Tattered leaves, distorted flowers, and corky fruit may indicate capsid bugs.
Capsid bug identification
There are several capsid bug species, but they all have one thing in common: a triangle on their back. Capsid bugs can be green or brown and up to ¼” long. They fold their wings over the abdomen. The 2/3 of the wings closest to the body are darker and thicker-looking. The outer third is translucent, showing a diamond-shaped area on the insect’s rear end. Nymphs are pale green and wingless.
Some of the more common capsid bug species include:
Capsid bug hosts
Capsid bugs feed on many different flowers, including butterfly bush, chrysanthemums, clematis, dahlia, fuchsia, hydrangea, roses, and salvia. They can also be found on apples, beans, and pears. Some capsid bugs are predators.
Capsid bug damage
Early capsid bug damage is easy to overlook. What starts as several small leaf holes can transform into something that looks like gale force shredding. Leaves growing near shoot tips may also be misshapen with several small, brown-edged holes. Flowers often become distorted. Apples and pears develop corky growths where capsid bugs fed on them during their early development. These bits can be cut off. The rest of the fruit is fine.
Capsid bug lifecycle
Capsid bugs are true bugs, which means they have mouthparts designed for piercing and sucking. These pests are active in late spring through summer. They lay their eggs in the bark of twigs and branches. Those eggs hatch in spring. Except for the tarnish bug, which overwinters as an adult. Depending on the species, there can be one or two generations each year.
Capsid bug management
Minor capsid bug infestations can be ignored. The threat of capsid bug feeding can be reduced by planting resistant cultivars. Capsid bug management starts with monitoring susceptible plants, starting in spring, and removing weeds from around those plants. At the end of the growing season, remove plant debris from around these plants, as well. This eliminates hiding and overwintering places for capsid bugs.
Birds and ground beetles eat capsid bugs, so making the garden safe and appealing for them will help. Severe infestations can be treated with summer oils, neem oil, or pyrethrum [not pyrethroids].
It would be nice to think of spotted lanternflies as Asian equivalents to our gentle fireflies of summer evening fun, but that would be a mistake. According to Penn State, lanternflies “could be the most destructive species in 150 years.”
Native to China and India, invasive spotted lanternflies (Lycorma delicatula) were first detected in the U.S. in 2014. But it appears they snuck in on shipments of stone, woody plants, firewood, wood products, landscaping materials, and outdoor furniture two or three years before that. [Why in the world we are shipping stones from China is beyond me…]
Today, spotted lanternflies occur in several states, and they threaten gardens and farms everywhere. There are also serious concerns about our nation’s forests.
Crops vulnerable to spotted lanternflies include apple, cherry, chestnut, grape, hops, nectarine, peach, pear, plum, and walnut. Vulnerable ornamentals include birch, maple, pine, poplar, and rose. Its favorite host is the tree-of-heaven (Ailanthus altissima), also known as Chinese sumac, and varnish tree (because of its stinky odor).
There may be more plants at risk. We don’t know yet. What we do know is this—we need to report these pests every time. Let’s learn how.
Spotted Lanternfly identification
As far as bugs go, spotted lanternflies are rather pretty. They are large, mothlike bugs, approximately one inch long and an inch-and-a-half wide. Adults have a black head and grayish-brown forewings with black spots. The plump abdomen is yellowish with black and white stripes. If you see one in flight, you’ll see that they have red underwings and a white triangle in the middle of the wing. Their hindwings have a brick-and-mortar pattern around the edge of the wings.
Spotted lanternfly lifecycle
Yellowish-brown eggs are laid in inch-long, rectangular masses on stones, smooth-barked trees, or other vertical surfaces. These egg masses are covered with a gray or yellowish-brown waxy coating and are referred to as egg cases. Each cluster contains 30–50 eggs. In spring, the eggs start to hatch. Wingless nymphs go through several developmental stages, or instars, before reaching adulthood. The first instar is black with white spots. As they develop, red spots become visible. In the final instar, the upper body is red, and you can see red wing pads if you look closely. These spotted lanternfly nymphs crawl or hop to feed on a wider variety of plants than adults. I guess as they mature, their taste buds change.
By midsummer, adults are actively seeking mates and wreaking havoc in gardens, fields, and orchards. While lanternflies can fly, they seem to prefer jumping. Eggs are laid starting in autumn and ending as winter arrives. Late season eggs overwinter unseen, and the cycle begins again in spring.
Spotted lanternfly management
Because this pest is new on the scene, there is a lot we don’t know. While spotted lanternflies have natural enemies in China, that may not be the case elsewhere. At this point, the Pennsylvania Department of Agriculture makes the following recommendations:
There may still be time to eradicate spotted lanternflies from North America, but only if we all keep our eyes open and report any sightings.
I can’t stress this enough: if you see a spotted lanternfly, catch it, kill it, and report it to your local County Extension Office or Master Gardeners.
Bright yellow, red, or purple leaves may indicate beet western yellows, though this plant disease is not limited to beets or the west.
Found around the world, the beet western yellows virus is responsible for significant losses in many different crops. Unfortunately, free-to-use photos are not as readily available. You can search online to see what this disease looks like.
Beet western yellows host plants
This disease occurs on over 250 plant species, including beets, broccoli, cabbage, canola, cauliflower, chickpeas, endive, escarole, fava beans, lentils, lettuce, mustard, peas, peppers, radish, spinach, sunflowers, tomatoes, turnips, and oilseed rape. Oilseed rape is a member of the cabbage family grown for its oily seeds and as food for livestock.
