Late SJV crop causing concerns

“Unfortunately, it’s July,” said independent pest control advisor Jim Hall of Kerman, Calif. at a recent mid-season University of California Cooperative Extension cotton production workshop held in Fresno County.

The 670,000-acre SJV crop is behind historical norms. Heat unit data verify what everyone already knows. It was one of the latest starts over the past decade. According to Fresno County farm advisor Dan Munk, heat units should total about 1,000 for the end of June. They were running 30 to 40 heat units behind that norm on July 1, 2003.

This season is comparable to 1998 and 1995, both under par seasons. Munk says 2003 has been most similar weather-wise to 1995, “a terrible year for pests—aphids and lygus.” Fortunately the pest pressure has not been as great as it was almost 20 years ago.

Variability is great among fields. Some are less than a week behind normal. Others are two to three weeks or a month behind. Fields in the northern part of the valley are generally in better condition than the rest of the valley because most in Merced and Madera counties were not planted under adverse, cool weather early in the planting season.

However, all fields are catching up fast under generally ideal weather conditions. Growers have been aggressive in protecting the crop they have in hopes of nearing last year’s excellent crop that averaged 1,440 pounds for Acala and 1,332 pounds for Pima. Those averages were at best a long shot at mid-season.

Munk says his research at the University of California research and extension center at Five Points, Calif. shows cotton fruiting later and higher on the plant this year.

Growers have been vigorously protecting crops against pest losses. Some are stressing the plant, forcing it to set. Others are using more nitrogen.

Munk’s recommendation: “Don’t rattle the cage” by promoting excessive vigor. That can collapse yield potential by shading out lower crop. Excessive stress can also reduce yield potential. Second irrigation stress to promote fruit set should be minimal.

And, he reminded producers and pest control advisors that a flower after Aug. 20 to Aug. 25 will not likely develop a harvestable boll in the central San Joaquin Valley.

One of the debates this year will be whether to go for a top crop. Independent PCA Nick Groenenberg of Hanford, who consults primarily in western Kings and Fresno counties, said he expects producers to try for that top crop. “That is where growers on the West Side get yield…in the top.”

Hall is going to recommend to his growers “that they don’t chase that dog into the woods” because it would be risking delayed harvest and in the case of Pima, significantly reduced income from lower grades.

Use of the plant growth regulator mepiquat chloride or Pix has become almost automatic for most SJV producers, but UC cotton specialist Bob Hutmacher believes it may have become overused.

He recommends using a vigor index to determine if Pix should be used and if it is warranted, what rate to use. He likes to use the internode difference approach to make a Pix application decision. It was developed by Delta and Pine Land Co.

Using delayed irrigation to stress the plant into fruiting and combining it with Pix is too much stress. “My impression is that people are combining the two and hitting the plant too hard,” warned Hutmacher.

From almost the very beginning of this season, the fear of high pest pressure, especially from fruit-robbing lygus has been paramount on the minds of growers and consultants. The late spring rains not only delayed planting, but created weedy habitat for lygus.

Veteran West Side consultant Galen Hiett who works in the Three Rocks and Cantua Creek areas said he has experienced “lousy square retention” at very low lygus counts, even with Temik. Counts only occasionally have reached five, six or seven per 50 sweeps. Typically, it has been zero to only two.

“However, I also have fields with good retention at the same low lygus counts. I have not been able to pin down what is going on,” said Hiett.

Hall also has seen low lygus counts, but reported no problems with square retention. He was concerned about the late start and ordered treatments at a two to three count. He has used a new DuPont product, Steward, which he says is a “softer material” to bring low lygus counts under control before they get out of hand.

Groenenberg said “the smart money this year was to control mites early.” Lygus in the fields he monitors has been sporadic. Worms have been a “constant problem.”

Halls says worm pressure has been “horrendous” in his fields.

Aphids and silverleaf whiteflies are the next pest in line to invade fields. UC entomologist Larry Godfrey says aphid problems and a late crop, unfortunately, go hand-in-hand. Aphids can create sticky cotton.

Godfrey said growers who used pyrethroids for lygus control have the potential for later aphid outbreaks. High nitrogen also attracts lygus. Hairy-leaf Pima also attracts more aphids.

Hall is so concerned about late-season aphids; he has recommended to his growers that they reduce nitrogen use by 20 percent this year.

Whiteflies are being picked up now in Kern County in the southern end of the valley, said IPM advisor Pete Goodell. “The crop is late and so are the silverleaf whiteflies…but they are coming.”

The valley is struggling with a sticky cotton image among textile mills after problems with the 2001 crop. California Cotton Ginners and Growers Associations have spearheaded an aggressive anti-stickiness campaign with UCCE being the point agency to bring the pest under control.

Goodell warned once again that just because a crop has been defoliated, that does not make it immune from high populations of silverleaf whitefly depositing honeydew on lint.

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