Posted April 9, 2019

SOURCE: NE CropWatch

Burndown Weed Control

Looking ahead at the next 10-14 days, there is tremendous workload for everyone to get this season started. Hopefully mother nature lends a helping hand, otherwise it will get even more challenging. Once dry enough, field work will snap into action quickly and fertilizer application and tillage are tempting tasks. However, herbicide applications should be a high priority.

From a few brief walks into muddy fields, it is very evident that we already have weeds out there. As seen in this picture, the weed densities in some areas are there just waiting for the right weather to take off and grow.

Marestail, henbit, pennycress and dandelions are present; and summer annuals will be right on their heels. While the cold temperatures have kept us in check to this point, they will need to be addressed quickly when fields warm up. Tillage will be an option for some acres, but more than likely burndown herbicides will be the best option. Some of the tilled fields could quickly get woolly before we are able to work them, meaning that herbicides may be needed to remove weeds before tillage. Dense mats of winter annual weeds often cause soils to dry out slower, remain cooler longer, make tillage challenging, and can attract early insects like black cutworm. Planting into fields with dense populations of these winter annual weeds is not a very conducive environment for maximizing yields. Consider using Sharpen® herbicide or Verdict® herbicide in your fields to utilize the fast burndown needed to start clean.

Sharpen and Verdict Best Practices:

Choose the right rate For fields going to Corn – Burndown/Setup rates:
Verdict @ 5-10 fl oz/A or Sharpen at 1-2 fl oz/A
For fields going to Soybeans – Burndown/Setup rates:
Verdict @ 5 fl oz/A or Sharpen @ 1 fl oz/A with no planting restriction (30 days for coarse soils that have less than 2% OM)
Verdict @ 10 fl oz/A or Sharpen @ 2 fl oz/A with 30-day planting restriction (44 days for coarse soils < 2% OM)

Use nozzles that provide good medium to coarse droplet coverage (unless tank mixed with dicamba products and then use approved nozzles only)

Add glyphosate, AMS, and MSO
In corn, addition of atrazine may aid in winter annual control
In soybean, 2,4-D or dicamba products can be added to aid in control (follow dicamba product labels when using). Remember to follow the required plant back restrictions when using auxin products in front of soybeans
15-20 GPA minimum carrier volume

Contact your local BASF Representative for more information about how Sharpen and Verdict can aid with your spring burndown needs.

Using Growth Regulators Herbicides (Dicamba and 2,4-D) Prior to Soybeans

There are plenty of soybean fields that contain hard to control winter annual weeds like fast growing marestail, in these cases you need a second site of action working on these weeds. In many Nebraska fields, glyphosate is no longer active on marestail so we need another herbicide site of action to bring in to the mix for proper control. Traditionally this has been a group 4 growth regulator herbicide, usually in the form of 2,4-D amine. Adding 2,4-D amine also adds a preplant interval of at least 7 days.

In addition with the launch of dicamba tolerant soybeans in 2017, new options are available for use in burndown applications even after planting. Engenia®, BASF’s approved dicamba formulation for dicamba tolerant beans, can be tank mixed with Sharpen, Verdict or Zidua PRO as long as the dicamba tolerant soybeans have not emerged. This combination allows for the control of those hard to kill winter annual weeds like marestail even after the dicamba tolerant beans have been planted.

While Engenia can be used prior to planting, there have been some inquiries on utilizing generic or not approved dicamba products in burndown applications before planting dicamba-tolerant soybeans. As a reminder, the only approved dicamba products for use in-season for dicamba-tolerant soybeans are Engenia®, XtendiMax® With VaporGrip® Technology, and FeXapanTM Plus VaporGripTM Technology. This includes any burndown applications made within 28 or 14 days of planting (depending upon use rate and rainfall). If a dicamba product different from these three products were to be used in the burndown application, such as Clarity® or a generic dicamba, then we must follow the preplant interval directions on these products’ labels for soybeans. This would be a 28-day interval after an inch of rain for a rate of 16.0 fl oz/A
or a 14-day interval after an inch of rain for a rate of 8.0 fl oz/A.

Any applications of dicamba that occur in front of dicamba-tolerant soybeans with the intent of not having a preplant interval must be made using any of the three approved dicamba formulations for this use: Engenia®, XtendiMax® With VaporGrip® Technology, and FeXapanTM Plus VaporGripTM Technology.

Aerial Applications of Residual Herbicides

One way to combat the wet field conditions that persist in the use of aerial application to apply residual herbicides in front of corn and soybean. Several BASF products are labelled for use through aerial application equipment. While this can be an effective way to deal with fields too wet to apply with ground equipment some application differences should be understood.

Applicators should understand the range of herbicide rates listed in the tables below are typically dependent on soil type. If you have questions consult the label or contact local BASF rep for further information. Applicators should ensure you are using the right type of nitrogen source when needed. While 28 or 32% Nitrogen is recommended for aerial application, liquid AMS or well mixed dry AMS products used at the equivalent rate of 8.5-17 lbs / 100 gal may be used in place of 28 or 32% nitrogen. Non-slurried dry AMS as well as water conditioning products are NOT recommended. Finally, consider using overlapping residuals, instead applying all highest rate of one residual herbicide aerially, instead apply the first residual by aerial application and then return with a second residual herbicide at the early post-emergence application time. An example might be using 10 oz of Verdict applied by air and then following with 16 oz of Armezon PRO applied to corn post emergence.

Aerial applicators need to also:

Not apply to fields with standing water Observe all buffers listed on the label between point of direct application and non target or endangered species Use reduced drift nozzles. DO NOT use nozzles producing a fine mist spray droplet. Spraying a pre-emergence herbicide is different than a fungicide or insecticide. Maintain proper application height. Without compromising aircraft safety, applications should be made at a height of 10 feet or less above the spray target. NOT apply during temperature inversions or stable atmospheric conditions.

Below are tables for BASF corn and soybean residual herbicides that are labelled for aerial application. Please contact your local BASF rep with questions.