It can also occur on annual phlox, bee’s friend, false flax, and lupine. Weeds that harbor beet western yellows include chickweed, common groundsel, prickly lettuce, little mallow, shepherd’s purse, sowthistles, and pennycress. [Even though it is a weed, pennycress is commonly used to salvage toxic soil through phytoremediation.]
Beet western yellows virus symptoms
Symptoms of beet western yellows infection vary depending on the affected species. To complicate matters, there are multiple strains of this virus, which can make diagnosis tricky.
Most plants infected with BWYV don’t show any signs at first. Then red, blue, purple, or black discolorations that start at the tips and edges of leaves appear. Eventually, the entire leaf turns bright yellow or orange. Petioles and veins remain green or may be pale. Infected leaves feel thick and brittle, and they may curl upward. Stunting is common and leaf crinkling may occur. These symptoms often look similar to iron or nitrogen deficiencies, or chemical overspray.
Beet western yellows virus management
Beet western yellows virus is a luteovirus. Luteoviruses are spread by aphids. Specifically, green peach aphids and wheat aphids, though other aphid species are involved. So, the best way to prevent and manage beet western yellows is to control aphids and eliminate rouge host plants.
Also known as turnip yellows and turnip mild yellows, resistance to this disease is indicated on plant labels with the letters TuYV, BWYV, and TuMYV. Buying resistant plants makes your job a lot easier.
Avoid planting too early in a season as this can make plants more vulnerable to beet western yellows. Infected plants should be tossed in the trash.
There are no chemical controls for viruses (yet).
Asian bean thrips were first seen on US soil in March 2020, in Florida. Native to tropical Asia, this pest now ranges from Japan to Australia. And in March of 2021, it was found in Central America, in Belize. It’s probably only a matter of time until it spreads to our gardens, so let’s see what we’re up against.
Asian bean thrips damage
Asian bean thrips (Megalurothrips usitatus) suck the sap out of snap bean, cowpea, lima bean, peanut, and soybean plants. And potatoes. They also feed directly on host plants. This feeding usually begins in the flowers. Pods and growing tips become deformed and twisted, with streaks of russeted reddish-brown where thrips feeding has occurred. Heavy infestations can cause stunting, wilting, and poor pod set. In China, Asian bean thrips are responsible for crop losses of 30% to 100%.
Asian bean thrips identification
To me, Asian bean thrips look like hoverflies with pointy rear ends. They are very small. You could almost fit 10 females across the face of an American dime. Males are only half that size. Size isn’t the only difference. Females are black, with yellow or white bands. Their wings are banded, too. Males are yellow, with a similar but less defined banding pattern. Both males and females have black antennae with white bands. Larvae start yellow but turn red as they near adulthood.
Asian bean thrips lifecycle
These pests love warm weather and they can complete their lifecycle in as little as 10 days. Eggs are inserted into flowers, leaves, and pods. After hatching, larvae go through two molts over 2 or 3 days before dropping to the ground to pupate. Pupae seem to prefer moist, sandy soil, so they probably won’t feel welcome on my sun-scorched clay, but I’ll still keep a lookout. Just in case.
Adult Asian bean thrips feed on pollen, mate, and lay eggs. If no mate is available, they can reproduce without them. This ability is called parthenogenesis and it is why aphid populations can seem to explode overnight. I can only imagine that Asian bean thrips populations can do the same thing.
Asian bean thrips management
Since this invasive pest is new to North America, we’re not really sure what we’re up against. Many beneficial insects eat thrips, but we don’t know their efforts will be enough. We’re not even sure if those garden helpers like the taste of Asian bean thrips. All we can do is hope.
Actually, we can also remove plant debris once a crop has finished its cycle. Adding that plant material to the compost pile may help reduce hiding places for this new pest. Since thrips, as a group, are known to develop resistance to pesticides rather quickly, chemical sprays are not recommended. My guess is that mechanical control methods, such as diatomaceous earth (DE) and sticky barriers may help. They can’t hurt.
If you think you have Asian bean thrips in your garden, try to catch one or take a picture and reach out to your local Master Gardeners, County Extension Office, or Department of Agriculture. Those groups work hard to protect our gardens from invasive pests, and we can help them with any information we might have.
Chubby, round peas, tearing through your garden without their pods is not pea streak, but it conjures a cute image, doesn’t it?
Unfortunately, there isn’t anything cute about this viral disease. [And I couldn’t find a usable image, sorry about that.] Pea streak virus (PeSV) is spread by aphids. The virus responsible for pea streak also causes chickpea wilt.
Aphids infected with the pea streak virus often hide out in alfalfa, clover, and other perennial legumes.
Pea streak symptoms
Stems of infected plants develop dark brown, gray, or purple longitudinal streaks. These streaks are similar to those caused by alfalfa mosaic and bean yellow mosaic. When plants have been infected by pea streak, you will also see deformed pods with sunken areas. Pods do not fill out properly and leaves wither and die. Dieback starts at tips all around the plant and moves inward, toward the center.
Pea streak management
All you can do for infected plants is remove them and toss them in the trash. You can reduce the likelihood of pea streak occurring in your garden by starting with certified disease-free seeds and seedlings and, removing potential hideouts. Control aphids as well as you can. There are no chemical treatments for pea streak.
