Orange tortrix (Argyrotaenia citrana), also known as the apple skinworm, is a moth common to coastal regions of the West Coast states.
Cousin to the light brown apple moth (LBAM), orange tortrix and other tortrix moths all roll up leaves to create a protective place to feed.
Orange tortrix identification
Adult orange tortrix are very small, bell-shaped moths when at rest. They are approximately 1/2 an inch long. Both male and female orange tortrix moths are orangish brown with a faint V-shaped marking midwing. Males have darker markings than females. Each female lays 50 to 150 off-white eggs in clusters, usually on the tops of leaves, stems, and fruit. The larvae are 1/2 inch long and greenish to straw-colored. Larvae have a tan head and a prothoracic shield. Prothoracic shields are hard plates that wrap partially around the larva’s body where a neck would be (if they had a neck). Orange tortrix larvae are very active and will wriggle backwards or sideways, drop to the ground, or hang by a silken thread if disturbed.
Orange tortrix damage
Orange tortrix larva are pests of grape, Valencia and navel oranges and other citrus, pear, and apple. Damage to pear and apple fruits are usually limited to mild scarring, but their feeding can lead to other diseases gaining a foothold. The larvae devour any soft plant tissue they can find, including vines, developing buds, young fruit, and new shoots. As they feed, they often create protective webbing around new leaf clusters, or they may roll, fold, or tie a leaf down over a fruit to create a safe place to feed. Older larva will burrow into mature fruit, providing an entry for organisms that cause bunch rot and other diseases.
Pheromone traps can be used to monitor for male orange tortrix moths. These traps should first be used in late December. There can be up to three generations a year, but these moths prefer temperatures between 45°F and 80°F. Our scorching summers usually send these pests into dormancy. If pheromone traps are used, you will need to know the difference between the orange tortrix pest and the garden tortrix, which is not a pest. Garden tortrix (pictured below) have a light colored band in front of the dark V and they have dark, crescent shaped marks on the outer edge of each forewing. There’s no sense treating for orange tortrix if your trees are being visited by garden tortrix. If pheromone traps indicate that you have orange tortrix moths, use these tips to help protect your vines and fruit trees:
While the orange tortrix moth is generally not a big threat to your garden or landscape, it can cause problems, so keep a look out for those rolled leaves!
Leaf holes can be used to identify common garden pests and diseases.
Leaf holes can be caused by insects, disease, and chemical or physical damage. Many rose bush leaves exhibit holes caused by their own thorns. Wind whipped branches can also cause holes in leaves. In these cases, there’s really nothing you can do. Chemical damage is usually caused by herbicide overspray. Using chemical herbicides more carefully (or not at all) can prevent this from happening. The signs of pest and disease damage, however, can be used to fight back.
When a leaf has a hole in it, photosynthesis is reduced, the plant may be weakened, and it becomes more vulnerable to other pests and diseases. Use the information below to learn how to identify the cause of leaf holes in your garden or landscape plants.
Irregularly shaped holes and complete defoliation, with the leaf midvein generally left intact are usually caused by:
Once you identify the cause of holes in your leaves, you can select the best treatment. This list is by no means exclusive, but it should give you a good starting point. If you have other causes of leaf holes, please share photos in the comments below!
Devil’s apple is a poisonous weed from Africa.
Called Devil’s apple because of its toxic yellow fruit, Solanum linnaeanum made an appearance under my almond tree. When I went to pull it out, I discovered its substantial thorns.
Considered an invasive in Australia, Devil’s apple has been getting a lot of press lately. Dramatic statements declare that Solanum linnaeanum can cure skin cancer. And I could not find a single piece of scientific evidence to back up those claims. Hmmm. Yet another snake oil salesman… Why do we tolerate all those untruths?
The truth about Devil’s apple is interesting enough on its own, so let’s learn what we can.
Devil’s apple is a member of the nightshade family, along with potatoes, tomatoes, and eggplants. These shrubs can reach 6 feet in height, and those spines can be 1/2 an inch long. I sure wouldn’t want to fall into one of those bushes!
Also known as apple of Sodom, Afghan thistle, and Dead Sea apple, this weed invades pastures, agricultural fields, roadsides, and now, my yard.
The yellow berries start out as a star-shaped, 5-petaled purple flower, the way most nightshades do, but then they start looking more like a small apple, hence the name. The fruit changes from white or green to bright yellow and it contains toxic alkaloids. DO NOT EAT THEM!!!
Devil’s apple is also host to the Malaysian Fruit Fly, which earns it a listing in the California Code of Regulations, as part of the state’s emergency eradication program. Other than that reference, I have not been able to find any mention of the plant in California, so I have submitted an information request to local Master Gardeners and UC Davis to see if this is a new weed in the Bay Area. I’ll keep you posted.
For the time being, if you see one of these in your garden or landscape, dig it out.
Transplanting young seedlings is a rite of spring for many gardeners. Learn how to transplant your seedlings safely and easily to help them thrive.
Benefits of seed starts
Some plants, such as lettuce, have very tiny seeds that need light to germinate. Planting these directly in the ground often leads to losses due to wind dispersal or rotting under too much soil. Starting these plants in containers makes it easy to monitor them closely and keep the soil moist until the seeds sprout. As seedlings grow, they can become root bound, which means the roots start wrapping around the inner wall of the container. Many store-bought plants are root bound. Before this happens, you can up-pot or transplant those seedlings. Up-potting means moving a seedling from a small container to a slightly larger container. Transplanting means moving the plant to where it will live out its life.
