Evaluating Mustard Seed Meal for Weed Control and Crop Yield In California Strawberry Production

The loss of methyl bromide (MB) has created a need to develop and evaluate management tools for the control of soil borne pests for California (CA) strawberry growers. Although alternative fumigants are registered for use in CA strawberries, they face a multitude of regulatory constraints that make the use of these products difficult. Hence there is a need to evaluate alternative products that do not involve fumigant use. In the past few decades, several studies have evaluated the efficacy of plant-derived allelochemicals that are produced from glucosinolates for weed and pathogen suppression. More recently, potential has been found for dehydrated plant tissues and glucosinolate containing mustard meal pellets to suppress weeds and pathogens. A study was initiated in Oct. 2009 at Salinas, CA, to evaluate the effects of mustard seed meal (MSM) derived from white mustard (Sinapis alba L.) on weed control and fruit yield in commercial strawberry production systems. The study included six treatments applied once, pre-plant, with four single bed replicates in a randomized complete block design. Each bed was 1.3 m wide by 19.8 m long. Treatments were MSM at 560, 1120, 2240, and 4480 kg^.ha^-1, methyl bromide:chloropicrin (MBPic 67/33% v/v) at 392 kg^.ha^-1, and an untreated control. MSM treatments were applied with a fertilizer applicator by shanking into the soil up to a depth of 15 cm. MBPic was applied through the drip system. Strawberry ‘Albion’ was planted on 24 Nov. 2009. Weed density, weed fresh biomass and hand weeding times were periodically recorded through the growing season. Weed data collected and analyzed indicates that regardless of the dosage, MSM treatments did not control weeds. None of the treatments injured strawberry plants. Crop plant diameter rating collected on 15 Mar. 2010 indicated that the strawberry plants grew most vigorously in the MBPic plots, but those treated with MSM treatments at 1120, 2240 and 4480 kg^.ha^-1 were almost as vigorous. Berries were harvested from 29 Mar. through 18 Oct. 2010. There was a dose response from the MSM treatments on strawberry yield, with yield being the highest in MSM treatment at 4480 kg^.ha^-1. However yield from MSM treatment at 4480 kg^.ha^-1 was not as good as in MBPic treatment. Results from this study imply that MSM will need to be integrated with other tools to effectively replace MBPic fumigation.