Monday, July 2, 2012

Patience Can Pay Off When Making Treatment Decisions

It’s a familiar scene: You’re stopped at a busy intersection and another driver pulls next to you and starts revving up his engine like a wannabe drag racer. Trying to time the signal, he punches the gas pedal and speeds through the intersection – before the light turns green.

Lately, I’ve seen a few cotton growers resemble over-eager drivers.  They seemed to be jumping the gun on treating their fields for lygus. I believe they could have waited.

This is where using a sweep net to take pest samples and plant mapping to measure fruit retention becomes an important tool in the treatment decision-making process. I wholeheartedly agree with this advice from UC IPM: “If retention is higher than expected you may be able to wait and monitor again that week before making a treatment decision. If retention is lower than expected and lygus bugs are present, consider treating.” To read more about this topic, here’s a link to the lygus pest management guidelines.

- UC IPM graphics
As I tell growers, cotton plants can’t hold all their fruit and it’s normal to lose a certain amount. My rule of thumb is to hold off on treatment for a fruit retention rate above 80 percent. The treatment threshold comes into play when the rate falls below 80 percent retention, especially for Pima varieties which have small bolls.
A cotton boll in pre-bloom.
I saw one field being treated even though fruit retention was at 85 to 90 percent. When you’re above the 80 percent threshold, you should continue monitoring your field and taking pest samples. You may see lygus counts drop because the bugs are heading off to more preferred conditions in nearby alfalfa fields.

By jumping the gun, growers could impact the ecological balance by harming natural predators which play a big part in using biological controls to managing crop-threatening pests. Besides, beneficial insects are good for the pocketbook as well as the environment. Using softer materials can help preserve the beneficial insect population.

Alfalfa is drying around an uncut strip.
In the alfalfa fields, growers are cutting their crop for the third time this season. Some already are preparing for the fourth cutting, irrigating the fields and adding a bit of fertilizer to spur growth. Remember to keep leaving strips of uncut alfalfa to keep lygus from migrating to nearby cotton fields. Be a good neighbor.
I’m seeing an increase in worm activity. So far, there no signs of growers treating their alfalfa for worms. Remember to keep monitoring the fields.

Looking ahead, July will be another busy month with little time to rest – even on the Fourth of July holiday this Wednesday. Like farmers around here, Independence Day is another work day for Valley agriculture. Wishing everyone an enjoyable Fourth of July holiday.

No comments:

Post a Comment