Updated July 5, 2018:
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SCREENING COVER CROPS TO REDUCE SOYBEAN CYST NEMATODE IN INFESTED FIELDS
Dr. Guiping Yan, Principal Investigator, Dept. Plant Pathology, NDSU
Co-investigators: Dr. Marisol Berti, Dept. Plant Science, NDSU and Dr. Samuel Markell, Dept. Plant Pathology, NDSU
Soybean cyst nematode (SCN) is a devastating pest of soybean in North Dakota (ND). Host resistance and crop rotation are common practices to manage SCN, but limited sources of resistance to this nematode put pressure on virulence change in populations to overcome resistance. Thus, integrated management strategy is necessary for sustainable management of this devastating soybean pest. Cover crops have the abilities to reduce plant-parasitic nematodes and may provide an alternative means to manage SCN.
Our objectives were to evaluate common and potential cover crop species in ND for their hosting abilities to SCN and for reducing SCN numbers in infested fields. Greenhouse and microplot experiments were performed by using SCN-infested soils from two fields in Cass and Richland counties in ND.
Twenty-one cover crops and two susceptible soybean checks were evaluated for host status in a growth chamber for 35 days by inoculating each plant with 2,000 eggs. Out of the cover crops tested, 13 (annual ryegrass, camelina, carinata, cow pea, ethiopian cabbage, faba bean, foxtail millet, radish, rape dwarf essex, red clover, sweet clover, triticale, winter rye) did not support SCN reproduction, suggesting non-hosts. Six crops (crimson clover, turnip cv. Purple top, hairy vetch, forage pea, Austrian winter pea, field pea cv. Cooper) showed low reproduction for at least one SCN population as poor hosts. Field pea (Aragorn) and turnip (Pointer) showed some reproduction, suggesting hosts for at least one population. SCN reproduced less in all the tested crops compared to the two susceptible checks.
Ten cover crops were selected for microplot experiments. Crops were planted in pots each containing 5 kg of infested soil. After 75 days of growth before winterkill, soil samples were collected from each pot, and samples were collected again in the spring after winterkill. In both soils, majority of the crops reduced SCN populations compared to the susceptible soybean and non-planted control, in which annual ryegrass and radish were more effective than others. The spring sampling showed no much reduction in nematode populations compared to the populations before winterkill. Annual ryegrass and radish greatly reduced SCN by 61% and 64%, respectively, for the two SCN populations.
Cover crops, which are non-hosts with greater population reduction abilities, can be integrated in SCN management strategy. The research findings will be useful to navigate selection and use of cover crops for farmers for reducing SCN damage to increase soybean yield in ND.