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 may have played with (or been horrified by) potato bugs as a child. The Colorado potato beetle is not that bug. [Those bugs are Jerusalem crickets, which are neither crickets nor from Jerusalem, but we will discuss those pests another day.]
The Colorado potato beetle looks more like a striped cucumber beetle. Unfortunately, the infamous Colorado potato beetle eats more than just potatoes. To make matters worse, this pest has an impressive ability to become resistant to even the harshest chemicals.
History of the Colorado potato beetle
The Colorado potato beetle (Leptinotarsa decemlineata) is also known as the ten-lined potato beetle, ten-striped spearman, or simply the Colorado beetle. First identified in 1824, this pest is native to southwest North America. Initially, this dome-shaped beetle preferred wild members of the nightshade family, but, by 1840, the domesticated potato became its favorite food, followed closely by tomatoes, peppers, and eggplants. Exports of potatoes (and the Colorado potato beetle) to France and Germany inspired the world’s first plant quarantine laws. During the Cold War, the CIA was accused of releasing Colorado potato beetles in Russia, in an effort to threaten the Soviet Union’s food supply. In 2014, to call a pro-Russian separatist of the Ukraine a ‘koloradi’, a nickname given to the invasive Colorado potato beetle, was an insult directed at their similar orange and black stripes. In Hungary, a statue commemorates the arrival of this difficult to control pest.
Colorado potato beetle description
This stubby, round beetle has the same size and shape as a Japanese beetle. It is usually 1/ to 1/2 an inch long and tends to be bright yellow or orange, with five stripes on either side of its wing covers (elytra) and scattered holes (elytral punctures) on its shoulder covers (thorax). Colorado potato beetles are easily confused with their close cousins, false potato beetles. False potato beetles, L. juncta, have stripes, too, but their stripes tend to be white, with light brown center stripes, and their elytral punctures are spaced in an orderly fashion.
Colorado potato beetle lifecycle
Adult females can lay over 500 eggs in one month. These bright yellow or orange, torpedo-shaped eggs are laid in clusters on the underside of leaves. These beetles go through four stages, or instars, on their way to adulthood. Each instar only lasts 2 or 3 days. Eggs hatch after 4 to 15 days, depending on temperature. These larvae have humped backs, are dark reddish brown, with two rows of spots on either side (if you look very closely). They can usually be found near abandoned egg cases. By the time these baby beetles reach their third instar, they are bright red with black heads. These pests will continue feeding and growing until they reach adult size. Then, during the fourth instar, they enter a nonfeeding, prepupal stage. These larvae are a lighter color and they don’t move around very much.
Natural predators, such as ladybugs, pink lady beetles, spiders, ground beetles, lacewings, wasps, damsel bugs, beneficial nematodes, and praying mantids all enjoy feeding on these pests, so avoid using broad spectrum pesticides.
Neem oil and Bt sprays can be used as effective controls. Dusting with diatomaceous earth (DE) has also been shown to be effective.
Defoliation refers to the widespread stripping away of leaves.
Leaves are a plant’s food factory. This is where the majority of photosynthesis occurs. Without leaves, a plant cannot convert the sun’s energy into the sugar and carbohydrate molecules needed to survive and thrive. Leaves are also used to breathe, maintain moisture levels, filter pollutants, and stabilize soil temperatures. They are also part of the plant’s disease and pest resistance, and winter hardiness. Yes, leaves are all that. Losing all its leaves is perfectly normal behavior for deciduous trees in autumn, but defoliation can be a sign of serious problems, otherwise.
Every autumn (okay, most autumns), the leaves of deciduous trees turn bright yellow, orange, red, and even purple, before falling to the ground. This occurs because the green pigment responsible for photosynthesis, chlorophyll, is in short supply. Without all that chlorophyll hanging around, you can actually see the other colors that were there all along, and some new colors that are produced especially for winter preparation. These senescent leaves fall naturally, in a behavior called abscission, and they make excellent additions to your compost pile. Other causes of defoliation are not as colorful or as beneficial. And trees aren’t the only plants that risk defoliation.
Herbivores, such as deer, rabbits, and voles can devour entire gardens, given the opportunity. While voles and rabbits generally do not have access to tree leaves, deer can reach just about anything. And those height-challenged rodents and lagomorphs can girdle a tree by gnawing through the bark, interrupting the supply of sap, water, and nutrients through the vascular tissue, causing defoliation.
Environmental factors, such as water stress, pollution, and salinity can all lead to defoliation. Water stress can mean too much or not enough water. Whether it is caused by flooding or drought, water stress can result in partial or complete defoliation. Water stress, pollution, and injury together are causing severe defoliation in a condition called shade tree decline. Too much salt in the soil or in irrigation water can also cause plants to lose their leaves.
