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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.  Adult male guava fruit fly (UCANR) California invasion 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.  Adult female guava fruit fly, with ovipositor sheath and fully extended ovipositor. (UFL Division of Plant Industry) 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.  Adult guava fruit fly (Ken Walker) 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.
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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.  Missouri Botanical Gardens (Kate Russell) 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.”  Missouri Botanical Garden caretakers home (Kate Russell) The gardens 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.  Missouri Botanical Gardens Climatron (Kate Russell) Garden visions 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:
Container Gardens 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.  Leonhart Fuchs, 'De historia stirpium' (1542) (Photo by Kate Russell, taken at the Peter H. Raven Library)  (Photo by Kate Russell)
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.  Asparagus plant infected with Fusarium crown and root rot (MSU Extension) 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. Disease pathogens 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.  Reddish brown discoloration of asparagus roots infected with Fusarium crown and root rot (UMass Extension) 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.
Disease lifecycle 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 (UC IPM) 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.  Mature frosted scales and exit holes on parasitized scale (UCANR) 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. Underground pests 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.  Adult Colorado potato beetle 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.  Native range of the potato (green) and the Colorado potato beetle (yellow); Beetle range as of 2002 (orange). (Franz Geller-Grimm) 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.  Defoliation of rose bush by chilli thrips (UFL) 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.  Typical fall foliage in the Adirondacks (DigbyDalton) Autumn leaves 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.
Grazers 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
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.  Brown bud symptoms on broccoli (UCANR) 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.  Broccoli head with poor bud growth (NC State Extension) 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.  Close-up view of brown bud on broccoli (NC State Extension) 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].  Black cherry inflorescence (UVM Extension) 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.  Carrot umbel (Alvesgaspar) 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 clusters 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
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 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.  No-dig garden bed (UCANR) Problem areas 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. Traditional cultivation 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 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.  Digging vs. no-digging (UCANR) 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).  Initial black rot symptoms on cabbage (WSU) 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.  Dried black rot lesions on cabbage leaf margins (UCANR) 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.  Cabbage wilting and dieback due to black rot (WSU) 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.  Strawberry, an accessory fruit (FoeNyx) 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.  Parts of a flower (University of Illinois Extension)l 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 speed up this process by setting the jars in a Pyrex baking pan and pouring boiling water around (not in) the jars.
Check out my pages on deciduous, abscission, and senescence to see what those different colors mean. If you enjoy curry, you may want to try growing your own fenugreek. But don’t do it for the wrong reasons. Fenugreek is one of those foods touted as a miraculous cure-all for cramps, hair loss, high blood sugar, insufficient breast milk, indigestion, and diabetes. While there may be some truth to the diabetes claim, all the other claims lack any scientific proof, and even the diabetes research is incomplete at this time. That being said, there are plenty of delicious reasons to grow your own fenugreek.  Fenugreek plants (SandeepHanda) Fenugreek as food For over 4,000 years, people have grown this annual legume. It thrives in semiarid conditions, and its seeds and leaves are popular ingredients in dishes from South and Central Asia. Like other legumes, fenugreek is high in protein and fiber. A 3.5 ounce serving of fenugreek seed provides 323 calories, 58g. carbohydrates, 25g. dietary fiber, and 23g. of protein. It also contains significant portions of the RDAs for thiamine (28%), riboflavin (31%), Vitamin B6, (46%), folate (14%), iron (262%), magnesium (54%), manganese (59%), phosphorus (42%), and zinc (26%). [Who knew curry was so good for us?!!?] Fenugreek seeds are generally roasted to reduce bitterness and enrich flavor. And it’s not just the seeds of the fenugreek plant that are eaten. Fresh fenugreek leaves, which are said to taste similar to spinach, are used as a vegetable in many Persian and Indian dishes. Dried leaves are used as an herb.  Fenugreek seeds (Ajale) The fenugreek plant
