Monday, July 9, 2012

Insect and Weather Update for the week of July 9th 2012

The past 10 days have been characterized by heat, drought, scattered thunderstorms, aphids, and in some cases spider mite decisions. Some areas have received one or more rainfall events of 1 to 3 inches or more while others are still suffering extreme drought. Some of these storms have brought high winds, downed trees, demolished buildings and hail.

Insects have been rather quiet overall. Many field men have made aphid treatment decisions with significant acres treated. In at least one incidence, both aphids and mites were at treatment levels. Other more sporadic fields have needed adult tarnished plant bug controls. In the majority of cases the plant bug population has now shifted to immatures. In these cases field men need to switch from sweep nets to drop cloths to quantify these immature plant bugs. Two or three immatures per drop could be considered a threshold level requiring treatments, especially if “dirty” blooms are present. Pinhead square retention is no longer the best way to look for plant bug damage since they spend more time down in the canopy feeding on larger squares (which later become dirty blooms).

I have not had any calls yet, but field men in the southern areas of the state need to pay attention to stink bugs since our oldest fields are now at week three, four or more of bloom. Weeks three through six of bloom is when stink bugs are most damaging. A good threshold for treatment during this period is 10-15% internal damage to quarter diameter (still soft) 10-12 day old bolls. Look for brown areas near the seed  and warts on the inside boll wall where stink bugs have penetrated in search of a protection source in the form of developing seed. If the population of stink bugs is primarily the southern green species then we have choices of both pyrethroid and phosphates. However, as most likely the case, the population may be predominately brown stink bugs. Here we would need a phosphate such as Bidrin or either a high rate of bifenthrin and get decent suppression.

Reports were just received of an increase of small larvae on peanuts in south-central Alabama. My guess would be that they are tobacco budworms. By July 15, newly hatched larvae will more likely be corn earworms.