Daily Dicamba Update: Mastering the Downwind Buffer Requirement Requires Research, Data
May 8, 2018 There’s really no way to sugarcoat it — understanding the downwind buffer requirement of the new dicamba-tolerant cropping systems remains difficult for many applicators.
To get us started, the dicamba labels are quite clear on the required buffer size: they necessitate applicators to apply the products in such a way that they “maintain a 110- to 220-foot downwind buffer for all applications.” Downwind buffers are required for all applications no matter what. (Note: Conservation Reserve Program acres can be included as part of the buffer).
The real question for many applicators becomes just how much of the downwind buffer zone will come out of your field, and how much out of the neighbor’s?
A “buffer” is defined as “the area NOT sprayed, and it is always perpendicular to the wind direction.”
Applicators should keep in mind that the liability to scout all adjacent and neighboring fields for sensitive/susceptible crops, prior to undertaking the application, falls under the purview of the professional applicator, not the grower-customer. Checking sensitive crop registries like DriftWatch is a legal requirement and can help alleviate some of the manual workload associated with this task, but it must be noted that DriftWatch doesn’t map or report non-dicamba-tolerant soybean varieties – as well as other potentially susceptible crops (and you can never be sure if the grower has even placed their crops on DriftWatch). So, when in doubt it is probably best to travel to the field to pre-scout (or visually check the surrounding environment) just prior to application and, if still in doubt, try to get in touch with the neighbor and ask him or her about the variety of crops growing on an adjacent field.
What defines a field as “neighboring or adjacent?”
That would be the field or area next to (i.e., it has to be touching) the target field where application will take place. This also means that, according to Purdue University, the “field or area separated from the target field by only a fence row, vegetative strip, tree row, lane, driveway, road, drainage ditch, residential area, creek, river, etc.” qualify as neighboring or adjacent fields. Applicators should check with their state regulatory agencies to see if neighboring or adjacent has been defined in their state.
It’s also important to remember that if the wind is blowing at ANY SPEED in the direction of neighboring or adjacent sensitive crops (the applicator will already have this information from complying with the label by measuring wind speed and direction at boom height prior to each application), the application cannot move forward until the wind has shifted.
Sensitive Crops, as defined by the label:
- Non-dicamba-tolerant soybeans and cotton
- Cucumber and melons
- Fruit trees
- Grapes
- Ornamentals (including greenhouse-grown and shade-house grown broadleaf plants)
- Peanuts
- Peas and beans
- Peppers
- Tomatoes
- Other fruiting vegetables
- Potatoes and sweet potatoes
- Tobacco
- Nurseries
- Other broadleaf plants
- Certified organic crops (not listed specifically on the label but in certain states/regions, like Indiana, certified organic crops would be considered sensitive and/or susceptible)
How much of the required 110- or 220-foot downwind buffer must come from within my field?
Purdue says that depending on what is downwind of your dicamba-tolerant soybeans, the buffer may be calculated:
- All from within your fields (100%);
- Partially from your field and partially from the neighboring property; or
- All from the neighboring property (100%);
- What you are allowed to use as part of your buffer past the last downwind row will be limited by the label, and the 220 foot buffer is for burndown/preplant only for Xtendimax and FeXapan (up to 44 oz/A), not Engenia.
The label specifies that the entire buffer will always be in your field, except when the following are immediately adjacent to the downwind side of your field:
- Agricultural fields prepared for planting (NOT certified organic ground – check with your state);
- Planted agricultural fields containing asparagus, corn, dicamba-tolerant soybeans, sorghum, proso millet, or small grains (NOT certified organic ground – check with your state);
- Manmade structures with walls and a roof (limited usefulness);
- Paved or gravel road surfaces (WARNING: vegetative shoulders alongside many roads prevent nearly all roads from being used as part of the buffer calculation).
As stated earlier, new dicamba labels do not specifically address the protection of organic crops/fields. However the labels do state, “Do not apply under circumstances where spray drift may occur to food, forage or other plantings that might be damaged or the crops thereof rendered unfit for sale, use or consumption.” Thus making application with certified organic crop production in adjacent or neighboring fields illegal.
ADDITIONAL RESOURCE:
For applicators looking to work through some real world scenarios before hitting the field, Purdue University’s published mandatory dicamba 2018 training module (“Threading the Needle”) can be accessed here; See slides 46 through 59 on downwind buffer requirement scenarios for applicators.
Read more on the label requirements here:
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