2019 ASHS Annual Conference

The southern root-knot nematode, Meoidogyne incognita, is a major constraint to the carrot production. Preplant soil fumigation is an important approach to manage the nematode in double-cropping systems. On a commercial vegetable farm near Statesboro in the southeastern part of Georgia, Telone II (1,3- dichloropropene), Pic-Chlor 80 [1,3- dichloropropene (20%) and chloropicrin (80%)] and Pic-Chlor 100 [chloropicrin (100%)] were applied to a field naturally infested with M. incognita. Treatments were assigned to 300 m long, three-bed plots (0.2 m tall, 1.5 m bed top width), which were arranged in a randomized complete block design with three replicates. Broadcast applications of Telone II (112 L/ha) were made with a Harrell six-bottom switch plow with knives spaced 0.5 m apart delivering fumigant at a depth of 0.3 m in non-bedded soil. Beds were then formed with a Kennco three-row bed shaper and the center bed was used only in this work. Pic-Chlor 80 (112 and 168 kg/ha) and Pic-Chlor 100 (112 and 168 kg/ha) were applied with a tractor through subsurface knives (5 knives placed 0.3 m deep) during bed formation. Fumigant applications were made 4 weeks before carrot seeding into the area. A control block with no chemical application was included, and both treated and untreated blocks were monitored for nematode infection. Carrot samples containing taproots and fibrous roots, and soil samples were taken at harvest on 11 Jun. 2018 to examine the nematode reproduction and yield losses. Pre-plant soil fumigation with Telone II and Pic-Chlor did not completely affect root-knot nematode populations allowing the nematode to develop and damage carrot during the growing season. Carrot plants in the fumigant-treated plots had significantly (P < 0.05) lower nematode numbers, gall rating and root rating than the untreated control. Plots treated with Telone II had often numerically reduced nematode numbers and gall and root ratings compared to the plots treated with Pic-Chlor. Total carrot yield was not significantly different between treated and not-treated plots, however, total yield in the plots treated with Pic-Chlor 80 (112 kg/ha) and Pic-Chlor 100 (112 kg/ha) were numerically higher than that of the Telone II treatment.