When NOT to transplant
Plants that are fruiting, flowering, infested, or infected should generally not be transplanted. New transplants need to be able to focus on building a strong root system. Also, just as some people are more sensitive than others, some plants do not take kindly to being transplanted. The following plants should be sown directly into the ground whenever possible:
How to transplant seedlings
For many vegetable crops, you can transplant seedlings with the first leaves (cotyledons) below the soil line. Very often, these meristem tissues will transform into root tissues, adding nutrients and vitality to your plants. Once your seedlings are a couple of inches tall, you should prepare their new home, making sure that the soil is loose. The Bay Area’s heavy clay can form an impenetrable barrier to new roots if it is left smooth from a trowel or shovel. Be sure to rough up the edges of the planting hole. Then, follow these steps to successfully transplant your seedlings:
Caring for new transplants
New transplants should be treated gently for a few days. To help a young seedling thrive in its new environment (ecesis), be sure to:
Be sure to use plant markers when transplanting. This will help you recall where everything is!
Veraison refers to the time when grapes begin ripening.
If you grow grapes, you know that they start out as clusters of tiny spheres that don’t look anything like a grape. As they grow, they become more grape-like in appearance, but you wouldn’t want to eat one. An unripe grape is tough and very sour.
Grapes first grow to full size and then veraison begins. This is when acidity drops and sugar levels rise. This is also when grapes start to change color. Scientists do not know what triggers veraison, but now you know a garden word that most other people do not!
The golden threads of saffron currently sell in the Bay Area for $130 an ounce. That works out to over $2000 a pound. And you can grow your own. For free.
While you can certainly buy saffron for less, there’s no denying that it is one of the world’s most expensive spices. One of the biggest reasons for these prices is that harvesting the threads is very labor intensive. Also, it takes approximately 4000 flowers to create one ounce of saffron threads.
What is saffron?
First, a quick flower review: the male part is called the stamen, which is made up of the anther and filament. The stamen usually surrounds the female part, or the pistil. The pistil is usually in the center of a flower and is made up of the stigma, style, and ovary. Saffron threads are the dried styles and stigmas of a specific crocus flower species.
How saffron crocus plants grow
Farmed primarily in Iran, saffron crocus plants prefer full, blistering sun in the summer, heavy rains in spring, and they can tolerate a surprising amount of cold in the winter. The two things they don’t like are shade and soggy soil. Saffron crocus flowers are sterile, which means they cannot produce viable seeds. Instead, crocus plants reproduce by creating corms. Corms are similar to bulbs. Each corm lives for only one season, but each one can produce up to 10 cormlets. Cormlets are usually small and brown, covered with a fibrous coating called a ‘corm tunic’.
How to grow saffron crocus
Plant your saffron crocus (Crocus sativus) bulbs in June in a sunny, well-drained location. Keep in mind that these plants will continue to propagate (potentially) for decades. Crocus corms should be planted 3 to 6 inches deep, depending on the variety, with the pointy end up. Once a bed of saffron crocuses is established, these cormlets will need to be dug up and divided every so often, to prevent overcrowding.
Saffron crocus pests and diseases
Squirrels. Of course, squirrels. Also, rats, moles, birds, nematodes, and other bulb eaters can damage crocus corms in the ground. The only diseases that seem to affect crocus are rust and corm rot.
In mid-autumn, purple blooms will begin to emerge. Each morning, check your crocus plants for new flowers. Within each flower, you will find three golden saffron threads. Gently pluck them from the flower and place the threads in a paper envelope so that they can dry in darkness. I keep my saffron threads in my spice cabinet, where it is nearly always dark and dry.
These unobtrusive flowers spend most of their year underground. Come fall, dark green spikes emerge, followed by lovely purple blooms, and a jackpot for your spice cabinet. Put some in this year for yourself!
Photo of saffron crocus by Liné1
As fruit trees begin putting out fruit in spring, it is your job to take some of that fruit off.
It may seem counterproductive. Why on earth would I plant a fruit tree only to take the fruit off when it has only just started growing? Why would you want to reduce your crop that way? Read on and find out!
Why thin fruit?
Most fruit trees will produce far more fruit than can be supported or made flavorful. Too much fruit and branches start breaking. Now, the tree doesn’t care how the fruit tastes, as long as it tastes good enough to cause animals to help with seed dispersal. To get the sweetness, size, and shape that we want, we have to intervene. Thinning fruit also helps reduce the likelihood of pests or diseases getting established in the nooks and crannies between fruit. Finally, fruit thinning reduces the chance of your tree taking a year off of production (alternate bearing) out of sheer exhaustion.
How (and when) to thin fruit trees
Different trees have different thinning needs. Generally, the time to thin fruit is dictated by fruit size. Stone fruits are thinned when they reach 3/4 to 1 inch in diameter, while pome fruits can be thinned when they are 1/2 to 1 inch. This is usually in April and May in the Bay Area. You can also predict the time for thinning by noting it 30 to 45 days after full bloom on your calendar. To actually remove the fruit, give it a gentle twist. Sometimes, pruners are needed. Your fruit tree is working very hard at this stage, so be kind. Do not be tempted to thin your fruit trees too early, as this can lead to split fruit later on, especially in peaches. Of course, thinning too late won’t help your fruit become as large as it might have.
Fruit thinning by species
Some trees do not require thinning. These include cherries, figs, citrus, Bartlett pears, pomegranates, and persimmons. You may want to monitor your persimmons tree, however, as a very productive year can lead to breakage. Use this information to determine just how much to thin, depending on tree species:
Natural fruit drop
We are not the only ones who want to protect our fruit tress from breakage due to too much fruit. These trees have evolved to protect themselves with what is erroneously called “June drop”. June drop normally occurs in May in the Bay Area and it refers to a fruit tree dropping many immature fruits. Fruits that are diseased or infested may also drop prematurely.
Don’t be afraid to get up close and personal with your fruit trees in spring. Thinning fruit will ensure a better crop and a healthier tree. Thinning also gives you a chance to see what’s really going on for your fruit trees, allowing you to halt a minor pest invasion before it causes any real damage.
