Listen to the program above for Hanson’s tips and points for growers.
As more weed species show resistance to glyphosate in orchards and vineyards, almond growers should focus on a resistance management weed control program that blends pre- and postemergent control for winter weeds and, where necessary, consider sequential applications to extend pre-emergent control to summer grasses.
UC Cooperative Extension weed specialist Dr. Brad Hanson said that managing for herbicide-resistant weeds requires monitoring and record-keeping to understand weed history in the orchard, rotating among multiple modes of action and, where necessary, thinking differently about applications to get residual control with pre-emergents through the summer.
“A lot of the issues with glyphosate resistance in almonds and other tree crops the last few years have been focused on winter weeds like horseweed, fleabane and ryegrass,” Dr. Hanson said. “But in recent years, we are also seeing more issues with summer grasses like junglerice.
“Lately, the discussion has revolved around using existing weed management tools in a different way without increasing herbicide load and cost to address this new reality.”
Almond growers have excellent broad-spectrum pre-emergent tools to control the winter weed spectrum. Hanson said tank-mixing different classes of chemistry for winter weeds is a very good strategy to broaden the weed control spectrum, but does not necessarily enhance duration of the application’s efficacy. Applying higher rates of broad-spectrum pre-emergents in fall can enhance residual duration, but is not necessarily the most cost-effective and environmentally sustainable approach.
Read the full article on the Almonds.com website.