The looser the soil is, the better. Then, simply press the root end of each bulb down, into the soil, leaving the shoulders of the bulb above ground. Space plants 6” apart. Rows should be 10” apart. Do not mulch heavily on top of the bulbs as this can interfere with initial growth. Straw works well.
In spring, as your shallot bulbs begin to develop bulbs, give them a nutritional boost with aged compost or a well-balanced organic fertilizer. Shallots use 1” of water a week, so be sure to irrigate regularly during dry spells.
If flower stalks emerge, remove them. Continue watering and weeding your shallots until the tops of the leaves begin to turn yellow and fall over.
Shallots grow very well in containers and look lovely on windowsills, especially when so many other plants are dormant. In the Bay Area, I have been able to keep growing the same shallot plants for 3 years. When I need one, I simply wiggle it out of the soil and cut it off 1/4 inch above the roots and cover the roots back up with soil. Nearly always, a new shallot bulb develops (but not always).
If you harvest the entire plant, cut the leaves an inch or two above the bulb and allow the bulb to dry in a cool, dark area. If cured properly, they can be stored for up to 6 months. If you leave some of your shallot plants to continue their life cycle, you can collect your own offshoots for the next season’s crop.
Shallot pests and diseases
Leek moth larvae will burrow into the bulbs and leaves of shallots, but I have not had any problems with my container grown shallots. Gophers are a big problem, so you may need to bury hardware cloth under your shallot bed. I have dogs.
Shallots are pricey in the store, but easy to grow at home. Give shallots a try today!
Fire ants are an experience you will never forget.
For me, it happened when I was a child, playing with friends. We sat down on the ground to continue our game, I started feeling something tingly, and then, all of a sudden, my legs were on FIRE!!!! I jumped up and tried to rid myself of the horrible burning sensation, but it was several hours before I was comfortable.
The burning, itching sensation that comes from being bitten by fire ants is not to be ignored. So, how is it that these tiny insects can cause so much pain? And are they a problem where you live?
Types of fire ants
There are three basic types of fire ants (and countless variations) found in the U.S.: native southwestern fire ants, red imported fire ants, and their close cousin, the black imported fire ant. Our domestic fire ants are not as aggressive as their South American cousins, and their stings are not as painful. Red imported fire ants (Solenopsis invicta) and black imported fire ants (S. richteri) are extremely aggressive and their stings can be excruciating. Black imported fire ants are currently only found in the Southeastern U.S., and they are similar enough to their red-headed cousins, that we will be focusing on our biggest problem: the red imported fire ant.
Originally from Argentina, red imported fire ants are believed to have entered the U.S. in the 1930’s, in Alabama. By 1998, these stinging insects had made their way across the country to California. When the imported species meet our domestic fire ants, the home team loses.
Fire ant description
Red imported fire ants look like common ants, only bigger. Females are reddish colored. Males are black. Eggs are white and oval-shaped. Within one week, the egg looks more like a larva and the egg casing falls away. The larvae go through four stages (instars) before they reach adulthood. There are castes within a fire ant colony. The queens are the biggest, and then there are two castes of workers: major and minor. Smaller, minor workers tend to stay indoors and care for the brood, while larger, major workers go outside and forage for food. Major workers are twice the size of minor workers.
Fire ant colonies
Fire ants live in colonies. Since they need water to live, these colonies are generally found near water. Colonies may be found under a sidewalk, near the base of a tree trunk, in electrical equipment, and in and around your home. Colonies in the ground will often mound the soil up 12 to 18 inches. Each colony hosts 100,000 to 500,000 workers and several breeding queens. These queens may live for a few years, while the sterile workers only live a few weeks. If nearby water levels rise, fire ants will build floating islands to protect the colony.
Red imported fire ants have developed symbiotic relationships with insects, such as mealybugs, that produce honeydew. As omnivores, fire ants often eat dead animals and insects, fruit, and seeds. Their favorite food, however, is honey, so protect your hives!
Harm caused by fire ants
Fire ants can ruin more than a child’s game or a picnic. A red imported fire ant colony can make working in the garden nearly impossible. If a fire ant colony feels threatened, it can swarm an area with thousands of angry, stinging insects. These swarms are responsible for killing young livestock, such as rabbits, pigs, and even cattle. [Never restrain an animal or place a playpen near a fire ant colony.] The Stock Island tree snail is believed to have become extinct because of fire ants. Even if nothing in your garden becomes extinct because of fire ants, these pests, along with other ants, can carry diseases that may harm your plants.