For those of you (like me) who need ways to remember what and how to thin, give this a try:
Spring season of thinning, no need to despair
Help them grow stronger with inches to spare
Small apricots and plums, give them two to four
Peaches, nectarines, they need three or more
Then muster the clusters of apples and pears
Save just the biggest, only one or two there
Twins, mutants and mummies all must be removed
Leave only the best for flavorful food
Photoperiodism describes the way living things detect and react to the changing lengths of nights and days.
Just as many of us feel more energized in summer and more likely to hibernate in winter, other living things are hardwired to behave certain ways in different seasons. In the world of plants, this ensures the proper timing of flowering, fruit set, building food stores, and preparing for dormancy, making it more likely that a plant will be able to pass on its genetic information.
Many angiosperms (flowering plants) contain photoreceptor proteins that can detect and signal information about the length of each consecutive night. This is done by two different proteins: one absorbs red light and the other absorbs far-red light. These proteins then trigger seed germination, internode elongation (stem length), and flowering. While we call certain plants long-day or short-day varieties, we should technically be calling them short-night and long-night plants, respectively.
Plant responses to hours of darkness are categorized as either obligate (mandatory) or facultative (likely to occur). In most cases, a plant with an obligate photoperiodic response is triggered to flower at a particular length of darkness, while a facultative plant may be more likely to flower within a range of nighttime hours. Temperature, plant age, environmental conditions, and plant health also play roles in the way plants use this accumulated information. In some cases, plants can be obligate at one temperature and facultative at a different temperature. To further complicate things, some plants need long nights followed by short nights to start flowering!
Long-day (short night) plants
Long-day plants are triggered to flower as nights get shorter. This usually means they tend to bloom in late spring and early summer. If a long-day plant is exposed to more than 12 hours of darkness each day, it will not bloom. Lettuce, peas, barley, and wheat are long-day facultative plants, while oats, henbane and carnations are long-day obligates. Spinach (13 hours), potatoes, California poppies, dill (11 hours), asters, and coneflowers are all long-day plants.
Short-day (long night) plants
Short-day plants require long periods of continuous darkness to develop flowers. If these plants are installed near a motion-detector light that goes on and off during the night, they are less likely to flower. Some short-day plants include sorghum, onion, cotton, soybeans, poinsettia (10 hours), chrysanthemum (15 hours), and marijuana.
The flowering of day-neutral plants is not affected by light. Many of these plants evolved close to the equator, where day length changes very little. Tomatoes, corn, cucumbers, roses, and other day-neutral plants respond instead, to changing temperatures, other environmental conditions, or as a function of plant development.
Artificial light and darkness
Commercial nurseries use photoperiodism to ensure that there are plenty of flowers for specific holidays by artificially creating longer and short nights. To lengthen daylight hours, grow lights can be added outside of daylight time, much the way hens are exposed to artificial lighting to keep them laying eggs during winter. To simulate longer nights, plants can be covered, to block sunlight.
In your own garden, you can use photoperiodism to place short-day plants where they will not be exposed to nighttime lights. You can also cover plants that tend to bolt in summer, or that need longer nights to start flowering.
If you want to read more about the science behind photoperiodism, check out Photoperiodism in Plants (Thomas & Vince-Prue, 1997).
An interesting note on photoperiodism: when leaves of one plant have been exposed to the correct amount of light, and are then removed from the parent plant and grafted onto a plant that has not received enough light, flowering is triggered in the new plant. This is because the leaves release plant hormones that initiate flowering after the correct amount of darkness has occurred.
Sweet or hot, bell-shaped or elongate, all peppers are members of the nightshade family.
People have been growing peppers for several thousand years. Native to the Americas, peppers (Capsicum) are now grown all around the world. Spicy peppers are commonly called chilis and sweet peppers are called bells. In Singapore, India, and Down Under, the bells are called capsicum. The popular spice, paprika, is made from a type of capsicum fruit.
Peppers are usually classified as sweet (bell) or hot (chili). All peppers start out green [think green beans]. If left on the vine long enough, different varieties may turn yellow, red, orange, or purple. Depending upon who you ask, there are 20 to 27 species (and hundreds of varieties) of peppers. These five species of Capsicum are domesticated:
All peppers are self-pollinating, but crops are significantly larger when other pepper plants are nearby.
Hot peppers and the Scoville scale
Hot peppers are rated using the Scoville scale. Scoville heat units (SHU) are a function of the amount of capsaicin found in the fruit. For comparison, pepper spray used by law enforcement can have 500,000 to 1 million SHUs and sweet bell peppers have a Scoville rating of zero. Here are some common peppers and their Scoville ratings:
Choose your pepper accordingly (and be sure to wash your hands after handling hot peppers and their seeds before you do ANYTHING else). Seriously.
How to grow peppers
Peppers love warm weather. In fact, there’s no sense starting pepper seeds early, because they won’t germinate. Even if they do, they won’t grow well. To get a head start on the growing season, many gardeners use seed heating mats. The soil needs to be 70 to 84 °F for peppers to really get going. Peppers prefer loose, loamy soil (or even sand), so you may want to grow them in raised beds or containers. Peppers can also grow well in straw bales. Seeds should be planted 1/4 inch deep. Ultimately, you will want to place plants 18 to 24 inches apart. When thinning, snip unwanted plants off at soil level to avoid disturbing other plants’ roots. At first, the soil should be kept moist but not soggy. Soggy soil can cause damping-off disease.
