Garden Word of the Day
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Pepper Mild Mottle
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.
Tomato Gray Wall
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.
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 when the fruit is green. As the fruit matures, these areas can turn gray and become sunken. These symptoms are not the same as yellow shoulder.
When tomatoes develop yellow or green shoulders, it is from 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. Look closely, and see 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 you can change, and some 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 cause blotchy ripening. Overly wet or compacted soil can also cause tomato graywall. Too much nitrogen, or insufficient potassium or boron, can also cause tomato gray wall. [Have you tested your soil lately?] Scientists also believe some bacteria, fungi, and the tomato mosaic virus may be part of the problem, but they’re still exploring those possibilities.
Tomato gray wall prevention
You can prevent tomato gray wall by providing good drainage, improving soil structure, planting tomato mosaic-resistant varieties, and feeding your plants appropriately.
Gray Leaf Spot
Gray leaf spot doesn’t exactly live up to its name. Rather than gray spots on leaves, this fungus causes small brown or yellow dead areas that merge to make larger necrotic areas.
Gray leaf spot is a fungal disease commonly caused by Stemphylium solani fungi. S. floridanum and S. botryosum may also be involved, but the symptoms are the same. These pathogens favor tomatoes, potatoes, peppers, and other nightshade family plants. Gray leaf spot can also occur on amaranth, broad beans, coriander, peas, sorghum, spinach, and wheat. When seen in the onion family, it is called leaf blight.
Gray leaf spot symptoms
Older leaves tend to show symptoms of gray leaf spot before new growth. It starts 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 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, 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 specks in the middle. Septoria leaf spot infections do have those black specks.
Gray 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, twig, and stem surfaces. Each infected plant part becomes a new point of infection. Infected leaves can spread the disease to neighboring plants just by touching them.
Gray leaf spot prevention
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 plants so that they are not touching their neighbors. The gap slows the spread of disease and improves airflow for faster drying times. Avoid overhead watering and water in the morning to give leaves time to dry during the day.
Once an infection begins, remove infected leaves to slow the spread of the disease. Just make sure to sanitize your garden tools between every cut. You can use bathroom cleaner. And it’s a good idea to give them (and your hands) a good soap and water washing, drying, and oiling after the ordeal. Throw infected leaves in the trash. 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 fixed copper sprays or Bt (Bacillus thuringiensis). These treatments may 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 to prevent sunburn
Rhizopus Soft Rot
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.
Cucurbit Wet Rot
Are your squashes rotting on the vine? It may be cucurbit wet rot.
Cucurbit wet rot is a fungal disease caused by Choanephora cucurbitarum. Also known as Choanephora fruit rot and wet rot, this disease affects members of the melon family, such as pumpkins and cucumbers. Beans, peas, and okra can also be infected.
Cucurbit wet rot symptoms
Cucurbit wet rot first appears as a soft area on the blossom end of fruit or pods. Those spots can also appear around wounds in the fruit. White fungal growth develops, turning purplish-black and causing the whole fruit to rot. Cucurbit wet rot is often confused with blossom end rot and Rhizopus soft rot.
Cucurbit wet rot management
Like most rots, cucurbit wet rot needs moisture to become 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:
Infected fruit should be removed and tossed in the garbage.
Chocolate Tube Slime
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?
Brown Stink Bugs
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 gray 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.
Alternaria Blotch of Apple
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
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.
Are you seeing spots? Black or brown spots on apples and apple leaves? It may be apple blotch.
Apple blotch (Marssonina coronaria, M. mali, Diplocarpon mali) is a fungal disease that attacks apple trees around the world, damaging fruit, causing early defoliation, and weakening trees. Also known as Marssonina blotch, this disease was first seen in Japan in 1907. While it is not the problem it used to be, thanks to the use of Bordeaux mixture, it is still a good idea to know what to look for.
[Note: I was unable to find photos of this disease that I could use. Any volunteers?]
To muddy the waters just a bit, there is another apple blotch disease. This one is caused by Phyllosticta solitaria fungi. The symptoms and treatments are mostly the same, but there are a few differences. Also, when these two diseases occur, it is not uncommon for other diseases to appear. Sooty blotch and flyspeck is one of those diseases. Alternaria blotch of apple is another. We will get to those another day.
