Organic Control of Perennial Weeds with Vinegar and Biologicals

Organic Control of Perennial Weeds with Vinegar and Biologicals

Summary

All four participants realized some successes in 2011 controlling four common noxious weeds – whitetop, Canada thistle, leafy spurge and bindweed. Participants are attempting this noxious weed control solely through organic methods; the use of biological controls, spray-applied 15-20% vinegar and competing crops.

Objectives/Performance Targets

The goal for the first year of this project was for each participant to begin applying their chosen use of control on the weeds of concern. The vinegar spray treatments were expected to have the most immediate effect, and the biological controls and cropping management are expected to take several years to provide a noticeable effect on noxious weed populations.

Accomplishments/Milestones

Three participants had very good results from the plant burn-down from the vinegar application. They all did note that several applications were needed to control newly sprouting weeds after each treatment.

In 2011, these participants made three applications of vinegar to maintain control on bindweed, knapweed and Canada thistle. One participant seeded 65 acres of alfalfa in an effort to provide some competition to Canada thistle growing in a cropped field. He noted that the alfalfa came up well, and, after swathing the field twice this year, the thistle patches already seemed to be shrinking in size.

Insect releases were completed by three participants on Canada thistle, and one participant completed the releases on leafy spurge. Participants did note in several cases where the insects had an impact on weed growth and the ability of the weeds to propogate themselves immediately this year, but it will take several years before the participants will be able to determine if the insect populations will establish at a level significant enough to control that targeted weed.

One participant is still planning to release insects in 2012 on bindweed to determine their effectiveness as a weed control strategy for this weed. In 2011, the particular insect sought for this purpose was not available.

• Alfalfa seeding germinating in Canada thistle patch
• Result of 1 vinegar treatment on whitetop; July 2, 2011
• Result of second vinegar application on Spotted knapweed

Impacts and Contributions/Outcomes

All four participants in this project had encouraging results in their first year of attempting noxious weed control through cultural, biological and organic spraying means. The vinegar spray treatments had the most dramatic and immediate effects, but they were noted to be very time-consuming and labor-intensive due to the need for repeat applications. The cultural and bioligical controls enjoyed some success as well this firat year, but the jury will be out for some time on these techniques, as the participants learn where and how to use them to their best advantage and then allow time for these techniques to take full effect. The first year treatment certainly shows that noxious weed control can be accomplishd with much less reliance on commercial chemical alternatives. Over the next two years, the impact of the cultural practices should become more evident.

Collaborators: