On the underside of leaves opposite these spots the pathogen produces dark spores. Fungal species that cause powdery mildew in greenhouse. In addition, downy mildew is strongly suspected on cucumbers in jefferson county. Leaf lesions are initially yellow and irregular as seen here on butternut squash. Downy mildew is a disease caused by the funguslike water mold, pseudoperonospora cubensis, which attacks only cucumbers and related crop species gourds, pumpkin, squash, melons. Powdery mildew vs downy mildew university of florida. For further information on downy mildew of cucurbits, refer to the compendium of cucurbit diseases, published by the american phytopathological society, st. Powdery mildew on cucurbits is now beginning to progress. Managing downy mildew in organic and conventional vine crops pdfthe ohio state. Commercially important species of cucurbits include watermelon citrullus lanatus, muskmelon cucumis melo, cucumber cucumis sativa, squash cucurbita pepo, cucurbita moschata, and pumpkin cucurbita maxima.
It has been reported worldwide in production areas where humidity and temperature favor its establishment. Cucurbits belong to the family cucurbitaceae and form an important and a large group of vegetables, grown extensively throughout india and other tropical and subtropical regions of the world. The funguslike pathogen that causes this infection will trigger some characteristic symptoms in your garden, so know what to look for, catch it early, and take steps to manage the disease to save at least some of your harvest. Downy mildew of cucurbits purdue extension purdue university. This yearround ipm program covers the major pests of cucurbits in the sacramento, san joaquin, coachella, palos verde and imperial valleys, as well as riverside county. Details on carrying out each practice, example monitoring forms, and information on additional pests can be found in the cucurbit pest management guidelines pmg. Cucurbit downy mildew management for 2019 landgrant press. Cucurbit downy mildew can destroy your tasty crop of cucumbers, watermelon, squash, and pumpkins. This disease is caused by the funguslike pathogen pseudoperonospora cubensis. Powdery mildew, mainly caused by the fungus podosphaera xanthii, infects all cucurbits, including muskmelons, squash, cucumbers, gourds, watermelons and pumpkins. A fine whitetograyish downy growth soon appears on the lower leaf surface. Today, well go over everything there is to know about downy mildew. Prevention before it appears, and prompt action afterwards, are needed to manage this aggressive pathogen. In the absence of chemical or biological control ishida et al.
Powdery mildew is a serious fungal disease that attacks a wide range of plants. Cucurbitaceae, including cucumber, watermelon, cantaloupe, pumpkin. The pathogen can attack all cucurbits and cause economic damage to field and greenhousegrown crops. Downy mildew, caused by the fungal organism pseudoperonospora cubensis, is most destructive to cucumber and cantaloupe, though all cucurbits are susceptible. There has been no report of occurrence of downy mildew in illinois in 2005 yet. The largest percentage of downy mildew control was for grape downy mildew caused by plasmopara viticola 54% followed by the cucurbit downy mildew caused by pseudoperonospora cubensis 10%.
The first report in nc earlier this month was on cucumber in duplin county. Cucurbit downy mildew north carolina cooperative extension. This disease of cucurbits is caused by two powdery mildew fungi. Management of cucurbit downy mildew for gardeners dr.
In illinois, this disease usually occurs toward the end of the season. Pseudoperonospora cubensis downy mildew caused by pseudoperonospora cubensis is one of the most important foliar diseases of cucurbits. Downy mildew of cucurbits pseudoperonospora cubensis downy mildew is caused by a funguslike water mold which infects cucumbers, pumpkins, winter squash, and melons. It has a wide host range as the pathogen can infect over 60 different hosts, including cucurbits such as. Cucurbit downy mildew was reported june 17th in watermelon in nash county, nc. Downy mildew of cucumber, melon and squash umn extension. The disease occurs primarily on foliage, resulting in reduced photosynthetic activity. Downy mildew of cucurbits downy mildew, caused by pseudoperonospora cubensis, is one of the most important foliar diseases of cucurbits. These breeding programs produced many cucumber varieties and a few melon varieties that had resistance to strains of downy mildew present in the u. Cucurbit downy mildew is a major disease that affects all cucurbits.
