Crop Watch News Crop Protection
Hot weather in Ontario speeds up development of insects

Hot days in May have accelerated the development of insects in Ontario potato fields, according to Eugenia Banks’, potato specialist with the Ontario Potato Board, June 12 update.

Banks shares how Ontario scouts have found Colorado potato beetles (CPB) mating and laying eggs, plus flea beetles, black cutworms and leafhoppers. However, at the time of the update all numbers were below threshold levels.

Admire, the first neonicotinoid to control to control CPB was registered in Ontario 15 years ago, and Banks says insecticide resistance may be just around the corner. “Scouts should keep an eye on CPB numbers and collect samples for a spray or dip test if hot spots are found.”

Dip tests are a simple technique where adult pests or larvae are immersed for a few seconds in insecticide solutions. The mortality rate determined for each insecticide indicates the products that are likely to be most effective under field conditions. Banks explains that dip tests are reliable, fast tests that use the same insecticide concentration that growers would use as foliar sprays.

“Actara or Clutch, which contains the same active ingredient of Titan, are registered as a foliar treatments and can be used for dip tests. The active ingredient of Admire is very weak compared to that in Titan or Actara,” Banks continues.

Banks shares how a potato scout from FS Partners in Norfolk County, Ont. found some widespread leaf burning symptoms caused by the hot and dry weather in May. Other problems detected in fields at low levels are blackleg and Rhizoctonia.

Widespread leaf burning found on a potato crop in Ontario after hot weather in May. Photo courtesy of Eugenia Banks.