In most cases, thrips are pests. Their feeding causes stippling, stunting, and scarring. Some varieties of thrips can even spread tomato spotted wilt and other diseases. But some thrips are predators These tiny hunters may not look like much to us, but predatory thrips are other thrips’ worst enemy. In fact, predatory thrips control other thrips more effectively than other natural enemies. Mites, spider mites, and whiteflies are in the same boat. Predatory thrips are worth their weight in gold. These tiny hunters share many traits with their prey. Males are rare and females can produce offspring without mating. Predatory thrips also eat plant material, but they cannot survive without eating meat. While most thrips congregate in massive numbers, predatory thrips tend to be loners. There are four major species of predatory thrips:
Like other thrips, these insects are vulnerable to broad-spectrum insecticides and pesticides, horticultural oils and insecticidal soaps, so leave them as a last resort. Instead, create a habitat that attracts these and other beneficial insects. Your predatory thrips need food, water, and shelter, like every other living thing. You can buy predatory thrips. Or, you can simply provide a water source and a variety of places to hide, and these garden helpers will find your garden on their own.
Western flower thrips feed on much more than flowers. In fact, this group sucks the sap out of over 250 different plants. They can also bring tomato spotted wilt and other tospoviruses to your garden. And they bite! Western flower thrips (Frankliniella occidentalis) are native to the Southwestern United States but have spread to several other continents on contaminated plant material. [Yes, Virginia, invasiveness goes in all directions.] In fact, western flower thrips have earned the dubious distinction of being one of the world’s most important agricultural pests. And they have developed a resistance to many insecticides, so don’t bother spraying. Some scientists believe that western flower thrips have become such a problem and experienced such a significant population explosion as a result of genetic mutations caused by the insecticides we used to try to kill them. Oops. Western flower thrips description Male thrips of any type are rare. The same is true for this species. If you do see one, you might notice that they are yellowish-white. They are also larger than many other thrips, measuring up to a whopping 0.06 inches (1.4 mm). When male western flower thrips come together, they fight by flicking the tip of their abdomens at each other. Wouldn’t that be a sight?
When those eggs hatch, hungry, mobile larvae start feeding. They use raspy mouthparts to shred and pierce to get at the sugary sap they crave. When not eating, they hide in tight little spaces where they are difficult to find. After they have eaten their fill, they enter a two-step, non-feeding pupal stage. In some cases, they drop to the ground to pupate. There can be up to 15 generations each year. Western flower thrips host plants It would probably be easier to list the garden plants not affected by western flower thrips, but you need to see just how damaging these micro pests can be. Members of the carrot, broccoli, citrus, legume, melon, mint, onion, sage, stone fruit, and tomato families are all susceptible to western flower thrips. So are apples, artichokes, beets, blueberries, figs, grapes, lettuce, pistachios, rye, strawberries, and wheat. See what I mean? These pests also feed on several native plants and many popular ornamentals, including carnations, chrysanthemum, gladiolas, impatiens, orchids, petunias, roses, and sweet peas. As thrips feed, their saliva damages the surrounding plant tissue. And nymphs feed heavily on newly forming fruit and leaves, causing damage and spreading disease. But they aren’t all bad. Western flower thrips also feed on certain mites that attack cotton crops. [I still don’t want them in my garden.] Western flower thrips damage You may have to look closely to see these pests, but the damage they cause is more visible. As they feed, they leave behind scarring and stippling of petals, leaves, and other plant parts. You may also see distorted growing tips, pimpling of flower petals, or leaf silvering. The damage varies based on where and when the damage occurred. In some cases, you won’t see it until much later. This later damage may include distorted or spotted fruit, which bruises more easily, Fruit splitting may also occur and Western flower thrips are the main vector of tomato spotted wilt. Being attracted to bright colors, especially blue, white, and yellow, these pests will land on people wearing those colors and bite them. Thrips won’t drink your blood or make you sick, but you might be uncomfortable for a while. And you can use that information to help control these pests.
Blue sticky sheets are very effective at attracting and capturing western flower thrips. Sadly, beneficial hoverflies are also attracted to those blue sticky sheets. You can protect those garden helpers by surrounding the blue sticky sheet with a mesh that will allow the thrips through, but not the hoverflies. Reflective mulches actively discourage western flower thrips and insidious flower bugs are particularly fond of western flower thrips. For dinner. Names can be misleading. While it’s true that onion thrips feed on onions, they also eat asparagus, beets, broccoli, cabbage, cauliflower, cucumbers, garlic, leeks, melons, potatoes, pumpkins, strawberries, and zucchini, along with several other fruiting and ornamental plants. If that weren’t trouble enough, they can carry serious plant diseases, too.
Adult onion thrips can be yellow to dark brown and sometimes black. Most of them are female. Using a hand lens, you can see that their wings have a single, central vein and long hairs. Eggs are white at first but turn orange a few days later, just before hatching. Larvae are also yellow to brown. Onion thrips lifecycle Females use an ovipositor to cut into leaf tissues. Then she tucks her eggs in, under the epidermis, of up to 80 leaves. Less than a week later, those eggs hatch and start sucking the sap from those and neighboring leaves. There are two larval stages during which a lot of sap is eaten. Larvae then stop eating and go through prepupal and pupal stages. Adults generally only live for two or three weeks, but they can overwinter in legumes, grains, weeds, and plant debris. Damage caused by onion thrips To get at the sap they love, thrips use their raspy, piercing mouthparts to shred and penetrate the surface of predominantly young leaves and flower petals, breaking open plant cells and drinking their fill. Since they are feeding on young parts that continue to grow, the damaged areas become elongated, silvery streaks. You may also see leaf curling, stippling, scarring, stunting, leaf tip browning, white patches, and smaller crop sizes. On cauliflower, you may see brown streaks on curds. Damaged areas of leaves cannot perform photosynthesis, injured areas lose water faster than normal, and provide points of entry for other pests and diseases, such as bacterial rot. But onion thrips can infect your plants with a variety of diseases simply by feeding. Onion thrips are vectors (carriers) for Impatiens necrotic spot virus (INSV), Iris yellow spot virus (IYSV), purple blotch, strawberry necrotic shock virus, tobacco streak virus, and tomato spotted wilt virus (TSWV). Onion thrips management Onion thrips are easily dislodged with a garden hose, but that won’t fix the problem. There are some cultural practices you can adopt that will help reduce onion thrips problems. First, clean up plant debris at the end of each growing season. When planting, only use certified pest- and disease-free seedlings, seeds, and onion sets. Monitor the areas surrounding your garden for signs of onion thrips and other pests, and remove volunteer plants that may harbor pests and diseases. Beneficial insects, such as lacewing larvae, pirate bugs, and predatory thrips will help in the fight against onion thrips, so avoid using broad-spectrum pesticides and insecticides.