Fenugreek (Trigonella foenum-graecum), also known as methi, samurai, and hilba, among others, is a fragrant annual. It may grow as a single stem, or as a small bushy plant, reaching a height of 2 feet. Green to purple oval leaves are small and trifoliate (having three leaflets). It looks a lot like clover and alfalfa. Flowers are small and either white or purple. Seeds develop inside curved yellow pods. This plant is moderately drought resistant and it can handle a light frost. How to grow fenugreek This plant needs heat, so you may want to grow it in a container, maybe on a windowsill. Fenugreek has a shallow root system, so the container does not need to be very large. You can grow fenugreek as a microgreen by simply sprinkling seeds on top the soil in a shallow container, and then lightly covering them with more soil. Fenugreek seeds should be planted 1/4” deep, in rich potting soil. Keep the soil moist until germination occurs. Fenugreek does not like our heavy clay, and it does not take kindly to being transplanted, so it is best started where it will stay for the growing season. These seeds sprout very quickly, usually in only 2 to 4 days, making it an exciting children’s activity. Fenugreek pests and diseases Fenugreek is susceptible to root rot, powdery mildew, and charcoal rot. These diseases can be minimized by allowing the soil to dry out between waterings. Aphids are the most common pest of fenugreek. Harvesting fenugreek Fenugreek can be grown as a microgreen, or you can go for the full growing experience. Generally, young leaves and shoots are snipped off the plant early in the growing season. Then the plant is allowed to continue growing to produce seeds, usually 3 to 5 months after planting. To harvest seeds, the plant is removed and hung upside down to dry. Have you had your fenugreek today? Arugula is a tangy salad green that grows best in the Bay Area’s cooler seasons. Back in Roman times, it was forbidden to grow arugula in monastery gardens because it was considered an aphrodisiac. My guess is, it got that reputation because of all the Vitamins A, C, and K, and potassium it provided, giving diners the energy and good health needed for physical activity. In any case, arugula is now recognized as a delicious, healthy, gourmet salad green.  Flowering arugula (Public Domain) As a member of the cabbage family (Brassicaceae), arugula is cousin to cauliflower, turnips, kale, and sweet alyssum. Also known as rocket or Mediterranean salad, arugula (Eruca vesicaria ssp. sativa) makes an easy addition to any foodscape. Arugula grows rather quickly. Within 40 to 50 days after planting seeds, you can begin harvesting its tasty leaves. Because arugula grows so quickly, it makes a good catch crop. Catch crops are those plants added between bigger crops, to maintain soil microorganisms and to reduce erosion. Arugula plants Arugula plants look like a deeply lobed, open growth lettuce. Some arugula plants will only reach 8” while others can be more than 3’ tall. Arugula seed pods look much like many other cabbage family plants: they are long, narrow pods filled with rows of seeds. As temperatures begin to rise, arugula plants will bolt, sending up a flowering stalk (pedicle) with lovely, edible flowers. You can slow this process by making arugula part of your shade garden. Being a shallow-rooted plant, arugula can also be grown in containers.  Arugula flower (Alvesgaspar) How to grow arugula
Arugula roots enjoy muddy, mucky soils. Since the Bay Area’s clay soil can hold a substantial amount of water, autumn and early spring are the perfect times to plant this healthy salad green. Start by planting seeds 1/2” deep, and water them in well. When seedlings are 1” tall, thin them so that they are spaced 6 to 9” apart. You can do this by tickling their roots apart and transplanting, or you can snip off any extras at ground level, reducing stress to delicate new roots. To keep leaves tender and tasty, be sure to keep the soil evenly moist. Periods of dryness will increase bitterness and trigger bolting. Continuous crop By regularly snipping off outer leaves for kitchen use, you will stimulate your arugula plants to continue producing new, tender leaves through the cooler weather. Because arugula becomes peppery and bitter as it matures, you may want to continue planting new seeds in succession, for a continuous crop. If allowed to go through their lifecycle unmolested, arugula plants will readily self-seed an area, providing many years of salad greens with little to no effort on your part. Local pollinators, and pollen and nectar eaters, will appreciate the banquet, as well, increasing your garden’s biodiversity. Arugula pests and diseases As with many other older species of plant, arugula tends to be relatively pest and disease free. Bacterial leaf spot, downy mildews, and white rust may occur if water stays on the leaves for an extended period. Bagrada bugs can also be a problem, but your arugula plants will be relatively trouble-free. Try adding arugula to your garden today! Glyphosate is an herbicide. It is the active ingredient in RoundUp and other popular broadleaf weed and grass killers. And recent scientific research has shown us that glyphosate may be killing honey bees along with plants.  