Reducing Herbicide Rates

1
Reducing Herbicide Rates

• When is it appropriate to reduce herbicide rates?

Modified by Georgia Agricultural Education
Curriculum Office July 2002
2
Reasons to consider reduced application rates

• A desire to cut costs of production
• Concern about the environmental effects of
  herbicides
• New regulations on herbicide use
• Concern about herbicide carry-over

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Methods of Application That Were Tested
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• Sprayer broadcasting over entire field at 100
  percent of recommended level
• Sprayer broadcasting over entire field at 50
  percent of the normal label rate
• This method reduces herbicide use by 50
• Herbicide is sprayed in bands at 100 percent of
  the normal label rate.
• Herbicide rate is again reduced by 50
• Herbicide is sprayed in bands at 50 percent of
  the normal label rate.
• Use of herbicide is decreased by 75 using this
  method

5
Possible concerns for the farmer center on the
possibility of reduced yield if weeds are not
controlled by the reduced-rate application.
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Sound weed management programs include several
components

• Mechanical cultivation
• Promoting vigorous crop competition
• Crop rotation
• Herbicide use

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Additional factors must be considered

• Cultivation, labor, and time must be available
  when needed.
• Herbicides degrade at a faster rate when applied
  at a lower rate.
• Cultivation in a timely manner ( 30 to 40 days
  after planting) becomes critically important.
• This is more essential when there is no rain
  within 7-10 days after herbicide application

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• Increased field management is required to
  accurately identify weeds, to monitor weather,
  and to ensure that weed cultivation occurs while
  the weeds are relatively small.
• Reduced-rate herbicide applications do not
  provide adequate control for all situations.
• When facing weeds such as quackgrass full rates
  are needed.
• Soils with cloddy surface or where a substantial
  amount of crop debris is present may not provide
  acceptable results.

9

• Herbicide manufacturers have no liability if the
  application rate is below specifications.
• Success depends largely on the farmers
  willingness to follow through with timely
  cultivation.

10
REMEMBER

• As with any new method, growers should try the
  reduced-rate approach on a limited basis at
  first, until they become comfortable with the
  methods and field management
• Reduced application rates are not recommended if
  timely cultivation cannot be assured, or if there
  is a problem with hard-to-control weeds.

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TEST TIME
12
One of the reasons to use reduced rates is to
increase yield?

• A) true
• B) false

13
Overall herbicide use can be reduced by 75 if
the field is sprayed at

• A) 100 rate over entire field
• B) 50 rate over entire field
• C) 100 rate in strips only
• D) 50 rate in strips only

14
Cultivation for fields must be done in a
_________ manner when using reduced rates.
15
Name one of the difficult to control weeds that
would make full strength application necessary.
______________
16
Herbicide manufactures will stand behind their
products if they are applied at less than
recommended rates?

• A) true
• B) false