CROP ADVISOR’S SOLUTION SOLVED — OUT-OF-C0NTROL FOXTAIL BARLEY
When I talked to Darcy in the fall of 2008, he had spent three years fighting a losing battle with foxtail barley in the southwest corner of Manitoba. Despite pre-seed burn-off and both pre-season and post-harvest glyphosate applications, the weed just seemed to be gaining strength and territory.
With his yield at risk, Darcy was understandably feeling tense and in need of a solution. He was looking for the magical year-round control for his foxtail barley.
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The fact that increasing glyphosate rates only offered moderate improvement and allowed the affected areas to expand really got my goat. Scott, our area marketing rep, and I went back to the drawing board and went through the post-harvest herbicide options again.
We finally stumbled upon a product called Assure II from DuPont. Although it’s not registered for foxtail barley control, many growers find it to be a good control option in a variety of crops, including flax and canola.
In fact, since there are no recropping restrictions, some growers have used it as a post-harvest herbicide in combination with a one-litre-per-acre equivalent of glyphosate, with positive results. After consulting with the local DuPont rep, we decided it was our best option.
We called Darcy with the news that minute. He applied the product last fall post-harvest. It was a long winter, as Darcy prepared for spring and we both wondered what we’d find the following season.
Amazingly, the level of foxtail barley control met and exceeded our expectations. The perennial foxtail barley control was near 100 per cent. As well, seedling control was maintained by conventional in-crop herbicides once the perennial problem was fixed.
Darcy felt pretty good when we looked at an adjacent field where glyphosate and surfactant were used post-harvest in an attempt to control the foxtail barley. The grim situation there was similar to what Darcy had dealt with in the past. Really, the cost involved in going with the Assure plus glyphosate blend was quite reasonable based on the control he had achieved.
When you’re dealing with something as aggressive as foxtail barley, tillage is just not the answer, and you can only expect marginal control with glyphosate alone on perennial foxtail barley.
It was another lesson learned for me. You’ve got to keep up with your research and learn about new products as they appear.
Marty Logan is a crop inputs manager with Richardson International in Brandon, Man.
CROP ADVISOR’S CASEBOOK WHAT IS CUPPING THIS CANOLA?
Dave called me at the beginning of June from his farm near Lumsden, Sask. He farms 3,200 acres of wheat, canola, peas and barley. On a regular cruise past his fields, he noticed patches in his canola.
When Dave pulled over and headed into the field to take a closer look, he noticed the leaves didn’t look quite right.
“The leaves seem to be cupping. They’re even turning purple around the edges and backsides of the leaves,” Dave said. “I’m wondering if I’ve got some herbicide residue in the soil doing this to my canola.”
I made my way out to Dave’s the following day and he led me to the canola in question. Most of the canola plants were in the three-to five-leaf stage. Just as he’d described, there were patches in parts of the field that showed leaf cupping and some were purple. These patches were irregularly shaped and seemed to be in areas where there were sandy soils, particularly in knolls.
Dave’s suspicions could be true. It was possible that we were looking at the effects of Group 2 herbicide carry-over from two years ago. Herbicide carry-over is affected by different soil types, organic matter and slope in the field, which could explain the patches. It could also be some sort of nutrient deficiency, even though Dave felt he had fertilized the crop well. I also suspected too much seed-placed fertilizer may be causing stress on the canola seedlings.
We eliminated these possibilities one by one. We’d had adequate rainfall the previous year, which would have helped to break down possible chemical residue in the soil. There were no signs of the sprayer overlapping either, which could have caused a double rate. And when I thought about it again, the leaf cupping was not typical of Group 2 chemical injury either.
I asked Dave about his fertilizer application. He said he’d used nitrogen, phosphorus, and sulphur according to soil test lab recommendations. It sounded good so I didn’t suspect a nutrient deficiency, unless a micronutrient was lacking. Dave said he only seed places phosphorus with his canola, so it was unlikely that he would have had any seedling injury considering how wet the spring was.
Still, there was something about that fertilizer program that made me think we were close to a culprit.
What’s the problem with Dave’s canola? Send your diagnosis to COUNTRY GUIDE, Box 9800, Winnipeg, Man, R3C 3K7; email [email protected]; or fax 204-947-9136 c/o Krista Simonson.
Correct answers will be pooled and one winner will be drawn for a chance to win a COUNTRY GUIDE cap and a one-year subscription to the magazine. The correct answer, along with the reasoning which solves the mystery, will appear in the next Crop Advisor’s Solution File.