Since healthy plants are better able to protect themselves against onion thrips, water and feed your plants with that goal in mind and get your soil tested by a lab. You’ll be glad you did. Bean thrips (Caliothrips fasciatus) were first found in the 1800s on orange leaves, but they prefer eating beans and other legumes. That being said, these California natives are also found on avocado, pear, and walnut trees, in the navels of navel oranges, mandarins, and other citrus, as well as cantaloupes and other melons. They don’t eat all of these plants, but they do like using them for shelter because of how close they are to your legume crops.
Adult bean thrips have dark, greyish-black bodies with white wing bands. The legs have light and dark bands and both genders have fringed wings that they fold over their backs when at rest. Of course, these pests are about the size of any letter on an American penny, so you probably won’t see all that. If you use a hand lens, you can. You would also be able to see that larvae are yellowish to orange. Those larvae are about 1 mm long at their biggest. Eggs are even smaller, at only 0.008 inches. If you could see them, you’d notice that they are banana-shaped. What you are more likely to see is the tiny black frass (bug poop) deposits which are often found on the top and underside of leaves, in and around citrus navels, and where clusters of fruit touch. You will also see the damage they cause. Bean thrips damage Both larvae and adults feed on leaves and growing tips. As they feed, they cause leaves and growing tips to turn brown and distorted. Silvering and premature defoliation can also occur, reducing plant vigor and resulting in sunscald. Bean thrips also feed on immature beans. Bean thrips lifecycle Female thrips lay eggs in the leaves and fruit of legumes. Legume fruits are also known as pulses. Pulses are the beans and lentils we enjoy eating. When bean thrips eggs hatch, first and second instar larvae feed heavily on leaves, growing tips, and immature pulses before they fall to the ground and go through two-stage pupation. Winged adults emerge and the cycle starts again. Like most other thrips, mating is not needed for reproduction to occur: unfertilized eggs produce male offspring and fertilized eggs produced females, but there’s more to it than that. Research has found that females generally only live 20 to 55 days. At the 10-day mark, short-lived females stop producing female offspring. If they happen to live for more than 50 days, they will produce female offspring until the 30-day mark. How does this stuff evolve? And how do they know? It baffles me. Bean thrips control Bean thrips are very bad fliers. They can only fly a few feet in a crazy zig-zag or spiral pattern. But they can catch rides on the wind, so you have to monitor plants for signs of thrips during warm and hot weather. Bean thrips thrive in hot weather and there isn’t anything you can do about that. But there are steps you can take to make your garden less appealing to bean thrips. First, they like to hide out in weeds, such as prickly lettuce (Lactuca serriola) and wild blue indigo (Baptisia australis) so keep weeds, especially those in the legume family, several feet away from your garden beds. Yellow sticky sheets attract and capture all sorts of thrips and other pests and they are inexpensive. While research has shown that green sticky sheets are more effective at capturing bean thrips in particular than other colors, you’ll probably do fine with the yellow.
So, what’s going on (and under) your plants’ leaves? Even if you aren’t growing avocados, avocado thrips are pretty fascinating. [Just a reminder, the word thrips is the same for one thrips or many thrips.] Avocado thrips (Scirtothrips perseae) are native to Mexico and Guatemala. In 1971, a single female was stopped at the border. By 1996, avocado thrips were found throughout California and Hawaii. By 1999, it was estimated that avocado thrips infested 99% of California’s avocado trees.
Damage caused by avocado thrips These pests may be tiny, but they can cause significant damage. Thrips populations explode rapidly in spring and autumn, leading to defoliation and premature leaf drop. This, in turn, reduces tree vitality and crop size. The biggest problem with avocado thrips is the scabby, brown scars on the fruit they create. These damaged areas don’t look very nice and they can create points of entry for rot and other diseases and pests. Avocado thrips identification These suckers are tiny. At 0.03 inches long (0.7 mm), you could put 23 adult avocado thrips end-to-end across a dime, making them one of the smaller thrips species. If you could see them up close, you would see that adult avocado thrips are straw-colored, with three red spots on the top of their heads, between their eyes. Those dots are called ocelli and they are light-sensitive organs. They also have yellow abdomens with brown stripes, but their bellies may look greenish because of all the chlorophyll they consume. [I was unable to find a free-to-use image of an avocado thrips, but they look enough like chili thrips that that’s what I used above.] Avocado thrips first instar larva are pale whitish-yellow, while second instar larvae are bigger and brighter yellow. Avocado thrips lifecycle Avocado thrips have six distinct life stages and adult females can lay eggs whether they have mated or not. Unfertilized eggs produce males and fertilized eggs produce females. How’s that for efficiency? Eggs are laid on immature leaves and fruit. When they hatch, they begin feeding in the first larval stage. Then they enter a voracious second larval stage, followed by two non-feeding pupal stages. These pupae hide out in cracks and crevices in the bark and on branches, or in leaf litter (duff) under the tree. Flying adults emerge and begin feeding on leaves and fruit as they search for mates and good sites for egg-laying, and the cycle continues. Avocado thrips management Scorching summer heat seems to do a number on thrips, but the eggs they lay beforehand are waiting for conditions to improve. You can use yellow sticky sheets, mulch, and natural enemies to battle avocado thrips. Those natural enemies include various green lacewings and a fascinating predatory thrips called Franklinothrips. I can’t make this stuff up, but we will learn more about that pest later this week. Some predatory mites also like to feed on avocado thrips larvae. To help these predators succeed, avoid using spinosad and other insecticides. Avocado thrips and several other pests