Green bean weed control
06:43 (GMT+2), Thu, Thursday, July 21, 2011
Fortunately, there are now several weedkillers available for green beans.
Fortunately, there are now several weedkillers available for green beans. Many aren’t registered for this crop, as the manufacturers would rather play it safe. So many new green bean varieties regularly come onto the market that they’re afraid a new variety might be sensitive to their product, resulting in claims.
The area planted to green beans is relatively small compared to dry beans, so it’s not worthwhile for manufacturers to pursue the green bean market. Farmers who go for products that are only registered for dry beans do so at their own risk.
One of the first really effective and easy-to-apply products for green beans was Dual. Since it was introduced, the formulation has changed many times, and there’s now an array of similar products available, many of which are more potent against a broader range of weeds. It’s worth chatting to your chemical representative about your specific weed problems and the potential risks of various products.
How much to apply?
In trials with the original Dual, I could apply five times the recommended rate in trials on light soils without harming the crop. Some newer versions don’t have quite that safety factor. We do need a bit of safety leeway on a crop which is harvested 60 days after transplant, as any setback will likely lower yield.
The tricky part is being able to control the whole weed spectrum without harming the beans. Most of the registered products are therefore more potent against grass weeds than broad-leafed ones, as beans are broad-leafed. A product called Basagran is registered for beans and will control both broad-leafed weeds and yellow nutsedge (Cyperus esculentus).
I found that at the stage where it would be recommended to apply the product to beans, many of the weeds could still resist it in certain weather. However, hot, dry conditions, especially when the weeds were showing some signs of stress, resulted in less than optimum weed control at the recommended 2â„“/ha to 3â„“/ha.
When conducting my trials, I found that smaller weeds always succumbed to the herbicide. Bearing this in mind, I started to do trials when the beans and weeds were younger. Using flat nozzles (Teejet 8004) and 1â„“/ha, I directed the spray between the rows so that only a little product would touch the beans’ lower leaves.
Contact Bill Kerr on 016 366 0616 or e-mail firstname.lastname@example.org.
Issue date: 8 July 2011
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