Apple blotch symptoms
Spotted fruit and early leaf drop are signs something is wrong. Closer inspection of a tree infected with apple blotch will reveal dark green circular areas on the tops of mature leaves. Tiny yellow spots develop within those areas. Those yellow spots get bigger and turn into grayish-brown round lesions (0.2”–0.4” diameter) with black pinhead-sized fruiting fungal bodies called acervuli. As the infection spreads, leaves turn more yellow than green with brown patches. These symptoms usually appear in mid-summer and severe defoliation usually begins two weeks after the first symptoms are seen. These symptoms look a lot like black rot and Alternaria blotch of apple.
Fruit is less commonly affected by Marssonina fungi, while fruit infected with Phyllosticta will often display brown spots that can coalesce into large, scabby areas. Fruit infected with apple blotch it’s still edible but I would give it a good wash first.
Apple blotch management
Since apple blotch fungi overwinter in leaf litter, you can help prevent this disease by removing fallen leaves from under the tree each autumn. If an infection is suspected, those leaves should be thrown in the garbage. Bordeaux mixture sprays are effective against apple blotch, as are several fungicides. These treatments are usually applied as soon as blossoms fall. Then you need to start counting the hours that tree leaves are wet from rain. After 175 hours, spray again and then spray every 10 to 14 days throughout the growing season.
You can help your apple tree healthy with good pruning, sanitation, and regular feeding. This helps your tree protect itself.
Lesser Appleworm Moths
Lesser appleworm moth larvae burrow into apples—a bad surprise when eating an apple.
Native to northeastern North America, these pests of pomes and stone fruits have moved across the U.S. and into Canada.
Lesser appleworm moth hosts
Lesser appleworms (Grapholitha prunivora) call members of the rose family home. Hawthorn trees are the primary host of lesser apple worm moths, along with oaks and serviceberry shrubs. Unfortunately, apples and pears (pomes) are also vulnerable, along with stone fruits, such as apricots, cherries, nectarines, peaches, and plums. As such, they are commonly known as plum moths.
Lesser appleworm moth identification
Adult lesser appleworm moths are only ¼” long. They are dark brown to almost black with white, grayish orange, or brown bands on the forewings. Larvae start out creamy-white with a dark head and only 1/20” long. As they feed and grow, they turn pinkish white and can reach up to 3/8” in length. Lesser appleworm pupa are golden brown and 1/5” long. Eggs are flat, oval, and very tiny (1/40”). These eggs start out white and shiny but they turn yellowish as they mature and you can see a red ring inside.
Lesser appleworm moth lifecycle
Lesser appleworm moths lay eggs on fruit and leaves. In 7–10 days, they hatch and larvae begin feeding on fruit. Three weeks later they spin cocoons around themselves where they will pupate under bark or on the ground in plant or fruit debris. This cycle continues allowing an average of three generations each summer.
Lesser appleworm moth damage
Lesser appleworm moth damage looks very similar to codling moth and oriental fruit moth damage, though the tunneling doesn’t usually go as deep. Initial infestations often cause fruit drop. Fruit entry holes are often seen near the calyx, or bud end, of the fruit, so check your fruit before taking a bite.
You can use pheromone traps to monitor for these pests, but control measures are generally not needed.
Oriental Fruit Moths
Oriental fruit moths are also known as peach moths, but more than your peaches are at risk. Apple, apricot, cherry, nectarine, pear, plum, and quince trees and fruit may become infested by this invasive pest of pome and stone fruits. Originally from China, Oriental fruit moths (Grapholita molesta) are now found throughout much of the world.
Oriental fruit moth damage
Oriental fruit moth damage starts early in the growing season when newly hatched larvae burrow into leaf axils (where leaves are attached to stems). From there, they tunnel several inches into tender young twigs to feed on sap. This kills the twigs, creating ‘flags’ and can lead to a bushy appearance. As the season progresses, Oriental fruit moth larvae start feeding on the ends of established twigs (terminal growth) and developing fruit.
