Wayne Mitchem- Small Fruits Weed Specialist
If you have not already applied herbicides in your vineyard it is definitely time to get started. I know many grape growers control weeds with multiple applications of postemergence herbicides, leaning heavily on glyphosate. This is not something I recommend as it can lead to several issues and requires consider time and trips.
Multiple yearly applications of glyphosate over several years is how resistant weed populations develop. In addition to concerns about weed resistance, multiple glyphosate applications (3 or more per year) have been link to reduced crop vigor in perennial fruit crops and is actually known to cause internal browning of apples held in cold storage. Beyond the stewardship concerns, total postemergence weed control requires a lot of time and management. Applications have to be timely, to small weeds and with regular rainfall events will need to be applied every three to four weeks.
Using preemergence herbicides in combination with glyphosate and glufosinate (Rely) offers growers the best opportunity for weed control success by mitigating the potential herbicide resistant weed development, maintaining healthy vines, and reducing the number applications during the year so management can focus other facets of grape production whether that be canopy management, disease control, or whatever is pressing.
There are a number of preemergence herbicides registered for use in vineyards. Chateau (flumioxazin), Matrix (rimsulfuron), simazine, Prowl H2O (pendimethalin), and Spartan Charge are all options that have proven to be very effective at providing good preemergence weed control. Growers use several timing options and tank mix combinations of these products to be very successful at controlling summer annual weeds.
To get a complete list of recommended herbicides for vineyards as well as application timing information you can visit https://smallfruits.org/ipm-production-guides/ or the link on the blog to a resent presentation for vineyard weed control.