If you notice defoliation occurring, try to identify its cause. This is the only way to help your plants recover, and reducing the likelihood of it happening again. Frequent defoliation nearly always results in plant death.
If defoliation is a natural process, or if the plant survives whatever caused the leaf loss in the first place, the recovery process is called refoliation. Factors involved with a plant’s ability to recover from defoliation include its age and overall health, the time of year when defoliation occurs, the frequency of defoliation, any secondary pests or diseases that make have taken advantage of the plant’s weakened state, and the availability of irrigation and nitrogen.
You’ve probably seen it in your garden. Instead of developing a tightly packed head of green florets, your broccoli looks a little loose and floppy. Then, the florets turn brown. This die-off of unopened flowers is called brown bud, or brown bead.
As a farmer, brown bud can make a crop unsellable, devastating your family’s financial situation. As a home gardener, the situation isn’t nearly so dire. Now, we are not talking about the tiny black and brown spots that occur on a broccoli that has been kept too long. That’s usually a fungal disease. You can cut those spots out and eat the rest, but that particular broccoli is probably past its prime.] Brown bud is not a disease. Instead, it is a physiological disorder.
Symptoms of brown bud
Unlike your standard grocery store variety of broccoli, with its tightly packed head of unopened flower buds, heads affected with brown bud have a loose arrangement. The unopened florets at the center of the head turn yellow (chlorotic), and then brown. This browning can spread across the head. These dead florets break off, providing easy access for bacterial diseases and rotting.
Causes of brown bud
This poorly understood condition most frequently occurs when temperatures are higher than normal for this cool weather crop, especially when clay soil is present. Brown bud is more likely to occur when there is not enough nitrogen in the soil, and during periods of low relative humidity. Some people believe that insufficient calcium is a contributing factor in the development of brown bud, but research does not support those claims.
Controlling brown bud
If brown bud has been a problem for you in the past, try starting your broccoli at a time when cooler, wetter weather is expected. Also, be sure to provide plenty of nitrogen, since fast growing heads are less likely to develop brown bud. Regular irrigation can also help prevent this disorder. Some cultivars, such as ‘Skiff’, are more likely to develop brown bud. While others, such as ‘Coaster’ and ‘Shotgun’, are less likely.
To avoid brown bud in your garden, feed those heads plenty of water and nitrogen!
Flowers come in many shapes and sizes. When a flower cluster has a flat or dome-shaped profile, it is said to be corymb [kor-im].
Corymb comes to us from the Greek word (korumbos) for ‘cluster’. The only reason this information is important, besides helping you win more often in word games, is that it can help you to identify plants of mysterious parentage. So, let’s find out more about corymbs and flower clusters. [And don’t let all the new words scare you off.]
Umbels and corymbs
First, we need to differentiate between umbels and corymbs. Umbels are flower clusters that look like umbrellas. The tiny stems, called pedicels, all emerge from a central stalk. Carrot, dill, and parsley flowers are all umbels.
If a flower cluster has many branches, instead of a single point of contact, it is called a panicle. [But don’t panic! You can do this!]
Flower stems are called peduncles. As soon as the tiny stems of a flower cluster begin to emerge, that main stem changes its name to rachis [ray-kiss]. Each individual stalk within a flower cluster is called the pedicel. Each pedicel holds a floret. Pedicels can be arranged in pairs (parallel), or they can take turns (alternate).
Types of corymbs
Corymbs may be flat-topped or convex. This is because the tiny stems, or pedicles, get progressively longer as they move away from the center. If the pedicels of a corymb all emerge from the central rachis, it is said to be racemose. If there are several layers of branching rachis, it is called cymose.
Cymose corymbs are said to be determinate. Determinate inflorescences have a flower on the top that halts further growth. This top (apical) flower is the oldest one in the bunch. Younger flowers develop below this primary flower. Forget-me-nots, jasmine, and figs are all cymose.
Racemose corymbs, or racemes, are said to be indeterminate. Indeterminate inflorescences are those with the oldest florets at the base and newer growth at the top. They just keep on growing. Cherries and other stone fruits all have racemose corymbs. Snapdragons and yerba maté are also racemes.
The next time you look at a flower cluster, take a moment to see if it is built like an umbrella (umbel), if its branches are all connected to a central stem (raceme), or if there is a complex system of branches (cymose). This can help you make better use of the many plant identification tools available online.
