Weather Conditions and Pest Control

First we will give an overview of weather conditions, especially since this may be impacting some of our insect and pest control decisions in the coming days. After a good moisture and rainfall pattern of about 10-14 days ago, our crops have reached a hot-drought stressed condition at present. The situation is worse in the northern area of the state where less rainfall fell during the last thunderstorm period. I saw corn wilted bad in the Tennessee Valley on Tuesday (June 19).

This droughty situation could well impact spray decisions with pests such as aphids and s. mites in the immediate days ahead. Aphids are building state wide and drought stress plants are where I am more suggestive for chemical controls instead of waiting for the natural fungus.

Tarnished Plant Bug adults are also being reported from some fields from the Tennessee line in the north to the Florida line in the south. Square retention is dropping, especially in fields in South Alabama that are a couple of weeks into bloom – these would be early-mid April planted cotton. Also in these some fields, adult brown stink bugs are being reported. We know from past years what stink bugs do to small thumb sized bolls when no larger ones are present.

If present in cotton, stink bugs will feed on small bolls to develop. Knowing this impacts the chemical that we may want to choose for TPB control. It needs to be a product that also controls or highly suppresses Brown Stink Bugs. The best options here would be Bidrin or a high rate of bifenthrin. Aphids in the picture would further complicate the chemical selected. Of the neonic type products, Centric might be the best choice for Tarnished Plant Bug adults, Brown Stink Bugs and aphids.

Three-Cornered Alfalfa Hopper damage is still evident in cotton, in reddish stunted plants that have a girdled and swollen area around the main stem. However, this damage is old now and most plants are too tough for main stem girdling by the Three-Cornered Alfalfa Hopper.

The biggest insect news of the week in Alabama was the finding of the Kudzu bug in soybeans in Cherokee County, Alabama on June 21. The Kudzu bug had been found in about 25 counties on Kudzu but this was the first find on soybeans. Alabama growers will want to lean heavily on recent research conducted in Georgia, South Carolina, and North Carolina on this new envasive pest. We need to beef up our scouting on soybeans for this pest – especially the immature stage.

Tobacco Budworms in Early Season

A tobacco budworm moth flight this week resulted in eggs being deposited in cotton terminals as far north as Prattville, Alabama. On June 5^th, about 40 budworms were collected from 100 tobacco plants at Prattville. All plants had feeding signs but parasites and predators were working on the population. Budworm feeding was also noted on tobacco planted as a sentinel crop at Headland, Alabama yesterday (June 7^th).

A call was received a few minutes ago about what is believed to be budworm larvae on peanuts from the Covington County Alabama-Florida panhandle area. These peanuts were young and had a limited amount of foliage with up to four budworm larvae (3-7 days old) per row foot. This same situation occurred about 3-4 years ago where budworms defoliated some fields of peanuts in June. At this early stage of the season, controls may be necessary due to the limited amount of vegetative growth of the peanuts.

Be prepared to scout corn for stinkbugs during the early ear formation stage!

We are fast approaching the early ear formation stage with our earliest planted corn. This is the time when stinkbugs do the most significant damage to corn. Early ear formation occurs about 10-12 days before silking, and is the stage when the ear shoot is less than ¾ inch long. In fact, you will not see the tiny ear shoot on the plant unless you pull back the leaf sheaf. Stinkbug damage at this time will result in ears being aborted or severely deformed. The deformed ears are C-shaped and are often called banana ears or cow horn ears. Note stinkbug damaged ears below. The direction of the curve is the side of the ear in which the damage occurred. Growers with corn fields located close to wheat fields or any small grains should especially be prepared to scout, as stinkbugs will migrate from maturing small grains into green corn. Also, fields located close to pine plantations often experience severe stinkbug damage as stinkbugs will over-winter under the bark of pine trees. We typically see more stinkbug damage in south Alabama and the Florida panhandle than north Alabama, but I would still encourage growers in north Alabama to scout their corn for stinkbugs. Pyrethroids work well on the green species while an organophosphate material, such methyl parathion, works best on the brown species. Auburn University recommends treatment when 5 percent of the plants have stinkbugs during the early ear formation stage. Be still when scouting, as stinkbugs will often try to hide behind the stalk.

By: Rob Duffield, Area Agronomist, Pioneer "Walking Your Fields Newsletter"
May 7, 2012