Cucurbits downy mildew cucumber, melon, pumpkin, squash, and zucchini howard f. The above mentioned publications are available from university of illinois ag services, p345, 1917 south wright st. Cucurbit downy mildew msu extension service mississippi state. Downy mildew is a potentially devastating disease of cucurbit crops that can cause significant yield losses. The cucurbit downy mildew pathogen pseudoperonospora cubensis.
It thrives in wet or very humid conditions as a water mold. Cucurbit powdery mildew is a fungal infection with a couple of culprits. The downy mildew pathogen does not produce many spores on cantaloupe leaves, thus the dark fuzzy downy fungal growth that commonly occurs on the underside of. Downy mildew can be a serious disease on any vine crop, but may be especially devastating to cucumbers where the appearance of initial symptoms. Downy mildew is primarily a disease of the cucurbitaceae family including cucumber, watermelon, cantaloupe, gourds, squash and pumpkin. Downy mildew of cucurbits downy mildew, caused by pseudoperonospora cubensis, affects all cucurbit crops. Cucurbitaceae downy mildew caused by pseudoperonospora cubensis is specific to cucurbits e. Yellow to orange spots develop on the upper surface of leaves. Downy mildew of cucurbits purdue university vegetable. All cucurbits are susceptible, but symptoms are less common on cucumber and melon because many commercial cultivars are resistant.
Linderman may 2016 recognizing downy mildew on cucurbits yellowing on top surface of leaves bound by veins velvety or fuzzy dark spore growth on the underside of leaves downy mildew causes symptoms on the leaves similar to angular leaf. Downy mildew, caused by pseudoperonospora cubensis, is an oomycete that is not a true fungus. The disease is one of the most significant diseases of cucurbits worldwide. This profile provides an overview of organic cucurbit production in kentucky, including market demand potential, key production considerations, and baseline economics. But downy mildew is a completely separate problem, even if it might look similar. The water mold cucurbit downy mildew affects cucurbits vine crops in the squash family in south carolina every year, especially in summer and fall. As you may remember, a couple weeks ago cucurbit downy mildew cdm was found in new jersey and up until this week, most of eastern ny was under low risk of spores blowing in. In severe cases, powdery mildew can cause premature death of leaves, and reduce yield and fruit quality.
Although it can be a problem in field, hoop house and. This disease, sometimes referred to as cucurbit downy mildew, is known to infect more than. If youre looking for how to get rid of powdery mildew, check here. Fungicide resistance management guidelines for cucurbit downy and powdery mildew control in the midatlantic and northeast regions of the united states in 2018. Downy mildew of cucurbits was first reported in 1868 in cuba. Cucurbit downy mildew mississippi state university. Managing downy mildew in cucurbits cornell university. Pseudoperonospora cubensis can infect cucurbit plants at. It occurs worldwide where conditions of temperature and humidity allow its establishment and can result in major losses to cucumber, melon, squash, pumpkin, watermelon, and other cucurbits. Cucurbit downy mildew nc state extension publications. Downy mildew causes a severe foliar disease of all cucurbit crops, which include cucumber, gourd, cantaloupe, squash, watermelon, and zucchini. Now, this disease occurs in most of the cucurbit growing areas in the world. Recent changes in fungicide regulations leaves fewer options for farmers to control cdm, economically the most important disease for cucumbers.
This disease occurs in squashes, melons, gourds, cucumbers, and pumpkins. Cucurbit downy mildew affects the leaves of all commercial cucurbits cucumber, cantaloupe, squash, watermelon, pumpkin, etc. A powdery mildew infection acts as a sink for plant photosynthates causing reductions in plant growth, premature. Downy mildew and powdery mildew are often confused. The oomycete pathogen is an obligate parasite that requires a host to survive during harsh winter months. The overwintering structure, the oospore, has not been observed in the united states, and the pathogen does not survive on crop debris between.
Cucurbit downy mildew is a potentially serious disease of all plants in the gourd family. This disease is known to infect more than 40 cucurbit species, including cantaloupe, cucumber, pumpkin, squash, and watermelon. Powdery mildew is one of the most common diseases of tomatoes grown in greenhouses and high tunnels. Downy mildew, however, has been reported on cucurbit. Higgins january 2020 recognizing downy mildew on cucurbits yellowing on top surface of leaves bound by veins velvety or fuzzy dark spore growth on the underside of leaves dm causes symptoms on the leaves similar to angular leaf spot. Cucurbit downy mildew is an important foliar disease that affects all types of cucurbits.