are attracted to yellow sticky sheets. These are inexpensive and very effective, just keep them away from your hair. Also, studies have shown that mulching under (but not touching) trees can result in 50% fewer thrips making it to adulthood. This is because 78% of larvae drop from the tree to pupate on or in the soil. Apparently, a mulch of arborist chips or composted organic yard waste contains enough different predatory nematodes, fungi, bacteria, and other killers of thrips to put a serious dent in their population. Three cheers for biodiversity! To reduce the chances of the problem in the first place, only buy certified pest- and disease-free rootstock. Of course, while they do it badly, thrips can fly, sort of, so a brisk breeze may be all they need to reach your avocado tree. Be on the lookout. Remember, they like to hide on the underside of avocado leaves. Life in a greenhouse can be idyllic if you are a seedling, whitefly, or a thrips. The same conditions that provide for optimal plant growth also create a perfectly protected habitat for pests, such as greenhouse thrips. Of course, those pests then escape their Eden and end up in our gardens. The thrips family is huge, with thousands of varieties worldwide. Most of them are pests, sucking sugary sap from leaves, buds, and stem tips. But the insects themselves are very tiny (1 mm long or less). In most cases, you will see the damage they cause before you see the actual insect. Invasive greenhouse thrips (Heliothrips haemorrhoidalis) are also known as glasshouse or black tea thrips. They were originally from Brazil but are now found pretty much everywhere except extremely cold regions. Greenhouse thrips damage These pests prefer perennials with thick, broad leaves, which means their diet often includes avocado, bay laurel, and citrus. They also feed on coffee, guava, kiwifruit, macadamia, pecan, stone fruits, and stone pine, along with several ornamentals, including azalea Grecian laurel, rhododendron, and St. John’s wort. Feeding punctures result in stippling that can expand to create whitish-gray areas on leaves, reducing plant vitality. Severe infestations can cause defoliation. You may also see leaf curling and cupping. These pests can carry tomato spotted wilt virus. The biggest problem with thrips feeding is the scarring, cracking, and lesions they cause on fruit. Greenhouse thrips identification Adult thrips have black bodies with white legs and wings and yellow bellies. Their wings are not well-designed for flight, being fringed hairs instead of membranous panels. To move quickly, thrips use a cla p-and-fling method which is why you may suddenly see something shoot by as you work in your garden. Greenhouse thrips have heads and jaws that are sideways and somewhat backward. I have no idea why. The technical term is ‘hypognathous head’.
As far as we know, there are no male greenhouse thrips in California, which might sound like a good thing with regards to pest control, but it has no effect on the local thrips population. Thrips can reproduce through something called parthenogenesis, which means fertilization of the ovum is not needed to produce baby thrips. Each female lays up 60 eggs in her lifetime. Those eggs are inserted into fruit or leaf surfaces. As they grow, they can create a swelling known as an egg blister. Four to five weeks later, those eggs hatch, and larvae start feeding. There are usually five or six generations each year, but there can be up to twelve generations if conditions are good. That ends up being a lot of thrips. Greenhouse thrips management
These pests, like many others, have developed resistance to insecticides and spinosad, so don’t bother. Instead, put nature to work for you. Natural predators, such as robber flies, will put a dent in thrips populations. If thrips are a serious problem in your landscape, you can buy predaceous thrips and you may be able to find egg parasites, such as Thripobius semiluteus or Megaphragma mymaripenne, that you can release in your landscape. Cultural thrips controls include thinning fruit to reduce hiding spaces (and improve fruit quality) and harvesting fruits as soon as they are ripe. Wheel bugs are big, armored, and dangerous. When disturbed, these slow-moving giants can inflict a painful bite that starts out feeling like a bee sting, followed by days of numbness. But that’s okay because wheel bugs more than make up for that possibility by the number of garden pests they hunt down and devour. Native to North America, wheel bugs (Arilus cristatus) are a type of assassin bug. At up to 1½” in length, they are one of our largest true bugs. True bugs (Hemiptera) have piercing and sucking mouthparts and they go through an incomplete metamorphosis. Unlike aphids and leafhoppers, which feed on the sap of our plants, wheel bugs pierce, liquify, and consume other insects. Wheel bug identification Wheel bugs are easy to identify but they are shy. Besides being large, they don’t move very quickly. This makes it easy to take the time to see details. They do fly, however, so don’t startle them. The first thing you will notice about a wheel bug is its dorsal crest. Dorsal crests are raised ridges along the back. In the case of wheel bugs, that crest looks like part of a cog or spoked wheel. And when they fly, wheel bugs make a buzzing noise and are easily mistaken for grasshoppers Wheel bug adults are usually gray to brown. They may look nearly black right after molting. And males are slightly smaller than females. Wheel bug nymphs do not have the cog-shaped crest. Instead, they look more like spiders with red or orange abdomens. Wheel bug lifecycle Wheel bugs mate in autumn. Females lay clusters of 40-200 brown, cylindrical eggs on bushes, trees, and other surfaces. After laying eggs, the female eventually dies. Eggs hatch in spring and the nymphs go through five molts before reaching adulthood. Wheel bug diet Wheel bugs feed on a variety of garden pests, including cabbageworms, caterpillars, Japanese beetles, Mexican bean beetles, and tent caterpillars. Wheel bugs are usually active during the day but may hunt at night in areas with lights. When they hunt, they capture their prey with their front legs and inject it with paralyzing and dissolving enzymes. While wheel bugs also prey on honey bees and ladybugs, they are considered highly beneficial. Their presence indicates a healthy environment with abundant biodiversity. To encourage wheel bugs in your landscape, avoid using broad-spectrum pesticides and insecticides, and add some goldenrod and sunflowers.