Boring into the fruit, they create the perfect opportunity for brown rot and other fungal diseases. Significant amounts of frass (bug poop) can usually be seen around entry holes. In apple and pear trees, this damages looks similar to codling moth and lesser appleworm damage.
Oriental fruit moth identification
Adult Oriental fruit moths are gray to grayish-brown with brown markings. They are small moths with 1/4"–1/2” wingspans. Larvae are born white and then turn pink to cream-colored. They have dark heads and grow to 1/2” long. Eggs are white and flat.
Oriental fruit moth lifecycle
Female Oriental fruit moths lay up to 200 eggs each spring. Those eggs are laid singly on the underside of leaves and on twigs and they hatch as fruit trees begin to blossom.
Oriental fruit moths overwinter as larvae in protective cocoons which may be found attached to the host tree or nearby on the ground. There can be up to seven generations each year.
Oriental fruit moth management
Checking trees regularly for signs of infestation, starting early in the season, will help keep this pest in check. Pheromone traps can be used to monitor for Oriental fruit moths and disrupt their mating. While commercial growers still rely on broad-spectrum pesticides, home growers can use less destructive insecticides, such as spinosad. Infested plant tissue should be removed and thrown in the garbage.
If their sunny yellow flowers and delicious seeds weren’t reason enough to grow sunflowers, it ends up that small stands of sunflowers will attract Macrocentrus ancylivorus, an Oriental fruit moth parasite. These helpers will also parasitize peach twig borers.
European Corn Borers
European corn borers are the larval form of an unassuming tan moth. This invasive pest bores into all parts of corn, millet, and other grain plants, but that’s not all. If corn isn’t available, these pests will also feed on lima beans, peas, peppers, and potatoes.
As far as I know, this pest is currently only found East of the Rockies, but that may change as early as tomorrow. You may as well learn about it today, wherever you are.
European corn borer identification
Known as the European high-flyer, these moths are one inch long with a one-inch wingspan. Females are tan with light brown markings. Males are smaller, with darker markings. If you see an adult at rest you will be able to see the abdomen sticking out from under the wings. European corn borers (Ostrinia nubilalis) can be dark reddish-brown to pinkish gray. They have brown spots on each segment and are just under one-inch long.
European corn borer lifecycle
European high-flyers lay clusters of whitish-yellow eggs on corn and other host plants, usually on the underside of leaves. Females lay two clusters of eggs each night over 10 days. This translates into 400–600 eggs per adult female.
Just before hatching, the eggs become translucent. Then the larvae chew their way to freedom and begin feeding on the host plant. Once they’ve eaten their fill and made a mess of your corn, they enter a pupal state. Inside the chrysalis, larvae transform into adults. In some cases, there may be two pupal stages. I have no idea why.
As daylight hours shorten, larvae enter hibernation. The scientific term is diapause. I wonder if that’s a reflection of “die or pause”—hard to say.
European corn borer damage
As larvae bore into leaves, stalks, and ears, photosynthesis is reduced, nutrient and water transport are slowed, and dozens of points of entry for Fusarium and other pathogens are created. This sets the stage for some very unhealthy, unproductive plants.
Symptoms of European corn borer feeding include clumps of what looks like sawdust (it’s bug poop) on top of mature leaves, frass and damage where leaves emerge from the stalk, and a shot-hole type of leaf damage.
European corn borer management
While immature corn plants can protect themselves against this pest with an antibiotic substance they create, that protection doesn’t last into adulthood. Commercial corn growers often plant varieties of GMO seed corn that contains a synthetic version of a gene from Bacillus thuringiensis kurstaki, an insecticidal bacteria. For the home gardener, there are other ways to manage European corn borers. For one thing, insidious flower bugs, predatory stink bugs, and Trichogramma wasps all prey upon or parasitize these pests, along with ladybugs and lacewing larvae, so you’ll want to avoid using broad-spectrum pesticides.
Beyond that, monitor your corn plants for signs of entry holes. You can also use pheromone traps. You can apply your own Bacillus thuringiensis kurstaki or spinosad to treat severe infestations.
Moth caterpillars devour garden crops, but they aren’t all bad. In fact, they can also be important pollinators. Let’s see if we can sort out the Good Guys from the troublemakers.