Have you been enjoying fresh, crisp beans from your garden lately? It amazes me how prolific these plants can be, providing fresh beans for dinner practically every day of summer. Except sometimes things go wrong. Sometimes bean plants start to turn yellow. It’s normal for lower, older leaves to turn yellow and fall off. It’s not normal when entire plants start turning yellow.
Bean leafroll virus (BLRV) goes by many other names: chickpea stunt virus, pea leafroll virus, legume yellows virus, and pea yellow top virus are just a few. This disease is caused by a luteovirus. Luteoviruses are spread by aphids. Infected plants to turn yellow. And bean leafroll virus attacks more than just peas and beans.
Once found only in peas and beans, this disease has spread to include alfalfa, chickpeas, lentils, soybeans, and many other legumes. It can also occur in clover and vetch.
Bean leafroll virus symptoms
Plants infected with bean leafroll virus turn yellow, and the leaves curl. If you look closely, you will see that the chlorosis is occurring between the leaf veins. Stunting is common. These symptoms look very similar to beet western yellows virus (BWYV) and nutrient stress. Symptoms can vary between species. In addition to these symptoms, these species-specific symptoms may occur:
There can be a 50% to 90% reduction in pod production due to bean leafroll virus. In some cases, symptoms may appear and then fade away. This can be a problem since the plant is still infected and any aphids that feed on it can then spread the disease to neighboring legumes.
Bean leafroll virus management
The best way to reduce the chance of bean leafroll occurring in your garden is to control aphids —easier said than done, I know. While you can dislodge aphids with a strong spray from your garden hose, not all plants take kindly to that sort of treatment. Neem oil and insecticidal soaps are organic methods of aphid control.
Removing other host plants, such as burr medic and subterranean clover, can help reduce the spread of this disease. Since aphids and aphid eggs are easily brought into your landscape on other plants, putting new plants into quarantine is always a good idea.
There is no treatment for bean leafroll virus. Infected plants should be removed and thrown in the garbage. Resistant varieties are being developed, so keep a lookout for plants labeled with BLRV. Finally, rotating your legumes with cereal crops, such as barley, corn, millet, or oats can help break the disease cycle.
There are two types of torus in the plant world. One is related to flowers, and the other is a donut-shaped plug that protects plants when they cavitate.
The donut-shaped plug variety occurs within the xylem. The xylem is part of the vascular bundle that pulls water from the ground. The torus found within the xylem protects plants from cavitation. Cavitation occurs when the water pressure within the plant is greater than the atmospheric pressure outside the plant. You can hear it happening to trees in summer. It sounds like a large crack. Cavitation causes sap to vaporize, creating embolisms. The torus, held within a pit called the torus-margo structure, acts as a plug. This plug reduces the spread of the embolism.
Flowering plant torus
The place where a stem meets a flower is called the torus, or receptacle. The torus is the thickened part of a stem from which flowers emerge. Accessory fruits, such as apples and strawberries, grow from the torus. And it is the way you can tell blackberries from raspberries! That mammoth sunflower head? It’s a torus, too.
Types of flowers
The torus is found at, below, or surrounding a plant’s reproductive organs, depending on the species. Flowers can be hypogynous, perigynous, or epigynous. Don’t let the words scare you off. The -gynous part of these words means it refers to the Lady Parts of your plant. Stamens and petals are below the ovaries (or gynoecium) of hypogynous flowers. They are at the same level in perigynous flowers. The ovary is enclosed in the torus of epigynous flowers, with the petals and other parts above. You can use this information to help identify plants and win at Scrabble.
Raspberry or blackberry?
Do you know how to tell blackberries and raspberries apart? It’s not the color. There are black raspberries and red blackberries. The only way to tell the difference between blackberries and raspberries is to look at the way the fruit comes away from the torus.
If the torus comes with the fruit, it is a blackberry. If the torus breaks away from the fruit, it is a raspberry.
Now you know.
I was so inspired by Linda King’s guest post, Gardening With Nature, that I decided to transform my backyard lawn into a meadow, as well.
Living in California, the first, most obvious reason for shifting a lawn to anything else is water conservation, but there are several other reasons to let nature take its course. Within reason.
For many years I thought California was called the Golden State because of the gold mining. It ends up that the name refers to the hillsides turning a golden brown as everything dies in the scorching heat. My lawn was no exception. My normal summer landscape is green where I water it and brown where I don’t. Until July. By that time, most of the lawn is brown no matter what we do.
We made every attempt to make our lawn look like a golf course. In California, that’s pretty unreasonable when you consider how much water a lawn takes. No matter what we did, the scorching summer sun would burn our green grass to a crisp. We watered. We edged and weed-whacked. We mowed. We aerated. We altered the pH and added missing soil amendments after a lab-based soil test told me my soil had no iron and too much of everything else. For 2–4 weeks of the rainy season, we have a beautiful lawn. That’s in February. The rest of the year has been a struggle. After reading Linda’s post, I decided what the heck. We stopped mowing. We stopped edging. We pretty much left it alone. What happened surprised us. Before I tell you what happened, let’s find out more about meadows.
What is a meadow?
Meadows are open habitats that feature grasses, herbs, and other non-woody plants. There can be occasional trees or shrubs, but the main idea is an open field. Traditionally meadows were used to grow hay for livestock. The word meadow comes to us from the Old English mǣd, which came from the Germanic word for mow.
