2019 ASHS Annual Conference

Broadleaf weeds, nutsedge, and plant-parasitic nematodes (PPN) can negatively affect strawberry yield in Florida. In organic production systems management of these pests requires that the primary management techniques should be preventive and cultural practices. Cover crops have been shown to be useful for suppressing weeds and PPN, while promoting soil health. Additionally, leguminous cover crops can serve as a nitrogen source for the strawberry crop. A field experiment was conducted between 2016 and 2018 to evaluate the effect of off-season cover crops on soil health, weed suppression and PPN densities in organic strawberry production in Florida. Sunn hemp (Crotalaria juncea, cv. Tropic Sun), hairy indigo (Indigofera hirsuta), and a four-way mix (sunn hemp cv. AU Golden, hairy indigo, Crotalaria ochroleuca, and Aeschynomene americana) were compared to a weedy control during the summer of each year. Following the cover crop treatments, four strawberry cultivars were established for evaluation in October of each year. A split plot design was used with cover crops in the main plots arranged in a randomized complete design with 4 replications and strawberry cultivars were assigned to the sub-plots. Data were collected on photosynthetically active radiation penetrating the cover crop canopy, leaf area index, cover crop biomass soil health score and PPN populations. Weed density and biomass were assessed during the cover crop and the strawberry crop. In 2016, sunn hemp resulted in 22% higher biomass than hairy indigo and the 4-way mix. In 2017, there was no difference biomass production among the cover crop treatments, while in 2018 the 4-way mix resulted in the highest biomass compared to the rest of the treatments. There was no effect of the cover crop on soil health score, cover crop leaf area index, PPN populations, broadleaf, sedge and total weed density. However, cover crops reduced broadleaf weed biomass by 70% compared to the weedy control. This biomass reduction may be linked to light competition between the cover crop and the weeds as cover crops reduced light penetration through their canopies by 50%, on average, across the three years of the study. Longer than three years of cover crop use may be needed to impact soil health. The cover crops were selected for their reported resistance to sting and root-knot nematodes to which strawberry plants are susceptible. Future assessment of efficacy against PPN will be undertaken in a field with these PPN, which were absent from this site.