Update:
Completed work
Soil samples were collected from two SCN-infested fields in Cass and Richland counties of North Dakota based on our previous work. Nematodes were extracted from soil and counted under a microscope to determine the initial population densities of SCN and other vermiform (motile) plant-parasitic nematodes. The soil samples collected from these two fields were used for the greenhouse and microplot experiments.
Twenty-one cover crop species and cultivars plus two susceptible soybean cultivars (Barnes and Sheyenne) and two common rotational crops (wheat and corn) were tested in the naturally infested soils from the two fields in the greenhouse. Plants of the 25 entries each in five replicates were grown in a growth chamber for 35 days at 27o C. After 35 days of growth, cysts were extracted from roots and soil in each pot and white females (cysts) were identified and counted under a microscope. The host status was determined by comparing number of white females in each of the cover crops with the susceptible soybean check Barnes.
Ten cover crops including Alfalfa, Chickling vetch, Daikon radish, Faba bean, Flax, Oilseed radish (Concorde, Control, Image), Sunn hemp, and White mustard were selected for the microplot experiments using the infested soils from these fields along with the soybean check Barnes and an unplanted control. The crops were planted in large plastic pots each having 5 kg of soil from each of the fields. After germination, standard seeding rates were used to keep required number of plants per pot. Plants were grown in the greenhouse for two weeks for better establishment before they were moved to the microplot in natural field conditions. The microplot experiments were set up on August 14. Pots were buried into soil leaving approximately 10 cm of pot remaining above the soil surface. Each of the entries had 5 replications. Height of the plants from each pot was measured on October 9. After 75 days of growth in the microplot, three soil cores were taken from each pot to make a composite sample on October 28 before the snowfall killed the plants. All the soil samples are stored in a cold room until SCN eggs and other nematodes are extracted and counted to determine the final population densities.
Preliminary results
Out of the 21 cover crops tested in the greenhouse, 18 crops [Alfalfa (cv. Bullseye), Balansa clover, Berseem clover, Winter camelina (Joelle), Faba beans (Petite and VNS), Flax, Forage oat, Japanese millet, Brown mustard (Kodiak), White mustard (Master), Daikon radish (Eco-Till), Oilseed radishes (Image, Concorde, and Control), Pennycress, Sunn hemp, and White proso millet] did not show any reproduction for the two SCN populations from the fields. As expected, two common rotational crops, Corn (DKC44-13) and Wheat (Glenn) did not support any SCN reproduction. The results indicated that these crops were non-hosts of SCN. Two cover crops, Chickling vetch and Crambe (Belann) showed limited reproduction with average numbers of white females from 5 to 13 for the SCN population from Cass County and from 1-3 for the population from Richland County, suggesting they were poor-hosts. However, one cover crop, White lupine showed considerable reproduction with 177 white females when tested with the SCN population from Cass County and 60 white females with the population from Richland County, suggesting as a suitable host. SCN reproduced less in all the tested crops compared with the susceptible soybean cultivars Barnes and Sheyenne with white females from 560 to 888 and from 450 to 676, respectively.
The results of interaction of three industrial cover crops (Winter camelina, Brown mustard, and Crambe) and SCN have been summarized and presented in a manuscript which has been published in the journal, Industrial Crops and Products. The results of host range of other cover crops to SCN from repeated experiments are being summarized in another manuscript that will be submitted to the journal, Crop Protection. The information on host and non-host cover crops of SCN was also prepared in an extension publication to disseminate the research findings to farmers.
View uploaded report