USING COTMAN ™ TO DETERMINE YIELD LOSSES DUE TO THE ROOT-KNOT NEMATODE IN COTTON GROWN IN NORTHEAST ARKANSAS

Recent surveys have suggested the frequency of root-knot nematode-(Meloidogyne incognita) infested fields is increasing in cotton-growing counties of Arkansas (Kirkpatrick et al., 1992; Bateman and Kirkpatrick, 2000). Although cotton yields often are suppressed as a result of M. incognita infestations, cotton continues to be the major row crop produced in northeast Arkansas. Landowner preferences and commodity prices have forced producers in this area to abandon crop rotation strate-gies that could help reduce the effects of M. incognita on cotton yield. In order to maintain profitable production, accurately quantifying crop loss due to root-knot and identifying effective and economically feasible control measures are required. BACKGROUND INFORMATION Recently, both increased rates and multiple applications of Temik ® (aldicarb) have been shown to improve yield of cotton grown in fields infested with M. incog-nita. Benson et al. (1994) showed positive yield responses when Temik was applied in-furrow at planting. Temik rates used in this study ranged from 3.5 to 7.0 lb/acre. Al-though initial root-knot nematode populations ranged from 106 to 280/500 cm3 soil, yields resulting from the varying nematode populations were not analyzed. Studies in southwest Georgia resulted in no significant yield increases from nematicides when nematode populations varied across the test site (McGriff et al., 1997). These data suggest a “lower-end ” threshold should be defined. Lorenz et al. (1999) indicated that yields were significantly increased above that of untreated plots when Temik was applied at planting (5.0 lb/acre) followed by an additional 5.0 lb/acre sidedressed at pinhead square. Temik applied at these rates would exceed $30.00 per acre, and may not be cost effective in low or moderate M. incognita infestations