Fire ant stings
A single burning, itching sting can capture your attention for about an hour. After that, the sting turns into a blister that will bother you for 3 or 4 hours. This blister transforms into a pustule that resolves in a couple of days. That’s if you’re lucky enough to only get stung once. If you develop an allergic reaction after a fire ant sting, get to the emergency room right away.
If you are not allergic to fire ant stings, wash the area with soap and water and apply a cold compress to reduce the pain and swelling. Antihistamines and topical steroid ointments may also provide some comfort, but nothing will get rid of it completely.
It is estimated that 14 million people are stung by red imported fire ants each year in the U.S., and that many of those people will develop an allergic reaction over time.
How to control fire ants
Luckily, fire ants are susceptible to the same control measures as other ants. Over-the-counter ant bait systems can be placed near the colony. If a severe infestation is present, contact local county pest control agencies by calling the statewide red imported fire ant hotline at 1-888-434-7326.
Apparently, high level conflicts attract one another. As much as 75% of a black widow spider’s diet is, you guessed it, red imported fire ants.
Other fire ant predators include earwigs, dragonflies, beetles, and other ants. To keep these somewhat beneficial insects alive, it is a good idea to avoid using broad spectrum insecticides. Birds and armadillos also find fire ants to be a tasty snack, but the strangest predator, in my opinion, is the fire ant decapitating fly (Pseudacteon obtusus).
These flies lay an egg on the back portion of a fire ant’s head, where the ant cannot reach it. The egg hatches and the larva starts feeding on the ant’s head, until it falls off. The fly larva enters the fallen head and stays there to pupate. [You can’t make this stuff up.]
So, if you see a mound that might be a fire ant colony, be careful!
Copper is an element necessary for healthy plant growth, and it is a superhero when it comes to fighting plant disease.
Copper (Cu2+) is a very soft metal. It is also nonreactive and conductive, which is why we use it for water pipes and electrical wires. [I’m not sure why, but rats seem to enjoy chewing on copper pipes and wires.]
How plants use copper
Copper is a micronutrient. While plants only use a tiny amount, copper is critical to many life processes and a tasty harvest. Copper is used by plants in photosynthesis and reproduction. It is a metabolic catalyst that breaks down proteins, increases sugar production, intensifies color, and makes plants taste better. Copper is used to make reproductive enzymes responsible for flowers, fruits, and seeds. Copper also helps roots eat and breathe. Yay, copper!
Sadly, copper can’t always get to where it is needed.
To complicate matters, nutrient deficiencies are not always caused by a simple lack in the soil. Extreme temperatures, insufficient water, and soil compaction are common culprits in nutrient availability. Nutrient deficiencies can also be caused by imbalances with other nutrients. For example, if there is too much phosphorus, which is common in the Bay Area, it is difficult for plants to absorb copper. The only way to really know what your plants are dealing with is to get a soil test from a local, reputable lab. [I wish that those colorful, over-the-counter soil test worked, but they are not accurate enough to be useful. Maybe someday…]
Copper deficiencies appear as chlorosis, twig dieback, and bronzing. It can also cause leaf rolling and curling. If a soil test indicates more copper is needed, be sure to read labels and decide if your soil needs copper that is chelated or not, before adding anything. Chelation is a process that can make more nutrients available to plants, especially in areas with alkaline soil, but too much of a good thing can turn out to be a bad thing. Copper amendments come in different forms. Make sure you get the form your soil needs.
Forms of copper
Beyond pipes, wires, and old pennies, copper can take many forms. In the garden, we generally talk about fixed copper and Bordeaux mixture. Bordeaux sprays consist of copper sulfate, lime, and water. You can make your own Bordeaux spray using materials available at most garden centers. Fixed copper is specially formulated to delay the release of copper ions. When copper ions are “fixed”, they become less soluble in water. This means that, after being sprayed onto leaves and stems, only a little copper is released each time it becomes wet. If a plant receives too much copper all at once, it can be poisoned in a condition called phytotoxicity.
