The pod stage is the critical time to watch for insect feeding in canola. When flowering is done, the crop cannot produce more flowers to compensate for insect losses. Thresholds for insects such as bertha armyworm, diamondback moth larvae (shown in the photo above) and lygus bugs are based on losses at pod feeding.
However, take care with timing. Jumping the gun with early insecticide applications on flowering canola can create a whole lot of trouble for beneficials, have limited benefit in terms of insect management, and be a step back in sustainability. With a healthy beneficial population, insect outbreaks are never as severe as they will be without the beneficials to keep populations in check. Adding insecticide to a fungicide mix may “only” cost $5 per acre, but the timing is not right for insect management — other than for cabbage seedpod weevil if at thresholds. There are likely many other better ways to spend that money — including waiting until early pod stages to spray. If finding time to scout is an issue, consider spending part of the $5 per acre to hire someone to scout for you.
Tweet of the week, from the July 17 #ABbugchat on Twitter: