In his weekly Call of the Land radio interview, Alberta crop pest specialist Scott Meers says that there have been several reports of both diamondback moth larvae and pupae on small canola plants.
"This is really early for that," said Meers, who works for Alberta Agriculture and Rural Development at Brooks.
"What it is telling us is we'll have the population buildup -- how bad it will get or if natural enemies will keep in under control we don't know at this point but this is a very high level of early calls that we are getting."
Manitoba's provincial crop entomologist John Gavloski said in his weekly report Friday that diamondback moth traps continue to show the highest counts around Beausejour and Morris and "all the higher counts" are in the province's east.
"West of Carman, the counts have all been low," says Gavloski, who works at Carman. So far, he added, "we have not had any reports of high levels of larvae of diamondback moth."
In its latest Canola Watch, the Canola Council of Canada also warns that diamondbacks are reaching threshold levels for spraying across the southern Prairies, much earlier than usual.
The Canola Council says that before spraying, growers will need to make sure that:
- Large areas within the field have reached the nominal threshold of 25 per cent or more of the leaf area lost.
- Diamondback larvae are still present.
- They are actively feeding. (Many diamondback moth larvae may have started to cocoon and are no longer a threat.)
- The newest leaves are being eaten. If the newest leaves are in good shape, the crop will probably grow through the threat.
If you answer "yes" to all four, then consider a spray. If you answer "no" to any one, keep scouting. Situations can change -- for the good or bad -- in a matter of one or two days.
More details including details and photos on identifying damage are on the council website.
Alberta's Meers also says there have been lots of calls on cutworms on pea stubble. "The worst-hit fields are almost without exception canola seeded on pea stubble," he said.
There have also been reports of wireworm damage, he says. "It's important to differentiate between a cutworm which we can spray for and a wireworm which we can't."
If it is wireworm damage and reseeding is required, producers should use treated seed, he said.