Root, bulb, leafy and brassica vegetable pest report – 8 July 2013

See below for the degree days accumulated from April 1^st until July 8^th, 2013.These values are provided as guidelines only. Local environments, soil type, field history, etc. are likely to influence activity of these pests.

Second generation of onion maggot flies have likely started to emerge in the Windsor area and are likely to emerge over the next couple days in the London, Ridgetown, Thedford and Bradford/Holland Marsh areas. According the Muck Crops Research Station report, onion maggot fly activity around the Holland Marsh is moderate. Onion thrips have been seen on onions in the Holland Marsh and some areas in Southwestern Ontario. Be sure to scout for thrips. No onion downy mildew has been reported; however, in the Holland Marsh, the risk of downy mildew on transplanted onions is moderate to high. Risk is low to moderate on seeded onions at this time. The risk of Botrytis leaf blight is moderate to high in the Holland Marsh based on BOTCAST (predicts the risk of Botrytis leaf blight in onions). Purple blotch and Stemphylium leaf blight of onions have been observed in some onions fields around the Holland Marsh.

Peak flight of 2^nd generation cabbage maggot flies has likely started in London and Ridgetown areas.

The second generation of carrot rust flies will likely start emerging in the Windsor area in the next 5-7 days. Around the Holland Marsh, carrot rust fly activity is moderate to high in some locations. Based on sticky trap counts, treatment thresholds are 0.1 and 0.2 flies/trap/day for fresh market and processing carrots, respectively. Aster leafhoppers have been caught on sticky traps in the Holland Marsh, but at low levels. We’ve also seen some active in carrots crops in the Southwest parts of the province (based on a quick field walk with a sweep net). Be sure to monitor for leafhoppers in aster yellows susceptible crops.

Data provided by Environment Canada.

*Data provided by Muck Crops Research Station, University of Guelph.

Degree day model information for pests