Features Cereals
Taming the wild ones

Like death and taxes, wild oats can’t be avoided. The weed is widespread across the Prairies, highly competitive and causes approximately $500 million in annual losses. For tame oat growers, they are especially problematic since no herbicide options exist for the control of wild oats in a tame oat crop.

“The inability of oat growers to use in-crop herbicides means growers face challenges when it comes to managing wild oats,” says Brianna Senetza, who conducted her M.Sc. research at the University of Saskatchewan’s Plant Science Department under the supervision of professor Chris Willenborg and in collaboration with research scientist Bill May with Agriculture and Agri-Food Canada at Indian Head.

Senetza investigated two alternative methods for controlling wild oats in a tame oat crop. The objective was to determine the potential of utilizing inter-row spraying and weed wicking of non-selective herbicides for wild oat management. Funding was provided by the Saskatchewan Agriculture Development Fund and Western Grains Research Foundation.

Inter-row spraying uses shielded spray nozzles to apply herbicides between the crop rows. Senetza says the shields are shaped like canoes and help push the crop aside and out of the way so the spray is precisely applied to the weeds between the crop rows.

Weed wicking works to control weeds that are taller than the crop. A herbicide is brushed onto the taller weeds, leaving the crop untouched.

“We were able to use weed wicking as a strategy because wild oats typically grow taller than tame oats,” says Senetza.

The research was carried out over two years at U of S Kernen and Goodale research farms and AAFC Melfort, Sask. Camden oats were seeded at 30 plants per square foot (300 plants/m2), and the plots were supplemented with wild oats.

Inter-row spraying controlled weeds between seed rows.
Photos by Brianna Senetza.

Thirteen herbicide treatments were applied with four replications. Wicking treatments were done using glyphosate at 0.45 litres per acre (600 g ai/ha). Inter-row spraying used glufosinate at 1.62 l/ac. (600 g ai/ha) plus clethodim at 76 ml/ac. (45 g ai/ha).

Application timing for both methods was at the four-, six- and flag-leaf stages, four-leaf + flag-leaf, six-leaf + flag-leaf and four- + six-leaf stages. These treatments were applied as inter-row alone, wicking alone or dual inter-row and wicking treatments.

Plant counts were done two to three weeks after emergence, and phytotoxicity ratings for the crop and wild oats were done at seven to 10 days and 21 to 24 days after treatment. Yield, wild oat percentage, thousand kernel weight, test weight and percentage of plump grains were measured. Analysis of the treatments found there were no significant differences in oat yield, thousand kernel weight and test weight. Conversely, the percentage of wild oats and wild oat biomass weight were significantly lower, and plump kernels were significantly higher for some treatments.

“When I look at yield, although we expected to see differences with better wild oat control, the proportion of wild oats in the plots was really high at 34 per cent in some cases and could explain the reason for no differences in yield,” says Senetza. “But you can look at it another way and see that there was no spray damage to the crop that affected yield, so that is a positive finding.”

The poorest wild oat control occurred with the four-leaf wick and flag-leaf wick treatments. The best wild oat control occurred when dual inter-row and wick treatments were conducted at the four- + six-leaf stages and the six- + flag-leaf stages.

The treatments with the best wild oat control, along with the six-leaf inter-row plus wick treatment, also had the highest percentage of plump seed – which can mean a premium for better grain quality.

Senetza says the research helped to narrow down application methods and treatment timing. The four-leaf wick simply didn’t work because the wild oats were the same height as the tame oats so they couldn’t be wicked.

“Overall, the combination of inter-row spray plus wicking worked better together to control wild oats. The inter-row controlled wild oats between the seed rows while the wick followed up and controlled wild oats that emerged and grew in the seed rows,” says Senetza. “Both show promise and could potentially be used for wild oat control in tame oat.”