Pepper pests and diseases
Like many other of our favorite food plants, peppers are in big demand in the insect world. Cutworms, aphids, armyworms, flea beetles, leafminers, corn earworm, leafrollers, nematodes, weevils, thrips, spider mites, tomato psyllids, and whiteflies should be watched for, and some birds may want to take a bite, as well. Most pepper diseases are of the fungal variety: powdery mildew, crown rot, root rot, verticillium wilt, and tomato spotted wilt are common on Bay Area peppers. Also bacterial spot, several mosaic viruses, blossom end rot, and curly top may occur. Sunburn, or sun scald, can also be a problem on pepper plants. While too much nitrogen can cause excessive vegetative growth and not much fruit, the opposite is also true: low nitrogen levels can reduce leaf coverage to the point that fruit is damaged. Row covers can also be used to reduce sun exposure, once fruit set has occurred.
One of the most common mistakes gardeners make when harvesting peppers is that they do it too soon. If your peppers feel thin-skinned, give them some more time.
The scent of freshly cut grass and the sound of a lawn mower trigger many childhood memories of summer, but the history of lawns goes all the way back to our origins in Africa.
As far as historians can tell, our African ancestors maintained areas of low-growing grasses around their homes to make it easier to see predators before they got too close. That same train of thought continued well into Medieval times, when grand expanses of lawn exposed enemy armies as they approached. England’s 12th and 13th century nobility decided that lawns provided a great place for sports that eventually evolved into tennis, croquet, and golf. The less wealthy commoners also maintained grassy areas, but that was to feed their sheep and cattle.
Those grand expanses of greenery are easy to grow in England. Adequate moisture, fertile, well-drained soil, and lots of overcast days allow turf grasses to thrive. Plus, it’s much easier to find a sheep to keep your lawn neatly trimmed. Not so, here in the good ol’ US of A. The seed and sod originally brought to the U.S. was from plants native to England and cooler parts of Europe, which are completely unsuitable to our Bay Area climate. Also, lawns are work - ask any greenskeeper. Most home owners did not have the time or resources to maintain a lawn ‘just for show’, until the invention of the lawn mower, in 1830. Making it easier to maintain a neatly trimmed ornamental lawn, lawn mowers played a big role in making lawns popular among the poor and middle classes. In 1952, a man named Abraham Levitt created the first planned suburban community, complete with established lawns, and the American Dream, as we know it today, was born. (I’ll bet you thought it was a lot older than that, didn’t you? I did, too.)
Modern lawns are commonly grown from sod. Sod is squares of soil with the grass already growing in it. Lawns can also be grown from seed, but grass seed isn’t cheap. Either is sod, for that matter.
You can get warm season grass and cool season grass. The seasonality refers to when those particular grasses do the most growing. Bermudagrass, St. Augustinegrass, zoysiagrass, and kikuyugrass are popular Bay Area warm season grasses that stay green all summer (if watered regularly), but they tend to have a dormant winter period. Our fall grasses include bentgrass, Kentucky bluegrass, tall fescue, fine fescue, and perennial ryegrass. These stay green year round. Each region has its own characteristics that make one variety better suited than another. Grasses are generally categorized according to water needs, disease resistance, salinity tolerance, shade tolerance, traffic tolerance, and maintenance needs. Contact your local Cooperative Extension Office for recommendations for your area.
Lawn pests & diseases
Lawns, or turf grasses, have very few insect pests in the Bay Area. Cutworms, grubs, crane flies, masked chafers (white grubs), and chinch bugs may cause some problems. Birds, raccoons, and moles may cause further damage by hunting and digging up the insects. Lawn diseases are equally rare. Leaf spot, rust, anthracnose, Fusarium blight, fairy rings, and other fungal diseases can occur, but these are usually the result of frequent, shallow watering.
The key to a beautiful lawn is good cultural practices. Cultural practices that ensure a healthy lawn include:
Weeds are the bane of every lawn aficionado. The list is long and the battle never ends. Some of the more common Bay Area lawn weeds include:
If you live in Santa Clara County, Ca, you may be able to take advantage of the lawn replacement program designed to reduce water use. I did it and received a check for $960! Instead of grass that required watering, fertilizing, weeding, mowing, and edging, I now have CA native blackberries, a dwarf pomegranate, a pineapple guava tree, and an artichoke. Soon, CA native hazelnuts will be added to the mix. Once these plants are established, they require little or no care at all, plus they provide food. Many other counties and municipalities are offering similar lawn replacement rebates to encourage home owners and businesses to step away from the wasteful lawn habit, to replace it with more suitable plantings. I encourage you to investigate your options.
There are many low-growing plants that use far less water and fertilizer and mowing and edging to look and feel nice. Oregano, yarrow, mint, chamomile, and creeping thyme all provide the added benefit of being edible. Lawns can also be replaced with rain gardens and rock gardens. For the sake of all things living, do not install a fake lawn. The plastic off-gases chemicals of dubious health and, honestly, they look like crap.
If you must have a lawn, give it the care it needs.
Insecticidal soaps are an easy DIY method of pest control in the garden.
People have been using soap sprays for a long time to protect their plants, but the science behind using soap has only begun to demonstrate just how insecticidal soaps work. Current research has shown that spraying soapy water on insects kills them off by:
Before jumping on the insecticidal soap bandwagon, however, you need to understand that not all soaps are created equally and that many soaps are actually detergents that can kill your plants.
Homemade insecticidal soaps
True insecticidal soaps contain potassium salts of fatty acids and are designed specifically for use on plants. These fatty acids are commonly found in fish oil, lard, and olive, palm, coconut and other plant oils. These fatty acids are mixed with potassium hydroxide, which is strongly alkaline, to create soap, much the way fatty acids are mixed with sodium hydroxide to make lye. While potassium salts and sodium salts will both kill insects, sodium salts are toxic to plants. [The same problem occurs when people use baking soda (sodium bicarbonate), rather than potassium bicarbonate, on plants to fight fungal disease. Baking soda is phytotoxic, whereas potassium bicarbonate is not.]