Herbicide used to kill dandelions in lawn (NCSU Extension) My soapbox Before we begin learning about this litigious herbicide, let me tell you from the gate that I do not use it, in any form. I practice sustainable, integrated pest management (IPM) and organic gardening. This is a heated topic and I want you to be aware of where I stand. The chemistry of glyphosate Glyphosate is a broad-spectrum, systemic herbicide, which means it is absorbed by and kills the plants it touches. It does this by blocking an enzyme pathway, called the shikimic acid pathway. [It gets this unique name from the Japanese shikimi flower, in which the process was first identified, back in the 1800s.] The shikimic acid, or shikimate, pathway is a 7-step metabolic process that synthesizes folates and amino acids necessary for plant survival. Herein lies the problem. The shikimic pathway is also used by algae, bacteria, fungi, protozoa, and others. When the shikimate pathway in any of these organisms is blocked, they die. Glyphosate in the environment More that 700,000 tons of glyphosate are produced each year, making it the world’s most used pesticide. As a substance, glyphosate molecules bind tightly to soil. While this means they are less likely to end up in ground water as, say, motor oil, it can cause a different type of pollution. Depending on soil type and weather conditions, glyphosate can be found in the soil 6 months after being applied. Soil bacteria break down glyphosate, but I have to wonder about the chemicals those bacteria poop out afterward. Maybe it’s just me. Some studies have found that carrots and lettuce plants absorb glyphosate long after the area was treated. Compounding the problem, many glyphosate products also contain other toxic ingredients.  (Public Domain) Glyphosate and GMOs Glyphosate use walks hand-in-hand with genetically modified plant development. GMOs are designed to be resistant to glyphosate and other weed-killing chemicals, making it possible to grow more food for our ever-increasing global population. It certainly has its appeal. It’s so simple - just aim, squirt, and you’re done. No more weeds. But at what cost? Glyphosate and overspray If you (or your neighbor) use a glyphosate product, you need to be aware of the overspray risk. Since none of us is perfect, and breezes do happen, these chemicals can be carried on the wind to places where they are not welcome. That delicate, well loved exotic, handed down from your great-grandmother, is just as vulnerable to death by glyphosate as the dandelions. Also, since glyphosate products kill all the plants it touches, indiscriminately, many plants important to local biodiversity are being lost. We do not yet know the full extent of that domino effect. Glyphosate and bees Beekeepers have long suspected that glyphosate is, at least partly, responsible for the recent decline in global bee populations. [Did you know that China now must hand-pollinate their apple and pear trees because there are not enough bees?] New research from the University of Texas at Austin shows that glyphosate kills some of the beneficial bacteria found in a honey bee’s gut, making the bees more susceptible to infection. [Maybe we need to start feeding our bees some type of probiotic? I’m guessing.] Glyphosate use Glyphosate first came on the market in 1974. It provided an easy way to kill weeds with just a squirt. Glyphosate is used in agriculture and forestry, and to control aquatic plants. It is sprayed along railroad tracks, between orchard trees, and in public parks. According to the National Pesticide Information Center, there is a sodium salt form of glyphosate that is used to regulate plant growth and ripen fruit. So, it’s very useful and convenient. There are over 750 products on American shelves that contain glyphosate, including RoundUp, Bonide KleenUp Grass and Weed Killer, and Kleeraway Grass & Weed Killer. Tragically, glyphosate is also found in many oat products on grocery store shelves, according to the Environmental Working Group (EWG). The worst offenders the EWG listed include Giant Instant Oatmeal, Back to Nature Classic Granola, Quaker Dinosaur Eggs Oatmeal, and, I hate to say it, Cheerios. I urge you to read through their entire list and shop accordingly. The FDA was/is aware of glyphosate in our foods, but has failed to release its findings to the public. More recently, glyphosate has been linked to the development of Parkinson’s and Alzheimer’s diseases, and may also cause cancer in humans. Herbicide safety As with any herbicide, always follow the package directions EXACTLY and COMPLETELY. This is not a time to be careless. You can harm other plants with overspray, or you expose yourself to dangerous chemicals. This can occur by breathing it in during the application process, eating or smoking after applying it, if you don’t wash your hands, or by touching plants that are still wet from the spray. If exposure occurs, follow the first aid directions on the product label. For more information about risks and treatments, contact the Poison Control Center at 1-800-222-1222. Pets are also susceptible to herbicide poisoning. Instead of using toxic chemicals to rid your garden and lawn of weeds, be industrious and put out the effort to pull them before they go to seed. While you’re out there, use it as a time to take a closer look at the other plants and the soil, and listen for the birds and insects that share your yard space.  Remove weeds, roots and all (WikiHow) Bottom line, glyphosate makes it possible to grow far more food, at least in the short term, but the long term costs, in my opinion, far outweigh any convenience or benefits it may provide.
The truth about nuts may surprise you. While you probably already know that peanuts are not nuts (they’re legumes), many of the other foods you have come to know as nuts are not true nuts at all. Let’s begin by learning the botanical definition of nuts. #/media/File:Fancy_raw_mixed_nuts_macro.jpg) Raw mixed nuts (Sage Ross) True nuts are hard-shelled, inedible pods that hold both the fruit and the seed of a plant. These pods do not open of their own accord, which means they are indehiscent. The pod, or shell, of a nut is made from the ovary wall, which hardens over time. Hazelnuts, chestnuts, and acorns are true nuts. So are kola nuts, which gives “cola” soft drinks their signature flavor.
