Weed management
There are few post-emergent herbicides for broad-leaf weed control in common vetch crops. As many broad-leaf weeds as possible should therefore be controlled, prior to crop emergence. There is also nil tolerance to cereals in many high value common vetch markets.
The majority of growers use either a Diuron/Trifluralin mix or Spinnaker. Spinnaker is preferred when sowing into very heavy stubble where Trifluralin is less effective.
When choosing herbicides consider crops that will follow common vetch within the rotation. Canola and many summer crops may be affected by residual Spinnaker and the continuous use of Trifluralin in both cereal and common vetch crops increases the risk of developing herbicide resistant weeds.
Lifters used during harvest can dig into wheel ruts left by spraying vehicles so avoid spraying when the soil is very wet and use low-pressure tyres.
Recommended Herbicides for common vetch
Croptopping
Common vetch is very well suited to croptopping to reduce ryegrass seed set. The canopy of vetches often collapses prior to the ryegrass flowering, leaving the ryegrass heads above the common vetch crop making chemical application of contact herbicides particularly effective.
Croptopping also allows for earlier harvest of the common vetch because it desiccates the crop and brings on an even maturity.
The correct timing for croptopping vetches is when 75 percent of the lower pods are yellow-brown and the seed has started to harden. The tips of the plants and upper pods will be green. Alternatively aim for when the top third of the ryegrass seed head is at soft to hard dough and the heads will have started to change from green to yellow. Desiccating the common vetch crop too early will result in smaller seeds, reduced yield and increased proportion of immature seeds in the sample. A common chemical used is 600-800 mL/ha of Gramoxone250. Higher rates (800-1000 mL/ha) of Gramoxone 250 have been known to reduce the seed set of Wild Radish.
The common vetch crop will be ready to harvest a very short time after croptopping; in some cases 1-3 days. Consideration must be given to the withholding period of chemical used in this process.
