Using Corn Herbicides and Protecting Water Quality
Guidelines for Corn Producers
Using Corn Herbicides and Protecting Water Quality
Best Management Practices for New York Producers
Best Management Practices (BMPs) are a significant part of an agricultural
chemical management plan. BMPs are designed to minimize the potential for
adverse impacts on the environment while maximizing the beneficial effects of
pesticide use. BMPs are economical and environmentally sound measures that, when
followed, will aid in the protection of water resources and ensure the continued
availability of modern pesticide production tools such as corn herbicides. While
the BMPs recommended in this program focus on corn herbicides, they are equally
valuable for other pesticides.
Learn All You Can
Attend a corn herbicides Best Management Practices workshop in your area. Know
the products you're using or that are being used on your fields. Develop your
management plan, taking into account conditions within the fields where corn
herbicides will be applied.
Corn Herbicide Product Description
Corn herbicides are herbicides applied for the preemergence and postemergence
control of annual grass and broadleaf weeds in corn. A listing of weeds
controlled by corn herbicides can be found on the product label.
Corn Use Information
Corn herbicides are herbicides applied for the control of annual grass and
broadleaf weeds. Corn herbicides may be preplant surface applied, preplant
incorporated, applied as a preemergence treatment in water or liquid fertilizer,
impregnated on dry bulk fertilizer or applied as a postemergence application.
Corn herbicides control broadleaf weeds during germination or soon after
emergence and grass weeds during germination. Susceptible weeds exposed to corn
herbicides either die or remain noncompetitive with the crop. Because the
herbicidal activity of corn herbicides on broadleaf weeds involves uptake and
translocation to weed growing points, adequate soil moisture is necessary for
optimal activity. Corn herbicides may provide residual control of susceptible
broadleaf weeds which emerge after application.
General Crop Protection Best Management Practices
Know Your Fields and Farm
- Conduct your own Farm Site Evaluation. Use the information to develop your Best
Management Practices and plan.
- Maintain field records:
- Scout fields to identify weed species and population levels.
- Select herbicides and application rates based on soil type, organic matter
content, soil permeability, soil pH and depth to ground water. Also, consider
types and populations of weeds present or anticipated.
- Record soil test results, crop planted, weed problems, pesticides used (active
ingredient, rate), application dates, weather and results.
- Identify highly erodible fields and their drainage patterns.
- Use the most appropriate tillage and herbicide practices for your crop and field
characteristics (soil type, past weed problems, environmentally sensitive areas
- Consider crop rotations, if appropriate, to reduce weed competition and to
lessen the chances for resistant weed biotypes to spread.
- If you participate in a soil conservation or water quality program, follow
- Work with your dealer or applicator and evaluate your fields before the planting
season. Additional information may be obtained from the Cooperative Extension
Service or the Soil Conservation Service.
Mixing and Loading
- Ideally, mix and load agricultural chemicals and rinse equipment on an
impervious surface (containment pad).
- Mix and load pesticides and rinse equipment in the field if you don't have a
containment pad, and vary the location. Stay away from any well (including
drainage wells and abandoned wells), stream or sinkhole during mixing and
loading operations. Follow any additional state and label requirements.
- Do not mix or load agricultural chemicals near public drinking water supply
wells unless you're using a containment pad. Follow any additional state
- Clean up chemical spills (even small ones) immediately. Don't let the material
soak into the ground. Have spill material (cat litter, sawdust, etc.) available
when mixing and loading.
- While filling your spray tank, make sure there's a fixed air gap (air break)
between the water source and the tank or an antibackflow device on the fill
hose. During filling operations, don't allow the water to be back-siphoned. Keep
the end of the fill hose above the surface of the water/chemical solution in the
tank at all times.
Container and Equipment Cleaning
- Minimize container and equipment cleanup needs by mixing only enough product for
the job at hand.
- Always start with a clean, calibrated sprayer that can provide appropriate
- Clean containers and equipment at the application site if you don't have a
mixing and loading pad. Put the rinsate in your spray tank and apply evenly over
a field or dispose of as the label specifies.
- Rinse product containers immediately. Delays can result in residue drying and
becoming much more difficult to remove.
- Pressure- or triple-rinse disposable containers immediately after emptying. Be
sure to add the rinsate to the spray mix. Puncture the containers before
disposing of them.
- Participate in container recycling programs for empty disposal containers when
offered in your area.
- Properly dispose of rinsed pesticide containers that cannot be refilled or
recycled. Do not burn pesticide containers.
- Stay away from all wells including abandoned wells, drainage wells and sinkholes
when mixing, loading, rinsing or washing containers and equipment unless these
operations are carried out on an impervious pad. Follow any other applicable
Background Information -- Guidelines For Corn Producers Using Corn Herbicides
And Protecting Water Quality
The United States Environmental Protection Agency (EPA), under mandates of the
Clean Water Act (CWA), is requiring states to develop comprehensive water
quality management plans to restore water quality where degradation has taken
place, maintain quality and eliminate contamination. EPA has provided a role for
states that grants flexibility to fit the solution to the problem and provides
funding to assist in development of management programs to address water quality
Components of the CWA management plans address point source pollution, nonpoint
source pollution (farming) and dredge and fill operations. The CWA was amended
by Congress to address water quality impacts from storage tanks, added wellhead
protection, protection of sole-source aquifers and protection of groundwater.