Fixed copper comes in many different forms: copper sulfate, copper oxide, copper hydroxide, and copper oxychloride sulfate. There are also products that link copper ions to fatty acids or other organic molecules.
Copper and pests
We’ve all heard that copper strips repel slugs and snails. This is only partly true. If the strip is wide enough, it will repel snails, but not slugs - and I have no idea why. Of course, if you install a double strip of copper and electrify it, you’ll probably have better luck. Bordeaux mixture or copper sulfate alone can be brushed onto tree trunks to discourage snails. Fixed copper sprays, combined with horticultural oil, applied when pests are in the crawler stage, winter through early summer, can help control scale insects.
Copper as a disease fighting hero
Copper fights diseases by breaking down protein molecules and enzymes within pathogens. There is an astounding number of bacterial and fungal diseases that can be prevented and treated using copper. This is just a partial list:
Generally speaking, copper sprays are applied right after leaf drop and again, just before buds open. If heavy rains occur, additional applications may be needed. Keep in mind, the protection provided by copper only works while the pathogen is on the plant surface. Once infection occurs, copper is ineffective.
Penny for your thoughts on gardening…
Bokashi is advertised as a fast, convenient process that allows you to convert kitchen scraps into nutrient rich soil in record time, without the mess and smells associated with traditional composting. Sounds great, doesn’t it? What could be simpler than tossing everything into a bucket? Before you jump on the band wagon, however, let’s find out the truth about bokashi.
First, bokashi does not produce soil. Soil is made up of minerals (sand, silt, and clay), organic matter (dead bugs and plants), and spaces (micropores and macropores) that fill with water and gases. The mixture that comes out of a bokashi bucket is not soil. It is fermented versions of whatever went in. This mixture can be added to soil, but it does not create soil. More accurately, it is a soil amendment. Secondly, bokashi is not composting.
Traditional composting uses air, water, and microorganisms to decompose yard and kitchen waste. This makes composting an aerobic exercise. Traditional composting can be done in several different ways:
Many people feel that they do not have the space needed for composting. If you live in an apartment without a balcony, you’d be right. Otherwise, composting is nearly always an option. So, how is bokashi different from composting?
What is bokashi?
While composting is aerobic, bokashi is an anaerobic (without air) process. Instead of relying on the microorganisms already in the soil and air to cause decomposition, wheat bran is treated with specific yeast, fungi, and bacteria that cause the contents of the bucket to ferment. Without them, everything in the bucket would simply rot. Yuck! But, because bokashi is a fermentation process, this method can be used to break down meat and dairy products, which is not recommended for traditional composting, though it can be done.
To get started, sprinkle some of the bran on the floor of the bucket, add food scraps, sprinkle more bran, squish out as much air as possible, and put on the lid. Some people use a plastic bag on top of the mixture, to press the air out, while others use a plate. Advertisements claim that there are no smells, but that isn’t exactly true. Each time you open the bucket to add more material and sprinkle on more bran, you will smell it - a vinegary molasses bran smell. You continue this layering of waste and bran and pressing out air until the bucket is full. Then, you set the bucket aside for two or three weeks and let nature take its course.
Because this is a fermentation process, liquids are produced. You need to remove those liquids every few days, using the spigot., to reduce the chances of it going sour and smelling bad.. I’m not sure what I would do with this liquid. The material I found on the subject suggested using it to combat slime in drains and septic systems. Other sources claimed it was perfectly usable as a fertilizer, but some sites said to use it full strength, while others said to dilute it to 1/100th strength. Sorry, but I love my plants. I’m not going to risk them, trying to figure out which claim is accurate.
How to use bokashi mixture
After the fermentation process is complete, much of what is in the bucket will look like a pickled version of what it was when it first went in. Proponents of bokashi call this resulting mixture “pre-compost”, which must then be added to your compost pile or dug into the soil. Just be sure there are no plants nearby for another couple of weeks. This initial mixture is very acidic, with an average soil pH of 4.0, which can burn plant roots. Before you think this will be a way to acidify your soil, you need to understand that soil pH is very difficult to alter and that it would take A LOT of bokashi mixture to make a lasting change. The fermented mixture can also be added to your worm bin, if you are practicing vermiculture. I don’t know if it is safe for worms (or if it gets them drunk) but, aside from the meat and dairy, you could have added the raw materials to the worm bin in the first place and skipped the whole fermentation process.