Leaf spots vary in appearance between cucurbit species and within cucurbit species. In 1996 the global fungicide market was estimated at approximately 6. It is caused by pseudoperonospora cubensis, which is an oomycete pathogen, otherwise known as a water mold. Breeding for resistance to downy mildew has been ongoing since the 1930s. Gent identification and life cycle downy mildew of cucurbits is caused by the funguslike pathogen pseudoperonospora cubensis. Prsvw affected zucchini fruit photo courtesy of david commens sps figure 16. Downy mildew of cucurbits university of illinois at. Downy mildew occurs in temperate and tropical areas with sufficient leaf wetness periods. Downy mildew of cucumber is caused by pseudoperonospora cubensis, a member of the water mold group oomycota of fungallike organisms. Growers in nearby areas should take care to manage downy mildew if they have valuable cucurbit crops. Angular chlorotic lesions bound by leaf veins on the foliage of cucumber. Downy mildew can begin to develop at any time during cucurbit crop.
Management of cucurbit downy mildew in florida 2 epidemiology and disease cycle cucurbit downy mildew is caused by a biotrophic organism or obligate parasite, which means it needs a living host to survive. Powdery mildew of cucurbits university of connecticut. Printable pdf click on images to see larger view powdery mildew is a common and serious disease of cucurbit crops in connecticut. Marketing and market outlook direct markets for organic cucurbits in kentucky in. More recently, downy mildew was reported on cucumbers and butternut squash in knox county in southwestern indiana. It primarily infects the leaves, resulting in decreased photosynthesis leading to reduced yield and poor fruit quality. Downy mildew cucumber, melon, pumpkin, squash, and. Symptoms first appear as pale green areas on the upper leaf surfaces. Powdery mildew symptoms first appear as pale, chlorotic spots on leaves that soon turn powderywhite in appearance fungal spores and spread to petioles and. Cucumber downy mildew caused by the funguslike organism pseudoperonospora cubensis was confirmed recently on a cucumber plant from morgan county, mo by the university of missouri plant diagnostic clinic. Downy mildew institute of food and agricultural sciences. Cucurbit powdery mildew treatment managing cucurbit with. Resistance management is of utmost importance for cucurbit. Cucumber downy mildew missouri environment and garden.
Effectively managing cucurbit downy mildew in ny in 2017 pdf. Downy mildew spreads quickly on cucumber, cantaloupe, and watermelon. The powdery mildew pathogen is windborne and, unlike many other pathogens, can even efficiently infect during dry periods. Cucurbit downy mildew is caused by the funguslike oomycete pathogen pseudoperonospora cubensis p. While fruit infection is possible, the greatest damage comes from decimation of the leaves leaving the fruit exposed for sunscald and decreasing the surface area available for photosynthesis. Cucurbit downy mildew update chuck bornt, team leader, extension vegetable specialist eastern new york commercial horticulture. Isolates belonging to clade 1 tend to more frequently infect watermelon, pumpkin, and squash while isolates belonging to clade 2 more frequently infect. Downy mildew can infect all cucurbits including cucumber, melon, pumpkin and squash.
Downy mildew of cucurbitspseudoperonospora cubensis. This disease primarily affects the foliage and can cause severe yield losses in a short period of time. While nonresistant crapemyrtle trees are especially susceptible, this disease can also attack flowers like zinnias, roses, and gerbera daisy, as well as edibles like squashes, strawberries, and tomatoes. It affects any type of cucurbit, but is less common in melons and cucumbers. The downy mildew pathogen is an obligate parasite that needs living cucurbit plants in order to grow and survive. Downy mildew of cucurbits american phytopathological society. Downy mildew is almost exclusively a foliar leaf spot problem of cucurbits. Cucurbit powdery mildew pm is one of the most severe fungal diseases, but the molecular mechanisms underlying pm resistance remain. The characteristic white, powdery mold is pretty easy to spot, but management and prevention of the disease requires several steps.