If you grow raspberries, you should be on the lookout for spur blight. Blackberries and other bramble fruit are not affected by the Didymella applanata fungi, but red raspberries are especially vulnerable. Currently found most often in Scotland, Oregon, and Washington, spur blight can significantly reduce your raspberry crop. Spur blight symptoms Spur blight first appears in mid to late summer. Initial symptoms of spur blight look similar to anthracnose, fireblight, and cane blight, with brown and purple lesions on leaves, around buds, and on the lower area of stems. These lesions cause buds to shrivel up. By spring, lesions will look ashy gray, and the buds will be weak or dead. Stems that grow from these infected buds will be wilted and weak. Infected leaflets have triangular-shaped brown areas and may fall off, leaving the petiole (leaf stem) in place. You might also see dead spots on the canes near petioles. This infection causes premature leaf drop, which weakens the plant overall. As the blight progresses, splits and cracks may form in the bark. Look closely to see tiny black dots emerging from those cracks. Those dots are fungal fruiting bodies called pycnidia. If you look at pycnidia with a microscope, they are flask-shaped. A different type of fruiting body, perithecia, comes next. Perithecia are also black, but they are medium-sized and, if you watch, erupt with spores.
Spur blight lifecycle Spur blight spores travel in wind, rain, and irrigation water. These spores are released each time wet weather occurs, even if that wetness is your garden hose. Infected water that lands on or near young canes, newly forming buds, leaves, wounds, or stomas, can result in infection. Once inside, this disease spreads throughout the plant, overwintering inside the lesions. How to manage spur blight Proper sanitation and pruning methods will go a long way toward preventing spur blight on your beloved raspberries. In late winter or early spring, before new canes emerge, remove all dead, diseased, or weak canes and put them in the trash rather than the compost pile. Keep canes properly spaced for good airflow, and train them up trellising to allow canes to dry quickly. It makes watering your raspberry plants at ground level easier, too. Keep weeds away, as they compete for water and nutrients and reduce airflow around the canes. Unless a lab-based soil test has indicated a need for fertilizer, avoid feeding your raspberry plants when spur blight is a problem. The presence of too many nutrients causes plants to produce an abundance of vulnerable tissue. As always, only buy certified, disease-free plants and place new plants in quarantine. In the case of severe infection, fixed copper or lime sulfur treatments may reduce lesion size and control internal infection, but only if applied when new shoots are 8-10” long. Spur blight is easier to prevent than treat. And raspberries are worth the effort.
1 Comment
Strawberry vein banding is an invisible viral disease spread by strawberry aphids. You will never know it has infected your plants until another virus infects your strawberries. As soon as another virus infects your plants, usually strawberry crinkle, the leaf veins of your strawberry plants suddenly start to turn yellow. And if the strawberry mottle virus comes along, those yellowing veins won’t be visible. This triple threat is called strawberry decline.
Symptoms of strawberry vein banding The leaves of infected plants tend to be significantly smaller. Vein yellowing, when visible, appears erratically in new growth first. Sometimes only part of a vein has turned yellow. The two halves of each unopened leaf may look closer together than is normal, and the margins, or leaf edges, are wavier than normal. Some crinkling of the leaf surface may also occur. As the leaf opens, the bands of yellow become a little more obvious. Symptoms appear more strongly in the second and third leaves but are not likely in later growth. Unfortunately, the other symptoms include stunting and reduced fruit and runner production. Vein banding can reduce strawberry crops by nearly 20%. If another virus takes hold, you can lose your crop entirely. Strawberry vein banding vectors Strawberry aphids and other aphid species carry strawberry vein banding to your plants. Grafts from infected plants also spread the disease. Strangely enough, dodder can also spread the disease, but the sap from an infected plant cannot. Stranger still, a clone of the vein banding virus can infect turnips, a completely unrelated species. Strawberry vein banding control In a word, you can’t. Strawberry vein banding can only be prevented by installing certified disease-free plants, placing plants in quarantine when they first arrive, and removing any infected plants. Since aphids can fly at points in their development, the threat of this and other viruses is constant. All you can do, besides the preventive measures listed above, is monitor your plants for signs of aphids and control them as well as you can. Insecticides and insecticidal soaps work against aphids, but your strawberry plants need honey bees and other pollinators to produce fruit. Those insecticidal controls will impact your helpers, too, so avoid them while plants are flowering. Closely monitoring your strawberry plants and keeping other plants that might host aphids at a distance can go a long way toward preventing vein banding in your garden. Strawberry pallidosis is one of several viruses that make up strawberry virus decline.