Not all household liquid soaps are safe for use on plants. In fact, I couldn’t find a list of any that are truly safe. Laundry soaps and dry dishwashing detergents are also too harsh to be used on your garden plants. Also, many liquid dishwashing soaps contain bleach, fragrances and colors, and other chemicals that can harm or kill your plants. As tempting as it may be to grab your bottle of dish soap from the kitchen sink, this is not a good idea. [I challenge you to take a close look at the ingredients list on your dishwashing soap and look up any words you don’t know.]
Effectiveness of insecticidal soap
Instead of burning up your plants with detergent, go to the store and buy a bottle of insecticidal soap. It is less expensive that many other pesticides, plus it is less damaging to the environment and other living things. Insecticidal soap that has been properly formulated and applied will kill many common pests, including:
Unfortunately, insecticidal soap can also kill off the larval forms of many beneficial insects, such as ladybugs and lacewings.
How to use insecticidal soap
Insecticidal soap only works when it comes in direct contact with and completely covers an insect pest. Use these tips to safely use insecticidal soap:
Insecticidal soaps have little or no residual effects, so treatments must be repeated regularly until the desired level of control is reached.
So, insecticidal soap isn’t the Quick Fix you might have thought it was before reading this post, but it is effective when used properly.
Caterpillars are the larval forms of moths and butterflies.
You generally won’t see moth or butterfly eggs, unless you look closely. During plant dormancy, these eggs may be on the underside of leaves, tucked into the crevice of bark, or hidden under leaf litter or in the soil. As temperatures rise, caterpillars invade our garden en force.
Hornworms (pictured below), cutworms, and budworms are all caterpillars. Caterpillars are often responsible for leaf damage, but some varieties feed on roots, buds, flowers, and tree trunks. There are even caterpillars that feed on your clothing, moths that feed exclusively on the hooves of dead ungulates, and caterpillars that eat other caterpillars! Caterpillars have only one purpose and that is to feed. Most caterpillar species molt their skin four or five times as they consume as much plant material as they can, before pupating. As much as we dislike the damage caused by adolescent caterpillars, adult moths and butterflies are good pollinators, so it’s a toss-up.
Some plants, such as lima beans, emit chemicals that call out to parasitic wasps whenever caterpillars start feeding. In this way, they protect themselves. Spiders, soldier beetles, green lacewings, praying mantis, pirate bugs, ground beetles, assassin bugs, bats, birds, lizards, frogs and toads all enjoy feeding on caterpillars. You can make their job easier by avoiding the use of chemicals and by providing a clean water supply.
If your caterpillar problem gets bad, you can apply Bacillus thuringiensis (Bt). Bt is a naturally occurring, pest-killing bacteria found in soil, animal feces, and in the gut of the caterpillar stage of some moths and butterflies! There are different types of Bt that can kill different types of caterpillars. [Don’t be confused. There are bacteria in our digestive systems that can kill us, too.]
Some caterpillars can be thwarted from climbing host plants by applying sticky barriers around trunks and stems. Row covers can also be used to protect vulnerable plants, just be sure there are no eggs under the leaves or you will be protecting destructive caterpillars from their natural enemies!
Horticultural oil works better at controlling caterpillar eggs, while neem oil can be effective against actual caterpillars. The best thing you can do is to be observant. Light or moderate feeding will not harm plants. Many of the larger caterpillars, such as hornworms, can simply be handpicked and tossed in the trash. I feed them to my chickens.
Not all bad
A few days ago, I noticed black flecks on my fennel leaves. Closer inspection showed nearly a dozen tiny black caterpillars with white saddles, and one particularly large specimen (below) that made identification easy. They were all the caterpillar stage of the black swallowtail butterfly. Well, I’m not a big fan of fennel, and the butterflies are lovely, so they can feed all they like and I will keep a look out for their chrysalis.
Cucumbers (Cucumis sativus) are a fruit from the gourd family (Cucurbitaceae).
Originally from South Asia, cucumbers have found their way into gardens around the world. Botanically, cucumbers are classified as berries because they are the fruit of a single ovary.
There are many types of cucumber: slicing, pickling, gherkins, bush, burpless, and seedless. Seedless cucumbers are a parthenocarpic cultivar, which means the plants develop fruit without being pollinated. These cucumbers are usually grown in greenhouses. All the other types of cucumbers are self-incompatible. This means they need to be cross-pollinated, from a different plant, for fertilization to occur. While any cucumber can be pickled, pickling cucumbers are bred for consistent size and shape, and they tend to have larger bumps. Varieties of pickling cucumber that perform best in the Bay Area include Pot Luck and Pickle Bush (good container plants), Saladin, County Fair 83, and Liberty Hybrid. Bush Champion, Parks Bush Whopper, Salad Bush and Spacemaster are good slicing varieties for containers. There are many good slicing varieties, including Marketmore 76, Marketmore 80, Dasher 11, Straight Eight, and Raider are good in-ground slicing cucumbers. New varieties are always being developed. In fact, I just discovered a Mexican Sour Gherkin cucumber that tastes like a cucumber but looks like a miniature watermelon!
How to grow cucumbers
Cucumbers love rich soil with a pH of 5.5 to 6.5, so moderate acidification may be helpful. Seeds should be planted 1 inch deep and 6 to 10 inches apart. After seedlings emerge, thin plants to every 12 inches. Cucumbers need lots of sunlight, so they are not the best choice for shade gardening. Cucumbers grow on creeping vines that can be trellised onto tomato cages, along fences, cattle panels, or on a teepee made from bamboo or other thin poles. Keeping your cucumbers off the ground will help reduce insect damage and fungal diseases.
Cucumber pests and diseases
Cucumbers have the same problems as other members of the squash family. Aphids, spider mites, whiteflies, nematodes, leafhoppers, leafminers, cutworms, squash vine borers, cucumber beetles, and squash bugs will all try to sink their tiny mouthparts into your delicious cucumbers, so keep a look out.