Do you have a spot where nothing (but weeds) will grow? Do you have a patch of lawn you’d rather use for growing food? No-dig gardening may be the answer.
Digging out a lawn is hard work, and it damages the living things that help soil stay healthy. Areas of ground that regularly fail to support plant life often have poor soil structure and are lacking beneficial soil microorganisms. No-dig gardening uses layers of organic material to create the conditions needed for worms and other invertebrates, plant roots, and soil microorganisms, to transform a barren or compacted piece of ground into a friable, fertile place to grow healthy food.
No-dig gardening is the opposite of traditional cultivation. For thousands of years, we have drilled holes, cut furrows, and plowed up the land we use to grow food. Traditional cultivation provides many benefits. It hides crop seeds from birds and other seed eaters, removes perennial weed roots, exposes pest eggs and larvae to predators, and it loosens the soil (sort of).
All those chemicals and disruptions are creating problems, and we need sustainable solutions. No-dig gardening may be one of those solutions.
Natural processes that have evolved over millions of years rarely result in furrows being dug in the ground. Instead, leaves, seeds, flowers, fruit, blood, urine, feces, and dead insects and animals all fall to the ground and lay on the surface. This mix is then walked on, blown around, and rained on until it is ground into tiny bits. These tiny bits of organic material are then pulled into the soil by worms and other invertebrates, and gazillions of microorganisms, that all convert organic matter into mineral elements plants need to grow and thrive. These processes also create soil with important spaces, called macropores and micropores, that allow the soil to breathe, and make room for water and roots to move freely. This nurtures soil microbes, which generate biologically active enzymes, vitamins, antibiotics, and glomalin (the glue that holds soil particles together). [Did you know that plants release one-third of all the organic matter they generate through their roots, to attract and feed nearby soil microbes? Pretty cool, eh?]
So, maybe we don’t need to dig to be able to garden…
How to no-dig gardening works
Clearly, if you are going to plant a bare root tree, you need to dig a hole. But, if you have a patch of ground that you want to convert into a garden bed, digging is not necessary in most cases. Instead of digging up weeds and existing, unwanted plants, you simply smother them with a 3 to 4” layer of organic material, be it compost, aged manure, wood chips, or whatever you have handy.
Benefits of no-dig gardening
First, let’s face it, digging is work. If your soil is heavy clay, like mine used to be, it’s damn near impossible to break ground in summer without power tools. In addition to saving your back, no-dig gardening leaves the complex world of soil life alone, to do it’s thing. This means beneficial fungi and bacteria, worms, and other invertebrates can go about their business, eating and pooping, unmolested, converting organic matter into plant food, and improving soil structure and texture as they go.
This is an excellent way to put those autumn leaves, and all that yard and kitchen waste to good use. Placing all that organic matter on top, rather than digging it in, reduces the number of weeds you have to deal with, and it encourages worms to come up to the surface and grab a bite before heading back down to safety. All that worm traffic helps aerate the soil.
No-dig gardening reduces erosion. Every time you dig or plow, you are exposing more soil surface area to sun, wind, and rain, which can lead to erosion. Over time, this exposed area develops a protective crust that repels water, interfering with the absorption of rain and irrigation water.
No-dig gardening also reduces soil compaction. Here me out on this: as you rototill, dig, or plough the soil, one layer gets churned up and aerated. Below that level, however, everything gets compressed, potentially creating hardpan, or plow pan, an impenetrable barrier to delicate roots.
So, why wouldn’t you want to try no-dig gardening?
Drawbacks to no-dig gardening
The first downside to no-dig gardening is that a lot of mulch and compost are needed on a regular basis. If you’re like me and raise your own chickens, this is not a problem. Or, if you live near a stable, manure is readily available, just be sure to age it first. If you have seriously compacted soil, no-dig gardening can and will, eventually, improve soil structure and texture enough to make it easier for plant roots, but it will take some time. [One of the easiest ways to reduce soil compaction in the garden is to install designated paths. This is true regardless of what gardening method you use.] Finally, because decomposition is occurring all around your garden plants, you may find that snail and slug, sowbug, and gopher populations skyrocket. While they are there to eat (and breakdown) all that compost, they may find your lettuce and young seedlings irresistible.
How to create a no-dig garden patch
If you want to try no-dig gardening, start with a small patch. First, water the area well. If there are any large, perennial weeds present, cut them off at ground level and place a piece of unwaxed cardboard or several layers of packing paper or newspaper over the area. Water the area again. Then, cover your patch lasagne-style with layers of aged compost or manure, straw, mulch, and other organic material, water it, and let it settle for a few days. While it may take a year or more for the benefits of no-dig gardening to fully take effect, you can plant large, spreading plants, such as pumpkins or squash in this patch right away, assuming its the right time of year. As the organic matter breaks down, simply add more layers on top and let nature do all the work. I use this method in my raised beds, adding organic material as a repeated top dressing.
