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Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only Publication Acceptance Date: 1/6/2012 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The three primary nematode pathogens of cotton are the cotton root-knot nematode (Meloidogyne incognita), the reniform nematode (Rotylenchulus reniformis), and the Columbia lance nematode (Hoplolaimus columbus). Those three nematodes are estimated to reduce US cotton production by 4.2%, with the cotton rot-knot nematode causing greater loss (2.4%) than any other single pathogen of cotton. For many years, application of nematicides has been the most commonly used method of nematode management, but the impending removal of aldicarb (Temik) from the market in the U.S. will force many cotton growers to change how they manage nematodes on their farms. Sources of resistance to root-knot and reniform nematodes are well documented, and the identification in recent years of molecular markers for the major resistance genes are allowing cotton breeders to make significant advances in developing root-knot- and reniform-resistant cultivars, but highly resistant cultivars have not yet been released. However, there are a few cultivars with moderate levels of resistance to the root-knot nematode, and those cultivars can contribute significantly to nematode management. Nematode resistance in cotton is species specific and will not affect other nematode species. Telone II (1,3-dichloropropene), which is a pre-plant fumigant nematicide, and various seed treatments are likely to be relied on more heavily in the absence of Temik. Recent research has identified methods of linking GPS coordinates to soil texture and other data to delineate different nematode management zones within a field, where the different characteristics of each zone can influence nematode levels and cotton yield potential. Nematode samples must still be collected from each nematode management zone, but sampling each zone independently greatly improves the ability to identify the parts of a field where nematode management is or is not needed, and in many cases the recommendations for nematode management may differ among the zones. Nematode management zones should be much more widely used regardless of what other nematode management tactics are used. Crop rotation with poor- or non-host crops can be an effective means of reducing the nematodes that damage cotton, but the use of crop rotation is often limited by the profitability of the rotation crop. In the coming years, the most effective programs for managing nematodes in cotton will probably combine nematode management zones with various combinations of fumigation, seed treatment, resistance, and, where profitable, crop rotation. The difficulty will be in determining which combinations will be the most cost effective for a specific field. |