When you shop for cucumber seeds and plants, you may see an alphabet soup of letters on the tags. These letters are a shorthand for disease resistance. Common cucumber diseases that have resistant varieties include:
If you see AAS, it means All-American Selection, which is a plant that resists most diseases. Some diseases, such as sudden wilt, belly rot, and bacterial wilt do not have resistant varieties (yet). Many fungal and bacterial diseases can be avoided by waiting until leaves are dry before working an area. This reduces the likelihood of any diseases spreading to uninfected plants.
Cucumbers and bitterness
Sometimes, cucumbers can taste bitter. It was once thought that water stress was the only culprit, but research has shown that this bitterness is often caused by two genes that control the creation and inhibition of two compounds called terpenoids, which are more likely to occur when temperatures are lower than normal. Bitterness can also occur when plants are exposed to temperature fluctuations that are greater than 20 degrees F, or when they are stored next to other ripening vegetables.
Cucumbers and cross-pollination
Cucumbers of differing varieties or cultivars can cross-pollinate. Although cucumbers are members of the gourd family and cousin to melons, squash, and pumpkins, they cannot cross-pollinate with these varieties.
Increase pollination and fertilization rates by planting flowers near your cucumbers. This will attract more honey bees and result in larger yields.
Acidification is a process that lowers soil pH.
Soil can be alkaline, acidic, or neutral. The pH scale ranges from 0 (acidic) to 14 (alkaline), with (neutral) 7 in the middle. Soil pH dictates the availability of many nutrients to your plants’ roots.
Your soil can be packed full of important minerals, but the wrong pH can make it impossible for plants to reach that bounty. Unfortunately for my plants, my soil has a pH of 7.7 and very little iron. Plants need iron to absorb many other essential nutrients. By lowering the pH, or acidifying, my soil, I can make the iron more readily available. If you live in the Bay Area and want to grow acid-loving plants, you will probably need to acidify your soil. The infographic below shows the likelihood of any nutrient being absorbed, based on soil pH:
Which edible plants prefer acidic soil?
If all of your plants prefer your soil’s current pH, you are in luck. It’s really the easiest way to go. Most garden and landscape plants prefer a pH range of 6.2 to 7.3. Acid-loving plants include:
Moderately acid-loving plants that prefer a pH of 5.5 to 6.5 include apples, basil, carrots, cauliflower, corn, cucumber, dill, eggplant, garlic, melon, peppers, pumpkin, rhubarb, winter squash, tomato, and turnips. Since the Bay Area’s tap water supply tends to be alkaline, and our soil is also alkaline, we can profoundly help our plants by lowering the soil pH. Or, grow native and other plants that have evolved to prefer what we already have.
Factors of acidification
There are three factors that determine the amount of acid needed to lower soil pH. Some of this stuff gets deep in the world of chemistry, but I think I have sorted it out well enough. [If you understand these things better than I have explained, please educate us all in the Comments section!]
How to acidify soil
While using the above information will give you more accurate data, you can gently acidify your soil by applying elemental sulfur (S) in stages. As the sulfur oxidizes, it turns into sulfuric acid, acidifying the soil. Changing soil pH takes several months to accomplish and it tends to require regular monitoring and adjustments. Since soil pH is a function of geology and climate, it will be an ongoing process. Just be sure to read and follow the package directions.
Fertilizers and acidification
Nitrogen has a powerful impact on soil pH. The form of nitrogen you use makes a difference. To lower the pH of your soil, use ammonium- rather than nitrate-based fertilizers. Your blueberry plants will thank you.
Corn is the biggest U.S. grain crop and you can grow it, too!
Fresh from the garden ears of sweet corn, heated, and then topped with butter, salt, and pepper, well, life just doesn’t get much better than that! Now, we are not talking about the corn used to feed livestock. That brand is called grain corn. Sadly, I wasn’t particularly happy with my Indian corn crop experience, either. It may have historical merit, but the kernels were tough and very starchy. Call me spoiled, but I prefer my corn with fat, sugar-filled kernels that burst on my tongue with every bite.
History of corn
For anyone who has had the opportunity to explore Mitchell, South Dakota, you know there’s a lot to be said for corn. Corn, or maize, was domesticated by people in what is now Mexico nearly 10,000 years ago. Early corn plants only grew 1-inch long cobs, and only one cob per plant. Selective breeding brought us to cobs of several inches in length and plants capable of producing multiple cobs on each plant. One of the three most genetically modified crops, nearly 90% of the U.S. corn harvest is of GMO corn. In addition to being eaten from the ear, or as grits or meal, corn (Zea mays) is also used as a sweetener (high fructose corn syrup), biofuel, and to make plastics, fabrics, adhesives, and liquor. There are six types of naturally occurring corn (and 142 GMO types, as of 2015). Those six types are dent corn, pod corn, flour corn, flint corn, popcorn, and our beloved sweet corn.
How corn grows
Being a member of the grass family (Poaceae or Gramineae), corn is cousin to bamboo, rice, and your lawn. Corn grows a hollow stem that is wrapped with leaf blades. Each corn plant produces both female and male flowers, but they are not self-pollinating. This is called monoecious. These flowers both start out bisexual (referred to as ‘perfect’ in the world of botany), and then develop into one gender or the other.
Corn kernels are actually female inflorescences, or flower clusters, that turn into fruit. These fruits are protected by tightly wrapped leaves that we call husks. At the top of each stem (or cob) is a male inflorescence (tassel) that releases pollen onto the wind. The silks we work so hard to remove are actually elongated stigmas from the female flower. There is an ovary at the end of each silk thread that must be pollinated for fertilization to occur, allowing a kernel to develop. Since pollen is carried on the wind, corn must be planted in blocks, rather than rows.
