|RUDOLPH, RACHEL - Washington State University|
|DEVETTER, LISA - Washington State University|
Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2017
Publication Date: 12/15/2017
Citation: Rudolph, R., Zasada, I.A., Devetter, L. 2017. Annual and perennial alleyway cover crops vary in their effects on Pratylenchus penetrans in Pacific Northwest red raspberry (Rubus idaeus). Journal of Nematology. 49(4):446-456.
Interpretive Summary: Cover crops, plants that are planted with our between commercial crops, can provide many benefits to agricultural systems, such as lessening soil erosion. In raspberry production in the Pacific Northwest of the U.S. cover crops are not commonly planted between raspberry plants. Growers are concerned about competition between cover crops and raspberry plants, as well as the chance that cover crops may increase population densities of the economically-important root lesion nematodes. Root lesion nematodes are microscopic soil worms that attack raspberry plants and cause significant loss in yield to this crop. Raspberry farmers face an enormous problem because they lack effective ways of reducing the numbers of root lesion nematodes. This research was conducted to determine if cover crops can be grown between raspberry plants without increasing root lesion nematode populations. Results indicate that cover crops do not make a root lesion nematode problem in raspberry worse. In addition, several cover crops that were very poor hosts for the nematode were identified. These findings will help guide growers in choosing and implementing cover crops into the raspberry production system.
Technical Abstract: Cover crop use is not common in established red raspberry (Rubus idaeus) fields in the Pacific Northwest. Raspberry growers are concerned about resource competition between the cover crop and raspberry crop, as well as increasing population densities of the plant-parasitic nematode Pratylenchus penetrans, which has a wide host range and has been shown to reduce raspberry plant vigor and yield. A two-year study was conducted in an established ’Meeker’ raspberry field in northwest Washington to evaluate the effects of nine alleyway cover crops, mowed weed cover, and the industry standard of bare cultivated soil on P. penetrans population dynamics, raspberry yield, and fruit quality. The host status for P. penetrans of cover crops included in the field experiment, as well as Brassica juncea ‘Pacific Gold’ and Sinapis alba ‘Ida Gold’, was also evaluated in greenhouse experiments. In the field experiment, P. penetrans population densities did not increase in alleyway cover crop roots over time or in alleyway soil surrounding cover crop roots (means range from 0 to 116 P. penetrans/100 g of soil) compared to the bare cultivated control (means range from 2 to 55 P. penetrans/100 g of soil). Pratylenchus penetrans populations did not increase over time in raspberry grown adjacent to alleyways with cover crops (means range from 1,081 to 6,120 P. penetrans/g of root) compared to those grown adjacent to bare cultivated soil alleyways (means range from 2,391 to 5,536 P. penetrans/g of root). Raspberry grown adjacent to bare cultivated soil did not have significantly higher yield or fruit quality than raspberry grown adjacent to cover crops in either year of the experiment. In the greenhouse experiments, ‘Norwest 553’ wheat and a perennial ryegrass mix were poor hosts for P. penetrans while ‘Nora’ and ‘TAM 606’ oat and ‘Pacific Gold’ and ‘Ida Gold’ mustard were good hosts. These results support the idea that the potential benefits of alleyway cover crops outweigh the potential risk of increasing P. penetrans population densities and do not compromise raspberry yield.