[Did you know that small nuts are called ‘nutlets”? To me, that sounds like the perfect name for a little chihuahua.] So, when is a nut not a nut?  Walnut showing interior (Böhringer Friedrich)
A nut is not a nut when it is a fruit seed. Fruit seeds can be angiosperm, drupe, or gymnosperm seeds:
These not-nut nuts are commonly referred to as culinary nuts. [Did you know that cashews are the seeds of an accessory fruit, which means they share characteristics with strawberries and poison ivy. Isn’t botany amazing?]  Ripe cashew apples with seeds hanging below (Abhishek Jacob) Of course, you can call any of these delicious morsels "nuts" whenever you want to. True nut or culinary nut, many of these yummy snacks find their way into our gardens and foodscapes. Which ones are you growing?
Did you know that soil has a wilting point? It’s not that soil wilts, instead, wilting point is reached when the water needed by a plant to stay upright has been used up.  A plant rooted in soil that is beyond the wilting point (Pewebe) Soil moisture Water, plants, and soil perform an intricate dance. The soil has spaces, called macropores and micropores, that allow air, roots, and water to move through. The water molecules in the soil are strongly attracted to each other, using surface tension. This is how soil holds onto water, despite the pull of gravity. The amount of water a soil profile can hang onto is called its water holding capacity, or field capacity. When a soil is holding all the water it can, and becomes saturated, any additional water is pulled into the ground water by gravity, or runs off as urban drool, where it eventually is discharged into rivers, lakes, and oceans. At the opposite end of the soil moisture spectrum, a soil can be so dry that it becomes hydrophobic. Hydrophobic soil actively repels water. Sponges act the same way. If you have a completely dry sponge, water will tend to run across the top, rather than be absorbed. Once a little water is absorbed, a lot more is pulled into the spaces that make up the majority of a sponge. Finally, if even more water is added, it will simply flow through the sponge.  (UCANR) Why the wilt?
Plants wilt for several different reasons. Bacteria or fungi may be blocking the xylem, there may be too much salt in the soil, ice damage may have occurred, or because the soil has reached the wilting point. When plants do not contain enough water, plant cells cannot remain plumped up, or turgid. As water becomes less available, cells shrink and become floppy. [Tree trunks do not get floppy because they contain lignin. Unlike cellulose, which is a sugar-based material, lignin is alcohol-based, but we will discuss lignin another day.] The problem with wilting is that there is a point of no return. This is a soil’s permanent wilting point. Permanent wilting point Permanent wilting point is death for plants. If a soil moisture rating reaches or surpasses the permanent wilting point, it doesn’t matter how much water you add later, the plant will die. This occurs more often with containerized plants, but it can happen anywhere. Soil texture plays a big role in how much soil moisture is not enough to keep a plant alive. This is due to the soil’s ability to hold the water so tightly that plant roots cannot suck it in. The permanent wilting point occurs at 15 to 20% for clay soil, 10 to 15% in loamy soil, and at 5 to 10% in sandy soil. You can monitor soil moisture using an inexpensive moisture meter. If you hang a bird feeder in your yard, you are probably already growing millet. Millet is those tiny, blonde seeds found in bird seed. It is also a delicious, easy to grow, gluten-free porridge. [In the same way as corn, rice, barley, and wheat, millet seeds are actually a specialized dry fruit, called a caryopsis, but we'll leave that for another discussion.]  Foxtail millet (STRONGlk7) Originally from Asia and Africa, people have been growing and eating millet for over 7,000 years. Some historians believe that millet played a major role in humanity’s shift from hunter-gatherers to farmers. Today, millet is still an important food source in many regions. You may be surprised to learn that millet, and not rice, is the primary carbohydrate food source in northern China. Millet can be eaten as a sweet, with milk and sugar, or as a savory dish, with the addition of meat and vegetables. Millet is high in protein, dietary fiber, and several B vitamins. A single serving of millet provides 76% of the RDA for manganese, which makes me wonder why we don’t eat more of it. The only cereal-related nutrient that millet is lacking is lysine, but buckwheat contains high levels of this important amino acid, so eating millet and buckwheat together makes for a healthy diet. Types of millet Millets are actually a group of plants in the grass family (Poaceae). Unlike most families, many millet varieties are only remotely related to one another. You can track down the different groupings, if you feel so inclined, but the most commonly grown are:
 Pearl millet (Public Domain) Sorghum, also found in bird seed mixes and cereal bowls, is sometimes called Great millet, but it is generally considered a separate cereal from millet. How millet grows Millet is an annual that grows quickly in hot, dry weather, on crappy soil. Of course, it performs far better when plant nutrients and irrigation are present, but it’s an extremely resilient plant. [The only thing it cannot tolerate is waterlogged soil and mud.] Depending on the variety, mature millet plants can reach a height of 2 to 5 feet.