Returning to our open field concept, meadows feature a variety of plants. This means there can be all sorts of flowers, seeds, and vegetation occurring at the same time, changing with the seasons. This makes food and habitat available to many amphibians, birds, insects, and reptiles that see lawns as desolate, unforgiving landscapes.
Types of meadows
I never gave it much thought before. It ends up that there are different kinds of meadows. They can be agricultural, transitional, perpetual, or urban. Agricultural meadows are those we mentioned earlier that are allowed to grow on their own to produce hay for livestock. Agricultural meadows are similar to pastures except that pastures are grazed during the summer and meadows are not.
Transitional meadows are more of the wild and woolly type. They are not mowed or grazed. They are just left to flower and go to seed. Transitional meadows generally do not last long.
Perpetual meadows occur naturally in a variety of environments. Alpine, coastal, desert, prairie, and wetlands are the primary types but there are others. Perpetual meadows reach a point of balance, an equilibrium that we can rarely replicate. Which leads us to urban meadows.
Urban meadows are the ones we create. Urban meadows are gaining in popularity as we learn more about the importance of biodiversity and least harm to the environment. As honey bee and monarch butterfly populations decline, many other creatures are at risk due to habitat loss. Urban meadows allow pockets of natural habitat to co-exist along with our driveways, air-conditioners, and patio furniture.
I live across the street from a park. This means seeds (and trash) are blowing in all the time. I used to see those seeds as weed sources. Now I recognize that they are the plants that grow in my yard without any help. In less than two weeks, seed heads have started appearing in what used to be my lawn. Goldfinches, Black Phoebes, California Towhees, and other birds I have yet to identify are now visiting my yard regularly. There are more butterflies, lacewings, and hoverflies, too.
Hiding under a self-watering container now lives a tiny lizard I affectionately refer to as Little Buddy. Little Buddy is the offspring of an alligator lizard that lives near one of my raised beds. I hope they stay.
The grass that was struggling is now 4” tall and still green. It’s even putting out seeds of its own. There are still brown patches but I expect they will be filled with herbaceous plants without any effort on my part at all. That doesn’t mean I’m completely off the hook by having a meadow. Urban meadows may not require watering, fertilizing, mowing, or edging, but you do need to be vigilant about invasive plants, unwanted weeds, such as foxtails, and disease.
Instead of a manicured (temporary) lawn, I now have a softer, richer environment that features more variety and takes less work. I’ll probably toss out some native flower seeds just to see what happens. Instead of working my lawn, I can now sit back and enjoy watching my meadow.
Pepper mild mottle virus (PMMoV) is not the same as pepper mottle (PepMoV or PeMV). This member of the tobacco mosaic virus family has been linked to tomato mosaic virus. Unlike pepper mottle, pepper mild mottle does not affect eggplant or tomatoes. This is a peppers-only disease (we hope).
Pepper mild mottle symptoms
Like many other diseases, pepper mild mottle causes stunting and chlorosis, or yellowing of the leaves. It also causes distorted and lumpy fruit, leaf curling, and streaking (not the 70’s kind). These symptoms will vary depending on the species and cultivar.
Pepper mild mottle management
The virus that causes pepper mild mottle occurs around the world. It is the most abundant RNA virus found, I beg your pardon, in human feces. It ends up that we are the Number One carriers of this disease. Just as livestock manure can carry many pathogens, such as E. coli, our own waste can, too. This virus also moves around on our clothing, tools, and skin. There is some suspicion that this virus can also cause disease in people, but more research is needed. Whether it hurts us or not, it can be devastating to your pepper plants.
This pathogen thrives in heat and humidity. This makes it a common problem in greenhouse environments. Once in an area, these viruses can enter plants through wounds and other damaged areas. This disease is very contagious in the pepper world and the virus is very stable. This means it remains viable on tools, containers, structures, and plant debris for a long time.
Once a plant is infected with pepper mild mottle, it must be destroyed. Pull it out and throw it in the trash. Do not add it to the compost pile and do not burn it. These viruses are so tough that they can travel on smoke! And wash your hands.
Commercial growers used to apply methyl bromide as a pre-plant treatment. That nasty chemical has been banned in most countries. One Japanese study has found soil rich in humus is less likely to harbor the pepper mottle virus, so keep mulching and composting. Crop rotation is a good idea, too.
The best way to prevent this disease is to only use certified disease-free seeds and seedlings.
Pepper mottle affects more than peppers. This viral disease infects eggplants, groundcherries, potatoes, tomatillos, and tomatoes. Especially tomatoes.
First identified in an Arizona Tabasco pepper in 1969, pepper mottle is a type of Potyvirus, similar to potato virus (PVY). It has since been found in several states and countries. Also known as chili mottle virus and pepper mottle potyvirus, this is not the same disease as pepper mild mottle, which we will discuss tomorrow.
Pepper mottle symptoms
Pepper model symptoms vary by the species infected and the age of the plant at the time of infection. Initially, peppers will show vein clearing, which later shifts to dark vein banding, mottling, crinkled leaves, and deformed fruit. [Unfortunately, I was unable to find a photo that I could use.]
Tomatoes have similar leaf and stem symptoms, but the fruit ripens unevenly with green, orange, and yellow areas that never fully ripen. Infected plants are stunted and produce significantly less fruit. Diagnosis can be difficult because pepper mottle often occurs at the same time as other infections and can look a lot like cucumber mosaic.
