Updates for Week of May 26th

Kudzu Bug adults depositing eggs in April planted soybeans in Barbour Co. (Eufala) on 5/28/13. Will wait for hatch to assess treatment needs.

Low level of cotton fleahoppers infesting 6-7 true leaf cotton at Prattville, AL.

Some controls still going out for adult grasshoppers in Central, AL. Stand loss detected from GH feeding on stems at or above soil line.

Mid May or later planted cotton with seed treatments should not need foliar thrips spray due to rapid growth of the plants.

Cotton Growing and Thrip and Grasshopper Treatments

Some of the April planted cotton is finally beginning to grow since the nights have become warmer. April 17 planted cotton at Prattville, AL now has 4-6 true leaves and is about 5 inches high. Thrips pressure is still heavy enough to cause a moderate level of visible injury to true leaves when no foliar insecticide was applied. Most cotton planted in April 2013 definitely needed a foliar spray at the 1-2 true leaf stage. Plants that emerged after May 15 likely will not need this foliar application.

I have had several calls this week about making a combination spray to target thrips and grasshoppers as an over the top herbicide is applied. My comment was positive to do this but realizing that some of the grasshopper population is now adults and will be difficult to control without going to the highest labeled rates of whatever insecticides are applied. I suggest staying with a lower rate and just targeting the thrips and immature grasshoppers.

I will come back in a few days to look ahead at out next potential cotton insect – tarnished plant bug. It has been my experience that wet springs, with delayed planting, have the potential to be bad plant bug years.

Thrips and Cotton Update

A lot of cotton has been planted this week (May 13-17). This is the first time many areas have been dry enough since early April. However, believe it or not, much of central Alabama missed rains in the last weather front and it is already too dry for seed to germinate.

Cotton that has emerged has not made much growth to this point. Cloudy weather, cool nights and a moderate number of thrips has severely hampered seedling growth. Based on my observations from monitoring four thrips research trials, I would suggest that the cooler than normal temperatures, especially at night, has done more to prevent seedling plant growth than has thrips injury.

Thrips numbers have not been abnormally high. In fact, it does not appear that the mass movement of thrips from grains and other wild host plants have occurred yet. Thrips damage is moderate to heavy primarily due to the fact that plants are not growing due to cool nights.

Cotton planted this week (May 13-17) should have better growing conditions and grow off rapidly. If that is the case, thrips injury will be minimal in spite of thrips numbers.

I would suggest that cotton emerging after May 20 will not need a foliar spray to supplement seed treatments. My thrips trials planted on April 10 did not emerge and put on a true leaf until more than 21 days after planting. In this situation, much of the thrips control provided by the seed treatments had dropped considerably before a true leaf even emerged.

The bottom line is that growing conditions, moisture and temperature are more important than thrips numbers or the type of thrips control a grower chooses.



No seed treatment and no foliar spray. Plant date 4/10/13.



Seed treatment and foliar spray. Plant date 4/10/13.



 

Highlights of 2011 Research Projects

A multiyear-multistate (Southeastern U.S.) thrips research project, funded by Cotton Incorporated, was initiated in 2011. Evaluations were made with the following variables:

1. Base fertilizer only versus Base fertilizer + Starter
2. Fungicide only versus Seed Treatment + Fungicide
3. No foliar sprays versus Foliar sprays at the first or second true leaf stage
Both dryland and irrigated sites were conducted.

Observations from the first year of the study in Alabama were as follows:

1. The starter fertilizer did not benefit thrips control, especially on dryland sites.
2. If planting prior to May 15, some form of seed treatment is a must for thrips control.
3. Under heavy thrips pressure, such as 2011, a seed treatment alone will not give adequate control, if planting prior to about May 10.
4. Foliar sprays for thrips control should be timed at the 1st or 2nd true leaf stage (when the leaf is the size of a small finger nail). Foliar sprays after the 4th true leaf are seldom necessary.
5. Effectiveness of several insecticides for thrips control.
-Acephate (Orthene or generics) was equal to, or superior to, all others evaluated. Certain pyrethroids did not give acceptable control. Two new chemicals (Benevia-Dupont) and (Radiant-Dow) gave good results at the rates tested. Labeling and their economics are uncertain at present.

Another project was conducted to define the role of fire ants in suppressing caterpillar damage in varieties with various insect traits. A small plot (8 rows x 45 feet) replicated study was conducted utilizing three varieties: DP174RF, PHY565WRF and DP1050B2RF in blocks with no fire ants versus normal fire ants. The trial was conducted in a reduced tillage system. An end of season worm damage boll count was made and the results are presented in the following visual.

The numbers on the left show the number of worm damaged bolls per 45 feet.


Impact of Fire Ants on Bollworm Damage in Alabama Cotton