Both mite and aphid populations have essentially been stable the past month or month and a half. Throughout this time, I only find a few adult black pecan aphids and no mites. Most of these orchards were sprayed with insecticide targeting aphids also. Finally, last week we saw one spot of mites on Stuart and Schley starting to develop in the very middle of the SE district. Today I observed mites, yellow aphids and black aphids at threshold in Jenkins County. This area has also been much more dry than anywhere else I’ve been in the Southeast. We are seeing the same pressure from both mites and aphids on dryland and irrigated orchards. The orchard pictured below has already been treated twice for black pecan aphids.
They are really hard to see without a hand lense, but on this leaflet, there are many crawling. I didn’t see damage on top of the leaf since the leaves were covered in sooty mold. Keep in mind, our mite threshold is 100+ mites on 2 leaflets in each compound leaf. It’s easy to see when they are building. On these leaves of Forkert, there were so many they were hard to count. On every single tree I see mites compounding on multiple leaflets, so this orchard got treated by the end of the day. Make sure to come back 10 days later and check mite populations. It is not unusual to have to come back again with another miticide.
Where sooty mold is present, you have yellow aphids. Yellow aphids here (and what I’ve seen all year) are Black-Margined Aphids. You can easily see these without a hand lens. You will also see nymphs as well. Without spraying broadspectrum insecticides (chloropyfos, pyrethroids), we can let yellow aphids ride the season. Usually when I see this type of sooty mold its where broadspectrum insecticides were used. However, this aphid pressure is building naturally as we move toward the end of the year – and why we need to scout our orchards for insects now.
Black Pecan Aphids
I’ve seen adults of BPA all season along with some damage. I’ve yet to really see heavy reproduction (nymphs) and a high build up. With black pecan aphids, the threshold for BPA is when nymph clusters appear on damaged leaves. We don’t have to have a lot of nymphs to pull the trigger, but we need to see them build some. The nymphs are green and look like little baby frogs. You want to treat before you see as many as are on the leaves below.
Make sure to note the adults black aphids with WINGS. You will see dark, black mummified aphids on the leaf that are not black pecan aphids. They are yellow aphids parasitized by wasps. I see more of these under leaflets than I do black pecan aphids.