Pepper mottle management
The pepper mottle virus is spread by aphids. Those aphids are likely to hide out in weeds from the nightshade family. This disease can also be spread mechanically by working with an infected plant and then moving to a healthy plant.
To reduce the chance of pepper mottle in your garden, remove Datura and other nightshade weeds and any rouge tomatoes. [I know, it’s hard to get rid of volunteer tomato plants. But they very often harbor diseases so add them to the compost pile and focus on the ones you planted on purpose.]
Garden tools can carry the virus, so it’s a good idea to sanitize them between plants any time disease is suspected. Bathroom cleaners work well. Control aphid populations with horticultural oils and insecticidal soaps.
When shopping for seeds and seedlings, investing in certified pest- and disease-free plants can save you a lot of time and effort later in the growing season and future years. Some pests and diseases can stick around for a very long time. Resistant varieties are being developed. When shopping for plants, look for the PepMoV or PeMV on plant labels.
Yellow, orange, or green shoulders on tomatoes is a common disorder that can be prevented.
Yellow shoulder, also known as greenback and green shoulder, appears as discolored areas on the tops of tomatoes. These discolorations are commonly yellow, orange, or green. Unfortunately, these discolorations enter the fruit as well. Fruit affected by yellow shoulder tends to be hard, white, and tough. Not exactly what you expect from a sun-ripened tomato. Despite what everyone says, extreme sunlight is not what causes yellow shoulder. It will cause sunscald if there isn’t enough leaf cover.
When scientists tried to figure out yellow shoulder, what they found was the normal red, neatly arranged cells of a healthy tomato became significantly smaller and erratic. The chlorophyll in these deformed cells failed to turn red. This is bad news in the world of tomato growers, so they set out to find out what was going on.
What causes yellow shoulder?
I would love to say that the solution is simple. Most garden gossip says that high heat and too much sunlight are the cause of yellow shoulder, but that’s not it. Research has shown that yellow shoulder is triggered by insufficient potassium, too much magnesium relative to calcium, and a pH above 6.7.
Lab-based soil tests can give you this kind of information. Luckily, those tests cost about the same as a large bag of fertilizer and provide a wealth of information. In case you hadn’t noticed, I recommended a soil test every 3-5 years. Now, back to our tomatoes.
Preventing yellow shoulder
A soil pH of 6.4 to 6.7 can help prevent yellow shoulder. The truth is, plants can absorb many more nutrients when the soil pH is between 6.2 and 6.5. This is probably where the extreme sunlight, extreme heat myth comes in. When plants are too hot or have insufficient water, they become less able to absorb nutrients. This is something like blossom end rot where there’s probably enough calcium in the soil but not enough water in the plant to move the calcium around. Yellow shoulder also occurs when temperatures get too low for the same reason.
Maintaining a magnesium/calcium ratio of 1:6 is good, 1:4 is ideal. Too much calcium or magnesium in the soil can trigger yellow shoulder. This gardening business can be tricky! You may want to check out my post on Mulder’s chart to see how intricately these chemicals interact. It makes me realize they could’ve made high school chemistry class a lot more interesting with some of this stuff, in my opinion. Ideally, potassium levels of 144 ppm are best at the seedling stage, and then 350 ppm as the plant start fruiting.
Since this disorder starts developing as soon as fruit appears, adding amendments later in the season does not help. Researchers are developing cultivars that are less prone to yellow shoulder, but that takes time. Until then, get your soil tested, irrigate regularly, and try to keep your soil pH in a good range.
Whiteflies are common greenhouse pests, but they can cause surprising problems in the garden, as well.
Silverleaf whiteflies (Bemisia argentifolli, also B. tabaci biotype B) feed on many garden plants. Alfalfa, beans, broccoli, cabbage, cantaloupe, citrus, eggplant, grapes, lettuce, melons, peppers, potatoes, squash, sweet potatoes, tomatoes, and watermelon are all plants that silverleaf whiteflies use as food.
These pests hide and feed on the underside of leaves.
Silverleaf whitefly damage
Whiteflies are sapsuckers. They have piercing mouthparts which they insert into leaves and fruit to suck out the sap. This feeding leaves a severe mottling or silvering on the leaves of many plants in the cabbage, squash, and nightshade families. This feeding creates points of entry for diseases such as squash vein yellowing. It also allows whiteflies to “plant” misinformation into their hosts, making life easier for these pests.
Whiteflies carry viruses that cause plants to defend themselves against the viruses rather than the whiteflies. As plants defend themselves against the viruses, they release chemicals that tell neighboring plants to protect themselves against the same viruses. This means the plants are too busy to protect themselves against the whiteflies.
You will rarely see any feeding damage on the leaves of tomato plants. Instead, the fruit will look very strange. What starts out looking like tomato gray wall evolves into longitudinal green or yellow stripes that never ripen. If you cut the fruit open, you will see that this uneven ripening affects the entire tomato. Squash and other crops will look bleached.
Silverleaf whitefly management
If you live in an area with cold winters, the weather should wipe out your silverleaf whitefly problem. Of course, they’ll be back in the spring. If whiteflies are in your garden, you can protect your plants by helping out natural enemies, such as big-eyed bugs, lacewing larvae, and ladybugs. You can also use row covers and crop rotation. Harvesting as soon as crops are ready and applying insecticidal soap or neem oil, as needed, will also help. Whiteflies are resistant to most insecticides.