Infected with only one of these diseases, strawberry plants often remain symptomless. It isn’t until a second virus enters the game that symptoms begin to appear. These other viral diseases include strawberry vein banding, crinkle, mottle, mild yellow edge, and beet pseudo yellows. Symptoms of strawberry pallidosis Stunting, reduced fruit and runner production, and older leaves turning red or purple are all symptoms of strawberry pallidosis. Also, roots are brittle and show fewer rootlets. Managing strawberry pallidosis Unlike many other strawberry viral diseases, whiteflies bring pallidosis to the garden. Management strategies are the same for all strawberry viral diseases: only install certified disease-free plants, quarantine new plants, remove infected plants, and control whiteflies as much as possible. Strawberry mottle is an unassuming viral disease that can cut your strawberry crop by 30%.
When strawberry mottle occurs alone, the damage tends to be relatively isolated. All too often, however, more than one virus appears simultaneously in a condition called virus decline. Virus decline can eliminate any chance of enjoying a sweet, juicy strawberry from your garden, no matter how well you care for your plants. Vectors of strawberry mottle disease Strawberry mottle is transmitted by insects, most commonly by strawberry, melon, and cotton aphids. Infected plants can also spread the disease. Unlike the strawberry mild yellow edge virus, which stays in an aphid’s gut for its lifetime, the strawberry mottle virus can only be transmitted for 2 or 3 hours after an aphid or other insect has fed on an infected plant, keeping outbreaks relatively localized. [Ten feet away probably looks impossible to a mostly flightless bug that is only 1/8” long.] Symptoms of strawberry mottle As insects pierce plant cells to suck out the sugary sap, viruses move from the insect’s saliva to the plant. As viruses tend to do, these pseudo-lifeforms start reprogramming plant cells to produce more viruses. All this reproduction clogs plant veins. Strawberry mottle first appears on young leaves as smaller-than-normal leaves. They may also show yellow distorted areas. Stunting may occur, and they produce less fruit and runners than they might otherwise. As the disease progresses, symptoms become more severe, with older leaves turning red. Strawberry mottle management Strawberry mottle is more likely when plants stay in place over the winter, but that doesn’t mean you must rip out your plants each year. [Note: don’t rip plants out of the ground. Instead, cut them off at soil level to leave valuable soil microbes in place.] To reduce the likelihood of strawberry mottle appearing in your garden, only buy certified disease-free plants and always place new plants in quarantine. As much as possible, try to control aphids around strawberry plants. If a plant becomes infected, remove it. For some reason, strawberry plants often get infected with more than one virus simultaneously. Strawberry mild yellow edge virus is one of those diseases.
