Brassicaceous seed meal, root removal, and chemical fumigation vary in their effects on soil quality parameters and Pratylenchus penetrans in a replanted floricane raspberry production system

Authors: RUDOLPH, RACHEL - Washington State University; Zasada, Inga; Hesse, Cedar; DEVETTER, LISA - Washington State University

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2018
Publication Date: 9/22/2018
Citation: Rudolph, R.E., Zasada, I.A., Hesse, C.N., Devetter, L.W. 2018. Brassicaceous seed meal, root removal, and chemical fumigation vary in their effects on soil quality parameters and Pratylenchus penetrans in a replanted floricane raspberry production system. Applied Soil Ecology. 113:44-51. https://doi.org/10.1016/j.apsoil.2018.08.024.
DOI: https://doi.org/10.1016/j.apsoil.2018.08.024

Interpretive Summary: 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 when planting a new crop. This research was conducted to identify chemical and nonchemical methods, including the meal by-product of brassica seeds, the removal of old root material from the field, and an alternative soil fumigant, to manage the root lesion nematode in raspberry. Results demonstrated that the nonchemical methods did not reduce numbers of root lesion nematodes in newly planted raspberry. The alternative soil fumigant evaluated in this study provided excellent control of root lesion nematode. Additionally, there were no negative effects of the management methods on raspberry yield or quality. These findings will help guide growers in ways to improve current management practices targeting root lesion nematodes.

Technical Abstract: A decline in red raspberry (Rubus idaeus) crop longevity has been partially attributed to parasitism by Pratylenchus penetrans. It is the most common plant-parasitic nematode in Washington red raspberry production systems. A three-year study was conducted in a replanted commercial red raspberry field with a history of P. penetrans to evaluate brassicaceous seed meal (BSM) soil amendment combined with root inoculum removal (RR) as preplant alternatives to traditional soil fumigation with 1,3-D and chloropicrin. Additionally, the fumigant metam sodium at full and half rates with root removal were evaluated. Treatments were applied once prior to planting and included: BSM at 3.4 t ha-1 with RR, full rate metam sodium (692 L ha-1; Max Fum) with RR, half rate metam sodium with RR (Min Fum), and full rate metam sodium without RR (Max Fum–RR; control). Data collected included: P. penetrans population dynamics in soil and raspberry roots, microbial (bacterial and fungal) commun-ities in soil, raspberry vegetative growth, estimated yield, and fruit total soluble solids (TSS) concentration. Population densities of P. penetrans in soil and roots were significantly higher in BSM (983 to 4,801 P. penetrans g-1 of root) than in Max Fum and Max Fum–RR (32 to 802 and 40 to 1,509 P. penetrans g-1 of root, respectively) during the first two years of the study. By the end of the study there were no differences in P. penetrans population densities among the treatments. Root removal did not affect P. penetrans densities as there were no significant differences between Max Fum and Max Fum–RR. Min Fum was more effective than BSM at reducing P. penetrans population densities, but not as effective as Max Fum or Max Fum-RR. BSM did not dramatically alter the soil microbial ecology compared to the other treatments. The only difference among treatments was observed in the first spring after treatment application, when BSM had a soil bacterial community that differed from the other treatments; this difference did not persist into the next sampling date.