ARS | Publication request: Integration of brassicaceous seed meals into red raspberry production systems

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 29, 2012
Publication Date: December 17, 2012
Citation: Gigot, J., Zasada, I.A., Walters, T.W. 2012. Integration of brassicaceous seed meals into red raspberry production systems. Applied Soil Ecology. 64:23-31.

Interpretive Summary: Soilborne pathogens, including microscopic plant-parasitic nematodes and the water mold Phytophthora, cause significant loss in yield to raspberry annually. Raspberry farmers lack effective and long-term ways of reducing numbers of these organisms in production fields. This research was conducted to evaluate brassica seed meals as a practice to manage these soil borne pathogens. Brassica seed meals are the byproduct of the biofuel and food industries oil extraction process and may increase in availability as these industries expand. Two brassica seed meals, yellow and white, were tested against soil borne pathogens in laboratory, greenhouse, and field experiments. Yellow mustard seed meal reduced populations of both pathogens at lower rates than that of white mustard. Combining brassica seed meals soil solarization, the passive heating of soil, improved soilborne pathogen suppression over seed meals applied alone. These results are significant because a soilborne management practice other than the normal practice of soil fumigation has been identified. This research will be used by scientists and farms to manage plant-parasitic nematodes and Phytophthora in commercial raspberry fields.

Technical Abstract: Brassicaceous seed meals are an alternative to synthetic chemical fumigation for the pre-plant soil management of soil borne organisms. Greenhouse, microplot, and field experiments were conducted to evaluate the effect of Brassica juncea and Sinapis alba seed meals on raspberry (Rubus idaeus) soil systems and against the oomycete pathogen Phytophthora rubi and the plant-parasitic nematode Pratylenchus penetrans, both chronic problems in these production systems. Phytotoxicity to raspberry, as well as the effect of brassicaceous seed meals on non-target soil organisms were investigated. In greenhouse studies, P. rubi and P. penetrans were effectively suppressed by B. juncea and S. alba seed meals at rates of 0.5 and 1.0%, respectively. In field experiments using buried bags of P. rubi inoculum, suppression of P. rubi by B. juncea and S. alba seed meals was enhanced with solarization, however only to a depth of 15 cm and only when target heat units in soil (222 hours > 29 °C) accumulated. In microplot studies, soils from two different raspberry fields were amended with B. juncea at 0.5% or S. alba at 1.0% seed meals; nematode community abundance and composition were evaluated over time. Both seed meal type and soil affected nematode community abundance and composition. Brassica juncea seed meal eliminated all nematodes, including P. penetrans, in both soils one week after application and this seed meal increased the overall enrichment index (EI) at five weeks. Sinapis alba seed meal reduced nematode population densities at one week after application, and increased the structure index (SI) at five weeks. In a greenhouse trial, phytotoxicity (> 40% plant damage) to raspberry ‘Meeker’ was observed one week after the application of S. alba seed meal at 1.0% only and did not extend beyond one week. A combination of field and greenhouse experiments demonstrated that brassicaceous seed meals have the potential to effectively reduce populations of P. rubi and P. penetrans, two important pests of raspberry.