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 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 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 grey to greyish-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 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.
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 aphid-borne yellows, 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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