Adding sugary, nutrient-rich molasses to gardens and compost piles is said to feed important microorganisms, raise sugar levels in your plants, and kill pests. Truth or myth? Let’s find out. What is molasses? As a young child, I thought nothing tasted better than freshly baked bread that had been slathered with butter and molasses. I still love it. But what is molasses and why do people say it’s good for your garden? Molasses is the sweet, syrupy residue left over after processing sugar cane and sugar beets to make sugar. Also known as black treacle (UK), molasses is mostly sugar. It also contains calcium, iron, magnesium, manganese, phosphorus, potassium, sodium, and a little zinc. Does molasses feed microorganisms? The microorganisms that support our plants love sugar and all those minerals. Adding molasses to compost piles and planting beds makes sense. Provide food for microorganisms and they will multiply, doubling their population every 20 minutes, for as long as the food supply lasts. Therein lies part of the problem. Natural processes take eons to find balances that allow them to continue. The variety of bacteria and other microorganisms responsible for decomposition, nutrient transfer, and healthy soil exist in a dynamic dance of available resources. Population explosions rarely end well and the same is true for all those microorganisms. As soon as the molasses is gone, they die. Your plants will get some nutrients from all those dead organisms. And your compost pile will cook faster until you wet it down tomorrow and wash the sugars away. But those potential benefits are short-lived and have not been demonstrated in lab or greenhouse tests. Yeasts tend to grow faster than the other organisms when fed molasses, which may not necessarily be what you want. To maintain healthy microorganism populations, you are better off adding healthy foods, such as wood chips, compost, and other organic matter, rather than the junk food rush of molasses.
Can molasses kill insects? If you pour molasses on a soft-bodied insect, it will die. This doesn’t happen because molasses contains some magical property or the pest’s supposed inability to process sugar. The insect would simply suffocate. And saying that eating sugar will kill an insect is ridiculous. Sap is sugar water. Beetles and cockroaches eat candy bars and cookies. When sugar is eaten by insects, they do not explode. They fart like everyone else. [Did you know that termite farts are responsible for generating 20 million metric tons of methane each year? I didn’t either.] So, there you have it. Molasses can briefly boost microorganism populations. It will not significantly increase sugar levels. And it is not an insecticide. Rather than pouring it on your garden, save molasses for your toast. Or, try your hand at George Washington’s recipe for small beer (below).
We’re all familiar with the NPK of fertilizer fame, but what about vanadium? When it comes to plant nutrition, most of us are familiar with nitrogen, phosphorus, and potassium. These are the entrees of a plant’s diet and they are called primary macronutrients. These macronutrients are used for leaf, root, and fruit growth, respectively. [Of course, that’s a massive oversimplification, but it’ll do for now.] Secondary macronutrients are the side dishes. They include calcium, magnesium, and sulfur. Continuing with our menu motif, I guess we could say the remaining micronutrients are the herbs and spices of a plant’s meal. We used to call these flavorings trace elements and they include boron, chlorine, cobalt, copper, iron, manganese, molybdenum, nickel, selenium, silicon, sodium, zinc, and vanadium.
What is vanadium? Vanadium is a biochemically active metal and it is the 20th most abundant element in the Earth’s crust. It is estimated that 100,000 metric tons of vanadium are released into the atmosphere each year by burning fossil fuels, so there’s no shortage. We used to think that vanadium (V) was toxic to plants. Now we know it’s not that simple. Vanadium is a tough nut to crack. Even though there’s plenty of it in most soils, only 1% of what’s there ends up being soluble in water, so it isn’t always easy for plants to absorb it. Also, vanadium can accumulate in plant tissues to the point that it becomes toxic. To makes things even more confusing, vanadium is believed to mimic phosphorus, tricking plants into absorbing vanadium when what they need is phosphorus. But plants do need vanadium. How do plants use vanadium? Vanadium is used by some plants as a substitute for molybdenum. Molybdenum helps plants use nitrogen by working with certain enzymes. But recent research has shown that there’s a lot more to vanadium than that. Vanadium plays a role in the movement and absorption of other nutrients, activating certain enzymes, and allowing for (and blocking) the absorption of several different elements. Vanadium has been found to stimulate corn, pepper, rice, tomato, and other plants’ growth and flowering. Lab studies have shown that vanadium is responsible for increased levels of amino acids, chlorophyll, and sugar, as well as N, P, K, Ca, Mg, Cu, Mn, and B. Adding vanadium made the plants being studied grow more, produce more flower buds, and sped up the flowering process. It also helped counteract the negative effects of too much copper and other metals. Other studies have shown that vanadium helps convert atmospheric nitrogen (which most plants cannot use) into ammonia (which plants can use as a nitrogen source). It does this by waking up a specific enzyme, called nitrogenase. Before you start adding vanadium to your soil or fertilizer mix, you need to know that this is one of those too-much-of-a-good-thing-is-a-bad-thing situations. Vanadium toxicity can harm your plants by causing a build-up of potassium, magnesium, and manganese in plant leaves, causing a domino effect of malnutrition. Since most soils already have plenty of vanadium, regular irrigation and periodic soil tests are your best bet. Soil tests don’t (yet) include vanadium in their results, but they will help you see if any other imbalances are present. My mother lived alone on 97 acres in Upstate New York. It was an old farmhouse that had been added onto over the years and generations. On that property, there had once been a barn, but it had fallen or been torn down years before, leaving a cracking concrete slab, some steps, and a silo. One of her many dreams was to transform the space into a folly, complete with special plantings, tables and chairs, and a spiral staircase to the top of the silo, where she would use a telescope to look at the stars. That particular dream never materialized, but we can use her idea to inspire some ideas of our own. What is a folly? The word folly refers to someone lacking in good sense. Architecturally, a folly is an outlandish building or other structure built primarily for decoration. These structures are more extravagant than would normally be seen in a garden. Follies were first created in the 16th and 17th centuries but became popular in the 18th century. People added decorative Roman temples, pyramids, and medieval castles to their gardens and surrounded these structures with a wide variety of plants. Follies were often named after their creator, as in so-and-so’s folly. Follies have certain characteristics that can guide you in creating your own folly:
Each area of your landscape has its own set of characteristics: wind and sun exposure, soil structure, moisture levels, and plants that thrive. What if you were to look at each of those spaces with an eye to creating a folly, or adding a touch of silliness? That’s one of the nicest things about gardening – there are no rules. We can create whatever we’re willing to invest the time in One of those characteristics, the “fakeness” of follies, opens up several possibilities to the home gardener. You may not be able to recreate a full-scale stone castle next to your tomato plants, but nothing says you can’t use that curb-scored iron headboard or plastic kiddie climbing toy to create a folly of your own.