If you haven’t guessed by now, I am not sold on the bokashi method. While it would be wonderful to simply drop all our trash in a bin that kicks out healthy soil, that mechanism does not yet exist. Making soil takes millions of years. You can certainly use bokashi to feed your soil, if you enjoy the process, but you can also raise worms, or just compost the old fashioned way.
The guava fruit fly is yet another invasive pest that home gardeners need to be aware of.
You may have driven through an agricultural inspection station on your way into California, at one time or another. These inspection points, along with those at international ports, and at shipping and postal centers, all work together to prevent infestations of foreign pests. This is a lot easier and cheaper than getting rid of them after they start feeding and breeding in a new area, which may not have native predators.
First seen in California in 1986, guava fruit flies are a major pest in Southeast Asia. In 2015, 15 guava fruit flies were found in California; 12 in Los Angeles, and one in Orange, San Mateo, and Santa Clara counties. Since a single female can lay hundreds of eggs that hatch and grow to sexual maturity in an astoundingly short period of time, a single fly is all it takes to trigger the need for extensive eradication programs. You can help in the fight against these pests by knowing what they look like and how they live.
Guava fruit fly hosts and damage
These pests enjoy several host plants other than guava. Common California crops that are threatened by guava fruit flies include black plum, cherry, citrus, peach, and melons. Banana, cashew, coffee, dragon fruit, mango, castor bean, papaya, sandalwood, rose apples, jujubes, bael fruit, sapodilla, and various gourds may also be at risk.
Guava fruit flies damage fruit by laying eggs in it. Females have a pointed ovipositor (egg depositor) that pierces the fruit. This provides points of entry for bacterial, fungal, and viral infections. When the eggs hatch, in as little as two days, maggots tunnel through the fruit, feeding and pooping as they go. None of us wants to bite into that. Maggots shed their skins twice over a two week period, depending on temperature, before dropping to the ground to enter a pupal stage. Within 1 to 2 weeks, adults emerge. Two to five weeks later, females are sexually mature. There are several generations each year.
Guava fruit fly identification
While most fruit flies are quite tiny, the guava fruit fly (Bactrocera correcta) is the same size as the common house fly. There are two major families of fruit fly: Drosophila and Tephritidae. Guava fruit flies are members of the Tephritidae, or peacock fruit fly family. They get that name because of the bright colors they display. It is mostly black, with yellow stripes, with two black spots on its face that can blend into a single band. Wings are clear with a dark line along the edge most of the way around, followed by a second line that continues around to the end of the wing. They look like they have a “T” on their butt, which is actually their abdomen. Research on this pest has only recently begun, so we will have to assume that earlier developmental stages look much like their close cousins, the Oriental fruit fly. This would mean that eggs are white, very small, and tubular, while larvae (maggots) are creamy-white and legless, and pupae are held in a dark, reddish brown cylindrical puparium. [Isn’t that a great word?]
The Northwest guava fruit fly (Anastrepha striata) is yet another invasive pest, but from the Americas, rather than Asia. Close cousins to the Oriental fruit fly, they can all be difficult to tell apart without looking closely.
Admittedly, capturing a fruit fly can be tricky business. After you’ve done it once, however, you will probably do it again. These creatures really are fascinating to look at up close. You will need to use a hand lens or a simple microscope to really see the amazing and colorful details.
If you even remotely suspect that you have a guava fruit fly, please call the Pest Hotline at 1-800-491-1899, or bring it to your local Department of Agriculture office. If guava fruit flies were to take hold in the U.S., crop losses and pesticide use would both skyrocket.
You should always protect your own garden by quarantining new plants, to ensure that they are pest and disease free.
Finding myself in St. Louis for the Sweet Adelines International 72nd Annual Convention & Competition [we came in 2nd place in the world for our division; you can see our performance here], I simply had to go to the Missouri Botanical Gardens. While writing about these prestigious gardens may not follow my regular content, I hope that it will inspire you to try some of the methods showcased. The Missouri Botanical Gardens is the nation’s oldest botanical garden in continuous existence. It is also registered as a national landmark.
