Whether undercutting or direct harvesting edible beans, a pre-harvest application of a desiccant can allow for a quicker harvest, while protecting yield and quality.
Proper desiccation timing is critical for maximizing the crop’s potential, explains Calem Alexander, field marketer with Hensall Co-op, in this Edible Bean School episode focused on setting the crop up for harvest.
“We’re looking for overall maturity in the plant, 80 to 90 per cent leaf drop, you want to see about 90 per cent of the pods change to that yellow, buckskin-type colour, and in the pod, you want to make sure 90 per cent don’t have green left in the meat of the bean, and it’s turned white inside,” he explains, standing in a field of navy beans near Miami, Manitoba.
As for which product to use, always consult your buyer to find out which chemistries are eligible, Alexander emphasizes. Glyphosate, for example, is no longer an option for most buyers.
“One of the most widely-used and common products available for a pre-harvest desiccant is saflufenacil,” he notes. “It’s a great product for doing a fall dry-down in dry beans.”
Saflufenacil, which is a contact herbicide, is sold under several different names, depending on geography — it’s known as Heat in Western Canada, Eragon in Ontario, and Sharpen in the U.S.
“There are a few things we can do to make it work better. Proper timing being the first one. Use lots of water — we’re shooting for 20 gallons per acre. Spraying during the heat of the day will improve its efficacy, and use of a deposition aid like Interlock will always help out the job as well,” explains Alexander.
BASF, the manufacturer of Heat and Eragon, also suggests avoiding applications when it’s hazy or smoky, as has been the case for extended periods in western bean growing areas this season.
Desiccation timing can also be complicated by extraordinary growing conditions. In Ontario, there are reports of pods nearing maturity while plants still have plenty of green leaves, likely due to ample moisture. It’s a different story in Western Canada and the Northern Plains, where extreme heat and drought stress have resulted in variable in-field maturity.
“The parts of the field where the plants had a little better life cycle are maturing normally and look good, but the areas of the field that were more stressed are staying greener a little longer,” notes Alexander. “Ideally, you want to shoot for the middle ground and hit the majority of the field at the right timing.”