Cucurbit downy mildew is a devastating disease for the United States cucurbit industry, which includes cucumbers, watermelon, squash, and pumpkin. The mold is a sort of cotton-candy vampire, sucking nutrients from the plant, so if you leave it untreated, a severe infestation can cause your plants to wither. Isolates belonging to clade 1 tend to more frequently infect watermelon, pumpkin, and squash while isolates belonging to clade 2 more … The cucumbers ‘Speedway’ (front) and ‘Bristol’ (back) in non-trellised plots with foliage yellowing due to downy mildew on June 23, 2017. Late in the day on July 31, cucurbit downy mildew was found on cucumber (Figure 1) in south-central Kentucky. The downy mildew pathogen tends to be specific to crops within a plant family. Make A Fungicide For Powdery Mildew On Organic Cucumbers. Growing your food organically means you have to be selective in how you treat pests and disease. Even if they … Downy mildew infects gourds, squash, pumpkins, melons and cucumber. Downy mildew on Cucumis spp., including cucumber and true melons, alone has been reported in 70 countries. While it has the widest distribution on all continents on the genus Cucumis , downy mildew is common on Cucurbita crops, including squashes and pumpkins, in Australia, North America and the Pacific region and occurs less commonly in Asia and Africa. Cucurbit downy mildew can destroy your tasty crop of cucumbers, watermelon, squash, and pumpkins.The fungus-like 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. Microscopy was used to confirm presence of the pathogen, by identifying Cucumbers are the most susceptible crop to this pathogen. Photo by Anthony P. Keinath With downy mildew so widespread, I and other researchers from Clemson University wanted to find … Several kinds of powdery mildew affect different plants. Cucurbit downy mildew is caused by the fungus-like oomycete pathogen Pseudoperonospora cubensis (P. cubensis).There are two types of P. cubensis isolates that can infect cucurbit crops and weeds referred to as clade 1 or clade 2 isolates. The pathogen that causes downy mildew in cucurbits will not infect legumes or spinach and vice versa. Several different strains (pathotypes) of this organism have been identified (Table 1).