Last year my cucumbers got fungus all over on the leaves and vines and died off part way through the season. How do I prevent this from occurring again this year? I was told to leave my garden plot empty this year to let the fungus die. Can I plan anything there or do I have to leave it dormant for a year to solve the fungus problem. Thanks for the help.
Marion County Oregon
Thank you for choosing Ask an Expert for help with your cucumbers this season. Powdery mildew is the most common fungus disease to attack cucumbers (plus squash, pumpkins, melons, and some ornamentals). The spores and other fungus parts can overwinter on crop debris left on the soil or weeds in the area. They will also be blown into your garden from other gardens, often from quite a long way off. This is why the disease is so hard to fight successfully.
Certainly, crop rotation will help reduce localized spread of the disease, but you would need to rotate out of any of the vegetables that this fungus attacks. And if you are in a community garden (or a community of gardeners) the infection would be even more difficult to control.
There are other ways to suppress the impact of this disease. The plants should be located in full sun to keep the plant as robust as possible, and space them out to avoid them shading one another. Use a resistant variety, such as Marketmore or Tasty Green.
Sprays can also be used to protect new growth. Bicarbonate products or horticultural oils require good spray coverage. Alternating copper fungicides and the biofungicide, Seranade, is another option. When using any disease control product, remember to read and follow all directions and cautions, especially their use on vegetables.
For information on growing all kinds of vegetables, check out this Oregon State Extension publication: Growing Your Own. See here: https://catalog.extension.oregonstate.edu/em9027