An Assessment of Small Grain Cover Crops As Potential Rotation Crops for Root-Knot and Reniform Nematode Infested Alabama Cotton Fields

The objective of this study was to assess plant growth and host suitability of small grain cover crops to root-knot (Meloidogyne incognita) and reniform (Rotylenchulus reniformis) nematodes in Alabama cotton fields. In 2019-2020, field trials were conducted on 31 entries of small grains in two locations in Central Alabama; this included 14 triticale, 5 oat, 5 barley, 4, wheat, and 3 rye varieties. Trials were organized by crop and replicated 5 times in a randomized complete block design. Root samples were collected after planting and near harvest to measure root-knot and reniform population density changes throughout the growing season. Root-knot populations per gram of fresh root were similar on all crops tested, except for barley, which had significantly (P≤0.05) higher egg population densities. Reniform populations per gram of fresh root were significantly (P≤0.05) higher on rye. Above-ground biomass was primarily affected by the presence of seed and foliar diseases. In the root-knot field, oat produced significantly (P≤0.05) greater above-ground biomass of all small grains tested, followed by rye and triticale, respectively. In the reniform field, oat, rye, and triticale, respectively, produced similar biomass that was significantly (P≤0.05) greater than barley and wheat. Oat, in the root-knot field, produced significantly (P≤0.05) more bushels per acre compared to the other grains tested. Grain yield in the reniform field was low due to delayed harvest, however, yields were more consistent with barley, oat, and rye, respectively, producing the greatest bushels per acre. The results indicate that the small grains tested are suitable hosts for root-knot and reniform nematodes. Rye, specifically the ‘Goku’ variety, was most successful in limiting root-knot nematode reproduction and ‘Willow Creek’ wheat was least suitable for the reniform nematode. Some high-reside and high-yielding varieties tested may be beneficial beyond nematode management for their value as either a grain or forage.