How to grow corn
Corn needs lots of nutrients in the soil, so be sure to prepare the beds ahead of time with plenty of aged compost. Corn does not transplant very well, so wait a couple of weeks after your last frost date before planting. Seeds should be planted one inch deep and 4 to 6 inches apart. Soil needs to be at least 60°F for germination to occur. Once your corn seedlings emerge, thin them to 8 to 12 inches apart. Corn plants have very shallow roots, so proper irrigation is important. In the heat of summer, your corn plants may need an average of 5 gallons of water per square yard each week. Since each microclimate is different, you will have to make your own adjustments. Just keep in mind that insufficient irrigation can reduce the number of silks that emerge and that means less developed kernels on your ears of corn. One way to give your corn seedlings an extra boost of nitrogen is to use the Three Sisters Method and plant corn with beans and squash. The beans ‘fix’ atmospheric nitrogen, making it available to nearby plants, and the squash produce large leaves that shade the soil.
Corn pests and diseases
We are not alone in our love of corn. An old saying tells us, “One for the blackbird, one for the crow, one for the soil, and one to grow.” You may or may not be able to scare away the crows (and chickens) with scarecrows (I use my dogs), but nothing can stop a determined raccoon. It is the smaller pests, however, that will probably cause you the most problems. These generalists include: armyworms, aphids, spider mites, thrips, wireworms, cutworms, flea beetles, cucumber beetles, and grasshoppers. Corn-specific pests you might see are leafhoppers, leaf miners, seed-corn maggots, and corn earworms. Corn is also subject to fungal and bacterial diseases, such as smut, soft rot, fusarium root and ear rot, maize dwarf mosaic, pythium stalk rot, seed rot, and damping-off disease. Of course, corn smut really is delicious, so don't panic if it shows up.
Sweet corn loses its sweetness soon after harvesting, so pick it as you will be eating it. Corn is ready for harvest when the tassels turn brown. If your harvest is bigger than you can eat, corn freezes well.
If you have a patch of ground, give corn a try!
Fronds are the primitive leaves of ferns.
Parts of a frond
Like other leaves, each part of a frond has its own name. Below, you can see these names (and their counterparts) with a short description:
Types of fronds
Fronds are described as simple (undivided), pinnatifid (with deep incisions but not compound), pinnate (compound to the point of looking like a feather), or compound.
What ferns, palms, and cycads do you have in your garden?
Bacterial spot on almonds is a relatively new disease to California.
When bacteria infect a plant, the plant’s first line of defense is often to surround the infected area with a strong barrier. While not always as effective as our immune systems, this often prevents further spread of the disease. These damaged areas usually appear as spots on leaves. Bacterial spot is just one of many different bacterial diseases that attack your plants.
First seen in 2006, this particular bacterial spot attacks almonds and other stone fruits, such as peach and nectarine. Bacterial spot (Xanthomonas arboricola pruni) first appears as an amber colored gum oozing from immature nuts. This disease is common in the Southeastern U.S., Europe, Australia, and the Middle East.
Bacterial spot symptoms
Symptoms first appear mid-April to early May. Damage looks similar to that caused by leaf-footed bugs and anthracnose. Use these notes to differentiate between the three conditions:
Leaves may become spotted, develop angular or circular red lesions, and drop early. If you cut open an affected nut, you will find a pencil eraser sized lesion. These lesions get bigger, transforming your delicious almond into an orange slime. (Ew!!!) Almond varieties most commonly affected are ‘Fritz’, ‘Monterey’, ‘Nonpareil’, ‘Mission’, ’Neplus Ultra’, and ‘Padre’.
How to control bacterial spot
Commercial growers use zinc sulfate in the fall to make trees drop all of their leaves, which are then gathered and destroyed. Leaf and mummy removal is followed by spraying with dormant oil and copper treatments, combined with the antibiotic oxytetracycline. Obviously, you are not going to hit your backyard fruit and nut trees with all these chemicals. These tips can help minimize the damage caused by bacterial spot in your garden:
To prevent infection, trees can be treated with oil and copper mixtures before winter. This is yet another reason why it is a good idea to quarantine new plants before installing them.
Lentils are packed with protein and fiber, add nitrogen to the soil, and they are easy to grow.
You see them in bags at the grocery story, but have you ever thought about growing your own lentils? People have been eating lentils for 13,000 years! These members of the pea family are called pulses because they are grown to be harvested as dried beans. Lentils are legumes that can “fix” atmospheric nitrogen, making it available to plant roots. Lentils grow 18 to 24 inches tall and produce small white to light purple flowers. The pods are very small, each containing only one or two seeds, so you will need 4 to 8 lentil plants per person. You can grow lentils in containers, but it takes several plants to get a decent crop.
Lentils come in several colors, ranging from brown and black, to yellow, orange, red, pink, and green:
How to grow lentils
Being a cool season crop, lentils (Lens culinaris) can be started two weeks before the last frost date. Lentil seeds should be planted 1/2 to 1 inch deep, and 1 inch apart. Lentils prefer full sun, loose soil, and a pH of 6.0 to 6.5, so you may need to acidify your Bay Area soil. I grow my lentils in raised beds, so pH and compacted soil are not issues. It makes weeding one heck of a lot easier, too!
At 68°F, they will germinate in about 10 days. Seedlings should be thinned to one plant every 4 or 5 inches. Rows should be 18 to 24 inches apart. You may want to use row covers, at first, to protect young plants from pests. Be sure to keep the soil evenly moist, at first. Lentils are very drought tolerant once they get a good start. You may want to provide a low trellis, but it is not necessary. Lentils take 80 to 110 days to reach maturity, depending on weather, soil, and sunlight. Stop watering when the pods begin to dry.
