Welasco, Texas
June 11, 2003

Midway through the Lower Rio Grande Valley's cotton growing season, the crop is much better off than it was last year at this time, but rain is badly needed.

John Norman, cotton IPM entomologist at the Texas A&M University Systerm Agricultural Research and Extension Center in Weslaco, said fall and spring rains have given this year's acreage a huge advantage. He predicts that, unlike last year, the majority of the crop planted will be harvested.

"If not for the deep soil moisture we got from rain late last year and the rains we got through early April, our dryland crop would be ruined by now for lack of rain, much as it was last year at this time," he said. "Clearly irrigated cotton is doing better than dryland, but even dryland cotton is showing a significant improvement over what we've had the last two or three years, maybe even over what we've had the past three to four years."

Norman estimates this year's crop at 235,000 to 245,000 acres, 50 percent to 60 percent of which is dryland, or without irrigation. Before the lingering drought that dates back eight years or so, area producers normally planted an overall ratio of about 60 percent irrigated cotton to 40 percent dryland.

"As less water is available to farmers, more of the acreage is planted dryland. But there seems to be a slight improvement in water availability this year. Based solely on personal observations, there seems to be more irrigated cotton this year than last," Norman said.

But rain is desperately needed to carry dryland acreage and some irrigated cotton acreage to harvest. Without moisture soon, immature cotton bolls will drop from plants without ever producing open, harvestable cotton bolls.

Dr. Bob Wiedenfeld, a soils scientist at the Texas A&M center in Weslaco, said temperatures and evapo-transpiration rates in May were higher than normal. The evapo-transpiration rate is the rate in inches at which plants lose moisture that needs to be replaced by irrigation or rainfall.

Rain would also help leech plant-stunting salt buildup in the soil that comes from salty river irrigation water. Most irrigated fields have been watered twice this year, replacing salts that previous rains had diluted. But as badly as they are needed, rains could also have a negative downside in the form of increased insect pest populations, particularly of the area's two main cotton pests, the boll weevil and bollworm. "The insect situation in cotton is not too bad now," said Norman, "but rains could cool off soil surfaces and increase the survival rates of these insects."

Boll weevils lay eggs in flower buds. When they hatch, Norman said, the grubs fall to the ground in the flower buds. If the soil is sun-baked and extremely hot, grubs usually die. But if the ground has been cooled by rains, grubs do well and can survive to damage cotton bolls as adults. Bollworms also fare better in cooler fields.

"We're not overwhelmed with insects right now; they're just getting started. But with rain, they will definitely do better than they have been," said Norman.

Harvest of the Valley's cotton typically begins in earnest in late July and continues through August. To eliminate over-wintering sites for boll weevils, state law mandates that cotton growers destroy all cotton crop residue by Sept. 1. Growers cannot legally plant before Feb. 1.

"The very early planted cotton should be producing the nation's first bale of cotton here any day now," Norman said. "I haven't seen too many open bolls of cotton out there yet, but typically our first bale comes from growers who planted very early in the year."

Norman planted a research field plot of cotton on Feb. 14, which he said still has green, unopened bolls.

Writer: Rod Santa Ana III, 956-968-5581, r-santaana@tamu.edu