Strawberry mild yellow edge virus is a long name for a disease that can reduce your strawberry crop by as much as 30%. Strawberry mild yellow edge virus often appears when the mottle virus does. They are both transmitted by aphids. Nematodes may also add raspberry ringspot virus to the mix. Strawberry mild yellow edge virus symptoms As with most viral diseases, stunting is a common symptom of strawberry mild yellow edge virus. Older leaves may turn bright red, but the leaves around the crown nearly always exhibit yellow margins or edges, hence the name. These yellowed areas eventually die and turn brown. Leaf cupping may also occur. Since these symptoms look much like water stress, fertilizer burn, overly acidic pH, boron toxicity, or bad weather, it is important to rule those out before deciding on a plan. Once strawberry mild yellow edge virus has made an appearance in your garden, there are steps you can take to minimize the damage. How to manage strawberry mild yellow edge virus Even though the fruits of infected plants are still edible, remove plants infected with strawberry mild yellow edge virus to prevent the disease from spreading. Aphids carrying the strawberry mild yellow edge virus are disease vectors for life. You can try to use insecticidal soap on every aphid that might be a carrier. Just be sure to do this at a time when honey bees and other pollinators will not be attending the flowers. Common lambsquarters and other Chenopods can also carry this disease, so keep these plants away from your strawberry plants. This disease is most common when plants are grown using a matted-row method. The matted-row system allows parent plants to send out runners, or daughter plants, which will produce fruit the following spring. This highly productive method has been around for a long time. It gets its name because the runners end up intertwined, creating a mat. The only problem with the matted-row system is that it means plants are in place longer, making infection more likely. As always, put new plants into quarantine until you know they are disease-free. Strawberry crinkle might sound like a delicious new candy bar. Instead, it is one of the most destructive viral diseases a strawberry plant can face. Strawberry crinkle virus was first seen in Oregon and California in 1932 and now occurs worldwide. Spread by aphids, it appears in tandem with other aphid-transmitted diseases, such as mottle, mild yellow edge, pallidosis, and strawberry vein banding. As aphids feed, their saliva transfers the virus to every plant they visit. Strawberry crinkle virus symptoms
Wilting, reduced runner production, smaller fruit, deformed or streaked flower petals, and crinkled leaves are all symptoms of strawberry crinkle virus. Vein spotting and lesions on petioles (leaf stems) and stolons may also occur. Infected plants may appear top-heavy, exhibiting a form of epinasty. These symptoms can vary in intensity. Strawberry crinkle virus management Since bees are critical to strawberry formation, insecticides are generally not an option against the aphids that carry this disease. Use these tips to prevent strawberry crinkle virus from impacting your strawberry crop:
Hopefully, your strawberry plants will never become infected with the crinkle virus. Until we figure out a sustainable way to eliminate aphids, we must be vigilant against these pests. Cytospora canker is a collection of symptoms caused by several species of Cytospora fungi. This disease also occurs on ash, birch, cottonwood, elm, maple, willow, spruce, and other conifers. Some Cytospora fungi are host-specific, while others can infect multiple tree species. Sadly, Cytospora canker can be fatal.
Cytospora canker lifecycle Cytospora canker fungi infect trees and shrubs that are stressed or weakened by injury, frost damage, drought, or pests. Spores enter your garden on wind and rain. Infection can occur at any time of year, but trees are most vulnerable during dormancy. Fungal spores enter through tiny wounds in the roots or bark and begin growing in the xylem and phloem. This fungal growth blocks the flow of water and nutrients. If infection occurs in the trunk, the tree will die. Cytospora canker symptoms The first sign of Cytospora canker is often the random dieback or flagging of tree or shrub branches. You can see long, narrow cankers on infected stems and branches. These fungi grow so rapidly that cankers may or may not be sunken or discolored. You might observe the bark split along the edge of these cankers as the tree tries to defend itself. These cracks allow for the formation of a callus that blocks the fungi from entering the rest of the plant. Sometimes this works, and sometimes it doesn’t. Sometimes, this girdling occurs without any visible cankers. Gumming is another defense trees use. Gumming is when stems and fruit ooze out a sticky sap. If you cut into a diseased stem, you may notice discoloration and a funky smell. If you see tiny black spots, you are looking at the fruiting bodies of the fungi. Cytospora canker prevention and control The easiest way to prevent Cytospora canker is to keep your trees and shrubs healthy in the first place. Healthy plants are less likely to become stressed enough to be vulnerable to infection by fungal spores in the first place. Since drought and flooding are the most common conditions that make trees susceptible to Cytospora canker, regular irrigation during summer and proper drainage in wetter months can prevent infection. These other tips can help you prevent Cytospora canker in your landscape:
Once infection occurs, remove any affected stems and branches by cutting close to, but not damaging, the branch collar. Be sure to disinfect your cutting tools with a household cleaner or ethyl alcohol between each cut. Then apply a fungicide to each cut. Do not use sealants, as these treatments can trap spores and moisture where you least want them. There are no known chemical controls for Cytospora canker, so keeping those trees and shrubs healthy is your best bet. 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. Mottled, stunted cilantro plants may have apium virus Y disease.
