Project Details:

Title:
Screening Cover Crops to Reduce Soybean Cyst Nematode and Other Nematodes in Infested Soils

Parent Project: Screening Cover Crops to Reduce Soybean Cyst Nematode in Infested Field
Checkoff Organization:North Dakota Soybean Council
Categories:Nematodes, Crop management systems
Organization Project Code:QSSB
Project Year:2020
Lead Principal Investigator:Guiping Yan (North Dakota State University)
Co-Principal Investigators:
Keywords:

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Soybean cyst nematode is an important soil-borne disease of soybean in North Dakota (ND) and can cause 15-30% yield loss without causing obvious above-ground symptoms. Managing SCN becomes crucial to reduce economic losses for farmers. Cover crops may provide an alternative means to manage SCN. In 2016 and 2017, we screened 21 cover crops for their abilities to host SCN and reduce SCN populations. However, some other important cover crops such as oilseed radish and white mustard were not tested in ND for suppressing SCN. Other vermiform (motile) plant-parasitic nematodes were reported from soybean fields in ND, but the effects of cover crops on these nematodes are unknown. With the funding support from the ND Soybean Council in 2018, we started testing additional 20 entries of cover crops that were not included in our previous experiments. In this proposal, we propose to conduct the second year of the research to continue screening these additional entries of cover crops that are being used or will likely be introduced to ND. The goal of this research will confirm the host status of the cover crops to SCN and validate whether these cover crops are capable of reducing numbers of SCN and other plant-parasitic nematodes in infested fields. The proposed research findings will be useful to navigate the selection and use of cover crops for farmers and the new sources that should be introduced to ND for reducing the damage caused by SCN and other plant-parasitic nematodes to increase soybean yield.

Project Objectives

Screen additional cover crops to reduce populations of SCN and other plantparasitic nematodes in infested fields. Twenty entries of cover crops that are being used or will be likely introduced to North Dakota will be evaluated for their hosting abilities (resistance or susceptibility) to SCN. Ten cover crops will be selected for evaluating their effects on reducing SCN and vermiform (motile) plant-parasitic nematodes in infested soils.

Project Deliverables

Twenty entries of cover crops will be evaluated under controlled greenhouse conditions for their hosting abilities to SCN and ten of them will be evaluated in the microplot experiments maintained at the outdoor field conditions for their effects on reducing SCN and vermiform plant-parasitic nematodes. The rankings of cover crops on hosting abilities and on reducing SCN and other nematode numbers will be summarized and disclosed.

Progress of Work

Updated November 30, 2019:
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.

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Final Project Results

Updated June 30, 2020:

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SCREENING COVER CROPS FOR MANAGING SOYBEAN CYST NEMATODE AND OTHER NEMATODES IN INFESTED SOILS

EXECUTIVE SUMMARY

NORTH DAKOTA SOYBEAN COUNCIL
JUNE 2020

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

Research Conducted
Twenty-five entries including 21 cover crops and species, corn and wheat as rotational crops, and two susceptible soybean cultivars were evaluated for host range in a growth chamber with two SCN populations from two soybean fields in ND. Ten cover crops were further evaluated in microplot experiments. Crops were planted in pots each containing 5 kg of infested field soil. After 75 days of growth, soil samples were collected from each pot. SCN eggs and other plant-parasitic nematodes were extracted and counted for evaluation of each crop for population reduction.

Why the research is important to ND soybean farmers
SCN is one of the major yield-reducing pests of soybean in 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, an integrated management strategy is necessary for sustainable management of SCN. Cover crops may reduce plant-parasitic nematode populations and provide an alternative means to manage SCN.

Final findings of the research
Eighteen entries (Alfalfa, Balansa clover, Berseem clover, Brown mustard, Daikon radish, Faba beans, Flax, Forage oat, Japanese millet, Oilseed radishes (Concorde, Control and Image), Pennycress, Sunnhemp, White mustard, White proso millet, Winter camelina) did not support any SCN reproduction, suggesting non-hosts. Chickling vetch and Crambe showed low reproduction as poor-hosts while White lupine showed some reproduction, suggesting a suitable host. SCN reproduced less in all tested crops compared to two susceptible soybean cultivars. All ten cover crops significantly reduced the population of SCN 103 compared to non-planted natural soil (fallow) whereas only Sunnhemp significantly reduced the population of SCN 2W . Sunnhemp, Alfalfa, Oilseed radishes, Daikon radish, and Faba bean (Petite) were more effective than others for population reduction. None of the crops significantly reduced populations of other nematodes in infested soil.