As a child, I always thought that butterflies were colorful and flew in the daytime, while moths were fuzzy and flew only at night. Like everything else, it’s not that simple.
Lepidopterans, as moths and butterflies are called by scientists, are one of the easiest insect orders to recognize. Their name comes to us from Ancient Greek words that mean ‘scale’ and ‘wing’. There are believed to be over 180,000 scale wing species around the world and 160,000 of those are moths. Together, they make up approximately 10% of the known insect world. More than 11,000 moth species call the U.S. home.
Moth or butterfly?
The easiest way to tell if it’s a moth or butterfly is to look at the way they hold their wings while at rest. Generally speaking, moths hold their wings out to either side, while butterflies hold their wings upright, over their back. [butterfly/up – moth/out] You can learn more about the differences between moths and butterflies on my post about them. Did you know that moths have ears and butterflies do not? I didn’t either.
Moths start out as eggs. Those eggs are normally laid in or around plant material. Some eggs are laid in the soil. When those eggs hatch, moth larvae (caterpillars) appear. Those larvae eat a lot. Seriously. It is that feeding that causes all the damage in the garden. Eventually, those caterpillars eat their fill and build cocoons around themselves. Within those cocoons, some pretty amazing changes take place. What started as a squishy, worm-shaped digestive system is transformed into a fuzzy, winged creature of the sky.
Most adult moths only eat nectar. Some moths don’t eat at all. They simply do not have mouthparts and do not live long enough to need food. This nectar-feeding means that moths are important pollinators. In some parts of the world moths are an important food source and some moths give us silk.
Hummingbird moths are an example of a daytime moth that acts as a pollinator. While most of their clearwing cousins are troublemakers, these lovely specimens are a good sign your garden has abundant biodiversity. In most cases, however, moths are not a gardener’s friend. Or rather, their offspring, the caterpillars, are not
Bad moths infest our pantries, closets, and our gardens. They chew holes in flour bags, sweaters, and leaves. Here is a list of the most common garden variety problem moths:
New threats to plant health are occurring all the time. For example, in 2005, a single European pepper moth was found in a shipment of begonias at a San Diego Home Depot. That serious pest is now found in 13 US states and Canada.
*NOTE: If you come across a tomato hornworm covered with tiny white oval protrusions, put it into something it can’t escape from but that will allow those protrusions to hatch and fly away. They are beneficial parasitic wasps
Before you start adding mothballs to your closet (or the garden), you need to know that carcinogenic mothballs are bad for us. You can more safely protect your clothing from common clothes moths (Tineola bisselliella) by bagging it or adding cedar or juniper to your closet. You can use yellow sticky sheets or commercially available moth pheromone traps to take care of Indianmeal moths (Plodia interpunctella). Garden moths are best controlled by natural predators. That list of predators includes amphibians, bats, birds, cats, dogs, lizards, and even rodents. [I have trained one of my dogs to chase imported cabbageworm butterflies out of my garden. It’s fun to watch and sometimes she even catches one.]
Since it is the caterpillars that are causing most of the damage, observation and handpicking are often the best organic controls. Personally, I allow caterpillars to grow large enough to be worth feeding to my chickens. It’s a case of how much one is willing to tolerate.
Lace bugs are not the same thing as lacewings.
There are over 2,000 lace bug species and each one is plant-specific. Most lace bugs spend their entire lives in the same area of the same plant, even though they can fly. And they bite! Apparently, they don’t fly very well because sometimes they fall out of their trees and bite the people they land on. While these bites do sting, they are not dangerous.
Lace bug identification
Lace bugs are very small. You could fit up to 8 or 9 lace bugs end-to-end across a dime, though some species are significantly bigger than that. Lace bugs tend to be tan, brown, or black, depending on the species.
Lace bugs get their name because of their diaphanous fore wings and lacy outgrowths on their thorax. They can be broad or narrow but most lace bug bodies are flattened and the heads are often hidden under a hood-like pronotum.
Damage caused by lace bugs
Lace bugs are host-specific sap suckers. They are most often found on the underside of leaves where they pierce leaf tissue and tap into plant cells to feed on sap. This feeding initially causes small yellow or white spots. Eventually, lace bug feeding leads to leaf silvering or bronzing. It can also provide points of entry for anthracnose.
