Native to North America west of the Rocky Mountains, Western conifer seed bugs (Leptoglossus occidentalis) have recently expanded their range to the East Coast and are occasionally found in Europe. Western conifer seed bug description These narrow, shield-shaped insects are brown and average 3/4 to 1” in length. They have the classic tags seen on the rear legs of all leaf-footed bugs and their antennae tend to stick out on either side. Eggs are brown. Nymphs have light-colored legs and look much like assassin bigs, until they start filling out. Conifer seed bug lifecycle Adult female conifer seed bugs lay 200 eggs in rows, usually along needles, leaf midribs, or stems of host plants. In spring, the eggs hatch and nymphs go through five developmental stages, or instars, before reaching adulthood. In North America, there is only one generation a year, but two or more generations have been seen in Mexico and southern Europe. Conifer seed bug damage These pests generally feed on the sap of developing conifer cones, causing the seeds within to distort and wither. Favored trees include lodgepole pine, white spruce, and Douglas-firs, though red pine, mountain pine, European black pine, Scots pine, and even pistachios are sometimes chosen. They can also vomit up digestive juices that soften hard seeds. I just hope they never find my stone pine! Even worse, conifer seed bugs have been found to use their piercing mouthparts to damage PEX tubing. PEX tubing is similar to PVC and is used to insulate high voltage electrical wires, and to transport offshore oil and natural gas, sewage, and chemicals. Insecticides are not recommended, though they can be used as a last resort against heavy nymph infestations. It is better to avoid using broad spectrum insecticides. Provide pollen and water for natural predators. Some tachinid flies have been known to parasitize conifer seed bug eggs. Spiders, assassin bugs, and birds also feed on conifer seed bugs.
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The fungi responsible for take all disease, Gaeumannomyces graminis, is found in the soil. It enters young plant roots and can often be seen as dying patches in a lawn or field. Take all disease symptoms The fungus enters the xylem and blocks the flow of water, causing stunting, yellowing, and reduced tillering. Tillering refers to the way lateral shoots emerge from the base of the stem, a common growth style of cereals. Infected plants mature faster than normal and have bleached seed heads and blackened roots and crowns. Preventing take all disease There are no effective chemical treatments against take all disease available to gardeners. There is a seed treatment that shows promise, so be sure to get certified disease-free seeds from reputable suppliers. Excessive liming and nutrient imbalances exacerbate this disease. If take all disease appears in your lawn, there isn’t much you can do besides improving drainage. If it appears in your barley, corn, millet, rice, sorghum, triticale, or wheat, the best thing you can do is rotate crops. Oats and rye, while cereal grains, are not susceptible to take all disease. Take all disease can build up in the soil, particularly in monoculture crops that are grown in the same place year after year. There is one soil amoeba that feeds on the take all disease fungi. This unique protozoa is a type of vampyrellid. Vampyrellids are affectionately known as soil vampires because of the way they leave puncture marks in their victims.
Streaked avocado skins may indicate a disease known as sunblotch.