Harvesting lentils is a labor of love. Allow the pods to dry out completely before using. Since each pod only holds one or two seeds, I suggest a good movie, a bowl for lentils, a towel on the floor, and a large pot between your feet to collect the discards. The job of hulling lentils becomes a rhythmic Zen sort of experience, once you find your rhythm. You can also harvest immature lentil pods the same way you would harvest green beans. Lentils can also be sprouted and added to salads.
Lentil pests & diseases
Aphids, weevils, nematodes, armyworms, cutworms, cucumber beetles, loopers, lygus bugs, leafminers, whiteflies, thrips, spider mites, stink bugs, and wireworms may try feasting on your lentils before you do. Insufficient air flow can lead to fungal diseases, such as Alternaria rot, anthracnose, root rot, Botrytis grey mold, leaf spot, collar rot, downy mildews, Fusarium wilt, powdery mildew, and rust. Lentils are also susceptible to viral diseases. These include bean leaf roll virus, bean yellow mosaic, pea seed borne mosaic, cucumber mosaic, broad bean mottle, and broad bean stain. It's a wonder that anything can survive! The best thing you can do to protect your lentils is to provide adequate air flow and monitor your lentils regularly. In spite of the number of threats, lentils are more rugged than they appear.
The rich, earthy flavor of lentils make it an excellent addition to soups, stews, and salads. How about adding some lentils to your landscape this year? Give it a try!
Jicama is my new favorite snack food. Cut like french fries, this crisp root vegetable is just sweet enough to be addictive, and without all the grease.
It may not look or taste like it, but jicama (Pachyrhizus erosus) is a member of the bean family. It grows on vines, mostly in Central America, the Caribbean, Southern Asia, and in the Andes. Also known as yambean and Mexican turnip, jicama leaves, stems, and skin contain toxins that should not be eaten. Once you get inside, however, the flesh is delicious and versatile. Jicama can be added to salads, soups, stir-fry, and it goes equally well with fruits as it does with vegetables. While low in calories, jicama high in insoluble fiber and Vitamin C. It also contains inulin, which a form of plant sugar (fructan) that promotes calcium absorption and good gut bacteria. So let’s get growing!
How to grow jicama
Jicama prefers short days and high temperatures, so you may have to plant your jicama in a location where it receives afternoon shade (or make your own) to trick it into thinking the day is shorter than it really is. Like peppers, jicama seeds need warmth to germinate. Seeds should be soaked in warm water for 24 hours before planting 1/4 to 2 inches deep. You can wait until temperatures rise, or use can use seed heat mats to speed germination. Jicama performs better in alkaline soil. To get well shaped roots, the soil must be loose and nutrient-rich, making it a good choice for raised beds. As blue or white flowers appear, they should be removed by hand to stimulate root development.
Have you ever grown jicama? Let us know in the comments section!
Leaf roll is not the newest thing in Burmese take-out. Instead, leaf roll is a symptom that can tell you a lot about what is going on in your garden.
Leaf roll can be caused by several different factors:
Evaluating leaf roll damage
If you notice leaves starting to roll on any of your plants, start by asking yourself the following questions:
Environmental, or physiological damage is normally visible near the base of a plant first, as leaves cup upward, toward the leaf vein. These leaves tend to thicken and become leathery, while remaining a normal green color, as the plant tries to protect itself. Environmental damage is a common problem when growing members of the nightshade family, such as tomatoes, peppers, and eggplant. Interestingly enough, bush (determinate) varieties are less likely to exhibit leaf roll than vine (indeterminate) varieties. Symptoms of environmental damage can indicate any of these problems:
Some viral diseases can also cause leaf roll. Viruses often enter plant tissue as insect carriers feed. These carriers are normally aphids, mealybugs, and soft scale insects. Leaf roll viruses can also be spread through infected scion wood. Once infected, vascular bundles become clogged as the viruses reproduce in the nutrient-rich phloem. This reduces water and nutrient flow within the plant.
Viral infections affect newer leaves first. Leaves cup upwards and turn pale green. They may also have yellow edges, mottling, and veins may look purplish. This color change is due to damage to the phloem. Infected fruit may start rotting from the inside out. There are three major types of leafroll that warrant concern:
Because these viruses can spread rapidly, over relatively great distances, close monitoring and control are in everyone’s best interest. Once a plant is infected with one of the leafroll viruses, it should be removed and destroyed. There is no cure or treatment. Be sure to disinfect tools with a household cleaner, such as Lysol, and keep weeds away from the area. This will help reduce the number of insects that may reinfect the garden bed.
Leaf curl caused by fungal infections can be particularly destructive, since the disease can be carried in by whiteflies. Peach leaf curl, bacterial blast, and botrytis are common examples. Symptoms include:
As aphids, leafminers, thrips, mites, scale insects, and mealybugs feed on sap, they can cause leaves to curl. Occasionally, a spider may curl a leaf to create a cocoon, but spiders are Good Guys in the garden, so leave them alone. The real pest when it comes to leaf rolling comes from the larva of certain moths. In particular, California has a problem with moths in the tortricid family. These pests can be found in citrus, pear, plum, apple, almond, apricot, raspberries and other cane fruit, quince, and walnut, plus most ornamentals. Light brown apple moths also fall in this category. Pest damage usually includes ragged edges on nearby leaves and tightly rolled nesting leaves. Inspect fruit and nut trees carefully from March through May for signs of these pests.
The ads make herbicides look so safe and helpful, but they are, in my opinion, anything but. Leaching, overspray, rain splash, a sudden breeze, and the failure to breakdown in the soil as advertised can put many other plants at risk. Symptoms of herbicide damage include:
If you notice leaf rolling on your garden or landscape plants, take a closer look to see if you can figure out what is causing this change. Knowing the cause helps you find a solution that allows your plants to thrive!
You can grow a surprising amount of food in your own yard. Ask me how!