Black aphid nymphs and feeding damage
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.