Efficacy of Summer and Fall Cover Crops at Managing Sting and Stubby-root Nematodes in Florida Potato Production

Sting (Belonolaimus longicaudatus) and stubby-root nematodes (Nanidorus minor) are major plant-parasitic nematodes (PPNs) of spring potatoes (Solanum tuberosum) in Florida. Fumigation is the primary PPN management tactic for growers in the area, but more options are needed. Cover cropping is one of the few potential PPN management options that fit this cropping system. The objective of this study was to test the efficacy of summer and fall cover crops combinations against sting and stubby-root nematode in potato production. Two field trials were conducted in 2022-2023 and 2024-2025. Experiments had a split-plot arrangement. Summer cover crops 1) sunn hemp (Crotalaria juncea 'Crescent Sun'), and 2) sorghum-sudangrass (Sorghum x drummondii 'SX19/Defiance') were main plot treatments. Sub-plot treatments were fall cover crops 1) caliente mustard (Brassica juncea 'Rojo') and 2) arugula (Eruca sativa 'Nemat'), 3) weedy fallow and 4) weedy fallow followed by 1,3-dichloropropene (1,3-D) fumigation. Sunn hemp generally suppressed sting nematode populations relative to sorghum-sudangrass although its effect on stubby-root nematode was inconsistent. Arugula or caliente mustard were not effective for managing sting and stubby-root nematode populations. Weedy fallow followed by 1,3-D provided the most sting nematode suppression of any fall treatments. Sunn hemp improved potato marketable yield in one of the trials, while arugula and caliente mustard reduced marketable yield of potato in both years compared to 1,3-D. In summary, sunn hemp is an additional tool to 1,3-D fumigation for managing sting nematode in potatoes, but arugula and caliente mustard are detrimental. No options were consistently effective against stubby-root nematode.