Evaluation of cover crops for reducing Heterodera glycines populations in microplot experiments

Abstract

Summary Soybean cyst nematode (SCN; Heterodera glycines) is a major yield-reducing pathogen of soybean worldwide. Microplot experiments were conducted to evaluate ten cover crops for their effects on two SCN populations (SCN103 and SCN2W) collected from North Dakota, USA, soybean fields in 2019 and 2020. Experiments were conducted in a randomised complete block design using naturally infested field soil. A susceptible soybean ‘Barnes’ and non-planted natural soil (fallow) were used as controls. Plants were grown in outdoor conditions for 75 days before soil samples were collected. SCN eggs and juveniles were extracted from the soil samples to determine final population, population reduction and suppression. Soybean had significantly greater final population densities than all the cover crops and fallow. All cover crops and fallow reduced the initial densities of both SCN populations. All the cover crops, except chickling vetch ‘Pulse’, had lower final population densities than fallow and suppressed the SCN populations throughout the experiments. Sunnhemp (cultivar not stated; CNS), oilseed radish ‘Concorde’ and ‘Control’, and daikon radish ‘Eco-Till’ significantly reduced the SCN103 population compared to fallow. Sunnhemp, alfalfa ‘Bullseye’, and daikon radish had significant population reductions of SCN2W than fallow. Sunnhemp was found to have the greatest reductions in SCN populations ranging from 55 to 86% compared to the initial densities. This study demonstrated cover crop species/cultivars with the ability to reduce SCN populations in outdoor conditions, and the findings indicate that they could be utilised in infested fields to manage SCN.