Evaluation of Chloropicrin Soil Fumigants for Management of Soil Borne Pathogens in Chile (Capsicum annuum L.)

Soil fumigants, Pic-Clor 60 and Pic Plus (Hendrix & Dail, Greenville, NC), were evaluated in 2009 to determine effectiveness in managing soil borne pathogens in overhead, circular pivot- irrigated chile (Capsicum annuum L.). Pic-Clor 60 is a mixture of chloropicrin (60%) and Telone^® (40%). Pic Plus contains chloropicrin (86%) and proprietary emulsifiers. Treatments included high (120 lbs/acre) and low (60 lbs/acre) rates of each fumigant and untreated control plots. Plots were arranged in a randomized complete block design with six replications. Fumigants were tractor applied from pressurized containers on 21 February by shanking in the chemicals eight inches below the surface of the soil, followed immediately by a packing pass. Untreated plots were also physically shanked and packed, but no chemical was applied. Soil temperature at time of application was 60°F. Plots were direct seeded with ‘Villa 96’ (3 lbs/acre) on 20 Mar. and emergence occurred 11 April. Stand establishment (plants/plot) and vigor (plant heights) were measured every two weeks after emergence until thinning. On 1 July, soil cores for nematode counts were taken. A second nematode root galling evaluation was conducted after harvest and rated from 1 (no galls) to 6 (75% galled roots). One week before harvest, a visual wilt disease assessment was conducted. Marketable green chile fruit were harvested from each plot and fresh weight yields were determined. No differences were observed in stand establishment or plant vigor. No plant loss due to wilt diseases was observed in either the treated or control plots. Direct soil counts did not reveal root knot nematodes, however galling rates indicated higher root knot nematode populations in the untreated plots versus the treated plots, with the high rate Pic-Clor 60 and Pic Plus showing significantly less galling (P=0.05) compared to the untreated control plots. Fresh weight yields appeared to correspond to the galling rates, with significantly higher yields (P=0.10) in the high rate Pic-Clor 60 (21% higher yield) and the low rate Pic Plus (22% higher yield) plots compared to the untreated control plots.