Responses of Cotton Yield and Meloidogyne incognita Soil Populations to Soil Applications of Aldicarb and 1,3-D in Florida.

In four tests conducted in loamy-sand soils in northern Florida, cotton lint yield increased and post-harvest soil populations of Meloidogyne incognita were more effectively suppressed by 1,3-dichloropropene (1,3-D) than aldicarb when both nematicides were evaluated over a range of recommended rates. Significant positive relationships existed between lint yield and rates of 1,3-D in three tests, whereas only one significant positive relationship occurred between lint yield and aldicarb rates. Yield increases ranged from 16% to 124%, depending on rate of 1,3-D, and 35% in one aldicarb-treated test. Only a weak negative relationship between post-harvest soil densities of second-stage juveniles (J2) and aldicarb rates was determined by combining data from the four tests. Aldicarb failed to suppress post-harvest J2 soil population densities in any test. All rates of 1,3-D significantly reduced post-harvest M. incognita J2 soil population densities in two tests and provided a stronger negative correlation between nematode soil densities and rates than aldicarb when all test data were combined for each nematicide.