Using nematacides to control nematode populations in Arizona

Variable rate computer technology married to a satellite tractor guidance system has proven once again to dramatically reduce input costs. This time is was in using nematicides to control nematode populations in Arizona.

“By pinpointing the exact location of large concentrations of root knot nematode numbers in the field, we applied 56 percent less Telone II compared to injecting the material across the entire field,” according to Randy Norton, UA regional Extension specialist and director of the Safford Agricultural Center in Safford, Ariz. “The procedure increased yield by more than 500 pounds of lint per acre in areas with the worst nematode populations.”

Root knot nematodes attack the cotton plant’s young tap and secondary roots, which reduces the ability to intake water and nutrients. Above ground symptoms include stunting and skippy stands.

Norton led the UA research on a 19.2-acre demonstration block in a grower’s field in Safford. During the ’05 cotton harvest, yield maps were created and special software created a prescription map for targeted nematode treatment for the ‘06 crop year. The map illustrated that just 8.1 acres needed treatment.

Telone II is commonly injected across entire cotton fields in Arizona. Dow AgroSciences, the manufacturer of Telone II, donated the nematicide for the UA project. A grant from the UA Integrated Pest Management program funded the development of a six-row injection implement built by AZ Drip in Coolidge, Ariz.

In February, global positioning satellite and geographical information system technology guided the tractor across the field while a computer varied the rate of Telone II based on nematode populations.

Norton said, “With a current market value for Telone II of approximately $11 per gallon, this would equate to a $55 per acre cost just for material. In the test field where 42 percent of the acreage was treated, the input cost for the material would fall to $23 per acre.”

From 2001-2005, more than 18,000 gallons of Telone was applied annually to Arizona cotton production systems. The UA-proven technology has the potential to reduce Telone II use by Arizona cotton growers by 10,000 gallons annually – an estimated $110,000 savings to growers.

Shift testing site

Norton will shift tests to another Safford field and generate soil texture data in ‘07, plus conduct tests in Coolidge, Ariz.

Norton cautioned that nematode distribution is highly variable across Arizona and some areas may require application across an entire field for adequate control. In some places, results could be greater than in the UA study.

He said the same technology holds savings opportunities for crops like grains and vegetables.

“When I started work in GPS/GIS, we actually did some work with phosphorus fertilizers based on yield. We collected the yield map and then developed a prescription application map so we bumped up the fertilizer level in lower yielding areas.” While no yield increase resulted, 27 percent less fertilizer was needed to maintain the same yield.

With so many possibilities, the mission remains clear – controlling growers’ input costs and creating a safer environment through reduced chemical use.

“Farmers and ranchers in the United States are competing in a global economy with markets influenced by countries with relatively inexpensive input costs while input costs for U.S. producers have continued to rise,” Norton said. “In an effort to reduce cotton growers’ production costs, we are researching ways to utilize new innovative technologies like GPS and GIS to improve farming system efficiencies with respect to both agronomics and the environment.”

University of California integrated pest management advisor Peter Goodell agreed that yield monitor/GPS technology in cotton makes good economic sense. Pinpointing root knot nematode populations would allow the direct and efficient application of fumigation products and sampling resources.

Monitors snap a valuable photo of yield discrepancies across fields and generate critical questions - are yields reduced by root knot nematodes, high ground, a lack of water penetration or any number of possible reasons?

While not aware of research similar to Norton’s under way in California, he said root knot nematodes are prone to less than 20 percent of the state’s remaining cotton ground.

Not economical

According to University of California Pest Management Guidelines, Telone II is not economical for cotton root knot nematodes in California due to costs.

Aldicarb (Temik) at planting has controlled nematode populations and increased cotton yields. Other products such as metam-sodium ( Vapam) are registered for pre-plant use on cotton.

Unfortunately, Telone’s future in California is under fire as a volatile organic compound (VOC) that the Environmental Protection Agency says generates short and long-term adverse health effects.

Goodell said, “VOC regulations will soon come out and agriculture may be staring down the barrel. Since Telone is under the gun, further research may not be warranted. It would be difficult to use with all of the regulations.” He said the California Department of Pesticide Regulation caps Telone use by township per calendar year.

“If a new cotton planting is grown near carrots or nursery crops in Kern County where the largest nematode problems are, the Telone cap may have been superceded by whatever is currently grown in the neighborhood.”

According to Goodell, the smartest management path to root knot nematode control is crop rotation. Instead of back-to-back cotton plantings, a rotation with alfalfa or black-eyed beans is as good as a fumigant.

Standard Acala cotton varieties are fairly tolerant of light nematode populations, Goodell said.

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