Commercial tomato growers use trap crops to lure silverleaf whiteflies away from their tomato plants. It ends up that squash plants are the trap crop of choice, so you may want to keep your squash plants away from your tomato plants. Cantaloupe and cucumber are also used as trap crops. Another silverleaf whitefly control method is to use an LED-CC trap. Inexpensive LED-CC traps use a green LED light to attract whiteflies to the trap. [I may need to get one of those!]
Take a look at the underside of leaves to see if silverleaf and other types of whiteflies are lurking.
Are your tomatoes ripening unevenly? When you cut into them, do the walls look gray? It’s probably tomato gray wall. Also known as graywall and blotchy ripening, this disorder occurs when environmental conditions are less than ideal.
[Sorry, but there were very few photos available for use, but you can search online to get a better idea of what this condition looks like.]
Tomato gray wall symptoms
While the rest of your tomato plant looks fantastic, with sturdy stems and lush leaf growth, tomatoes affected with graywall ripen unevenly with both red and yellow areas. This yellow mottling starts appearing while the fruit is green. As the fruit matures, these areas can turn grey and become sunken. These symptoms are not the same as yellow shoulder. When tomatoes develop yellow or green shoulders, they have been exposed to too much heat and sunlight, and symptoms are limited to the upper portions of the fruit. Tomato gray wall can be seen all around the fruit.
If you cut open an affected tomato, you will see that the walls of the fruit are gray, yellow, brown, or green. Anything but red. If you look closely, you might also see that the vascular tissue has turned dark brown. If the rest of the plant looks affected, it is probably tomato mosaic virus.
Tomato gray wall causes
Several conditions can cause gray wall in tomatoes. Some of them you can change and some of them you can’t. Extreme heat, fluctuating temperatures, and high humidity can stress plants into responding with gray wall. Overcast skies during hot weather, fog, and excess shade can also cause blotchy ripening. Overly wet soil or compacted soil can also cause tomato graywall. Too much nitrogen, or not enough potassium or boron can lead to tomato gray wall. [Have you tested your soil lately?] Scientists also believe that some bacteria, fungi, and the tomato mosaic virus part of the problem, but they’re not sure how.
Tomato gray wall prevention
You can prevent tomato gray wall by providing good drainage and improving soil structure, planting varieties that are resistant to tomato mosaic, and feeding your plants appropriately.
Grey leaf spot doesn’t exactly live up to its name. Rather than gray spots on leaves, this fungus causes small brown dead areas that coalesce into large dead areas, frequently seen with yellow.
Grey leaf spot is commonly caused by Stemphylium solani fungi. S. floridanum and S. botryosum may also be involved, but the symptoms are pretty much the same. These pathogens prefer members of the nightshade family, including tomatoes, potatoes, and peppers. Gray leaf spot can also occur on amaranth, broad beans, coriander, peas, sorghum, spinach, and wheat. When seen on members of the allium family, it is called leaf blight.
Grey leaf spot symptoms
Older leaves tend to show symptoms of gray leaf spot before new growth. My guess is it takes time for the fungi to grow enough to become a problem. It starts out as small spots on both sides of the leaves. Yellow halos may also be visible. As these lesions grow and mature, they become dry and brittle, ultimately causing leaf drop. Some people say these dead areas look gray. To me, they’re brown. [If you have a hand lens, you may be able to see gray fungal growth in the center of areas damaged by gray leaf spot.] Whatever you call it, these infections can lead to secondary infections, or other diseases, creating a domino effect of destruction in your garden.
Symptoms of gray leaf spot look a lot like Septoria leaf spot. The only difference is that the damaged areas of gray leaf spot do not have black spots in the middle, the way Septoria leaf spot infections do.
Grey leaf spot lifecycle
The fungi responsible for gray leaf spot can travel through the air, in rainwater, and on infected seeds. In areas with high humidity, gray leaf spot can easily take hold on leaf surfaces as well as on twigs and stems. Each infected plant part becomes a new point of infection. As infected leaves rub against their neighbors’ leaves, the infection can spread.
Grey leaf spot prevention
Gray leaf spot is one of those diseases you’d rather prevent than have to try to cure. Once an infection begins, you can remove infected leaves to slow the spread of the disease. Just make sure to sanitize your garden tools between each and every cut. You can use a bathroom cleaner to disinfect your tools. And it’s a good idea to give them (and your hands) a good soap and water washing, drying, and oiling after the ordeal. And those infected leaves should be tossed in the trash.
Preventing gray leaf spot is a lot easier than dealing with an infection. Start with resistant varieties and certified disease-free seeds and seedlings. Then, space your tomato plants out enough that they are not touching their neighbors. This will slow the spread of disease and improve airflow which will help leaves dry faster. Avoid overhead watering and water in the morning, which will give leaves time to dry during the day.
Since this pathogen can overwinter in life and plant litter, it is a good idea to clean up at the end of each growing season and practice crop rotation.
Commercial growers use fungicides to prevent and manage gray leaf spot. You can help prevent this disease with fixed copper sprays or Bt (Bacillus thuringiensis). These treatments may be able to halt an infection if they are applied early enough. Otherwise, get rid of infected leaves, harvest what you can, and give your tomato plant an umbrella if it loses too many leaves.
Rhizopus soft rot is one of those diseases that can come into your garden from the grocery store.