Sunblotch identification Unlike sunburn damage, which bleaches leaves, sunblotch appears as yellowish, reddish, or white streaks on the stems and skin of avocado fruits. Common symptoms of sunblotch include stunting, distorted leaves and petioles, and reduced fruit production. Rectangular cracking in the bark of older branches may also occur. Unfortunately, this disease can go unnoticed for years before symptoms become visible. By then, several nearby trees have probably become infected. Cause of sunblotch Until recently, botanists thought sunblotch was a genetic disease. Now we know it is a viroid infection. Viroids are the smallest known infectious pathogens, and they only attack plants. Unlike viruses, which contain DNA and RNA, viroids only contain RNA. This particular viroid attacks many tropical and subtropical plants, including avocados. Sunblotch control Trees infected with sunblotch must be removed and destroyed. Tree removal is expensive and potentially dangerous, so prevention is the only option. Sunblotch spreads through infected pollen, seeds and budwood. You can’t do anything about infected pollen if the source is on someone else’s property (besides educating your neighbor). But you can invest in disease-free bare-root trees. You can also ensure that any grafting projects you take on involve only healthy trees. And be sure to sanitize your garden tools after working on potentially infected trees with a household cleaner. European fruit lecanium scale might be a long name, but these garden pests can make short work of your pomegranates, citrus, and olives. European fruit lecanium scale description
European fruit lecanium scale is a soft scale insect. This means the shiny brown convex cover is not as hard as armored scale covers. You can identify European fruit lecanium scales because the brown cover has several ridges on it, while other soft scale insects do not. European fruit lecanium scale lifecycle European fruit lecanium scale larvae are normally found on twigs and small branches. As temperatures begin to rise in spring, they develop the telltale dome-shaped cover. Adult females fill the space under their cover with eggs and then they die. When the eggs hatch, the nymphs, or crawlers, come out from underneath the scale covers and hide out on the underside of leaves. By late July or August, these pests migrate to fruit. There can be two generations each year and most of the insects present will be in the same life stage. Damage caused by European fruit lecanium scale When European fruit lecanium scale larvae feed, they attach themselves to the outside of twigs and fruit and pierce the surface. This causes cosmetic damage as well as providing points of entry for other pests and diseases. Also, European fruit lecanium scale feeding results in the excretion of honeydew (sugary bug poop), which sooty mold fungi find delightful. The only exception is that scale feeding on pomegranates does not result in honeydew deposits. Instead, tiny piles of sugar are seen. These sugar piles are easily brushed off of twigs and fruit. European fruit lecanium scale controls Natural enemies are the best controls for European fruit lecanium scale. Twicestabbed lady beetles, steel blue lady beetles, and lacewings will all help fight soft scales. You can also wrap tree trunks with sticky barriers to remove the protection (and disease-carrying potential) provided by ants. Finally, prune trees for good air flow and structure to keep trees healthy. Adult cigarette beetles only live for a few weeks and do not eat. They can, however, fly. And cigarette beetle larvae are surprisingly destructive. Cigarette beetles (Lasioderma serricorne) favor tobacco plants. But they will also go after cereal grains, dried fruit, and these popular garden plants: Cigarette beetles will also feed on spices, including paprika, cumin, and sage. You may also find them in your flour, pet food, and even your favorite books! Cigarette beetle description These tiny brown beetles look almost identical to furniture and drugstore beetles, with a more humpbacked profile. If you use a hand lens, you can see that cigarette beetles have distinctive clubs at the ends of their antennae. Cigarette beetles are tiny. Eight of them could stand, end-to-end, across a dime. But don’t let their diminutive size fool you. Cigarette beetle lifecycle
Adult female cigarette beetles lay 30 to 100 eggs in and around preferred foods. As soon as the larvae hatch, they start feeding and moving around. After feeding and pooping, larvae enter a pupal stage in cocoons made from the foods they infested, making them difficult to see. While insecticides are effective against cigarette beetles, you are better off tossing out infested materials. Vacuuming and pheromone traps can also help control these tiny pests. Plum pox is one of the most destructive diseases of stone fruits, and I hope you never see it. Also known as sharka disease, plum pox was first observed in Bulgaria in 1915 and now occurs in many parts of Canada, Chile, Europe, India, the Middle East, and North Africa. In Europe, 100 million stone fruit trees are infected with the plum pox virus (PPV), resulting in 80–100% crop losses.
