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Fruit and Vegetables |
Downy mildew was detected on pumpkins in Edgecombe County on August 6, 2002. This is the first report of the disease in North Carolina in 2002. It is unusual to find this disease under current conditions (hot and dry), but this demonstrates its ability to develop under a wide range of conditions. Future rains and cooler weather will favor its development and spread. Preventative fungicide treatments and good plant coverage are critical to successful control. Several products have fair to good efficacy against the disease. These include Bravo, Ridomil Gold Bravo, and mancozeb. Refer to Table 6-18 of the North Carolina Agricultural Chemicals Manual for a complete listing of fungicides and their relative efficacy against downy mildew and other cucurbit diseases. Forecasts for cucurbit downy mildew are available on the Internet at: http://www.ces.ncsu.edu/depts/pp/cucurbit/. You also can check the photo gallery for a look at the symptoms and signs of this disease. Please report any future downy mildew outbreaks via this web site.
Procure 50WS (active ingredient triflumizole) was recently labeled for use on cucurbit crops (cucumbers, muskmelons, pumpkins, squash and watermelons) for controlling powdery mildew. Powdery mildew is an annual problem on most cucurbits and foliar fungicide applications are usually necessary to control the disease.
Procure is among the most effective fungicides for powdery mildew control. In recent fungicide trials Procure has performed as well as Nova (active ingredient myclobutanil). Procure should be alternated with other products with different chemistry. It should not be alternated with Nova since these come from the same class of fungicides (sterol biosynthesis inhibitors). Acceptable alternation partners with good activity against powdery mildew include Flint or Quadris. Refer to Table 6-18 in the North Carolina Agricultural Chemicals Manual for ratings of fungicide efficacy. A current label for Procure can be accessed on the Internet at: http://www.cdms.net.
Remember that for cucumbers, powdery mildew is controlled with resistant cultivars (all modern cultivars are resistant). However, the remaining cucurbits are susceptible, especially squash and pumpkins. Powdery mildew also has been increasing on watermelons in recent years.
For maximum fungicide efficacy, treatments should begin at the first sign of disease and continue on a 7 to 10-day interval. While many products are systemic or locally systemic, coverage of upper and lower leaf surfaces is still important. Scout fields regularly and look for powdery white lesions on lower leaf surfaces in shaded areas of the canopy. This is where the disease will appear first and often escapes detection.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on August 19, 2002 by Stephen J. Toth, Jr.