Small Grain Harvest Aids

Below is an overview of some options to consider for preharvest weed control in small grains. However, before applying any product, here are a few considerations:

• This may be a great opportunity to control perennial weeds prior to double crop soybean or prior to establishment of a late summer hay crop or covers. Although late summer/early fall is still the best time for perennial weed control, this is certainly better than early summer applications and may help fit into certain crop rotations.
• Don't expect miracles with harvest aids. It is still easier to control smaller weeds (less than 4 inches tall) than larger ones (2-3 feet). In some cases, the lower portions of the weeds may still be green and unaffected.
• It takes time to bring down a large weed. It usually requires about a week or more to obtain good control or dry-down of some weeds. This time may increase if cool/wet weather conditions prevail. Some of the small grain herbicides labeled for preharvest are systemic and slower-acting than a contact herbicide.
• Harvest aids are meant to help facilitate harvest and reduce harvest loss. Any yield loss is likely already due to weed competition throughout the growing season. Also, any weed seeds produced will contribute to next year's weed problems.
• Harvest aids are not intended to (and usually do not) help speed up crop maturity. If applied too early, they can interfere with the natural crop maturation process. Illegal herbicide residues can result if specific application timing and other label guidelines are not followed. See the specific product label to determine the correct rate, timing, weed species controlled, and other restrictions with this type of application.
• Herbicide drift from these applications at this time of year will cause injury/death to sensitive crops/plants in surrounding areas.
• Adhere to all restrictions regarding grazing and feeding of straw for each of these products.

2,4-D

Some formulations of 2,4-D ester are labeled for preharvest applications in wheat, barley, oat, and rye. (Only certain 2,4-D products have all of these small grains listed on their label under preharvest, so consult the specific label before application.) Use 1 to 2 pints per acre depending on the product (no adjuvants are recommended). Applications should be made after the small grain is in the hard-dough stage and at least 14 days before harvest. Do not apply to small grains with a legume underseeding. If a preharvest application of 2,4-D ester is made, double-crop soybeans can be planted 7 days later for 1 pint or 30 days for 2 pints. 2,4-D is volatile and can potentially damage nearby sensitive crops. Avoid use if temperatures are expected to exceed 75°F. (Enlist One/Duo and Freelexx are not labeled for this use.)

Aim

Can be used as a preharvest application in small grains.  Use as a harvest aid to desiccate a limited number of broadleaf weed species. Application of 2 fl oz/A Aim shall be made when the crop is mature and the grain has begun to dry down. Ensure spray coverage is sufficient, otherwise poor control will result. Methylated seed oil or crop oil concentrate at 1 to 2 gal/100 gal is required; liquid nitrogen fertilizer at 2 to 4 gal/100 gal or ammonium sulfate at 2 to 4 lb/A can be added to the methylated seed oil or crop oil. Allow at least 7 days between application and harvest.

Clarity/dicamba

Clarity or other registered dicamba products can be used at 8 fluid ounces per acre preharvest when wheat and barley is in the hard dough stage and the green color is gone from the nodes (joints) of the stem. Apply at least 7 days prior to harvest. Do not use if legumes are underseeded. Do not use preharvest-treated wheat for seed unless a germination test is performed on the seed with an acceptable result of 95% germination or better. Although the Clarity label allows double-crop soybeans following their application (with adequate rainfall and time), the potential for injury may preclude this use. See a Clarity label for specific guidelines on rotational crops. Be cautious of drift.

Glyphosate

Glyphosate products may be applied to wheat and feed barley. Apply after the hard dough stage of grain (20% or less grain moisture for feed barley and 30% or less for wheat) and at least 7 days before harvest. Do not apply more than 1 lb ae (i.e., 28 fl oz/acre Roundup PowerMax3 or 48 fl oz/acre 3S products), and do not treat wheat being grown for seed, as a reduction in germination or vigor may occur.  Additionally, do not apply to wheat with a legume underseeding. There are no restrictions on double-crop soybean planting when glyphosate is used as a preharvest treatment. Be cautious of drift.

Sharpen

Sharpen may be applied to wheat, feed barley, and triticale only. Apply after hard dough stage and the grain is less than 30% moisture. Ground applications require 10 gallons of spray volume per acre; aerial requires 5 gallons. No rotation restriction for soybeans; 1 to 5 months for vegetables. Apply with methylated seed oil (1 gal/100 gal) plus ammonium sulfate (8.5 lb/100 gal) or urea ammonium nitrate (UAN) (1.25 to 2.5 gal/A). Apply at least 3 days before harvest; the label recommends 10 days for optimum desiccation effect.

Other herbicides

Other herbicides, such as Gramoxone, Harmony Extra, Peak, Maestro/Buctril, etc., are not labeled for use in small grains as a preharvest aid.