The disease appeared in a Pennsylvania orchard in 1999, which led the U.S. Department of Agriculture to declare an extraordinary emergency that gave them access to the funds necessary to remove and destroy infected and exposed trees. Plum pox appeared again in 2006 in Michigan and New York. The Department of Agriculture responded quickly and thoroughly. These eradication efforts have cost over $65 million. And the Pennsylvania stone fruit industry may never recover. Plum pox was declared eradicated in the United States (for the time being). Plum pox symptoms There are multiple strains of the plum pox virus, but the results are always unfortunate for stone fruit trees. Symptoms can be very subtle. They can vary by virus strain and host cultivar. Generally, leaf veins turn yellow and light green, or yellow rings may appear on leaves, fruits, and pits. These symptoms may disappear during the heat of summer, only to return in autumn. Leaves may also exhibit crinkling, curling, and puckering. Cultivars with large, showy flowers may become variegated. Fruit may be deformed, turn brown, or develop concentric colored rings. Premature fruit drop may also occur. Unfortunately, these symptoms do not usually appear until the infection has been present for 2 or 3 years. During this time, several other nearby trees can become infected. Plum pox transmission The plum pox virus (PPV) can travel long distances on infected plant material and insects. Grafting infected scions can transfer the infection to healthy trees. Several aphid species can carry this virus. How to avoid plum pox Removing infected trees is expensive, and halting the spread of plum pox is the responsibility of everyone growing stone fruits. These tips can help prevent plum pox in your garden (assuming you don’t live where plum pox is already a problem):
Plum pox may not kill fruit trees, but it can reduce production so much that you will probably end up replacing the trees anyway. Infected trees often produce misshapen, acidic fruit. Efforts are underway to develop resistant cultivars, but those trees are not yet available. Raspberries and white spruce share a disease called late leaf rust and raspberry rust. Mid to late summer, spores of this fungal disease infect red and purple raspberries. Yellow rust is similar but produces yellow to orange pustules in early to mid-summer.
Late leaf rust symptoms The first symptom of late leaf rust (Pucciniastrum americanum) is small yellow (chlorotic) spots on the top of older leaves. These spots generally begin appearing in lower portions of the plant, slowly spreading upwards into younger leaves. As the disease progresses, reproductive uredinia form on the underside of leaves, containing masses of spores. Extreme infestations can defoliate the entire plant. Fruit and flowers can also be infected, which causes them to rot. Of course, if all the leaves have fallen off due to disease, there probably won’t be any fruit or flowers. If the fruit has already formed, late leaf rust will appear as tiny orange spots on individual drupelets. Affected fruits will also ripen unevenly. Late leaf rust lifecycle Spores of this disease overwinter in white spruce and infected raspberry canes. Wind can spread these spores, so your upwind neighbor’s raspberries can directly impact yours. Late leaf rust control Like other rusts, late leaf rust is best avoided by pruning plants for good airflow and avoiding overhead watering. Also, be sure to remove spent canes each year. Throw infected plant material in the trash, not the compost pile. Fixed copper sprays may help prevent and treat late leaf rust. You won’t see them, but fig mites can bring serious diseases to your figs.
Fig mites (Eriophyes ficus, also known as Aceria fici) are a type of eriophyid mite and they are found worldwide. Fig mite description Adult fig mites are pale yellow, wedge-shaped, and have two pairs of legs near the head, but they are extremely small. Even with a 20x hand lens, these mites are difficult to see. Larvae look something like a fat plant hair that moves. At only 1/250” long, the only way you will know they are present is by using a microscope or looking for signs of the damage they cause. Damage caused by fig mites Fig mites often infest young leaves and bud scales. Fig mite feeding causes russeting, most commonly seen on the underside of leaves and on the bottom of figs. Russeting transforms smooth, healthy tissue into rough, brown, dry tissue. Fig mite feeding also results in fruit and leaf drop and twig stunting. The real problem with fig mites is that they can carry and transmit fig mosaic. Trees infected with fig mosaic should be removed, so it is worth the effort. Fig mite control Monitor leaves for signs of mite feeding from late spring through summer. If fig mites are seen, apply sulfur or horticultural oils, depending on the time of year. [Oils can burn leaves in summer.] I have also seen anecdotal recommendations for the use of spinosad against fig mites, but I do not know how effective it is. Just before your cantaloupes, cucumbers, squashes, watermelons, and pumpkins are ready to harvest, they suddenly wilt and die, taking your crop with them.
