Not close to Ontario, but be aware of the development of late blight in the US…
Burlington County, New Jersey: Late blight found on potato on May 23. Sample analysis is in progress.
Rutgers Cooperative Extension reports that “the few infected plants were found at the end of a row were the boom sprayer was most likely turned off. The grower had preventative applications of manzate followed by chlorothalonil prior. Seed pieces were sourced from Maine. This is the first report of Late blight in NJ on potato or tomato this year.”
Suffolk County (Long Island), New York: Late blight found on potato on May 29. Sample analysis in progress.
Cornell University reports that “late blight has been found in one of the earliest planted potato fields on Long Island and in a potato field in New Jersey. The Long Island report is suspected to be from potato seed, and late blight was detected in another shipment of seed earlier this season.”
For Ontario growers:
Late blight has not been found near Ontario, so these US reports are not of immediate concern. It is important to scout your tomato fields regularly and know the symptoms of late blight. Refer to Late Blight Look-Alikes for photos of late blight and possible look-alikes on tomato. Remember that conventional tomato growers who are applying fungicide with their bacterial disease sprays or later, have initiated the fungicide program for early blight, septoria leaf spot, and anthracnose, are also protecting the crop from late blight infection.
Past OMAFRA articles on tomato late blight are found under the late blight tag to the right. Please report any occurrences so that we can keep the tomato community informed about its development and spread and so that we can collect samples to learn about the strains, fungicide sensitivity, and the biology of this evolving disease.
Contact OMAFRA at 519-674-1690 or firstname.lastname@example.org if you suspect you have found late blight in Ontario. Those in the US can contact their state cooperative extension service or report online at http://www.usablight.org/.