Foods may look perfectly healthy when you bring them home. What you may not see are thousands of bacteria, fungal spores, or viruses that quickly make themselves at home in your garden. Some of these pathogens can take years to get rid of.
Rhizopus soft rot hosts
Also known as black bread mold, Rhizopus soft rot is caused by Rhizopus stolonifer fungi. This fungal disease is commonly seen on sweet potatoes, strawberries, pears, peaches, melons, and mangos. These delicious crops have a high sugar content and are easily damaged. When these fungi appear in damaged almonds, we call it hull rot.
Rhizopus soft rot symptoms
Tiny wounds or bruises slowly become water-soaked areas. Those areas then turn soft and start to rot. When conditions are right, white thread-like mycelia appear with little black knobs (sporangia) on top. These fungi produce enzymes when they germinate that help them penetrate plant cell walls.
Rhizopus soft rot behavior
The fungi that cause Rhizopus soft rot are surprisingly athletic. Like many plants in the garden, they spread rapidly using stolons or runners. These fungal runners can move up walls and tree trunks, as well as horizontally across branches, stems, and soil. These fungi thrive when temperatures are 68°F–86°F and they can survive in weather as hot as 140°F.
Rhizopus soft rot prevention
Once fruit begins rotting, there isn’t much you can do besides trim out the bad bits and eat the rest. There are several things you can do to prevent Rhizopus soft rot:
If you are growing sweet potatoes, curing them properly after harvesting is the best way to prevent Rhizopus soft rot. This means storing them at 84°F at 90% humidity for 5 to 7 days.
Are your squashes rotting on the vine? It may be cucurbit wet rot.
Cucurbit wet rot is caused by Choanephora cucurbitarum fungi. Also known as Choanephora fruit rot and wet rot, this fungal disease also affects melons, pumpkins, and other cucurbits, as well as beans and peas, and okra.
Cucurbit wet rot symptoms
Cucurbit wet rot first appears as a soft area on the blossom end of fruit or pods. Those soft spots can also appear around wounds in the fruit. Those softened areas become covered with soft white fungal growth that eventually turns purplish-black. Eventually, the entire fruit rots.
Cucurbit wet rot management
Like most things that are rotting, cucurbit wet rot needs moisture to turn into a problem. You can prevent it with good drainage and by allowing the soil to dry out between waterings. Fungal spores can travel on the wind, with insects, or in splashing water. While there isn’t anything we can do about the wind, there are things we can do to prevent wet rot:
Once a fruit is infected, it should be removed and tossed in the garbage.
Chocolate tube slime sounded so strange that I had to learn more about it.
Like our beloved dog vomit slime mold, chocolate tube slime molds were once classified as a type of fungus. Scientists now include this family in the protists. Amoebas are another type of protist.
Slime molds have the bizarre ability to move across materials in their search for food. They do this so efficiently that city planners now use some slime molds to design roads and electrical grid systems. Normally found as individual cells, chocolate tube slimes, also known as pipe cleaner slimes and tree hair, converge into giant communities.
Chocolate tube slime (Stemonitis splendens) looks a lot like a sea urchin and is usually found on forest floors feeding on decaying material. They are sometimes found attached to older wooden houses. Chocolate tube slime mold also grows on planter pots but what I find particularly strange is that they can even grow on plants that are alive and green. I recently heard of chocolate tube slime growing on tomato stems. The tomatoes looked fine, they just had little brown tufts growing on them.
The sea urchin-like spikes are fruiting reproductive bodies. Fungal spores are released from these tubes. Before they reach the stage, they start as white spikes that are often topped with pink globs of I don’t know what. Those white spikes turn a golden yellow and the globs turn golden yellow. Eventually, these spikes turn chocolate brown. Sometimes they turn a reddish-brown. They can be ½” to ¾” tall or huge.
Since chocolate tube slime molds feed on decaying organic matter, they will not harm your tomatoes or other garden plants.
Have you ever seen chocolate tube slime mold in your garden?
We’ve already talked about brown marmorated stink bugs, consperse stink bugs, green stinkbugs, red-shouldered stink bugs, rough stinkbugs, say stink bugs, Uhler’s stink bugs, and predatory stink bugs. Today, we’re going to look at brown stinkbugs.
Like most stink bugs, brown stink bugs (Euschistus servus) feature the classic shield-shaped body and they smell bad once threatened or stepped on. Found in Central and North America, these pests damage a wide variety of garden plants including alfalfa, beans, buckwheat, corn, millet, okra, peas, pecans, sorghum, soybeans, sunflowers, and walnuts, along with several fruit trees.
Brown stink bug description
From above, brown stink bugs have a mottled grey to brown back, pointy shoulders, and rust-colored legs with tiny black dots. If you were to flip one over you would see that the underbelly is yellowish, with an orangish area in the middle of the belly. Adults average ½” in length.
Eggs are clusters of yellowish-white spheres that start turning pink before they hatch. Nymphs are tiny reddish-brown ladybug-shaped insects.
Brown stink bug damage
Brown stink bugs move through the garden as the seasons change. They love to start with peaches and nectarines, causing catfacing and other types of fruit scarring. From there, they move to whatever is nearby and edible. They feed by inserting needle-like mouthparts into fruits, leaves, stems, and seed pods. When they do so, they inject toxic substances into the plant that may slow or halt the further development of that plant part. Over time, the accumulated effects of brown stink bug feeding can be pretty devastating to a crop. They can kill seedlings outright, cause stunting of larger plants, and provide points of entry for several pathogens.
