Current Late Blight Risk In Ontario Field Tomatoes

on September 25 | in Ag News | by | with Comments Off on Current Late Blight Risk In Ontario Field Tomatoes

By: Amanda Tracey, Vegetable Crops Specialist, OMAFRA, Ridgetown and Cheryl Trueman, Department of Plant Agriculture, Ridgetown Campus – University of Guelph

As mentioned in a previous post, this is Year 1 of a three-year research project to assess the value of different spore traps and forecasting models to predict late blight risk for field tomatoes. We are comparing the Spornado and rotorod spore traps at eight sites in Kent County (Fig. 1), along with the BliteCast forecasting model.
DNA of Phytophthora infestans, the organism that causes late blight, was detected bySpornado traps at 0 of 8 sites for August 12-15 sampling period 4 of 8 sites for the August 15-19 sampling period (Table 1).
Rotorod traps detected spores of P. infestans at 3 of 8 sites for the August 12-15 sampling period and 3 of 8 sites for the August 15-19 sampling period (Table 1).

Table 1. Number of sites out of eight (8) in Kent County, with a positive detection for Phythophthora infestans, the organism that causes late blight.
* first sampling period with a positive detection for late blight.

Late blight symptoms caused by the US-23 genotype have been observed in New York, Pennsylvania and Wisconsin on tomato and/or potato. However, there are no reports of symptoms on any crops in Ontario or Michigan.

A summary of fungicides for late blight management is available here.

If you suspect late blight in your tomato crop, please reach out to Amanda Tracey (Amanda.tracey@ontario.ca, 519-350-7134) to confirm the diagnosis. Cheryl is away on parental leave and will not be available for the remainder of the growing season.

Project collaborators: Tomecek Agronomic Services, Sporometrics, Phytodata, and Genevieve Marchand (AAFC).

Funding acknowledgement: Ontario Tomato Research Institute, Fresh Vegetable Growers of Ontario, and the Ontario Agri-Food Innovation Alliance.

Links to previous late blight posts from the 2019 season: June 20July 10July 20August 7August 14.

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