Heavy infestations can lead to leaf curling, leaf drop, and reduced crop size. These pests frequently feed on young shoots which leads to wilting and twig death. If all that wasn’t bad enough, it ends up that these pests use both the upper and lower decks of their leaves as a toilet, leaving behind black flecks of excrement
Here are just a few lace bug species you may find in your garden:
There are also lace bug species that attack azalea, bamboo, banana, cotton, oak, sycamore, and willow, just to name a few.
Lace bug lifecycle
Lace bugs go through an incomplete metamorphosis that takes them through 4 or 5 instars, depending on the species. Generally speaking, wing pads appear in the second or third instar and continue to develop into adulthood. There may be two to five generations of lace bugs each year, depending on the species and environmental conditions. They may overwinter as eggs, nymphs, or adults.
Oblong lace bug eggs can be yellowish to black. Some species lay their eggs are at an angle, in circular arrangements, on the underside of leaves, similar to whitefly eggs. The only difference is that the eggs are then covered with black, sticky frass (bug poop). Yuck! Other lace bug species insert their eggs into stems and shoots, while some species lay their eggs along the edge, or margin, of nearby leaves or leaf veins. Unlike many other insects, lace bug mothers are protective of their young. When predators appear, Moms fan their wings and approach the threat as only a protective mom can do.
Lace bug management
Small populations of lace bugs are no cause for concern. In fact, their presence attracts many beneficial predators. Simply keep your trees and plants healthy with good drainage, mulch, and proper feeding and irrigation. These pests may overwinter on horsenettle (Solanum carolinense) and common mullein (Verbascum thapsus), so you may want to keep those plants away from your garden.
Assassin bugs, jumping spiders, lacewing larvae, ladybugs, pirate bugs, predaceous mites, predatory thrips, and spined soldier bugs will all help keep lace bug populations under control, so avoid using broad-spectrum pesticides. Severe infestations are best managed with insecticidal soap or narrow-range oil sprays.
Tomato Mosaic Virus
Stunting and yellowing leaves may mean your tomato plants are infected with tomato mosaic virus.
Tomato mosaic virus (ToMV) looks and behaves a lot like tobacco mosaic virus (TMV). While both viruses can infect tomatoes and tobacco, the tobacco mosaic virus can also be found on beets, cucumbers, lettuce, and petunias, while tomato mosaic virus spreads to peppers and potatoes, along with apple, cherry, and pear trees.
Tomato mosaic symptoms
Tomato mosaic symptoms can vary greatly, making it difficult to distinguish from other tomato viruses, such as tomato spotted wilt and cucumber mosaic. Along with stunting and chlorosis, other symptoms of tomato mosaic virus include:
This disease is very responsive to temperature. If plants are infected while young, they may not exhibit any symptoms until temperatures are warmer.
Tomato mosaic virus lifecycle
These pathogens can survive in dry soil, leaf litter, and infected root debris for up to two years. Add water and that time is reduced to just one month. While ToMV can be transmitted through infected seeds, it is most often spread by us. The virus gets on our hands, clothes, shoes, and garden tools and we spread it everywhere we go, to every plant we touch or brush against. Like tobacco mosaic, the tomato mosaic virus can even survive the tobacco curing process and is then spread by smokers who haven’t washed their hands before working in the garden.
Tomato mosaic virus management
There are no chemical treatments for tomato mosaic virus. Good cultural practices, such as hand washing, avoiding infected areas, and sanitizing tools can slow the spread of this disease.
Tomato mosaic can also infect lamb’s quarters and pigweed, so keep those particular weeds away from susceptible plants. Installing certified disease-free, resistant varieties is another way to reduce the impact of this disease.
If you suspect tomato mosaic virus in your garden, pull up the affected plant, roots and all, and put it in a plastic bag. Then, contact your local County Extension Office to see if they offer free testing since that’s the only way to know for sure. By identifying the disease early and notifying the Extension Office, they can help you and others in your area protect the remaining plants.
