FREQUENCY AND GEOGRAPHICAL-DISTRIBUTION OF PLANT-PARASITIC NEMATODES ON COTTON IN GEORGIA

A survey was conducted to examine the geographical distribution of pla nt-parasitic nematodes in Georgia cotton fields. A total of 778 fields in ii Georgia counties were sampled from 1 September through 15 Decem ber 1995. Four nematode genera parasitic on cotton were found in this survey: Meloidogyne spp., Rotylenchulus sp., Belonolaimus sp., and Mel oidogyne sp. Meloidogyne spp. was present in 9% to 56% of the fields i n individual counties. Rotylenchulus sp. was found in 10 counties, Hop lolaimus sp. was found in 6 counties, and Belonolaimus sp. was found i n 2 counties. From all of the samples collected for this survey, Meloi dogyne spp. were found in 3170 of the samples, Rotylenchulus sp. was f ound in 14%, Hoplolaimus sp. was found in 7%, and Belonolaimus sp. was found in 0.3%. Burke County had the greatest number of fields infeste d by at least one of these genera (67%) and the greatest number of fie lds above Georgia's action thresholds (38%). Laurens County had the fe west fields where these genera were present (13%), and only 3% of fiel ds had nematode populations above threshold levels. Data from samples collected from cotton fields and submitted by county agents from 1993 through 1994 were compiled to provide historical information about nem atode distribution and population density. The results from this surve y show that the major nematodes damaging to cotton are not present in all counties in Georgia. Counties in which cotton has historically bee n a major crop are likely to have higher levers of Meloidogyne spp., H oplolaimus sp., and Rotylenchulus sp. in current cotton crops. Countie s in which soybean has historically been a major crop are likely to ha ve higher levels of Hoplolaimus sp. and Rotylenchulus sp. in current c otton crops.