August/ September Aphid Flare Ups
In my last pecan update I spoke about how we had not seen much aphid or mite pressure yet but to stay on the look out. The week after that post the aphids hit us hard in Appling County, especially on sumners. I have seen several spots of defoliated trees in the county due to Black Pecan Aphids (BPA). Where this occurred, after speaking with the producer, we learned that a pyrethroid was applied in the orchards shortly before the insect pressure increased. When we apply a pyrethroid in our orchards we are risking flaring aphids, therefore we should make certain the pyrethroid application is justifiable and that there is not a better treatment before we make that application. After making the pyrethroid application we should stay on the look out for BPA. The picture below shows an immature BPA, the next picture below shows defoliation due to BPA damage.
Many may be wondering when to stop treating for insects at this time of the year… below are comments from Lenny Wells in years past on terminating insect treatments in orchards.
“On later cultivars which 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 14-21 day pre-harvest interval. You can add a material for aphids and mites to prevent flare ups but keep in mind the pre-harvest intervals of these materials as well. Most aphicides have a 7-14 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. Regardig miticides, Abamectin has a 21 day PHI. Nexter has a 7 day PHI and will work on both aphids and mites. You can consult the Georgia Pecan Spray Guide for details on other products.
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.”
Leaf Drop, Late Season Foliage Condition
This past week I have some calls on leaf drop in orchards. The leaf drop I have been seeing does not look like anthracnose or mites are the culprit. Reviewing Lenny’s posts in the past few years he recently spoke on Leaf drop due to a hot/dry period followed by a rain or an increase in irraigation, and i bleieve that is what we are experiencing. It has been very dry in Appling County over the past 2 weeks and we have began running some irrigation to the trees in response to the lack of rain . Lenny says “leaf drop due to drought stress usually doesn’t occur until you get rain because water is required to break down that abscission layer at the point of attachment to the tree. We often see this occur in June/July but it can happen at any time and late in the season like this it is often heavier because those dry, hot conditions late in the season accelerate the process of leaf senescence. Usually lower leaves in the shade will be the first to come off because, again, these are often the most stressed leaves and are generally the firsst to senesce. This can be observed in trees where those internal, lower leaves are yellowing already.”