History of the gardens
First, a quick history of Henry Shaw and his dream. As a young man, Henry Shaw came to St. Louis to sell tools and cutlery. He did very well for himself and became quite wealthy, expanding his business interests to include real estate, mining, furs, and other commodities. He retired when he was 39 and began traveling extensively, particularly enjoying the grand gardens of Europe. Returning to St. Louis, he decided to build a botanical garden of his own. As the idea evolved, it expanded to include botanic research and conservation, along with traditional gardening. The Gardens were opened in 1859 with the mission to “discover and share knowledge about plants and their environment in order to preserve and enrich life.”
What started out as open, undulating prairie is now home to nearly 5,000 trees, some of them directly attributed to plantings by Shaw, over 150 years ago. The 79-acre facility includes Shaw’s 1850 home, his mausoleum, nearly 7 million dried plant specimens, one of the world’s largest collections of orchids, and tens of thousands of live plants, nearly all of which are labeled, and it is all organized into several different gardens and displays. While I could list each of the gardens and tell you all about them, you can find that information online, at the Missouri Botanical Gardens website. Instead, I want to share with you the experience of walking around in this impressive collection, ending with a truly remarkable discovery.
When Shaw first came up with the idea of creating an immense public garden, I can only imagine the overwhelming scale of his thoughts. Looking at my own yard, I often find myself lost in all the tiny details of what needs doing, losing sight of the overall experience and view of my landscape. What I took away from the experience, among other things, includes:
Most of us grow plants in containers, but container gardens grow all the plants for a single recipe in the same, large container. For example, you may have a frittata container that holds scallions, summer savory, garlic, parsley, cherry tomatoes, spinach, chives, basil, and a sweet pepper plant, all in the same large container. A salsa garden may include tomatoes, onions, garlic, sweet and hot peppers, and cilantro. In each case, the variety of colors, shapes, and textures make these container gardens attractive, as well as useful.
I could go on, there is simply more to see than a person can do in a single day, but I would like to share my experience about a very special discovery that occurred during my visit.
A most amazing discovery
Wandering the gardens and trying to absorb and retain all that is there (an impossible task), I learned that the Peter H. Raven Library, housed in the Monsanto Bldg. and part of the Gardens has, in its collection, a first edition copy of Darwin’s The Origin of Species. Several emails and a fair measure of luck later, I found myself in a very special (and rather chilly) room in the Raven Library. With clean hands, I was allowed to handle some of the oldest botanical books known to mankind, including Darwin’s Origin and Carl Linnaeus’ earliest works. Then things got even more exciting, as I was allowed to turn pages in books written and bound in the 1700s, 1600s, and even the 1500s. It was a truly awe inspiring experience. It also reminded me of just how far we have come in just a handful of centuries.
Fusarium crown and foot rot means death for asparagus.
Heavy soil, poor drainage, over-harvesting, and insect feeding all work to create the perfect habitat for this ubiquitous fungi.
Fusarium is a large fungal family that causes several different disease in many garden plants. You may have already heard of Fusarium wilt, but there are several different crown and root diseases caused by these pathogens. One version attacks pumpkins, melons, and other cucurbits. Another group of Fusarium fungi attack asparagus.
Rather than having a single cause, there are three different forms of the Fusarium fungi that cause this fungal disease of asparagus. This trio of Bad Guys go by the names Fusarium oxysporum f. sp. asparagi, F. verticilliodes, and F. proliferatum. [Don’t worry, there won’t be a quiz.] All three fungi colonize the roots and crown, and the first one listed can also infect xylem tissue.
Symptoms of Fusarium crown and foot rot
Asparagus plants infected with the Fusarium fungi decline over time. At first, you may see one or more stunted, bright yellow ferns. This bright yellow coloration is a warning flag that should not be ignored. Wilting is also common. If you look at the crown area, you will see reddish brown discoloration. At this point, it is a good idea to pull the plant up, for closer inspection.
Cut open the crown or below ground area of the plant, to see if sunken brown lesions or reddish flecks are present. Then, look closely at the roots. Infected plants will have reddish brown, elliptical lesions on the storage roots. Feeder roots will probably rotted off completely, though any remaining tendrils will have the same reddish brown discoloration seen elsewhere.
Unfortunately, these fungi can survive in the soil indefinitely, and they are found pretty much everywhere. The disease is often spread as infected soil is moved from place to place on shoes, tools, and equipment. It can also be carried on seeds, which is why choosing reliable seed sources is so important. This disease can occur anywhere underground. Very often, insect feeding creates points of entry for these fungi. Asparagus miners are a common culprit.