Straightneck squash is, in my opinion, one of the most satisfying crops to grow. Sunny yellow fruits are easy to see for harvesting and their delicate flavor lends them to countless sautés, stir-fries, and salads. A close cousin to yellow crookneck squash and zucchini, these summer squashes are prolific and undemanding.
Straightneck squash plants
Like other bushy squash plants, straightneck varieties produce large, bristled leaves that make them useful when grown together with corn and pole beans in the Three Sisters Method. Stems are tubular and bristled. These plants take up some room, growing to three feet tall and wide aboveground and even wider root systems underground.
These plants produce both male and female flowers. Female flowers have tiny, unfertilized fruits at the base. Male flowers, which tend to come out first, do not have these structures. Since squash are not self-pollinating, bees and other pollinators are needed for a harvestable crop to develop.
How to grow straightneck squash
Squash plants are heavy feeders. Prepare growing areas before planting with lots of nutrient-rich aged compost and manure or fertilizer. Their taproots make them best suited to direct seeding, rather than transplanting. They can be grown in large containers, but prefer the ground.
Once temperatures stay at or above 60°F, seeds can be planted 2” deep and 3 to 4 feet apart, if planting in rows. Another option is to create hills that are 6” to 12” tall and 20” across. In each hill, plant 4 or 5 seeds, spread 3” apart, and keep only the best seedling for each hill, snipping off the others at soil level. In arid regions, you can use inverted hills or shallow areas. This makes watering easier, but it may increase problems with pests and fungal disease.
You can help them stay healthy and productive by top-dressing around plants with aged compost or fish emulsion. Avoid applying extra nitrogen. Nitrogen stimulates leaf growth, not fruit.
Insufficient pollination is a common problem with squash plants. You can overcome this problem by collecting male anthers and touching them to female flowers repeatedly until pollination occurs. Hand-pollinating takes little time and it works very well.
Straightneck squash pests and diseases
This is one case where you have to trust that your straightneck squash plants will produce abundant crops against all odds. There are astounding numbers of pests and diseases that can and will go after your squash plants, and you will still get big harvests.
Those insect attackers include aphids, armyworms, cabbage loopers, crickets and grasshoppers, cucumber beetles, cutworms, darkling beetles, dried fruit beetles, earwigs, false chinch bugs, flea beetles, green peach aphids, leafhoppers, leaf miners, Lygus bugs, melon aphids, melon flies, Mexican fruit flies, mites, nematodes, redhumped caterpillars, seed corn maggots, spider mites, squash bugs, squash ladybugs, squash vine borers, stink bugs, thrips, two-spotted spider mites, whiteflies, and wireworms. If you live in the southeastern U.S., melonworm moths and pickleworms may also be a problem. Deer, rats, squirrels, and other animals will also take a bite out of your straightneck squash crops. Monitor plants for signs of damage and treat as needed.
The disease arena is no less daunting, but you can take most of it with a grain of salt. These plants are, as I’ve said, productive and low-maintenance. Diseases that may occur on your squash include Alternaria leaf blight, angular leafspot, aphid borne yellow virus, ashy stem blight, bacterial leaf blotch, bacterial wilt, bean yellow mosaic, beet yellows virus, belly rot, charcoal rot, cucumber mosaic, cucurbit yellow stunting disorder, curly top, damping off, downy mildews, Fusarium wilt, leaf blight, measles, Phytophthora fruit and crown rot, potyviruses, powdery mildew, septoria leaf spot, squash mosaic virus, sudden wilt, Verticillium wilt, virus decline, and zucchini yellow mosaic. Spacing plants out properly, feeding and irrigating regularly, and checking on your plants every few days should prevent any serious problems.
Environmental conditions can also lead to problems such as bitter fruit and blossom end rot. These problems can often be prevented with regular irrigation. If your squash plants are growing well but there’s no fruit, it may be a molybdenum deficiency. An affordable lab-based soil test can tell you if this is your problem.
Two straightneck squash plants should keep your family supplied all summer. At the end of the season, let one squash grow past the tender stage and save its seeds for next year. Just keep different varieties of summer squash away from each other as cross-pollination can occur.
How many types of summer squash are you growing this year?
You can grow a surprising amount of food in your own yard. Ask me how!
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