Benefits/Recommendations to North Dakota soybean farmers and industry
Eighteen cover crops and species were identified as non-hosts for SCN. All ten cover crops tested in microplot conditions were able to suppress two SCN populations from two different fields of North Dakota. These crops have the potential to be used as cover crops or rotational crops in infested fields to reduce SCN numbers. The research findings will be useful to navigate the selection and use of cover crops for farmers to reduce SCN damage to increase soybean yield in infested fields.

Benefit to Soybean Farmers

Soybean cyst nematode (SCN) is a very important soil-borne disease for soybean production in North Dakota (ND) and can cause 15-30% yield loss without obvious above-ground symptoms. Managing SCN becomes crucial to reduce economic losses for farmers. Crop rotation and cultivar resistance are the major farming practices for control of SCN. However, crop rotation does not allow soybean growers to produce sufficient soybean every year. Resistant varieties could be short-lived because SCN is adapting to these and new virulent forms can develop and overcome the existing resistance genes. With the use of cover crops for improving soil health in ND, farmers are asking if cover crops can be used to reduce SCN populations in ND.
Cover crops may provide an alternative means to manage SCN. There are multiple mechanisms by which cover crops could reduce the SCN pressure. Cover crops such as radish, mustard and rapeseed can release compounds called glucosinolates and act as a biofumigant that can kill live nematodes when incorporated into soil. Some cover crops encourage SCN eggs to hatch. The hatched juveniles then would starve due to the absence of a host crop upon which to feed. Cover crops may serve as a trap crop for SCN. French marigold is a well-known example serving as a trap crop for controlling root-knot nematode (Tylka, 2014). Oil seed radish has been effective in reducing populations of sugar beet cyst nematode by 80 to 90% and improving sugar beet yields in Michigan (Poindexter, 2011). Reduction of sugar beet cyst nematode was also observed by using white mustard trap plants (Hemayati et al., 2017). However, the effectiveness
using cover crops to control SCN is not well studied.

In 2016 and 2017, we screened 21 cover crops for their abilities to host SCN and to reduce SCN populations. However, some other cover crops such as oilseed radish, white mustard, forage type faba bean, oat, flax, and alfalfa that are being used or will be likely introduced to ND were not included in these tests. Oilseed radish was reported to be very effective for suppressing SCN in European trials (Image Radish Page), but the seed was not available upon request in our previous experiments. Other plant-parasitic nematodes such as root-lesion, spiral and stunt nematodes (Yan et al., 2017a, b, c) were reported from soybean fields in ND, but the effects of cover crops on these nematode species are unknown.

With the funding support from the ND Soybean Council in 2018, we started testing additional 20 entries of cover crops that were not included in our previous study to determine their abilities to host SCN and to reduce populations of SCN and other plant-parasitic nematodes. In cooperation with extension agronomists and plant pathologists, we propose to conduct the second year of the research to continue screening these cover crops that are being used or will likely be introduced to ND. The goal of this research will confirm the host status of cover crops to SCN and whether these cover crops are capable of reducing numbers of SCN and other plantparasitic nematodes in infested fields. The proposed research findings will be useful to navigate the selection and use of different cover crops for farmers and the new sources that should be introduced to ND. Such information is important to help farmers make the best management strategies for reducing damage caused by SCN and other nematodes to increase soybean yield.

Performance Metrics

Progress in this research is measured by the number of cover crops that can be screened for
hosting abilities and for reducing numbers of SCN and other plant-parasitic nematodes. Some cover crops may reduce the population densities of SCN and other nematodes in ND. But the magnitude and consistency of the effects may vary among crop species and varieties. The best performing cover crops that are non-host of SCN and have great reductions on SCN and other nematode populations will be identified and recommended to soybean farmers.

Project Years