Unlike slow wilts, caused by lack of water (or too much water), or vascular diseases, such as Verticillium wilt and Fusarium wilt, sometimes leaves of cucurbits droop suddenly, and the entire plant collapses. It is sudden wilt, also known as parawilt. Sudden wilt is a soil-borne fungal disease that appears after heavy irrigation on hot, sunny days. Contrary to what you might expect, lots of water combined with hot sun is not what melons and squashes need. Sudden wilt occurs when there is an imbalance between water uptake and water loss, combined with certain fungi. Sudden wilt symptoms Sudden wilt starts as yellowing of the crown leaves, followed by total collapse of the entire plant. Death soon follows. If you dig up an affected plant, you will see that the roots are straw-colored or dark. There are three different fungi responsible for sudden wilt, and each one has unique symptoms: • Pythium spp. - appears as brown root rot • Acremonium cucurbitacearum - corky bands on discolored roots • Rhizopycnis vagum - upper portions of the taproot turn reddish and corky Sudden wilt treatments There are no chemical controls against sudden wilt. Careful water management, proper plant spacing, and removal of crop residue after harvest can help reduce the chance of sudden wilt in your garden. Monitor your cucurbits for signs of sudden wilt near the end of the growing season. Good drainage and 2- to 3-year crop rotations can help prevent this disease from wiping out your cucurbit crops. And let the soil dry out completely between waterings. Cucumber green mottle mosaic is a viral disease that can take a big bite out of your cucumber, watermelon, and other melon family crops. This cucurbit disease comes in on infected seeds. And there is no known cure. Before 2013, it was only in Russia, China, Japan, Korea, India, Spain, and Israel. Scientists believe it came to the U.S. on infected seed. Cucumber green mottle mosaic enters plants through wounds and root-to-root contact.
Cucumber green mottle mosaic control
Since there is no cure for this contagious disease, remove infected plants and a few of their neighbors to prevent it from spreading. Using certified disease-free seeds and placing new plants in quarantine can help prevent this disease from infecting your soil. Since this virus can travel on tools, shoes, and clothing, good sanitation practices can help protect your plants. Has a largish beetle with stripes ever hissed at you? It was probably a ten-lined June beetle. Ten-lined June beetles (Polyphylla decemlineata), also known as watermelon beetles, can kill mature trees outright. Ten-lined June beetle description The stripes are a giveaway for this relatively large beetle. Averaging 1.5 inches or longer, male ten-lined June beetles have distinctive antennae made up of overlapping scales, called lamellate plates. When these pests feel threatened, those plates are closed up and air is forced between the back and wings to create a hissing sound. Adult females do not fly. Eggs are 1/16" long, oval and cream-colored. Larvae have a white body and a brown head. They can grow to 2” in length with 3 pairs of legs. Damage caused by ten-lined June beetles Almond, apple, cherry, and plum trees are susceptible to damage caused by larval feeding of ten-lined June beetles. Trees may simply not thrive, at first. By the time the damage is significant, it is usually too late to save the tree. Adult ten-lined beetles feed on leaves, but that damage is insignificant. Ten-lined June beetle lifecycle Ten-lined June beetles are relatively long-lived insects. It takes 2 years to complete one generation of ten-lined June beetles. They can exist in the larval stage for up to 4 years. Larvae are found in the top 14” of soil where they feed on roots. Each summer and early autumn, adult females emerge from the soil and release pheromones to attracts males. Males fly from dusk until midnight or so. After mating, the females return to the soil where they lay eggs. Ten-lined June beetle controls
Heavily infested trees must be removed and the surrounding soil fumigated to prevent infestation of nearby trees. Luckily, that is rarely necessary in a home garden. Because female ten-lined beetles do not fly, populations spread slowly. Commercial growers use soil insecticides to kill beetles in the larval stage. Aboveground insecticides are not effective. Tachinid flies parasitize these pests, but not significantly. Because male ten-lined June beetles are attracted to light, you can capture them on your porch with a butterfly net and feed them to your chickens, or simply squish them whenever you see them. Bulb mites, also known as spinach crown mites, refer to a small collection of very tiny pests that can damage your onions, garlic, saffron crocus, and spinach plants. Bulb mite description
