Cucurbit Downy Mildew was confirmed on June 14th, 2012 in a cucumber field in Wayne County, Ohio. This significantly increases the risk of infections occurring here in Ontario. All cucumber growers should begin a preventative fungicide program immediately. Use one of the recommended targeted downy mildew fungicides every 7-days.
DO NOT WAIT UNTIL YOU SEE SYMPTOMS TO SPRAY. Unprotected crops are at the highest risk of experiencing serious losses to this disease.
Targeted Downy Mildew Fungicides
|cyazofamid + surfactant (Ranman 400SC)propamocarb/chlorothalonil (Tattoo C)
fluopicolide + chlorothalonil (Presidio + Bravo 500)
While watermelons, pumpkins, zucchini and squash are somewhat more resistant to downy mildew; growers of these crops should still follow a 7-10 day preventative spray schedule using broad spectrum fungicides.
Broad Spectrum Fungicides
|chlorothalonil (Bravo 500, Echo 720)mancozeb (Dithane DG, Penncozeb 80 WP, Manzate Pro-stick)|
Where the crop is still small (pre-vining), a banded application will significantly reduce the cost of these treatments. Use the following equation to calculate the amount of fungicide required for a banded application:
|Total Field Acreage x||Band Width ÷ Row Spacing||= Treated Acreage|
Always rotate between fungicides from different chemical families. Do not make sequential applications of any one fungicide.
• Use a minimum spray volume of 30-60 gallons per acre.
• Apply a preventative fungicide before a rainfall event
• Apply a preventative fungicide prior to overhead irrigation.
For more information on the management of cucurbit downy mildew, visit the OMAFRA 2011 Downy Mildew Control Strategy at: http://bit.ly/ONcdm2011