Friday, January 20, 2012

Overview of 2011 Cotton Insect Season

Early Season Pests
Thrips were extremely heavy from about April 15 to May 20. A major contributor to this heavy migration of thrips from wild hosts and wheat into cotton was the extreme drought conditions and absence of rainfall events during this period.

Plant Bugs
One peak movement of adult TPB into cotton occurred between June 20 and July 1. The majority of this infestation only happened in the earlier planted fields (most mature cotton). One insecticide application was targeted to these adult TPB’s when they were detected. Few immatures were detected in these fields in the coming weeks, so no in-field generation occurred. This may have been influenced by the extreme temperatures that occurred during this period (98-102⁰F).

Subeconomic numbers of bollworms occurred over an extended period from about July 15 to August 10. Few fields ever reached treatment threshold. 2011 was like the lowest bollworm pressure year on record. End-of-season damage boll counts on untreated genetic cotton were less than one boll per 10 feet.

Tobacco Budworm
Budworm numbers were non-detectable to extremely light all season long. Budworm larvae were too low to detect on conventional cotton and even on attractive crops such as tobacco when used as a sentinel crop.

Aphid numbers were very slow to build in 2011 but also slow to crash due to naturally occurring diseases. The fungal disease was slow to develop which left aphids in the system much later than normal. Aphids normally peak and crash prior to, or at, the early boll set stage but this did not happen in 2011. Also, observations indicated a resurgence of aphids in the mid canopy area of the plants in late season as opposed to the terminal area.

Stink Bugs
Stink bugs in 2011 were fewest in number and damage of any year since the boll weevil was eradicated. This was likely due to the colder than normal winter temperature effect on the southern green species and the extreme spring heat and drought effect on the brown species. The majority of the few stink bugs observed in 2011 was the brown species.

Fall Armyworms
The “rice or grass” strain of the fall armyworm was abundant over much of the season in pastures, hay, and grasses. This strain will feed on peanuts but not on corn or cotton. They are easy to control on pastures with pyrethroids and numerous other labeled agricultural insecticides.