To protect groundwater, states have been asked by EPA to develop a generic
management plan that tells how the state will set about the task of implementing
a protection program. In New York State, this plan has been developed by the New
York State Department of Environmental Conservation's (NYSDEC) Division of Water
and is available for review. The next step in the process is for EPA to identify
and label agricultural chemicals that have a potential to leach to groundwater.
It will become the responsibility of the states to develop and implement
chemical-specific management strategies and enforce those strategies. Under
EPA's current proposal, if a state fails to develop management plans to protect
groundwater, use of those chemicals could be denied. While enforceable
requirements are not expected until the 1998 growing season, there is
considerable merit to initiate protection initiatives in advance of these new
The DEC, along with a coalition of New York Corn Growers, New York Farm Bureau,
Agriculture and Markets, Cornell University, New York State Agribusiness
Association and manufacturers, developed a voluntary management plan that
addresses groundwater protection for all corn herbicides registered for use in
the state of New York. Management practices utilized for one material are
equally appropriate for all products. The emphasis of a voluntary best
management plan is on prevention of contamination.
Groundwater protection is your business. As a farmer, you and your family rely
on groundwater for drinking. Protection of this resource maintains the value of
your farm and will preserve the availability of crop protection chemicals for
your use. The coalition has prepared a best management plan that you can follow
in selecting and using corn herbicides on your farm. We urge you to adopt this
approach in your farm planning practices.
Best Management Practices Planning Your Way To Water Quality Protection
Determine if the fields where you intend to use corn herbicides are within the
shaded areas. These areas are thought to have highly permeable, coarse soils
underlain by ground water that is near the surface. Locations outside the shaded
areas indicated on the map also may contain coarse soils and shallow ground
Corn Herbicides State-Specific Best Management Practices and Plans
- Conduct a Farm Site Evaluation to determine conditions, practices and areas on
your farm that may present potential ground water concerns.
- If the Farm Site Evaluation reveals soils (classified as sand or loamy sand
soil) and the ground water table is shallow, use the lower recommended rates or
consider alternative weed control practices.
- Read the corn herbicides label thoroughly reviewing, in particular, parts
relating to personal protection equipment, rotational crop restrictions, spray
drift avoidance practices, pH limitations, and antisiphoning device utilization.
- Select appropriate rate and application techniques and, if applicable, tank-mix
- Calibrate application equipment prior to use. Use equipment that is capable of
continuous and vigorous tank agitation (rippling or rolling action at liquid
- Always start with a clean, calibrated sprayer.
- Pay particular attention to rotational crop restrictions and precautions.
Pesticide Best Management Practices
Farm Site Evaluation
Here's a list to help you determine if you're using Best Management Practices
(BMPs) which help protect ground water and surface water. Please take the time
to review the conditions within the corn growing areas on your farm while
referring to the list.
- Do you always read and follow the appropriate instructions on the pesticide
- Do you scout your fields for weeds every year before deciding what herbicide and
application rate to use?
- Do you maintain field records of pesticide applications?
- Do you consider alternate means of suppressing hard-to-control weeds (those that
may have become resistant to your usual herbicide), rather than simply
- Are you aware of the location of wells, abandoned wells, bodies of water, ponds
and streams in your fields?
- Do you know the percentage of the soil surface that is sand or loamy sand in
fields where you intend to use corn herbicides?
- Do you know the general depth of the water table (ground water) in the vicinity
of the fields?
- Soil pH can have a significant impact on herbicide performance. Do you know the
pH in all fields where you intend to use corn herbicides?
- If appropriate, do you maintain grass or other types of buffer strips between
the edges of your fields and runoff points that drain into bodies of water or
- If you farm on highly erodible soils, are you following all proper water quality
- Do you have a map identifying areas in your county or on your farm that may be
vulnerable to water quality concerns?
- Do you follow recommended methods for disposal of pesticide containers?
- Do you have an emergency plan and the necessary equipment to handle an accident
(fire or spill) where you have pesticides stored?
- Are your pesticides stored in a locked building, and do you have written records
of the products stored?
- Have you taken extra precautions to protect the areas around wells on your farm?
- Do you inspect and maintain your wells and plumbing connections on an annual
- Do you use devices to prevent back siphoning or back flow on fill hoses
connected to wells or other water supplies?
- Do you have a containment pad with an impervious surface?
- If you mix and load pesticides in the field, do you vary the location each time?
- Do you follow directions on the product label for proper disposal as soon as
containers are emptied?
- Do you clean up small spills as soon as they occur?
- If you clean tanks and spray equipment in the field, do you change the location
- Do you always check to be sure field location where you mix and load pesticides
or clean application equipment is away from any well, stream or lake?
- Are all people who handle pesticides on your farm properly trained?
If you checked (No) to any of the questions, please determine Best Management
Practices designed to address the particular point made in the question. Contact
your local Cooperative Extension Agent for information on the practices you
should be following. The Corn Herbicides Management Plan and training program
provide effective examples.
If you use a custom applicator or dealer who offers a full service program, he
or she can inform you of steps you can take to protect the water resources on or
near your property. You also may contact your state lead pesticide agency or
your local Ag chemical representative for more information.