Millet grows so fast that seeds will sometimes sprout while still attached to the spike! Normally, seeds germinate in 5 days, and spikes are ready to harvest in 50 to 180 days, depending on the variety and weather conditions. Because it grows so quickly, millet can also be used for erosion control, or as a green manure. It also tends to grow faster than most weeds. Millet is a good choice for filling in difficult spaces of the yard. Local birds will appreciate the free lunch, too!  Sprouting millet (Kaitha Poo Manam) How to grow millet
Millet seeds can be broadcast by hand over an area and raked in, or you can drill holes that are 1 to 4” deep for the seeds. [Did I mention that millet is rugged?] Once plants are established, they will readily self-seed the area, year after year. Because of millet’s high carbon to nitrogen (C:N) ratio, it is best balanced with low C:N plants, such as legumes, in crop rotation. Millet pests and diseases Generally speaking, millet has few pests, other than Bagrada bugs and crane flies. Millet diseases lean toward the fungal variety, with blast, leaf spot, downy mildews, ergot, rust, Johnson spot, smut, and blight causing the most problems. Simply provide good drainage and reasonable irrigation to avoid most of these diseases. Millet, it’s not just for the birds (though you may need to protect your crop with netting or row covers, if you want any left to harvest). You can have it for breakfast, use it to increase biodiversity in your yard, or, if you’re feeling adventurous, millet can even be used to make alcoholic beverages! Migration isn’t something people usually associate with gardening. But they should. When we talk about migration, we generally mean large groups of animals moving from one region to another, due to seasonal changes, depleted food supplies, safety, and/or reproduction. Obviously, plants do not migrate in the proper sense of the word. [Wouldn’t it be a sight, if they could?]  Monarch butterflies roosting on migration in Texas (Loadmaster) To most people, migrations are left to caribou and wildebeests, whales and salmon, swallows and robins, and monarch butterflies. And therein lies our clue: insects migrate. And those insect migrations can have a huge impact on your garden. Insect navigation Insects travel within a low, slow boundary layer, or significantly higher up, using fast-moving air currents. We are rarely aware of these massive migrations. Insects can sense polarized lights, and changes in wind speed and direction, helping them find their way. Insects also have built-in clocks that help them stay on schedule. The magnetic field theory related to bird and mammal migration appears to only impact short distance fliers. Which insects migrate? Several butterfly and moth, beetle, dragonfly, and African locust species migrate. [North American locust swarms do not occur seasonally, disqualifying them as migrations.] Even tiny aphids and lesion nematodes migrate, though their trips are significantly shorter.  African locust (Christiaan Kooyman) In some cases, insect migrations work much like bat, bird, animal, and fish migrations: adults get a genetically-initiated urge to travel to a better wintering or breeding area. After spending a predetermined amount of time in the new location, the urge to return strikes, and off they go. In other cases, one generation will take the outgoing flight, and the next generation handles the return trip. In many cases of insect migration, it takes multiple generations to make the complete trip. Mind-blowing numbers Between 33 million and a billion Monarch butterflies migrate each year, from Canada to Mexico and back again. Technically, since it takes four generations to complete the trip, these one-way excursions are called emigration, but we’ll ignore that detail. Monarch butterflies don’t harm our gardens, but other migrating insects can and will. And there are a lot of them. According to the journal Science, over 3 trillion insects migrate over south-central England each year. England’s cold, damp weather makes it fair to assume that those numbers are profoundly higher in warmer areas. _-_Echinacea_purpurea_-_Havr%C3%A9_(3).jpg) Painted lady, or cosmopolitan (Jean-Pol Grandmont) The distances some of these insects travel is truly amazing. British painted ladies, or cosmopolitans, travel 9,000 miles over 6 generations. Wandering gliders, a type of dragonfly, travel 11,200 miles, with individuals flying 3,730 miles. For an insect that is only 1-3/4” long, it would be the same thing as a 6’ person traveling over 153,000 miles - under their own power.  Wandering glider (Jee & Rani Nature Photography) Bay Area insects that migrate
Here, in the Bay Area, our gardens are impacted by several different migrating insects. These pests (and their favored foods) include:
You can join the citizen science movement related to insect migrations by reporting your sightings to The Big Bug Hunt. Your information will be added to countless other sightings to generate ever more reliable prediction models. This can help you protect your plants better, faster, and with less effort, using row covers. |
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