Aphid numbers continue to build, while most insects numbers remain at moderate levels

Insect conditions have not changed greatly in the past week or so. Aphids have continued to build in more fields. All other insects are low to moderate levels (mostly sub-threshold). These include plant bugs (including a few clouded plant bugs coming into the mix), bollworms, tobacco budworms and stink bugs. Most growers do not have enough of a single species to apply controls for. The two biggest surprises at this point in the season are the low number of bollworms and the low number of stink bugs in most fields. Numerous fields of conventional cotton still have less than 2 bollworms per 100 plants. Boll damage to stink bugs is less than 10% in most fields.

Most of the state has had abundant thunderstorms for several consecutive weeks. Cotton yield prospects have improved greatly and, if conditions continue, numerous fields have two bale plus potential. The two biggest limitations we now have are fields with “skippy” stands and too much late maturing cotton.

Cotton Insect Management 2011

Points for Discussion:
1. Low Input System - Conventional vs. Technology
2. Evolution of Bt Cotton - Various Genes Involved
How do they compare and what is in the future?
3. Phase Out of Temik
What will be the greatest impact?
4. Stink Bug Research Towards a More Rapid Survey Technique
Factors that influence external vs. internal stink bug boll damage.

5. New Damaging Insects
A. Plataspid (Kudzu) Bug

B. Brown Marmorated Stink Bug

C. Redbanded Stink Bug


A. Plataspid (Kudzu) Bug

 Native to Asia

First detected near Athens Georgia in the fall of 2009

Has since spread over much of Georgia, South Carolina and into a few counties in North Carolina and Alabama

Feeds primarily on legumes

Reduced soybean yields by about 20% in 2010 test fields in Georgia

Feeds on stems and leaves

Has high reproductive potential

Can be controlled with pyrethroids and other chemistry

Is a public nuisance problem in fall of the year as they enter homes and buildings to hibernate.

B. Brown Marmorated Stink Bug

First discovered in Pennsylvania in late 1990s

Native of Asia

Big problem in specialty crops in mid-Atlantic states (grapes, apples)

Caused 60-90% loss in peaches and apples in 2010

Called Interstate Bug since it spreads by trucks and campers

Has wide host range - feeds on about everything

Have been found in three Alabama counties in late 2010

Has long proboscis so can go through the husk of corn

Pecans may be huge host in the southeast

Causes more damage per bug on soybeans than green or brown stink bug species

Expect to be economic pest of cotton

Will likely have heavy field edge or border damage
Invades homes for hibernation sites in the Fall

3. Redbanded Stink Bug

Native to South America (Brazil)

First found in Louisiana in 2000

Observed on soybeans in Baldwin County, Alabama in July 2010

Is sensitive to winter temperatures below 20 degrees F

Has high reproductive potential

Is primarily a legume feeder

Can cause heavy damage to soybeans

Feeds earlier and more aggressively than other stink bug species

More difficult to kill than Southern green stink bug

This concludes Week Five of Cotton Insect Management 2011. The slide show can also be viewed at http://www.aces.edu/anr/crops/documents/CottonInsectManagement2011RonSmith.pdf

Soybeans

Loopers are the dominant soybean insect, up to 30% defoliation and damaging levels in some fields. A few velvetbean caterpillar and green cloverworms are in the mix. The “grass” strain of the fall armyworm does not appear to feed to a significant degree on soybeans. And, stink bug populations are not as high as anticipated.

Red banded stink bugs were discovered on the Wiregrass Research Farm, Headland, AL (Henry Co.) this week. Since they were found about 180 miles west of Headland last month, they likely may be present in other locations across south Alabama.

Red Banded Stink Bug in Alabama Feeding on Soybeans

Another significant insect event this week was the discovery of the red banded stink bug (Piezodorus sp.) feeding on soybeans in Baldwin County. This species had previously been reported from most other southern states, except Alabama. They have been reported to be very damaging to soybeans in Louisiana and other mid-south states. This species has the ability to be more damaging to beans than the other more common stink bugs (brown and Southern green). Most reports indicate the red banded may be more difficult to control with insecticides. All entomologists agree that populations can rebound greatly within 7-12 days after a spray.

Redbanded stink bugs

On Tuesday, I surveyed some soybeans at our Gulf Coast Research Station at Fairhope, and I’m 99% sure that I found red banded stink bugs there. These beans were at about 30% podfill. I was finding about 1 adult and 2 immatures per 6 row feet. If it is the red banded, that’s the first time the insect has been found in Alabama. It’s probably been in south Alabama, but maybe we just haven’t been looking for it enough.