Once your no-dig garden is established, you can install new plants by simply clearing an opening with a dibble, your hand, or other garden tool, and water around it. No-dig gardening may not be the cure-all to your back and garden problems, but it is certainly worth a try!
Black rot may sound like the perfect name for your next Halloween character, but this bacterial disease can wreak havoc on plants in the cabbage family (Brassicaceae).
Popular brassicas, or cole crops, include broccoli, cauliflower, kohlrabi, horseradish, Napa/Chinese cabbage, collards, turnips, rutabagas, Brussels sprouts, watercress, kale, radishes, bok choy, and mustard. Rapeseed (canola) is also a member of this family. And all of these plants are susceptible to black rot, a close cousin to bacterial spot.
Black rot symptoms
The early symptoms of black rot (Xanthomonas campestris pv. campestris) don’t look like anything serious. You will see some chlorosis (yellowing) along leaf edges (margins), and some V-shaped lesions pointing toward the center of the plant. Then, those lesions may dry up and fall away, lulling you into thinking the problem has resolved itself.
Instead, black rot bacteria have gained a foothold in the phloem and xylem of your cabbage. As they populate and block these important vascular tissues, wilting and dieback occur.
If you cut an infected stem longitudinally, you will be able to see blackening of the vascular tissue. [Just be sure to disinfect your cutting tool afterwards, so that you don’t spread the disease to other plants.]
Managing black rot in the garden
Since this disease is most likely to occur in warm, humid weather, planting your cole crops after any chance of Indian summer has passed can help prevent it from occurring. The moisture left behind from overhead watering can also create the perfect conditions for black rot to take hold, so water your cabbages at ground level. There are some resistant varieties available, so shop for those if you have had problems with black rot in the past. Also, it’s a good idea to use crop rotation with cabbages and cauliflower in particular, as these two crops are the most likely to be affected. Since this bacteria can survive on cruciferous weeds, be sure to keep your cabbage patch weed free.
Accessory fruits are not designer handbags or the latest fad. In the word of botany, accessory fruits are more familiar that you might expect.
What is fruit?
Fruit is the tissue that surrounds the seeds of angiosperms (flowering plants). Fruit tissue is made from the ovary. Except when it isn’t. In some cases, a fruit develops from both the ovary and nearby tissue, found outside of the carpel. These neighborly tissues can be either the perianth, the flower whorls, or the hypanthium, the flower base. When this occurs, the part we eat is called an accessory fruit.
Popular accessory fruits
Using our botanical definition of an accessory fruit, we learn that pineapples are accessory fruits because the fruit is made from the ovary plus tissue from the pistils and sepals. We also learn that strawberries are accessory fruits. [The seeds you see on a strawberry fruit are actually achenes, a type of dried fruit. Each achene develops from a single pistil.] Other popular accessory fruits include apples, figs, mulberries, and pears. And those delicious cashew nuts? Those are the seeds of the cashew apple, another accessory fruit.
Now you know.
Chromatography allows you to take a closer look at the glorious colors of autumn leaves.
Autumn leaves change colors because chlorophyll levels are reduced. These levels change because of plant hormones, called auxins, that prepare leaves to fall before snow or heavy rains in winter. This period of preparation is called senescence. The act of dropping leaves is called abscission.
Through most of the growing season, leaves are one shade of green or another. The green pigment we see is the chlorophyll used in photosynthesis. There are actually several other colors present, we just can’t see them. Chromatography gives you an inside view into those colors.
Chromatography and pepper heat
High-tech chromatography (and some crazy math) are used to rank the heat of chili peppers. The American Spice Trade Association (ASTA) measures the pungency of different samples with Scoville heat units (SHUs), as a function of capsaicin levels.
Chromatography and companion planting
While there is plenty of science to support the importance of installing plants where they will thrive, the concept of plants ‘liking’ and ‘helping’ one another is actually a failed attempt at simplifying complex processes. Back in the 1930’s, Dr. Ehrenfried Pfeiffer conducted a study he called the “sensitive crystallization method” using chromatography. Somehow, the good doctor decided that matching colors implied compatibility, which it doesn’t. But the process is very fascinating, nonetheless, so let’s get started!
Your chromatography experiment
You will need the following supplies:
Here are the steps:
You can grow a surprising amount of food in your own yard. Ask me how!