For those battling black aphids and considering using Pro Gibb to prevent the damage caused by this insect, applications should begin in mid July and continue for a total of 3-4 sprays. Pro Gibb prevents the development of chlorotic areas caused by black aphid feeding on the foliage.
In the past we have advised using the 4% Pro Gibb material since heavy rates or application at the wrong time can lead to negative results for your trees. However, the 4% material is no longer made and Valent has replaced it with a 5.7% material. This formulation is safe to use on pecans and is labelled at the 5 oz rate.
Based on Dr. Ted Cottrell’s work at USDA in Byron, the schedule for Pro Gibb applications should be as follows:
- Mid July: Pro Gibb 5.7% at 5 oz/acre
- Early August: Pro Gibb 5.7% at 5 oz/acre
- Mid August: Pro Gibb 5.7% at 5 oz/acre
- Late August: Same as above if needed
Apply an aphicide along with Pro Gibb when black aphids reach threshold levels (15% of the terminals sampled have more than one black aphid adult with nymphs present on a compound leaf) in August.