If you could build any sort of folly in your yard, what would it be? Personally, I’d love one of those Baba Yaga houses with the chicken legs, but that’s just me. A rose by any other name…just might be a peach tree. It’s true! The rose family (Rosaceae) includes a surprising number of popular fruit trees. Apples and pears, known collectively as pomes, are in the rose family. So are the stone fruits, such as almonds and nectarines. Cane fruits, such as blackberries and raspberries are part of the rose family. So are strawberries. So, how can all these different plants be related? Let’s find out. Rose family characteristics The rose family is large and diverse. It contains herbs and shrubs, along with all those trees. But they do share many common characteristics. Most of them are deciduous, deep-rooted, woody perennials. In general, leaves are arranged spirally, with a few exceptions, with serrated edges. You may see spines along the midrib and extrafloral nectaries are often present.
While most members of the rose family are edible, the seeds often contain amygdalin, which can release cyanide when chewed. [But you’d have to eat an awful lot to have any problems.] Like most families, there are some members of the rose family you wouldn’t want to invite to your garden. Weedy rose family members Not all members of the rose family are lovely, sweet, and delicious. Some can be a royal pain. Pale biddy-biddy (Acaena pallida) is a rose family member, native to the Southern Hemisphere, but now registered as a noxious weed elsewhere. Even our familiar thornless firethorns (Cotoneaster), hawthorns (Crataegus), thorny Pyracantha, and roses (Rosa) are technically invasive plants. Birds eat the seeds found in our landscapes, they then fly away and deposit those seeds where they will grow and displace native plants. This causes a domino effect of destruction for native birds, insects, and other living things. I’m not saying you shouldn’t grow these plants. I’m just saying there are consequences to the surrounding environment. Growing rose family plants
Rose family members grow best in locations with loose soil, good drainage, and full sun. These plants have chilling requirements that must be fulfilled before fruit can be produced, so be sure to pick varieties and cultivars that match the chill hours expected in your yard. Rose family pests and diseases It would probably be easier to list the pests and diseases that do not affect members of the rose family. The same characteristics that make these plants appealing to us attract insect pests. Of course, it depends largely on which plants you’re growing. In most cases, aphids, borers, caterpillars, leaf miners, Fuller rose beetles, leafhoppers, mealybugs, root nematodes, sawflies, scale insects, spider mites, thrips, and whiteflies are common pests. Rosaceae are susceptible to several fungal diseases, including black spot, gray mold, powdery mildew, rusts, stem canker, and Verticillium wilt. Bacterial blight and fireblight can also occur. Learn more about the specific plants you are growing to know how to protect them against these problems. Speaking of growing, how many members of the rose family are in your garden? Tell us in the comments! The Ribes plant family is a small but delicious group that includes currants and gooseberries. Botanically, Ribes is a genus (which is why it is italicized). The family name is Grossulariaceae, but Ribes is the only member of that family, so we will overlook that technicality. Ribes are native to the Northern Hemisphere. This pair of edibles is an interesting mash-up of characteristics. Gooseberries have thorny exteriors but tend to be well-behaved and undemanding. Currants, on the other hand, may look docile and approachable, but these plants defy description and can bring serious problems to a region. In fact, there are laws against growing Ribes in some regions! The Ribes family was banned in 1920. [I told you they were scoundrels!] This ban was put in place because Ribes can host white pine blister rust (Cronartium ribicola). This fungal disease has been devastating to East Coast white pines. Don’t worry, though. That ban was partially lifted in 1966, as resistant cultivars were developed. If you live in New Hampshire, North Carolina, or West Virginia, you are still not allowed to grow Ribes plants, as far as I know. If you live in Massachusetts, New Jersey, Rhode Island, or Delaware, you’ll need a permit. Currants Now, we’re not talking about those tiny raisins made from Corinth grapes when we say currants. Currants are small red, black, or white berries that grow in clusters. Scientists are still wrestling with this group, which defies classification. You can read more about that in my post on currants. Gooseberries Gooseberry plants have spiny stems and branches, making them tricky to work with. Since branches only produce fruit in a single season, removing heavily laden stems makes them easier to work with, plus it lets light in for new branches to grow. You can find sweet dessert varieties and tart culinary varieties. Gooseberries can be green, white, yellow, or reddish-purple. Ribes pests and diseases
Aphids, brown marmorated stinkbugs, clearwing moth larvae, currant borers, gooseberry fruitworms, gooseberry sawflies (Nematus ribesii), also known as currant sawflies, mites, imported currantworms, and the larva of some moths and butterflies are common Ribes pests. And birds. Problems are more commonly caused by mineral imbalances in the soil or improper irrigation. These plants are susceptible to several fungal diseases, such as American gooseberry mildew, anthracnose, currant cane blight, gray mold, leaf spot, powdery mildew, rust, and septoria leaf spot. Avoid overhead watering and be sure to provide good drainage. Ribes grow best in cool, moist surroundings with good drainage, but partial shade and regular irrigation make them possible elsewhere. These plants can be grown in containers and are self-pollinating. Ribes take well to regular pruning, making them excellent patio or balcony plants, and renewal pruning each winter keeps them healthy and productive. Ribes berries are delicious and their flowers provide nectar and pollen to a wide variety of butterflies. The mallow family (Malvaceae) is a mixed bunch. It contains several weeds and some favorite crops. It also includes several ornamentals, such as hibiscus, hollyhocks, and linden trees. Scientists are still arguing over the specifics of the mallow family, but let’s see how it applies to gardening. Mallow characteristics Most mallows are shrubs or trees that put out taproots. Leaves tend to alternate along a stem and are lobed. The leaves are usually smooth-edged. When they are toothed, you will see a vein reaching the edge of each tooth. You will also see a small, leaflike appendage at the base of each leaf, called a stipule. Stems of mallows contain mucous and may be covered with prickles. Mallow flowers tend to be large and showy. Fruits are usually capsules, nuts, or schizocarps. Members of the mallow family readily self-seed an area. Mallows grow best in full sun with regular irrigation in summer. Edible mallows Cocoa, kola nuts, and okra are members of the mallow family. So is durian, a tropical tree that produces giant-sized fruit. Some people love durian and others say it stinks. While you can’t eat it, cotton is also a member of this family. Even most of the mallow weeds are edible, but you probably don’t want to encourage them in your garden. Weedy mallows Mallow seeds have thick coats that protect them from harm. Those coats also slow germination until conditions are ideal. Very often, those seeds are weed seeds, and they can spread like crazy. Most mallow weeds are invasive to the US and are easily mistaken for one another. Common mallow weeds include:
Many of these weeds are edible, but they can also carry disease. Mallow pests and diseases
Weedy members of the mallow family can carry several diseases, including rusts, tomato yellow leaf curl, and tomato spotted wilt. Members of the mallow family are also susceptible to bacterial leaf spot, gray mold, and phytophthora blight. Aphids and spider mites are the most common pests. If you grow hollyhocks and okra, you may want to keep them at a distance from each other, to prevent the spread of disease. Finally, the marshmallow plant (Althaea officinalis), a native herb of Europe, is a member of this family and its roots were used to make marshmallows some 4,000 years ago in Ancient Egypt. Today, marshmallows are made out of sugar and gelatin. There’s more to the grass family than just your lawn. Grains and grasses (Poaceae) have long been a part of home gardens, landscapes, and agricultural fields. This group is the fifth-largest plant family and it includes cereal grains, bamboo, lemongrass, and sugarcane. Let’s see how these plants are all related and how many of them may be good additions to your garden. To start, members of this group are usually divided into grasses and cereal grains. Grass plants Grasses are monocots with fibrous roots and hollow stems, except at the nodes. They have narrow leaves that appear alternately up the stem. Each of those leaves wraps around the stem, creating a leaf-sheath, rather than growing out of a petiole. Very often, you will see a fringe, called the ligule, where the sheath meets the stem. This growth is believed to keep water and pests from entering. It can also be used to help with plant identification. Grass plants reproduce most commonly by seed, though some use rhizomes to create daughter plants, known as tillers. Grain seeds are encased in simple dried fruits called caryopses. Flowers of the grass family tend to form spikelets. These plants can be annuals or perennials, depending on the species. Unlike most other plants, the meristem tissue [think undifferentiated stem cell] of grass family plants is found near the base of the plant, rather than higher up. This allows the plants to recover from grazing (and mowing). These plants are all heavy feeders that use a lot of nitrogen. Planting them in blocks, rather than rows, increases pollination. Cereal grains Cereal grains are classified as warm-season or cool-season cereals. Corn, millet, and sorghum are warm-season cereals that need lots of sunlight and heat to thrive and are better able to withstand drought. Cool-season cereals include barley, oats, rice, rye, spelt, wheat, and wild rice. Many people consider amaranth, buckwheat, and quinoa to be cereal grains, but they are not. Instead, these are all broadleaf (dicot/eudicot) plants known as pseudocereals. Other seeds that are not grains include lentils, peas, and other legumes. And that “recreational/medicinal” grass? It’s not a member of this family either.
Grass family pests and diseases Grains and grasses are prone to fungal diseases, such as leaf scald, leaf spot, net blotch, stripe rust, and stem rust. Along with grasshoppers and crickets, and other common pests, this family battles crane flies, stinkbugs, and wireworms. Also, aphids may carry a viral disease called barley yellow dwarf. Your average lawn grass has a root system that only goes down a few inches. Other grass plants have roots that can go down 5-10’ or more. So, how about making a little room for a patch of grain? As a food crop, I expect that it will be much like endive, nasturtiums, lentils, and tomatoes—it will continue to turn up long after I have stopped planting it. The grain and grass family provides 51% of all human dietary energy. How much space does it get in your garden? You know how some families seem to be filled with troublemakers and then one offshoot ends up being helpful? Well, stink bugs are the same way. Most of them will suck the life out of your flowers, fruits, leaves, and young seeds. One, the rough stink bug, will eat caterpillars and leaf beetle larvae along with plants. But a few are full-on predators who feed on several different garden pests. Sadly, they also prey on bees and Monarch butterfly larvae. [They are members of the stinker family, after all.]
Anchor stink bugs (Stiretrus anchorago) are from Central and North America. They occur in several different color variations, ranging from black, white, and tan, to orange or red and black, to green and yellow. Florida predatory stink bugs Found predominantly in the southeastern U.S., Florida predatory stink bugs (Euthyrhynchus floridanus) hunt grasshoppers and other garden pests. They go after these larger insects by hunting in packs of up to twelve individuals. These bugs are just under ¾” long and bluish-black or purplish-brown with red rear ends with black markings, though they also come in a variety of colors. They have sturdier snouts than their sap-sucking cousins. Giant strong-nosed stink bugs The giant strong-nosed stink bug (Alcaeorrhynchus grandis) is found in South and Central America as well as in southern U.S. states. These bugs can be nearly 1” long and they have two distinct points on their backs. They tend to be variegated brown with dark bands on their legs and dark spots on their bellies. Some individuals are red with black leg bands. Unlike the smaller egg clusters of other stink bugs, the giants lay eggs in masses of 100-200 eggs. Nymphs have a bluish-black thorax and red abdomens with dark stripes. Spined soldier bugs Spined soldier bugs (Podisus maculiventris) are found throughout North America. They prefer feeding on the larvae of cabbage loopers, Colorado potato beetles, diamondback moth caterpillars, European corn borers, flea beetles, gypsy moths, imported cabbageworm larvae, Mexican bean beetles, and velveteen caterpillars, so count yourself lucky if you have these hunters in your landscape. You can even buy spined soldier bugs eggs to add to your IPM program. As you search your garden for stink bugs, with a bucket of soapy water in hand, keep in mind that not all of them are bad. Sorting between beneficial and pest stink bugs is made a little easier because many predators tend to be more brightly colored and patterned.
