The following article is from Dr. Lenny Wells, University of Georgia Pecan Horticulturist;
We’ve nearly reached the end of the pecan season. Pawnee will likely be ready to shake by the middle or end of next week, and we are nearing the end of kernel filling on most other cultivars. I’ve had many calls today about whether or not to spray a pyrethroid for stink bug and/or weevils and whether or not to be concerned with aphid/mite flaring behind any such sprays. I have also had multiple calls today about the appearance of black pecan aphids and whether they need to be treated at this point. Since we are so close to harvest, you need to pay close attention to the Pre-Harvest intervals of insecticides.
The rain over the last month has kept aphid and mite pressure relatively low. Now that we have clear weather in the forecast for the next ten days, it is possible these pests could flare up again, but this close to the end of the season, is it worth spraying?
First of all, its too late to worry about these pests on Pawnee, so just get ready to harvest this cultivar, and don’t worry about the bugs.
On later cultivars that have yet to split open, if you have had weevil or stink bug problems in the past, you should probably still spray them at this point. Most weevil/stink bug materials have a 14- to 21-day pre-harvest interval. You can add a material for aphids and mites to prevent flareups, but, keep in mind the pre-harvest intervals of these materials as well. Most aphicides have a 7- to14-day PHI. The exception to this is Carbine, which has a 40-day PHI. So, if you apply an aphicide, it is too late to use Carbine. Regarding miticides, Abamectin has a 21-day PHI. Nexter has a 7-day PHI and will work on both aphids and mites.
I would continue to monitor black aphid this week, and, if any nymphs are observed, it may be wise to spray. Following this week, I would not worry too much about them. We are getting late into the season, and aphid/mite populations do not usually build up as much in late September/October as they do in August.