![]() Remember that conventional tomato growers using a recommended fungicide program for early blight, septoria leaf spot, and anthracnose, are also protecting the crop from late blight infection, but once it is in the area, consider shortening spray intervals and choose products with good late blight activity (see below). Commercial tomato growers across Ontario should ensure they have a protective fungicide program on their plants and should monitor the crop closely. Consult the Canadian labels and your organic certifier for registered products that can be used in organic production.OMAF & MRA have now confirmed late blight in the Region of Waterloo, Wellington County, Lambton County, Brant County, and additional sites in Chatham-Kent. Note that crop protection products mentioned in her article relate to US registrations. Note: Organic producers may be interested in an article by Meg McGrath (Cornell University) on managing late blight in organically-produced tomato. This helps us alert others of late blight in the region and if possible, we will try to collect samples for late blight researchers studying the disease. Those in the US can contact their state cooperative extension service or report online at. 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.Ĭontact OMAFRA if you suspect you have found late blight in Ontario. Zampro (ametoctradin/dimethomorph – group 45/40)– two active ingredients – protectant and systemic, translaminar – can move into the plant ![]() Torrent 400SC (cyazofamid – group 21)– protectant, contact (limited locally systemic) – should be tank-mixed with a non-ionic or organosilicone surfactant Tanos 50 DF (famoxadone/cymoxanil – group 11/27)– translaminar, some “kickback” activity – has some ability to move into the plant – rotate chemistries and use in combination with protectants for resistance management Revus (mandipropamid – group 40)– translaminar, some “kickback” activity – has some ability to move into the plant – rotate chemistries and use in combination with protectants for resistance management Reason 500 SC (fenamidone – group 11)– locally systemic and translaminar – has some ability to move into the plant – must be tank-mixed with mancozeb or Bravo 500 ![]() Presidio (fluopicolide – group 43)– translaminar, some “kickback” activity – must tank mix with Bravo Orondis Ultra (mandipropamid/oxathiapiprolin – group 40/U15)– systemic Penncozeb, Manzate, Dithane, Polyram (mancozeb, metiram – group M3)– contact fungicides – have been very effective protectants in tomatoįorum (dimethomorph – group 40)– translaminar – has some ability to move into the plant – must be tank-mixed with another late blight fungicide from a different chemical family – rotate chemistriesĬabrio EG (pyraclostrobin – group 11)– translaminar – has some ability to move into the plant – strobilurins generally rated lower than the other targetted late blight materials by researchers – preventative only – tank mix with stronger late blight product Ratings:Īctivity (capitalized indicating stronger activity)īravo, Echo (chlorothalonil – group M5)– contact fungicides – have been very effective protectants in tomato of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY or information from other sources listed at the end of the article (*). Ratings are shown for late blight activity based on information from Dr. Know the symptoms. Refer to the Tomato Late Blight Photo Gallery and Late Blight Look-Alikes for photos of late blight and possible look-alikes on tomato. The disease is suppressed by hot, dry weather, but it can continue developing and spreading when suitable conditions return. If late blight has been identified in a field, use a fungicide with curative and antisporulent activity, see the table below for late blight fungicides and their properties.Ĭloudy and high humidity or wet conditions are favourable for late blight. Under continued high disease pressure, growers should consider adding a targeted late blight fungicide to the spray program. When late blight is in the area, spray intervals should be shortened. ![]() However, high disease pressure due to environmental conditions, combined with a dense leaf canopy and rapid growth may have resulted in poor spray coverage and reduced efficacy.Ĭommercial growers should scout often and ensure they are using fungicides with good late blight activity in their fungicide program. Typically, this disease is well managed in tomatoes with a broadspectrum fungicide program including chlorothalonil. We have had multiple reports of late blight in conventionally managed tomato fields this week. This information is updated from an earlier article by Janice LeBoeuf. ![]()
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