Which types of stink bugs have you seen? Red-shouldered stink bugs may invade your home as well as your garden. Red-shouldered stink bugs (Thyanta custator) use their piercing mouthparts to suck the juices from your almonds, apples, beans, corn, peaches, pears, pistachios, tomatoes, and wheat. Their feeding can cause cat-facing and corky fruit, as well as provide points of entry for other pests and diseases. And, of course, they poop on those crops, too. Red-shouldered stink bug identification Adult red-shouldered stink bugs are primarily green but can be brown, with a pinkish edge along the scutellum (just behind the head). That pink edge can be very dark and noticeable, barely present, or missing entirely. They have long antennae (for a stink bug) and, if you flip them over, you will see some of them have black spots on the abdomen. Nymphs are brownish, with tribal-like designs on their backs. Adults and nymphs average 1/3” in length. Eggs are gray, round to barrel-shaped, and flat on top. Red-shouldered stink bug lifecycle Tiny eggs are generally laid in clusters on plant stems and the underside of leaves. When those eggs hatch, nymphs start feeding on developing seeds and young leaves, buds, and flowers. As they mature, their diet expands to include all those crops mentioned earlier. Then, as temperatures begin to drop, they start looking for a place to overwinter. That winter wonderland may be in mulch, plant debris, or your living room. Similar to ladybugs, red-shouldered stink bugs are notorious for invading homes in autumn. And don’t try vacuuming them up or your vacuum will stink. Instead, invert a plastic bag over your hand, pick those little suckers up, and drop them into a container of soapy water. The same method works outside in the garden, as well.
Stink bugs can smell pretty bad. Even my hens turn up their beaks when one crawls by, so it’s up to you! When I say ‘stink bug’, you probably think of a green or brown shield-shaped bug, and you’d be right. But Say stink bugs (Chlorochroa sayi) can be such a dark green that they look nearly black with orange edging in winter. Then they switch to bluish-green with white edging in summer. This pest is native to western North America, but its range is expanding. Say stink bug identification and lifecycle These are large bugs, averaging ¾” in length. While in their green phase, adult Say stink bugs also have three light spots near where their shoulders would be, if they had shoulders. You may also see a white or pink spot just above where the wings emerge on nearly mature nymphs. Females lay clusters of 30 or so white, barrel-shaped eggs on plant material. Those eggs hatch into nymphs. At first, those nymphs stay clustered together for a few days before dispersing in search of tender flowers and germinating seeds. They also eat young leaves. Nymphs are smaller and softer than adults and do not have wings. They go through several developmental stages, or instars, before reaching adulthood. There can be up to three generations each year, depending on the length of the growing season. Say stink bug damage
Despite their fascinating wardrobe changes, Say stink bugs are much like other stink bugs. They emerge from leaf litter and ground cover in early spring, feeding on mallow, mustards, Russian thistle, and other favored weeds until your garden starts happening. They then move in, feeding on all those seeds you just planted. They especially like members of the grass family, which means alfalfa, barley, corn, millet, oats, rye, and wheat are all at risk, as well as your lawn. Then they go after your beets and tomatoes. Especially tomatoes. Using piercing mouthparts to suck the juices from your plants, Say stink bugs may also introduce yeasts that cause fruits to rot. Say stink bug management Removing weeds is one way to make your garden less inviting to Say stink bugs. Avoiding the use of broad-spectrum pesticides will encourage beneficial parasitic wasps and tachinid flies. And, as much as I dislike pill bugs, they do eat stink bugs eggs. At the end of autumn, remove over-wintering sites by composting leaf litter and other dead plant material, rather than leaving them in place. Have you seen Say stink bugs in your garden? Let us know in the comments! Green stink bugs are probably the easiest to spot in mulch and wood piles and one of the hardest to see among your plants. Common green stink bugs (Acrosternum hilare and Chinavia hilaris), also known as green soldier bugs, are bright green with red, orange, or yellow edges. One oddball is bright orange! Adults are ½ to ¾ inches long. Nymphs have bright dark bodies with orange edges near the front and yellow on the back. Barrel-shaped eggs are laid on the underside of leaves in double rows of twelve or more eggs. Eggs are also commonly found on the stems of salvia. A smelly subject Stink bugs get their name because they can smell bad. Both adults and larvae have large stink glands. When they are disturbed, they spew those smelly chemicals to deter potential predators. [Generally speaking, even my hens avoid them, which is a shame when you consider all the damage they can do.] Green stink bug damage Green stink bugs are found throughout North America. Using their piercing mouthparts, they damage a wide variety of garden and tree crops. The juicy fruits of apple, cherry, orange, and peach trees are common targets, leaving behind a trail of corky fruits prone to fungal diseases and other problems. As green stink bugs mature, they shift their focus to the seeds, stems, and leaves of beans, corn, eggplant, peas, soybeans, and tomatoes. Green stink bug lookalikes Green stink bugs are differentiated from southern stink bugs (Nezara viridula) by their black outermost antennal segments. There is one other green stink bug, Chinavia pensylvanica (no common name), found rarely in Maryland. That species has a more arched back (if you’re into that sort of thing). Green stink bug control Tachinid flies and parasitic wasps will lay their eggs in green stink bug eggs to provide a handy meal for their young, but there are often not enough of them to control a bad stink bug problem. Pheromone traps can be used, as well, but those traps attract pests which I find counterproductive. Those traps are used more effectively as monitoring tools. As with other stink bugs, the best control methods are being alert and handpicking. If you drop stinkbugs into a container of soapy water, the smell isn’t a problem.
