The only generalization that can be made about this year's 670,000-acre San Joaquin Valley cotton crop is that you cannot generalize about it.
Some fields reached cutout by Aug. 1 and were trying to restart; others were just beginning to cut out and were shutting down and some were “gigantic” in height, loaded with cotton and still fruiting.
“It is a definitely a mixed bag season,” said University of California Extension Cotton Specialist Bob Hutmacher, who has been hitting the county cotton meetings giving growers insight into how to handle the wide array of field conditions created by cool planting weather that delayed many plantings.
“The biggest thing we need this year is as an open fall. We are so late,” said Fresno County, Calif., producer Don Cameron.
Cameron has applied plant growth regulator three times to his cotton this year, trying to force fruit set. He has not been in an elite crowd. Pix has gone on often and heavy to try to set a crop and beat fall rains.
However, some cotton has not slowed at all. “There are some gigantic fields out there, especially Pima, with cotton over my head by mid-August,” said Hutmacher.
One pest control advisor at the recent Madera-Merced counties cotton meeting asked what Pix rate Hutmacher would recommend to apply to cotton in mid-August just to slow down growth and achieve reasonable defoliation.
High in nitrogen content
“I would think 16 ounces would be like pouring water on it — 24 ounces may slow it down,” he added, acknowledging that there is “no economic benefit” for Pix that late in the season. He added a caution: growers may be precluded from high rates late because it would put them over the season allowable for Pix use.
These giant-plant fields are often after tomatoes and are high in nitrogen. They've not been water stressed this season; are loaded with fruit already and continue to set more.
“Some of these fields went four to four and a half bales last season, and they have that potential again this year with an open fall,” said Hutmacher, who reminds growers that it takes 70 days from flowering to open boll.
While the yield potential of these fields is encouraging after such a late start, they are also vulnerable to late season whitefly and aphid infestations because of the same lateness.
UC IPM specialist Pete Goodell said silverleaf whitefly has not appeared yet in the Southern San Joaquin Valley as expected. However, growers from the Buttonwillow area through Tulare County and in the Three-Rocks/Cantua Creek area of Western Fresno County area have already treated for whitefly once and are looking at a second treatment as populations rebuild.
Aphids are showing up as well, and the California Cotton Growers and Ginners Associations (CCGGA) has applied for another Section 18 for Furadan. California has been joined by Texas and Mississippi in seeking the late-season emergency use registration.
Earl Williams, president of CCGGA, said the California Department of Pesticide Regulation has said it will not grant Furadan an emergency exemption as it has in the past because there are now five alternatives to Furadan.
Williams said growers report these alternatives are not working well and are expensive, five times of more as costly as Furadan.
“We recognize there is a need for Furadan this year, and we will be in there fighting for it,” said Williams.
California SJV cotton recovered nicely in 2002 from the sticky cotton crisis of 2001 when mills worldwide complained of sticky cotton caused by late season aphids and whiteflies. There were no mill complaints from the 2002 crop, but industry leaders are concerned that the lateness of this year's crop and heavier than normal overall insect pressure could create sticky cotton again this year.
“Just because you defoliate your crop, don't think you are out of the woods” and not susceptible to insects secreting honeydew to cause sticky cotton, warned Goodell. “If you wait for two weeks until defoliant is applied and another three weeks for the leaves too fall before picking, that is five weeks where your cotton is vulnerable.”
And, don't be fooled into thinking defoliants, even organophosphate materials, will take care of aphids.
UC entomologist Larry Godfrey in test last season at Shafter, Calif., said that defoliants provided no control of aphids or a barrier against stickiness. Defoliants can actually increase the danger of aphid-induced stickiness, according to Godfrey, who said when leaves begin to drop, aphids actually produce more offspring in a survival mode.
Aphid population levels were low in the Shafter trial (six to seven aphids per leaf) yet all lint from the trial registered as sticky using thermal instruments used by textile mills.
In other, late season, pre-harvest aphid control trials, Godfrey found control poor with many of the same materials that demonstrated good early-season control.
Some at cutout
While many fields remain vigorous and loaded, Hutmacher said some were reaching cutout or had already quit. That may not be a bad situation if harvesting early precludes late season pest control measures.
Some cut out fields have restarted growing, but Hutmacher warns that trying to set more fruit on these fields may be futile.
A heat wave in July did cause some shedding and small bolls to “freeze” on the plant, but Hutmacher said temperatures did not reach excessive levels where shed was widespread.
“Some fields were hit harder than others,” said Hutmacher, who said the difference seemed to be where growers irrigated to minimize the heat stress and those who “irrigated by the calendar.”
While some irrigation stress can control growth and speed up maturity, excessive water stress to the point of mid-afternoon leaf wilt can cause yield-robbing shed.
“This seemed to be more common in Tulare County than anywhere else,” he said.
Ron Vargas, cotton farm advisor for both Madera and Merced counties, said many fields were approaching 10 nodes above crack boll by mid-August. Ideal defoliation timing is four nodes for Acala and three nodes for Pima.
Timing is everything when it comes to defoliation, said Vargas. With the lateness of the seasons, growers may be tempted to defoliate and get lint off the field early before fall rains.
“Studies have shown you will suffer significant yield loss if you defoliate at seven to eight nodes above cracked boll,” he said.