We have black aphids on our austrees; have sprayed with ortho and seven several times this summer and no luck getting rid of them. Our trees are taller than our house. We are cutting them down this fall to 6′ or so to make it easier to control next spring. Would it be best to wait for freeze to kill the existing aphids and treat the ground before spring next year? What products should I use?
Thank you, N.
First, the products you mentioned aren’t the best options when it comes to dealing with black aphids. If you look over our APHID CONTROL ARTICLE, you’ll learn that aphids are both persistent and hard to control with conventional products. The BIFEN and NYLAR mix seems to work well and when combined with SPREADER STICKER, you should be able to knock them down quite a bit with just one or two treatments.
Second, cutting your austrees down to control any insect is rarely a practical solution. Insects will almost certainly continue to thrive even if their local food supply is diminished. Not only that, they will not just leave or disappear. In fact, what will probably happen is that you will force them to move onto a more suitable plant and I suspect this will be something else on your property or possibley a neighbors. To avoid further spreading of this pest, treat the trees now. There is still plenty of time to get aphids under control so that by next spring, your trees will be able to grow their leaves in normal fashion. This is the best way for them to star the new spring/summer and should enable them to lead a healthy comeback following the infestation.