We've already discussed invasive brown marmorated stink bugs and native Uhler's and rough stink bugs, but there are more than 4700 species of these shield-shaped pests worldwide and over 200 species in North America. Consperse stink bugs (Euschistus conspersus) are one of those. Stink bug damage
Nearly all stink bugs are sap-sucking pests. I say ‘nearly’ because stink bugs are omnivores and there are even some predatory stink bugs. We’ll get to them another day. Stink bugs suck the life out of buds, fruits, leaves, and stems. Damage caused early in the growing season can lead to cat-facing later on. If you find corky areas underneath the skin of fruits, it was probably stink bug feeding. Being omnivores, stink bugs also eat pesky beetle and caterpillar larvae, so they aren’t all bad. I still don’t want them in my garden. Consperse stink bugs, in particular, love apples and pears over everything else. They are also fond of almonds, blackberries, mustards, and many vegetables, including beans and tomatoes. Damage is worst during dry summers. Consperse stink bug identification Adult consperse stink bugs are ½” long and have greenish-gray to pale brown shield-shaped bodies, yellow underbellies, yellow to orange legs, and red antennae with darkened tips. You may also see alternating dark and light bands around the edge, or margin, of the upper shield. Nymphs can range from white to black with reddish markings. As they mature, they turn brown with black markings. White, barrel-shaped eggs are laid in clusters on leaves and twigs, and turn pink before hatching. Consperse stink bug lifecycle Like other native stink bugs, consperse overwinter in groundcover, emerging as soon as there are tender young weeds and other host plants to eat. Eggs can hatch in less than a week and nymphs can reach adulthood in a little over two months. Female consperse stink bugs lay an average of 225 eggs, but one researcher saw those numbers go as high as 640! This is why it’s so important to eliminate them as soon as you see them. Consperse stink bug management Consperse stink bugs eggs are often eaten by ants, earwigs, damsel bugs, and adult stink bugs. Except for predatory damsel bugs, most of us don’t want the rest of those critters in our gardens any more than necessary. There are commercially available pheromone lures that work to limit stink bug populations. Combined with sticky cards, these lures can be very effective. Keep in mind, however, that pheromone lures attract pests. Your best control measure is to be on the lookout and stomp any you see. Yes, they do stink when threatened or squashed, but it’s a small price to pay to protect your crops. Are damaged areas on tomatoes due to dehydration, deficiency, or disease? Is it blossom end rot, sunscald, or buckeye rot? And what can you do about it? Let’s look at all three in more detail so you will know what to do if you see damaged areas on your tomatoes or peppers.
If there isn’t enough water to move the calcium to where it is needed, cell walls surrounding the blossom end of the fruit will collapse, creating a uniformly dark brown or black area ONLY on the lower sidewall or blossom end of the fruit. If you see blossom end rot, irrigate more heavily and more often. If the damaged area is lighter in color and higher up the side of your fruit, it may be sunscald.
Buckeye rot symptoms
Buckeye rot is a disease caused by three Phytophthora: P. capsici, P. drechsleri, and P. nicotiana var. parasitica. Phytophthoras are water molds (oomycetes) responsible for several plant diseases. This disease occurs most often after extended periods of warm, wet weather with temperatures ranging from 75°F to 86°F. Buckeye rot can infect tomatoes, peppers, and eggplant. Pineapples, potatoes, and tobacco are also vulnerable to buckeye rot. At first, all you may see are smooth, grayish-green water-soaked spots. Damping off and stem cankers may also appear. As the disease progresses, those lesions turn into the classic bull’s eye pattern of large, concentric rings alternating between light and dark brown. The edges of these lesions will be smooth but not clearly marked. Eventually, white fungal growth becomes visible on the lesions. Other diseases that may exhibit similar symptoms include anthracnose, cucumber mosaic virus (CMV), and late blight. In each case, some differences can help you diagnose the problem:
Buckeye rot management Starting with healthy, disease-free seeds and plants is the first step toward preventing nearly all plant diseases. Buckeye rot spores can travel on seeds, transplants, clothing, and garden tools. Spores can also be splashed onto healthy plants by rain and overhead watering, so use soaker hoses or water at ground level and allow the soil surface to dry out between waterings. Mulching around plants can reduce the splash effect, as well as reduce weeds and evaporation. You can reduce the chance of many fungal diseases by providing good drainage and reducing soil compaction. Since buckeye rot spores are in soil, fruits closer to the ground are the first affected. If fruit is held up high with stock panels, tomato cages, or trellising, you can reduce the likelihood of buckeye rot. Three-year crop rotations also help prevent buckeye rot. Now you know. Touted as a miracle soil amendment, what’s true about rock dust and what’s not? Also known as mineral powder, rock flour, rock powder, rockdust, or stone powder, and soil remineralizer, rock dust is what’s leftover from mining and quarry work. This finely pulverized material claims to contain important plant nutrients, “enhance the ability of beneficial microbes to flourish”, improve plant structure, increases water retention and resistance to pests and disease, and create “intense flavor profiles for fruits and vegetables”. Wow. That sounds pretty important and impressive, doesn’t it? While it’s certainly true that plants need nutrients to grow and thrive, let’s see what research says about those claims. We can start by learning what, exactly, is in that bag of rock dust. What is rock dust?
The contents of your rock rust shipment will depend entirely on where it was mined. It may contain a lot of calcium. Or none. The same is true for other minerals. That being said, on average, rock dust contains significant amounts of aluminum, silicon, and sometimes iron. It may also contain copper, magnesium, manganese, potassium, sulfur, and zinc. But does your soil need these elements? Without a lab-based soil test, you really can’t be sure. Your rock dust may also contain toxic levels of aluminum, arsenic, cadmium, chromium, copper, lead, nickel, and sodium. Believe me when I tell you that dealing with toxic levels of nutrients is a lot harder and takes a lot longer than adding missing nutrients. I’m speaking from experience. If you do nothing else for your garden this spring, get your soil tested before you add anything. Big batch or specific sediments? If your soil is low on a certain nutrient, rather than relying on luck, you can order specific types of rock dust. If you know your soil is low in something, you can apply crushed versions of that nutrient in the form of rock dust. Of course, it costs more that way. The nice thing is, it is an organic method of fertilizing your plants. Making rock dust work for you If you decide to apply rock dust, combining it with nutrient-rich organic matter, such as aged compost or manure, creates a slightly acidic environment more likely to break down the dust into bits small enough to be carried by irrigation water into your plants. What rock dust is not Because it does not contain significant levels of nitrogen, phosphorus, or potassium, rock dust is not a fertilizer. Bottom line, in my opinion, rock dust is best left to commercial growers who regularly deplete their soils through heavy use and often have a fleet of chemists, soil experts, and lab technicians on hand to determine what’s needed and what’s in each particular load of rock dust. |
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