Apium virus Y disease is carried by aphids. This viral disease is also found on celery, carrot, dill, and poison hemlock. It can infect parsley, as well, but no visible symptoms occur. Apium virus Y disease symptoms Leaf mottling or mosaic patterns, stunting, cleared veins, and leaf distortions are all symptoms of apium virus Y disease. Older leaves may have yellow blotches, brown lesions, and yellow or brown line patterns. Younger leaves show only faint mottling. Lesions may form on petioles (leaf stems). How to prevent apium virus Y disease Since this disease is predominantly carried by aphids, you can help prevent this disease by controlling aphid populations (as much as is possible, of course). The virus can also be carried on clothing and tools, so be sure to sanitize your tools regularly and avoid walking through areas known to be infected. The virus does not remain vital for very long once it is inside an aphid. Creating physical barriers and increasing the distance between potential carriers can reduce the likelihood of this disease. Crop rotation and the CAREFUL removal of poison hemlock can also help control this disease. There are no effective chemical treatments for apium virus Y disease. 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. You’ve probably read dozens of articles and posts about the wonders of dish soap as a pesticide, fungicide, and surfactant in the garden. All of those posts are wrong.
How dish soap works
Dish soap is a detergent. Dish soap cleans dishes by cutting grease, oil, and wax. Dish soap generally contains colorants, fragrances, bleach, enzymes, phosphates, and rinsing agents. None of those are good for your plants. Dish soap damages protective, waxy coatings used by plants and insects. If you wash this protective coating away, infection, infestation, and dehydration become more likely. Dish soap v. insecticidal soap Insecticidal soap is not a detergent. It is a soap specifically formulated for use on plants. It must be used properly to be safe and effective. While liquid hand soap is a soap and not a detergent, it contains fatty acids that are phytotoxic (poisonous to plants). Despite popular opinion, dish soap does not belong in the garden. Save it for your dishes, and your plants will thank you. 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. 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. 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. Warty zucchinis with skinny leaves may mean the zucchini yellow mosaic virus has infected your plants. No garden would be complete without the versatile, fast-growing zucchini. A favorite in stir-fry, bread, and the ever-popular chocolate zucchini cake, zucchini can be a very productive plant, but only as long as it stays healthy. Zucchini yellow mosaic symptoms Whitened leaf veins, mottled, abnormally small leaves with alternating light and dark areas, and deformed, warty fruit are all signs of zucchini yellow mosaic. These are also symptoms of watermelon mosaic and papaya ringspot. These two viral diseases often occur in tandem with zucchini yellow mosaic. Watermelon mosaic infections exhibit blistered leaves, while zucchini yellow mosaic has long, narrow leaf lobes, creating a shoestring or ferny appearance. Zucchini yellow mosaic host plants
In addition to infecting zucchini, zucchini yellow mosaic also infects other cucurbits, including cantaloupe, cucumbers, melons, pumpkins, squash, watermelon, and some gourds. Aphids bring this disease to your garden. Zucchini yellow mosaic management Controlling aphids is difficult. These pests seem to appear overnight in huge numbers. And all it takes is one aphid to get the whole process started. Unfortunately, insecticides are rarely effective at managing zucchini yellow mosaic because the disease has often been transmitted before you even know the aphids are there. Reflective mulches can discourage aphids. Remove or cover the reflective material before it gets too hot, or your plants will cook where they stand. Row covers can reduce access to susceptible plants. This disease can also travel on infected garden tools and seeds, so sanitize your garden tools regularly and get your seeds from a reputable source (and not that zucchini from the grocery store). Remove infected plants and replace them with resistant cultivars. Since this virus is only viable for a few hours within their aphid carriers, creating a physical barrier of tall, non-host plants around your cucurbits can be enough to prevent the aphids from getting to the plants while the virus is still active. |
Welcome!You can grow a surprising amount of food in your own yard. Ask me how! To help The Daily Garden grow, you may see affiliate ads sprouting up in various places.
You can also get my book, Stop Wasting Your Yard! Index
All
Archives
April 2024
|