Selecting cover crop species for vineyards of the Niagara region

Abstract

Organic viticulture challenges growers to think and act sustainably when managing variables such as weeds, pests, and overall crop production. Ongoing climate change is adding to this challenge with projected increases in extreme weather events such as heavy rainfall and drought. Cover crops can be considered as an ecosystem-based adaptation measure when chosen carefully. They can help growers mitigate effects of climate change as well as increase vineyards biodiversity. Despite their common use, local knowledge of which species work best in what conditions is lacking. Furthermore, species are seldom tested for response to drought and flood conditions in both controlled and operational settings. The first objective of this project was to evaluate the responses of nine different cover crop species to simulated drought and flood conditions under greenhouse-controlled conditions. Of the nine species, Pennisetum glaucum (pearl millet) and Melilotus officinalis (yellow clover) were the only two species to withstand both extreme conditions without being significantly affected. Trifolium alexandrinum (berseem clover), Vicia villosa (hairy vetch), and Trifolium incarnatum (crimson clover) produced higher biomass in saturated condition, while Festuca rubra (red fescue), and Thinopyrum intermedium (pubescent wheatgrass) survived the drought without visual clear symptoms except for puny plants. The second objective was to screen 13 cover crop species in two vineyards under operational settings, where weed pressure, local weather and management may influence species establishment. After the two screening years, Pennisetum glaucum, Trifolium incarnatum, Trifolium repens, Trifolium pratense, Vicia villosa, and Medicago sativa showed promising results in terms of establishment despite facing weather challenges.