Friday, June 24, 2011

Cotton: The Case of the Missing First Squares

As I travel around the Valley, I’ve been noticing an unusual trend in many cotton fields.

The plants are at the seventh or eighth node, or true leaf, and showing the first pinhead squares. In all my years of scouting, though, I’ve never found so many first squares missing on young cotton plants. The first square location is important and can impact profits in the long run.  Losing the first square position causes the plant to become more vegetative and experience problems retaining fruit.
   I’m seeing missing first squares in 20 to 30 percent of the cotton fields that I’m scouting this season. In the past, the highest rate 5 to 10 percent of the fields.

   The squares are nibbled off by pests we had this spring. The growing      season is eight to 10 days behind schedule.

   Some growers irrigated too soon and ended up lowering the soil     temperature, which affected plant development. UC IPM is a good resource to learn about monitoring early squaring in cotton growth and development.

   Of course, this plant condition is worrisome to growers. Some might be tempted to apply growth regulators such as Pix, which are designed to increase boll retention and cut back vegetative growth.  Regulators can reduce yields if applied when plants are going through stressful, especially moisture-related, conditions. They also can lead to stunted plants, which could prompt growers to increase nitrogen into the soil to help the plants grow taller for easier harvest in the fall.

Determine the reasons why the first squares are missing. Some pest control advisors might want to start treating for lygus now.

Remember to keep monitoring the fields for pest pressures and be familiar with the surrounding fields. If you’re growing safflower nearby, you might want to treat it for lygus. If you have alfalfa, let borders or strips to prevent migration of worms and lygus. You could treat the alfalfa strips rather than the cotton field.

Lacewings are natural enemy to aphids.
Meanwhile, I’ve spotted some aphids in the cotton fields. Natural predators such as ladybugs and lacewings could take care of small problems. Spot treatment is another alternative.

I am starting a weekly release of 10,000 to 15,000 lacewings for each field I’m scouting to control the aphids.

Field Day Alert: I will participate in our Cotton Pest Management Field Day on Thursday, June 30 from 10 a.m. to noon at the Bettencourt Farm in Mendota. The featured speakers: Dr. Pete Goodell of University of California Statewide Integrated Pest Management at the Kearney Ag Center on managing lygus and Dan Munk, UC Cooperative Extension farm advisor and cotton specialist, on plant development and its role in IPM. Check our Sustainable Cotton Project website for directions. It’s sure to be extremely informative and give growers an opportunity to meet cotton experts directly.








                        

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