Vine Crop Edition by Elaine Roddy,  Vegetable Crop Specialist,
OMAFRA, Ridgetown elaine.roddy@ontario.ca

Downy Mildew Identified in Kent County

The first field infection of downy mildew in Ontario was identified in a cucumber field near Dresden on Friday, June 26, 2009.  Approximately 20% of the field is infected with 2% of the leaf area affected.  The infection is patchy in the field; the area closest to the windbreak is more severely impacted.

All growers should be on a regular preventative fungicide program.  Do not wait to spray.  Control of this disease is much more effective when fungicides are used prior to infection.

Rotate between Tattoo C and Ranman 400SC.  Apply Tattoo C at a rate of 1.2-2.7 L/ha (0.72-1.1 L/acre).  The rate for Ranman is 150-200 mL/ha (60-80 mL/acre) add 150 mL/ha (62 mL/ac) of Sylgard 309 as a surfactant. Tattoo C does not need a surfactant.  Use the higher rates under heavy disease pressure or when the canopy begins to close over.

The preharvest intervals are 1 day for Ranman and 2 days for Tattoo C.  Tattoo also has a 2 day re-entry interval.

Always rotate between fungicides from different chemical families. Use a minimum spray volume of 30-60 gallons per acre. Apply a preventative fungicide before a rainfall event or prior to overhead irrigation.

Questions?  Comments?Give me a call at 519-674-1616 or email elaine.roddy@ontario.ca