Evaluation of small grain cover crops as a sustainable nematode management strategy for Meloidogyne incognita and Rotylenchulus reniformis in the Southeastern U.S.

Abstract

This experiment investigates five small grain winter cover crops including multiple genotypes of barley (Hordeum vulgare L), oats (Avena sativa L.), rye (Secale cereale L.), triticale (x Triticosecale Wittmack), and wheat (Triticum aestivum L.) as a sustainable nematode management strategy for Meloidogyne incognita (root-knot nematode) and Rotylenchulus reniformis (reniform nematode) in cotton production in a Southeastern U.S. Greenhouse (2019), and field experiments (2019-2021) evaluated these crops for nematode host status, forage quality, and grain yield. Greenhouse experiments showed that all small grains had higher average M. incognita egg counts than a standard corn (Zea mays L.) variety. Overall, barley and wheat were suitable hosts (Rf>2), triticale and oat were moderate hosts (Rf=1-2), while three cultivars (Forerunner' and 'OG170039' triticale, "ORO 4372' oat) were poor hosts (Rf<1). In field trials, oat had the highest biomass and grain yield, followed by triticale, barley, rye, and wheat. Barley supported the highest population density of M. incognita. Oat, barley, and rye displayed similar population density of R. reniformis and were greater than triticale and wheat. Forage quality experiments showed oat with the highest biomass, wheat with the highest crude protein, and rye and triticale leading in fiber content. Oats had the greatest total digestible nutrients (TDN) and relative feed value (RFV), indicating superior digestibility. All small grains demonstrated high forage quality (RFV>100). Cover crop selection should be based on specific management and agronomic goals as nematode populations varied by cover crop but were low in all field trials. Further research on crop-specific responses and long-term effects on nematode populations and soil health is needed to optimize small grain winter cover crops in integrated pest management programs.