Brown stink bug lifecycle
Adult brown stink bugs overwinter in dead weeds, under boards, in hedgerows, and in the bark of trees. As soon as temperatures start rising they emerge to start eating, breeding, and reproducing. Each female lays an average of 18 egg masses. Each mass contains 60 eggs or so. There can be as many as four or five generations a year, depending on the weather. Adults are strong flyers so you have to keep a lookout.
Brown stink bug management
Assassin bugs, green lacewing larvae, some parasitic wasps, and earwigs are also known to feed on stink bugs, so you’ll want to avoid using broad-spectrum insecticides. In fact, most stink bugs are resistant to insecticides and pesticides. Row covers can also be used to protect specific plants and crops against stink bug damage. Your best defense against brown stink bugs is to monitor plants regularly, handpick stink bugs when you see them, and squash any egg or nymph clusters you see.
Do your apple leaves have big orange freckles? It may be apple measles. Or it may be Alternaria blotch of apple.
This leaf spot disease is also known as Alternaria leaf blotch, cork spot, and storage rot. This isn’t the same thing as apple blotch, though both are fungal diseases of apple trees.
Alternaria blotch of apple symptoms
Apples infected with Alternaria mali have raised black or brown lesions that are commonly found near the blossom end, though they may appear anywhere on the fruit. Infected fruit does not store well and may turn dry and corky.
Most symptoms of this disease are seen in the leaves. Leaves may turn unusual colors, dead areas develop, and yellowing is common. Most often, you will see rust-colored circular spots in late spring or early summer. These spots can merge into large, irregularly-shaped areas. Those spots have light brown centers and purple halos. Eventually, infected leaves die and fall off, reducing photosynthesis and increasing sunburn damage. Green, woody tissue, such as petioles, can also become infected, but this is rare.
These symptoms are easily confused with chemical overspray, frog-eye leaf spot, cedar apple rust, and magnesium deficiencies. You can take a sample to your local County Extension Office to find out for sure.
Alternaria blotch of apple management
There are already bacteria in the soil (Bacillus cereus) that attack Alternaria mali. The problem pest is red mites. While the connection isn’t fully understood yet, research has shown that high red mite populations correspond to serious damage by Alternaria blotch of apple. European red mites are controlled using delayed dormant horticultural oil. Miticides are not effective against red mites.
As always, remove mummies, prune for good airflow, and remove dead leaves from under the tree. Healthy leaves can be composted, while infected leaves belong in the garbage can.
Take a closer look at your apple tree. Are there spots on the leaves? What’s your favorite apple?
Sooty blotch and flyspeck are two different conditions. They occur together so often that the combined name is now used as an all-in-one fungal disease. It is also known as apple summer disease.
Apple summer disease can affect bananas, blackberries, citrus, crabapple, papaya, pears, persimmons, raspberries, and several other tree and vine crops, along with apples. Let’s look at the two conditions individually and then learn what we can do about them.
Sooty blotch looks like small gray patches just under the skin. These patches are usually ¼” in diameter or larger. They can merge to cover large areas of the fruit. These smudges are made up of hundreds of tiny fungi that are connected by hyphae. Sooty blotch is caused by several different fungi: Peltaster fructicola, Geastrumia polystigmatis, and Leptodontium elatius.
Flyspeck is caused by Zygophiala jamaicensis. It gets the name because of the clusters of black flecks that look like fly poop on the fruit skin. Those tiny flecks can coalesce into large scabby or blotched areas. If you rub or scratch off these scabs you will find normal healthy fruit skin underneath.
Together, sooty blotch and flyspeck (SBFS) create dark blemishes on fruit. These mycelia can also grow on leaves, stems, and twigs.
Summer apple disease lifecycle
Scientists are still learning about this disease. We do know that the damage is mostly cosmetic. This is because the fungi live on and in the waxy cuticle and do not actually enter the fruit.
It is believed that spores hibernate on ash and willow trees, hedgerows, and wild brambles, along with our beloved edibles. Humidity favors the growth of these fungi. In particular, temperatures between 60°F and 70°F with a relative humidity greater than 96% set the stage for massive fungal growth.
As apples and other fruit mature, they exude a tiny bit of fruit juice through microscopic tears in the skin. Fungal spores land on this juice and use it as food, entering the skin through the tears. Surprisingly, infection with summer apple disease does not lead to fruit decay, but it does reduce storage time.
Sooty blotch and flyspeck management
Sooty blotch and flyspeck is most likely to occur on lighter-colored, thicker-skinned, slower to mature fruit from older trees growing in regions with fog or frequent rain. Hot, dry weather halts the growth of these fungal pathogens.
Pruning for good airflow is the best way to prevent sooty blotch and flyspeck disease. Proper fruit thinning will also reduce the chance of disease, as does removing mummies and keeping the area under trees clear of weeds. Commercial growers spray fungicide to treat summer apple disease along with apple scab. Organic growers spray with cocoa soap or lime sulfur, neither of which I’ve ever heard of. Home growers are finding that sprays of potassium bicarbonate (KHCO3) work well. Do not mistake potassium bicarbonate with baking soda. They are NOT the same thing.
Keep your fruit dry and sooty blotch and flyspeck will never get to your harvest.
You can grow a surprising amount of food in your own yard. Ask me how!
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