What Actually Speeds Up Harvest
If your fields are drying down slower than you'd like this year, you're not imagining it. Cooler nights change how fast every pre-harvest product works, and the three main options don't behave the same way.
THE THREE APPROACHES TO SPEED UP HARVEST
Most pre-harvest passes fall into one of three categories: straight glyphosate, glyphosate plus a Group 14 product, or a true desiccant like diquat.
Glyphosate is the slowest of the three. In good conditions, it takes about 14 days to dry down and kill weeds. If it's cool, plan on closer to three weeks.
Glyphosate plus a Group 14 product moves faster, averaging around 10 days. Cooler weather still stretches that timeline out.
Diquat is the quickest option, usually three to four days, five or six if temperatures drop. It also delivers the strongest weed kill of the three when timed right, though a hot stretch after spraying can have you combining in as little as three days.
The tradeoff: diquat is a true desiccant, not a systemic herbicide. It burns down what it touches but doesn't move through the plant the way glyphosate does, so weed kill can be less complete on some species.
Pre-Harvest Options to Speed up Harvest
NOT EVERY FIELD NEEDS THE SAME ANSWER
Where you farm changes the math. In drier areas, some fields dry down naturally without much help. Further north, or on pivots, green stems can fight you all the way to the bin, and a pre-harvest pass becomes less optional.
COVERAGE MATTERS AS MUCH AS PRODUCT CHOICE
A lot of fields sprayed clean three to four weeks ago are weedy again after this season's rain pushed a second flush of growth. Before you go back in, check two things: your water volume, and whether the product needs a surfactant or adjuvant added to the tank. Diquat specifically needs a non-ionic surfactant to get the leaf coverage a clean kill requires. Talk to your agronomist about rates for whatever you're using, since every product is a little different.
THE BOTTOM LINE
If it's later in the season and you want to speed up harvest, diquat gets you there fastest. Not sure which route fits your fields?
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