After the cold, wet spring of 2011, Saskatchewan farmers were once again engaged in a flurry of production activity in the fair June weather — but they weren’t the only ones taking advantage of the warmer temperatures. Insects were also on the move, as one Kelvington-area producer was about to discover.
Bob, who farms 3,000 acres of peas, wheat and canola, was uptown having coffee with friends when his neighbour mentioned to him that he’d just finished settling the arrangements for a spray operator to spray his field for flea beetles. Now concerned about his own field of canola, which was located adjacent to his neighbour’s flea beetle-infested field, Bob returned to his own field to have a look-see. Then he called me.
“It looks like something’s eating the plants. It could be flea beetles or cutworms,” he said. “I was out a week ago and I never noticed any insect damage at all. It must have happened within the past week.” Bob and I agreed to meet up the next day to scout the canola field for insects.
The canola plants in Bob’s field were well into the three-leaf stage. We began scouting at the edge of the field adjacent to his neighbour’s field. Some of the canola leaves had notches in them at the leaves’ edges, while the leaves’ surfaces had small circular pits. At the periphery of the field I estimated the damage to the true leaves due to feeding at around 20 per cent. As we moved toward the centre of the field these symptoms decreased dramatically.
“It’s not cutworms,” I told Bob. “They sever the stems of the plants at the soil surface, so I’d expect to see severed or missing plants.”
“With the warmer temperatures, flea beetles are on the move — walking, flying or jumping into your field.”
I searched several nearby canola plants. “Here’s one of your culprits,” I said to Bob, pointing to a small, black flea beetle, about two millimetres in length, feeding on the leaf it was perched upon. “The important question we’ve got to ask ourselves now is does this infestation warrant spraying?”
Should Bob spray his canola field to protect his yield from flea beetle damage? Send your diagnosis to Grainews, Box 9800, Winnipeg, MB, R3C 3K7; email [email protected] or fax 204-944-5416 c/o Crop Advisor’s Casebook. Best suggestions will be pooled and one winner will be drawn for a chance to win a Grainews cap and a one-year subscription to the magazine. The answer, along with the reasoning which solved the mystery, will appear in the next Crop Advisor’s Solution File. †