Pre-harvest Glyphosate On Cereal Crops

Several glyphosate products are registered for pre-harvest application in barley, oats and wheat.

Advantages

The advantage of using pre-harvest glyphosate on cereal crops is that it gives you another option to control some of the more difficult weeds, particularly perennial weeds such as quackgrass (twitchgrass), Canada thistle, sow thistle and dandelions. The long term control on some weeds, such as sow thistle and milkweed, will be successful when applied during the early-bud to flowering stage. In addition to helping with weed control for the following year, pre-harvest glyphosate can also improve harvest conditions in fields with a lot of weed pressure.

When To Apply

Glyphosate should be applied when the crop is 30% grain moisture or less. In cereals, this is at the hard dough stage, when you can only leave a thumbnail impression on the seed. Apply at least 7 days prior to harvest and use ground application only. The application period of 7-to-14 days before harvest ensures the best weed control and maximizes harvest management benefits. Earlier applications (greater than 14 days prior to harvest) may reduce crop yield and /or quality.

Cautions

Glyphosate products are not registered for any crops if grown for seed production because glyphosate applied under the wrong conditions may reduce seed germination. Malting barley standards require at least 95% germination. Therefore, unless it is really necessary, avoid applying glyphosate on barley intended for malting to reduce the risk of not making malting barley grade.

Strawberry growers should not use straw for mulch if pre-harvest glyphosate was applied, because there may be potential glyphosate activity on the strawberry plants.

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