Bulb mites are a collection of pests from the Rhizoglyphus and Tyrophagus genus and they look like miniature ticks with spiky hairs. These pests may be tiny, but they can cause significant damage. Ranging in size from 1/2 to 1 mm long, you could 15 to 30 or more of them nose-to-tail across a dime. If you were to look at one with a magnifying glass, you would see that they are a shiny, creamy white, with four pairs of brown legs. Bulb mite host plants As the name implies, bulb mites infest bulbs, such as tulips, daffodils, and saffron crocus. They can also be found under the root plate of garlic and onion, or in the crown of spinach plants. Damage caused by bud mites Bud mite feeding is not particularly destructive by itself. The problem lies in the wounds created by that feeding. These damaged areas allow organisms responsible for decomposition to get inside your plants, causing them to rot. Overall stunting, leaf distortion, and softened stems are common responses to bud mite feeding. How to manage bulb mites Protect your bulbs against bulb mites by inspecting them before planting. Infested bulbs should be destroyed. Crop rotation and the removal of post-harvest plant debris can interrupt this pest’s lifecycle. If you grow red raspberries, monitor leaves early in the season for yellow rust. Like its cousin, the bright orange rust seen on the underside of rose leaves, yellow rust is a fungal disease. Unlike many other fungal infections, this rust only occurs on plant exteriors. When yellow rust occurs on wheat, rye, and barley, it is called stripe rust, a Puccinia striiformis infection.
Symptoms of yellow rust Plants infected with yellow rust (Phragmidium rubi-idaei) will initially have yellow pustules, called aecia, on the tops of the lower leaves. These symptoms are usually only seen in spring and early summer. In early to mid-summer, yellow to orange pustules, called uredinia, are found on the underside of leaves. As summer progresses, these growths darken. Black spots can be seen in the middle if you look closely. You may also see orange spots on the fruit. Similar infections that occur later in the season may be late leaf rust (Pucciniastrum americanum) or more severe orange rust (Arthuriomyces peckianus). Either way, infected leaves wither and die, reducing the plant’s ability to perform photosynthesis, which cuts crop size significantly. Yellow rust control Pruning for good airflow helps leaves and stems dry out, making life more difficult for these fungi. Since yellow rust spores (teliospores) overwinter in fruiting canes or floricanes, pruning those canes out at the end of the growing season can break this disease triangle. Canes of summer-bearing raspberries won’t produce any more fruit, so you might as well. Just dispose of these canes in the trash and not the compost pile. If unproductive canes stay in place, any spores they contain will spread the infection to the next season’s primocanes or vegetative growth. Keep the ground around cane fruit clear of dead leaves and other plant debris. If your raspberries are especially prone to yellow rust, you may want to cut the first spring growth of new canes back to ground level. Don’t worry. Their root systems will quickly put out new stems. That first growth is the most likely to have become infected. Fixed copper sprays and lime sulfur can treat severe outbreaks. Otherwise, remove infected leaves by hand and improve the airflow between plants to keep this disease in check and protect your delicious raspberries. Resistant varieties are available, so check with your local Department of Agriculture or Master Gardeners for recommendations for your area. If you grow peas or lentils, watch for pea seed-borne mosaic. The same is true for fava beans and chickpeas. Sadly, I was unable to find any freely available photos of pea seed-borne mosaic, so you will have to search for your own images. The purple-podded peas pictured above are perfectly healthy. Symptoms of pea seed-borne mosaic
