Cucurbits Disease Fungicides

Cucurbit Downy Mildew Confirmed in Ohio

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:

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