Announcing Alabama Scouting Schools

Announcement: Alabama Cotton Scouting Shortcourses Meeting Sites and Dates

• June 12^th (Tuesday) 2012; Autaugaville, Alabama- County Agricultural Center
• June 13^th (Wednesday) 2012; Headland, Alabama- Wiregrass Research Center
• June 19^th (Tuesday) 2012; Belle Mina, Alabama- Tennessee Valley Research Center

All meetings begin at 8:30 AM

Contact Person: Dr. Tim Reed (256-627-3450) or Dr. Ron Smith (334-332-9501)

Note: Dr. Austin Hagan will discuss cotton diseases at the Autaugaville and Headland sites. Dr. Tim Reed will cover soybean insects at all three sites.

Following are thirteen questions that represent the type of information that will be discussed.

1.      Why are grasshoppers easier to control in March/early April than May?

2.      If a foliar is needed for thrips suppression, when is the ideal stage of cotton to apply it?

3.      If you see damage to cotyledon stage cotton (no till) planted behind corn residue, what is the most likely culprit: snails, slugs, or pill bugs?

4.      What is the best method to determine when plant bug controls are needed in pre-bloom cotton?

5.      How would you measure the number of tarnished plant bugs in post bloom cotton?

6.      You are at week four or five of bloom, what would be the threshold for stink bugs?

7.      Under what conditions (situation) would a phosphate insecticide give better control of stink bugs than a pyrethroid?

8.      What new thrips insecticide entered the market this season and does not flare aphids or spider mites?

9.      Suppose you find high numbers of fall armyworms feeding on grass in your cotton field border- should you prepare to spray the cotton?

10.   How old does a green boll need to be to be safe from stink bug damage?

11.   Under what conditions would aphids be more of an economic pest or problem?

12.   At what stage is cotton normally beyond thrips injury?

13.   How long should you wait to evaluate control behind a stink bug spray?

Thrips, Grasshoppers and Slugs

I’d like to mention several pests today, these being thrips, grasshoppers, and slugs.

1. Thrips- The heaviest pressure encountered this season was from about May 1-20. From monitoring 5 thrips trials, it appeared to me that thrips were later than normal moving from wild hosts and wheat to cotton. In addition, thrips pressure was not uniformly heavy. In some fields it seemed only low to moderate pressure was encountered. Cotton is growing very rapidly now and once it reaches the fourth leaf stage should be safe from economic thrips injury. Cotton planted on or about May 15^th, with seed treatments, should not need a foliar overspray. Remember that seed treatments give adequate protection under most conditions until about 21 days after plant.

2. Grasshoppers- We lost another 45 ac. field in Talladega County to grasshoppers last week. The cotton was in the “crook” stage of emergence when attacked by grasshoppers. The strange thing about grasshopper feeding is that you can never predict when they will turn to cotton to feed. Grasshopper numbers do not mean much as far as thresholds. Sometimes a low number will cause a lot of damage and other times high numbers will result in no feeding. The usual damage from grasshoppers to cotton is in the form of stem feeding. They will feed on and cut the stem of the plant anytime from the crook stage up to about the 2-3 true leaf stage. Most grasshoppers in the system now are adults and are rather difficult to control. A max labeled rate of a pyrethroid or .75-1.0 lb. acephate is the usual grower choice in May. Back in March and April, a low rate of most any cotton insecticide will do a good job when the grasshoppers are still immatures.

3. Slugs- We have had two more locations last week where slugs were damaging stands of cotton or soybeans. This brings a total of five or more locations with loss of stands to slugs this season. These fields are always in no-till, high crop residue situations. Usually the grower/consultant looks in day time and sees pillbugs or snails and not slugs- only when observing at night do we find the real culprit, slugs. They bury deep in the residue during the day and only feed at night. Snails and pillbugs normally do not feed on cotton or soybeans. There is not much a grower can do about slugs. Metaldehyde at 10-40#/ac. is the only recommended chemical. At $2.25/lb. this would cost $25-85/ac. and controls, even then, may not be 100%. Seems to me that replanting would be the best alternative to slug damaged stands. Slug damage seems to usually be when cotton or soybeans are following corn.

Thrips Damge in Cotton

Thrips pressure is quite variable based on the location and field. The two most significant factors affecting thrips damage seem to be planting date and rainfall. Thrips trials at Prattville, AL, planted on April 16, are showing low to moderate thrips injury even without a foliar application on top of seed treatments at planting. Trials planted a week earlier, April 9, are showing heavy thrips injury behind all seed treatments. Rainfall occurred on all trials during 5 of the first 10 days of May.

Most April-planted cotton should be out of the thrips damage window within 10 days or less. Cotton planted in April had three true leaves or more with the fourth or fifth emerging on May 11.

Growers planting behind the rainfall that occurred between May 7 and May 11 will likely not have to be concerned about making a foliar spray for thrips at the first true leaf stage. Seed treatments alone should provide adequate thrips control.

Cotton up and growing should be beyond grasshopper damage. The concern about pill bug damage in the one field in Talladega County this week turns out to be primarily damage from slugs and not pill bugs.