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Apple Pest Update: June 25, 2019

The latest update on insect and disease activity in apple orchards across the province
 
Disease
 
Fire Blight
 
Very little fire blight has been reported. However, with the wet weather predicted this week, those orchards with active cankers could be found oozing. According to Dr George Sundin, Michigan State University, each fire blight ooze droplet can contain approximately 1 billion cells while it only takes 100-1,000 cells to initiate shoot infection. That means a single ooze droplet could have the potential to infect every shoot in an orchard if spread by insect, rain, wind or even workers and contaminated equipment. It is best to do any hand labour activities such as thinning, pruning or removing suckers in dry conditions in these blocks to avoid the potential spread of bacteria.
 
While many orchards may have got through bloom period without signs of fire blight, infection can still occur through open wounds caused by strong winds, heavy rain and hail, insect feeding, pruning or mechanical damage. Blossom blight does not need to be present for other parts of the tree to be affected such as shoots or rootstock. In fact, inoculum can be spread large distances throughout a region during storms.
 
Cueva and Double Nickel are registered for the control of shoot blight following a trauma event. Like all coppers, there is the risk of russeting with Cueva. However, if fire blight is active in your orchard at the time of trauma, better to lose some fruit this season than trees later. The preharvest intervals for Streptomycin and Kasumin are 50 and 90 days, respectively.
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