Stunting, deformation, and rosette-type growths at the ends of stems are all signs of pea seed-borne mosaic. Chlorosis, downward cupping, vein clearing and swelling, and the classic mosaic or mottling of mosaic diseases may all be present in infected plants. Vein clearing is a common symptom of viral infections. Vein clearing describes how leaf veins appear translucent. Seeds shrivel and become discolored. Pea seed-borne mosaic infection is easily mistaken for chemical overspray, nutrient toxicities, and water stress. Laboratory tests are needed to verify this infection. You can often take ziplock bagged samples to your local Department of Agriculture for analysis. How to control pea seed-borne mosaic The pea seed-borne mosaic virus (PSbMV) is carried to your garden by aphids. Do the best that you can control them. Remove any plants infected with pea seed-borne mosaic and dispose of them in the trash. Unfortunately, some infected plants will never show symptoms. As aphids feed on these asymptomatic plants, they then carry the disease to nearby plants, spreading infection. For the most part, as the name implies, this viral disease is carried by infected seeds. Plant infected seeds and the aphids do the rest. The only way to prevent pea seed-borne mosaic from occurring in your garden is to buy certified pest- and disease-free seeds. This disease can overwinter in nearby weeds, such as shepherd’s purse, vetches, and black medic. If you notice outbreaks of pea seed-borne mosaic, and you know your seeds were clean, look at what is growing nearby. You can prevent pea seed-borne mosaic by planting resistant varieties. Fig trees can be stately and highly productive, but fig mosaic can take a toll on your fig tree. Fig mosaic is a complex of several, as of this publication, unidentified viral diseases that all infect the Ficus subspecies. How fig mosaic spreads All eriophyid mites,, especially fig mites, can bring fig mosaic to your trees. As they feed, their saliva transfers the virus to plant tissues. Grafting and cuttings can also spread the fig mosaic virus. Fig mosaic symptoms Yellow leaf mosaic patterns are a common symptom of fig mosaic. These patterns are brighter yellow toward the center of each spot, fading to light yellow before reaching the healthy green leaf tissue. As the condition progresses, a rust-colored band appears around the edge of each mosaic. Leaves may also be deformed. Infected fruit shows mild mosaic patterning but may be smaller and less abundant than on healthy trees. Most often, fig mosaic causes early fruit drop, all but eliminating your crop. Look for signs of mite feeding if you suspect fig mosaic. Look around bud scales and young leaves for signs of mite feeding. You may also see faint russeting. Twig stunting and leaf drop may also occur. Fig mosaic management
Trees infected with fig mosaic must be removed and destroyed by a professional. Tree removal is expensive. You can help prevent fig mosaic with these tips:
Sulfur treatments and horticultural oils can control fig mites. And those delicious figs are worth the effort. Beetles among your squashes and melons are never good, especially when they carry the squash mosaic virus. Squash mosaic is second only to cucumber mosaic in damage to cucurbits caused by disease. There are two strains of squash mosaic: strain 1 affects melons most often, while strain 2 prefers squash. In both cases, your crop will be lumpy, discolored, and significantly reduced, though still edible. Crops vulnerable to squash mosaic All cucurbits are susceptible to squash mosaic, including cucumbers, melons, pumpkins, and zucchini. Except for watermelons, they do not get squash mosaic. Some legumes and umbellifers can also become infected with squash mosaic. Squash mosaic symptoms Squash mosaic causes a dark green mottling or mosaic pattern on leaves, blistering, yellowing (chlorosis), leaf hardening and distortion, and vein clearing. Vein clearing is a common symptom of viral disease. It refers to how leaf veins become almost translucent while the leaf blades remain green. Squash mosaic carriers
Unlike other mosaic diseases, aphids are not responsible for squash mosaic. Instead, striped cucumber beetles, leaf beetles, spotted cucumber beetles, and 28-spotted ladybird beetles are the most common vectors of squash mosaic. Many other beetles are also capable of hosting the virus. As these insects feed, their saliva transfers the virus to the plant, so remove any infected plants. Squash mosaic controls In addition to removing infected plants, beetle control helps prevent squash mosaic. And beetles can be tough to control. The virus can stay viable inside a beetle for up to 20 days, so it is worth the effort. A single beetle can infect dozens of plants in that time frame. Handpicking is one way to control beetles, but only if you are quick enough. You can also use neem oil to kill beetle eggs. Encourage beneficial predators, such as ladybugs, mantids, and soldier bugs, in the garden with fresh water, insectary plants, and little or no chemical use. Supporting beneficial insects is the easiest method of keeping beetle populations within reasonable limits. Squash mosaic can infect seeds, so get clean, disease-resistant seeds and seedlings from a reputable supplier (not that melon from the grocery store). Certain chenopod weeds, including lambsquarters, goosefoot, and Russian thistle, provide overwintering sites, so keep these weeds away from your cucurbits. As