Controlling Fusarium crown and foot rot
Environmental conditions that keep plants healthy also improve their ability to prevent these fungi from entering in the first place, so avoid water stress and feed plants regularly with top dressings of aged compost. [Asparagus plants are very heavy feeders.]
Once a plant becomes infected, it should be removed completely, along with nearby soil, and disposed of in the trash. To reduce the chances of the disease taking hold in the first place, your asparagus plants should be rotated every five years and be sure to provide proper drainage.
Remember, perennial asparagus can provide you with many years of delicious spring and autumn spears, so don’t let these pathogens stop you from trying to grow your own!
No, we are not discussing a breakfast cereal.
Frosted scale is a soft scale pest of walnuts. If you have a walnut tree (and why wouldn’t you), scale insect pests can be a major problem. These sap-sucking pests also feed on stone fruits, such as apricot and peach, along with apples, pears, raspberries, grapes, pistachio, roses, laurel, birch, locust, sycamore and elm, spreading disease as they go.
Frosted scale description
Like other scale insects, adult female frosted scale are 1/4 inch, dark brown ovals, with a protective, dome-shaped covering. As the name suggests, frosted scale has a waxy, frost-like coating over its shell. This frosty coating stays in place for a while, but it eventually wears off, leaving behind a brown shell that can remain in place for a year or so.
Frosted scale lifecycle
Nymphs overwinter on twigs. In early spring, these nymphs quickly grow to adult size. By late spring, females lay many eggs, filling the space between their body and their protective shell. After the eggs are laid, the female dies. When the eggs hatch, the nymphs, or crawlers, come out from hiding and begin feeding on the underside of leaves. They will continue feeding until fall, when they molt and move back onto twigs, where they spend the winter. There is one generation each year.
Problems associated with scale feeding
Frosted scale insects feed on the nutrient rich plant juices found in leaves and new twigs. As they feed, these nymphs produce large amounts of honeydew (sugary bug poop), which attracts disease carrying ants, and promotes the growth of sooty mold. Small numbers of frosted scale insects are not a problem. Heavy infestations, however, can suck the vitality from your trees, reducing crop size and quality. Also, as scale insects feed, they create wounds. These wounds make it easier for infections to take hold. One such fungi, Botryosphaeria, can lead to lower limb dieback and other potentially fatal fungal diseases.
Controlling frosted scale
In the world of commercial agriculture, insecticides are recommended if 5 or more nymphs are found per foot of the previous year’s wood. This means grabbing a hand lens and looking very, very closely. In the home garden, beneficial hunters, such as parasitic wasps, will provide the best protection. You can tell that a frosted scale nymph has been parasitized because it will turn black. Parasitized adults will have perforated shells.
You can increase the populations of these tiny, beneficial wasps by avoiding the use of broad spectrum insecticides and pesticides. Dormant oils can be used in winter and early spring to rid your tree of scale insects, but walnut trees are sensitive to horticultural oils and you need to use narrow-range oils to avoid harming the tree.
Scale infestations can sneak up on you. Be sure to take the time every month or so to inspect your trees for signs of infestation.
What pests are lurking in the soil of your lawn or garden? One easy way to find out is to conduct a drench test.
A drench test is simply pouring soapy water over an area and waiting to see what comes up. Most insects don’t handle soapy water very well, so they will come up, out of the relative safety of the underground world, when their home turf is saturated with the stuff.
The most common soil dwelling creatures that you will see are ants, earwigs, sowbugs, worms, and grubs. Most often, these grubs are pests. Common underground pests include armyworms, cutworms, fiery skipper larvae, sod webworms, and southern chinch bugs.
How to conduct a drench test
Soapy water probably isn’t very good for beneficial soil microbes, so this isn’t something you want to do all over, but it is an excellent test for measuring the presence of soil pests. Follow these steps to see what might be nibbling your plants’ roots:
Once you have an accurate idea of what sort of pests are present, you can make informed decisions about controlling those pests. [There's no sense treating for a pest you don't have, right?]
Let us know the results of your drench test in the Comments!
You can grow a surprising amount of food in your own yard. Ask me how!