Spring starts early for insect pests of conifers. Which means the message for landscapers and Christmas tree growers is: know when your pests are active and get scouting. Because it could be now.
For balsam twig aphid, white pine weevil and spruce spider mites, early treatment is important. It all has to do with their biology – the insects are out and about early before they find their hiding places. That’s why the treatments will work. And developmental stage is directly associated with temperature. That’s why Growing Degree Days (GDD) work! Indeed, any pest that gets going at less than GDD 50 should be on your short list — NOW.
True, not all trees need treating every year. For balsam twig aphid it’s important only for those trees that are close to harvest and spruce spider mite populations may not be high enough to worry about. To find out, tap branches over a white sheet of paper or paper plate, especially from trees that had symptoms last year. Count up what you find and decide your next move. White pine weevil adults fly so you won’t catch them by tapping. Check tree leaders for damage instead.
Want more background on balsam twig aphid and spruce spider mites? Put your feet up and watch these videos from Michigan State University— less than 5 minutes long.