with many other viruses, tools, clothing, and other surfaces can also become carriers. To prevent the spread of this disease, sanitize tools regularly and avoid working around plants while leaves are wet. Speckled, mottled, or otherwise deformed leaves and fruit usually indicate a mosaic disease. Mosaic diseases are a collection of viral infections that can infect most of your garden plants. Since these diseases are difficult or impossible to treat, recognizing and removing infected plants as soon as possible can help prevent the disease from spreading. Symptoms of mosaic diseases The classic mottled appearance of infected leaves is only one symptom of a mosaic disease. Leaf cupping, blistering, stunting, crinkling, and other distortions are other common symptoms of mosaic diseases. Stems may also be shorter, creating a bushy appearance to vines. Fruit may also show the same mottling and other distortions seen on leaves. Warty bumps are also commonly seen. Plants infected early in the growing season rarely produce fruit. Interestingly, plants infected later in the season retain their healthy, earlier growth and fruit production. Distortions only occur in post-infection leaves and fruit. Plants that host mosaic diseases It would be easier to list plants that are not affected by mosaics. But the plants most commonly infected with mosaic diseases include the following:
Common mosaic diseases
While there are dozens (hundreds?) of mosaic diseases, some of the more common varieties include this list:
Mosaic disease management Generally speaking, mosaic diseases are not curable. Remove infected plants and toss them in the garbage. Prevention is a far better course of action. Depending on the specific virus, it may catch a ride into your garden on seeds, tools, aphids, dryberry mites, and other sap-sucking pests. These tips can help reduce the chance of a mosaic disease robbing you of your harvest:
While mosaic diseases make plants look funny, the fruit of infected plants is still safe to eat. The viruses responsible for mosaic diseases are not harmful to people. You don't have to grow corn to have a reason to worry about seed corn maggots. Seed corn maggots mostly feed on decaying organic material, but sometimes they feed on the roots and seeds of over 50 different garden plants. Also known as the bean seed fly, seed corn maggots may be tiny, but they can ruin several of your crops.
Seed corn maggot description Seed corn maggots (Delia platura) are small, dark gray flies with gray wings, black legs, three stripes on the back, and scattered bristles. Less than 1/4” long, seed corn maggot adults looks nearly identical to onion maggot flies. White or off-white larvae are legless and have rounded tails and pointed heads. Pupal cases are brown and hard and look like skinny footballs. Seed corn maggot damage Seed corn maggots often feed on the seeds of corn, peas, beans, and soybeans but they do not always kill the embryos within the seeds. When those seeds germinate, they are spindly and rarely make it to maturity, wasting valuable resources. Other crops commonly attacked by seed corn maggots include cucumbers, melons, onions, peppers, and potatoes. Seed corn maggots may tunnel into the stems and roots of many different garden plants and feed on spinach leaves, often providing points of entry for other pests and diseases. Seed corn maggot lifecycle Adult flies emerge in spring and begin feeding on nectar and honeydew. After mating, females lay an average of 270 eggs in the soil, near the surface. One week later, larvae emerge and begin feeding. One to three weeks later, larvae move back into the soil where they pupate for one to three weeks, or over the winter. How to control corn seed maggots The key to controlling corn seed maggots is in the soil. While I am a proponent of no-dig gardening, repeated appearances of corn seed maggots warrants disturbing the top 2 or 3 inches of soil on a regular basis during the spring and summer months. Research is being conducted on the possibility of beneficial fungi being used to control these pests, but it is not currently an option. As is nearly always the case, prevention is far easier. You can reduce the odds of seed corn maggots attacking your crops by waiting for the weather to warm up before planting, and spacing plants properly. Anything that slows germination or initial seedling growth makes it easier for seed corn maggots. Yellow spots on leaves may indicate Septoria leaf spot. This fungal disease is very destructive. It affects celery, chicory, cucumber and other cucurbits, and tomatoes. Like other leaf spot diseases, Septoria reduces photosynthesis and the flow of critical nutrients through the vascular bundles, leaving plants to wither and die.
