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OMAFRA: Marssonina blotch confirmed in some Ontario apples

Surveys conducted in Ontario apple orchards by OMAFRA pest management specialists in October have found Marssonina (Diplocarpon) blotch in Gala and Empire blocks. This leaf fungal infection causes premature defoliation, resulting in lower tree health and yield loss. When foliage infection is severe, fruit lesions can occur, although they are uncommon.

As the disease appears able to build up over time and can overwinter in orchards, managing the disease early is important. Kristy Grigg-McGuffin, horticultural integrated pest management (IPM) specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), and Katie Goldenhar, horicultural pathologist with OMAFRA, ask growers who suspect their orchards are infected with Marssonina blotch and want to participate in the survey to contact them (info included in link below). |READ MORE

Marssonina (Diplocarpon) leaf blotch has been confirmed in Ontario apples. Seems to be a late season issue in blocks with reduced fungicide applications. @AppleOfMyIPM pic.twitter.com/RiVHPGmrI2

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— Katie Goldenhar (@kegoldenhar) October 26, 2021