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On August 27, 2017

As we move into corn silage harvest season, and with full season soybeans soon dropping their leaves, producers may notice some problem weed situations. Unfortunately, at this point in the season, few products are labelled and applying those that are can be even more difficult. Extension Agronomist Dwight Ligenfelter explains the only viable option might be to use a harvest aid prior to corn or soybean grain harvest. In corn, this type of application requires high clearance equipment or aerial application; hopefully, these fields are the exception and not the norm. Below is a brief list of products available for late season application or as a harvest aid for corn and soybeans.

Products for corn include Aim 2EC which may be applied 3 days before harvest at 2 fl oz/acre. Use as a harvest aid to desiccate certain broadleaf weeds. Apply in 10 gal/A water. Include necessary adjuvants and make sure spray coverage is sufficient otherwise poor control will result. Basagran can be used with no restrictions. Another product is Defol 5L which can be applied to desiccate problem weeds in early maturing corn. Apply 4.8 qt/acre, 14 days before harvest in 10-20 gallons/acre wate.
Additionally Impact/Armezon can be applied up to 45 days prior to harvest. Glyphosate can be used up to 0.75 lb ae/acre (32 fl oz of a 3 lb ae/gal formulation) to corn a week or more prior to harvest. Must be applied to grain corn when moisture is 35% or less and after maximum kernel fill. Gramoxone SL is also labeled and can be applied at 1.2 to 2 pt/acre after black layer and at least 7 days before harvest. The higher rate can be used to desiccate mature broadleaves and grasses over 18 inches tall. Be sure to include a nonionic surfactant. Additionally 2,4–D LV4 can be applied to corn at 1 to 2 pt/acre after the hard dough or dent stage. Do not forage or feed corn fodder for 7 days after application.

There are a number of options for soybeans as well. These include Aim 2EC applied at 2 fl oz/acre as a harvest aid to desiccate certain broadleaf weeds. Application shall be made when the crop is mature and the grain has begun to dry down and at least 3 days before harvest. Apply in 10 gal/A water and include necessary adjuvants and make sure spray coverage is sufficient otherwise poor control will result. Clarity can be applied at 8 fl oz to 2 quarts after soybean pods have reached a mature brown color and at least 75% leaf drop has occurred. Wait at least 7 days before harvest.

Defol 5L can be applied to desiccate problem weeds in early maturing corn. Apply 4.8 qt/acre, 7-10 days before harvest in 10-20 gallons/acre water.

Glyphosate can be applied to Roundup Ready soybeans through flowering (R2 stage) for late season control. For pre-harvest, glyphosate may be applied to Roundup Ready and conventional soybeans after 80% leaf drop (loss of all green color). Apply up to 0.75 lb ae/acre (32 fl oz of a 3 lb ae/gal formulation) in 10-20 gallons of water/acre to control weeds that may interfere with harvest or to control perennials such as quackgrass or Canada thistle. Allow a minimum of 7 days between application and harvest. Do not graze or harvest for hay within 25 days of application.
And finally Gramoxone SL can be pply 8 to 16 fl. oz/acre plus nonionic surfactant (1 qt/100 gallons of spray) to soybean plants that are mature (65% or more of the seed pods have reached mature brown color or seed moisture is 30% or less. Do not apply within 15 days of harvest and do not graze or harvest for forage or hay.

A special note on burcucumber: with the wet weather we have been experiencing this summer, conditions are ideal for late season burcucumber problems in corn and soybean. Under these conditions, burcucumber can germinate and emerge late into the season and it’s not until it gets above the crop canopy that it is often noticed. This late in corn, there are few options for managing this troublesome weed. Aside from the corn herbicides mentioned above, Beacon (applied before tassel emergence) and Maestro (formerly Buctril) can also be sprayed until tassel to slow burcucumber. Gramoxone is another option. As we get near harvest, the pre-harvest applications are targeting grain production prior to a frost and really are intended just to allow combine harvest of the crop. Gramoxone is probably the most effective of these three options at this time.

In soybean, as noted above, only glyphosate, Gramoxone, Clarity, and Aim may be used for late season control. Again, Gramoxone is probably the most effective of these treatments for burcucumber control.

Finally, if burcucumber can be harvested for silage and the seeds are immature or still green, the ensiling process will kill the seeds. If the corn or soybean is harvested for grain, the mature seeds will simply end up back in the field (or in the grain) making the problem worse for future years. Also, as you make plans for next season, include no-till in fields that are infested with burcucumber. Research suggests that no-till allows burcucumber seed to remain near the soil surface, thus allowing germination to occur over a shorter time period and reducing the number of germination flushes. This also improves herbicide effectiveness and performance.

To Understand The Status Of U.S. Crops

U.S. farmers are expected to produce a record-high soybean crop this year, according to the Crop Production report issued recently by the USDA’s National Agricultural Statistics Service. Up 2 percent from 2016, soybean production is forecast at 4.38 billion bushels, while corn growers are expected to decrease their production by 7 percent from last year, forecast at 14.2 billion bushels.

Up 7 percent from last year, area for soybean harvest is forecast at a record 88.7 million acres with planted area for the nation estimated at a record-high 89.5 million acres, unchanged from the June estimate. Soybean yields are expected to average 49.4 bushels per acre, down 2.7 bushels from last year. Record soybean yields are expected in Delaware, Georgia, Kentucky, Missouri, Mississippi, Pennsylvania, and South Carolina.

Average corn yield is forecast at 169.5 bushels per acre, down 5.1 bushels from last year. If realized, this will be the third highest yield and production on record for the United States. NASS forecasts record-high yields in Alabama, Louisiana, Michigan, Mississippi, New York, Pennsylvania, and South Carolina. Acres planted to corn, at 90.9 million, remain unchanged from NASS’ previous estimate. As of July 30, 61 percent of this year’s corn crop was reported in good or excellent condition, 15 percentage points below the same time last year.

Wheat production is forecast at 1.74 billion bushels, down 25 percent from 2016. Growers are expected to produce 1.29 billion bushels of winter wheat this year, down 23 percent from last year. Durum wheat production is forecast at 50.5 million bushels, down 51 percent from last year. All other spring wheat production is forecast at 402 million bushels, down 25 percent from 2016. Based on August 1 conditions, the U.S. all wheat yield is forecast at 45.6 bushels per acre, down 7 bushels from last year.

Today’s report also included the first production forecast for U.S. cotton. NASS forecasts all cotton production at 20.5 million 480-pound bales, up 20 percent from last year. Yield is expected to average a record-high 892 pounds per harvested acre, up 25 pounds from last year.

NASS interviewed more than 21,000 producers across the country in preparation for this report. The agency also conducted field and lab measurements on corn, soybeans, wheat and cotton in the major producing states, which usually account for about 75 percent of the U.S. production. NASS is also gearing up to conduct its September Agricultural Survey, which will focus on wheat, barley, oats and rye growers. That survey will take place during the first two weeks of September.

Quote Of The Week: “I hate war as only a soldier who has lived it can, only as one who has seen its brutality, its futility, its stupidity.” Dwight D. Eisenhower