Warm, wet weather is all these fungi need to set up housekeeping in your garden. And that wetness can be caused by poorly placed sprinklers, leaky hoses, and overhead watering. Temperatures between 60°F and 80°F are ideal for fungal growth. Knowing what to look for can help you protect your plants. Types of Septoria Septoria is a family of fungi. Different subspecies affect different plants. The most common types of Septoria, followed by their host plants and symptoms, include the following:
Symptoms occur first in older leaves. The disease spreads upward into newer growth. As the spots spread, leaves turn yellow, die, and fall off. This leaf loss reduces plant vigor and increases the risk of sunburn damage. Severe infections can result in complete defoliation. Septoria leaf spot lifecycle Septoria fungi travel in the wind and rain, so monitor regularly. Spores land on host plants and send out thready hyphae, which enter plants through cracks and injury sites. Spores overwinter in the soil and on infected plant debris. How to control Septoria leaf spot As with many other diseases, prevention is far easier than treating them. These tips will help prevent Septoria leaf spot in your garden:
If Septoria leaf spot appears, remove infected leaves and throw them in the trash. Also, sanitize any tools that may have come into contact with infected plants. While it might be cute to picture a fly buzzing around with a tiny saw, there is nothing to love about sawflies. Sawflies get their name because their ovipositor (egg-laying organ) is shaped like a saw and used to cut notches into plants for egg-laying. Sawfly description Sawfly larvae may look like caterpillars or slugs, but these pests are in the same order as bees, wasps, and ants, and are closely related to woodwasps and horntails. You can tell the difference between sawfly larvae and caterpillars by counting their legs. Caterpillars usually have five or fewer prolegs on their abdomen, while sawfly larvae, such as the California pear sawfly, have 7 or 8 pairs of prolegs on their abdomen and 3 more pair on the thorax. With over 8,000 sawfly species, spread out over 800 genera, there is a wide variety of coloration and body type in the world of sawflies. As a group, their soft bodies are stubby and only slightly wasp-like, and they tend to be weak flyers. The ovipositor is often mistaken for a stinger, though sawflies cannot sting. Some sawfly larvae, however, are known to puke up a noxious liquid that would-be predators find distasteful, while other sawfly species raise their rear ends up, cobra-fashion, weaving back and forth a warning. Sawfly species Some of the more common sawfly species include:
Sawfly lifecycle Adult sawflies only live for one week, during which time they mate and females lay 30 to 90 eggs. Eggs are tan, oval or kidney-shaped, and look like tiny blisters on the upper surfaces of leaves. In 2 - 8 weeks, depending on temperatures, those eggs hatch and then go through 5 or 6 larval stages, depending on the species, before heading to the soil, en masse, to pupate. Some sawfly species use webspinning and leafrolling to protect their young, while others spin cocoons. The entire process can take 2 years. It is during the larval stages when sawflies do the most damage. Sawfly damage Sawflies are defoliators, which means they strip the leaves from several garden plants. Species tend to be host-specific. Rose sawflies attack roses, pine sawflies attack pine trees, and so on. Plants vulnerable to sawfly feeding include apple, cherry, peach, pear, plum, and quince trees, along with most cane fruits. Larvae often feed in large groups, for added protection. Damage caused by larval forms of sawflies include leafmining, defoliation, skeletonizing, galls, and notching of leaves. Sawfly controls Generally speaking, handpicking is your best method of controlling sawfly larvae. You can feed them to your chickens for a tasty protein treat, or bag them and toss them in the trash. While Bacillus thuringiensis (Bt) can be used to control moth and butterfly larvae, it is not effective against sawfly larvae. Insecticides can be used against sawflies, but sawfly larvae are a popular food for many native birds, including partridges, black grouse, corn buntings, and chestnut-backed chickadees. Shrews, lizards and frogs also enjoy snacking on these pests, along with several predatory wasps, including ichneumon and braconid wasps.
You can attract these garden helpers by providing fresh water, growing a variety of insectary plants and plants that provide pollen and nectar, and avoiding the use of broad spectrum pesticides and herbicides. |
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