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 Knowledge for the CommonWealth

Care Needed in Selecting Transgenic Cotton Varieties

Crop and Soil Environmental News, May 1998

Charles Hagedorn
Extension Specialist

As growers make decisions this year about whether or not to try the new transgenic cotton varieties, they should remember that most of the new transgenics have not been through several years of public testing that is "standard practice" with new conventional cotton varieties. This situation is as true for other transgenic crops (e.g. soybeans and corn) as it is for cotton. This situation also means that growers are faced with making decisions on whether to plant the transgenics with considerably less information than they need. Some of the information in this article was presented at a cotton production cost session during the recent 1998 Beltwide Cotton Production Conference in San Diego.

Growers should also realize that the agronomic and fiber quality characteristics of the new transgenic cotton varieties do differ from the original varieties (recurrent parents) due to the required three or more backcrosses needed to develop the transgenic. While the normal advice to growers is to study local test results on a new crop variety or hybrid, in the case of transgenic cotton varieties, it may be better to look at variety performance over several locations rather than just considering the results of a single nearby location. This may give growers a better view of the potential for the transgenics at their own location.

While the transgenic cottons do offer "value-added" potential, farmers are being faced with more complex decisions as to whether the more expensive transgenics will pay their way on the farm. For the 1998 growing season, commercially available transgenic varieties will include varieties that possess Bollgard (BG), Roundup Ready (RR), BG + RR, and BXN and BXN + BG genes. As public testing of the transgenic varieties is still limited (most of the evaluations are made by the private companies), growers will have to rely on results from industry trials. Growers should also look at comparisons of yield and fiber quality characteristics against the parent varieties--and use their own experiences and observations.

Although cotton transgenics add desirable herbicide and insect resistance traits, they need to be further evaluated in different production regions to see if the results will offset the varieties' higher up front seed costs and licensing fees. Public testing to date suggests that the "greatest opportunity" with BG technology would be in production regions where growers spend more than $30 per acre to control bollworms, tobacco budworms, and pink bollworms. Rarely is this level of control needed in Virginia.

Factors to consider in selecting any cotton variety--conventional or transgenic--for planting in 1998, should be in order: yield potential, adaptability, fiber properties, "value-added" traits, disease tolerance/resistance, boll type (stormproofness), pubescence (hairyness) and others. Growers should be advised against "betting the farm" on only a single cotton variety--especially a new one that hasn't been extensively tested or grown in the area.

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