ISSUE #400

400 - Cost Effective Weed Control Strategies

5-15-01

The next step in profitable sugarbeet production after stand establishment is effective weed control. Losses from weed competition can easily be $100 per acre or more.

  • Sugarbeet growers rated weeds their worst production problem in 21 of the last 25 years.
  • Weed competition can cause losses of 50% in recoverable sugar per acre.

Microrate Use in MN and ND

  • Used by 95% of all growers in 2000
  • 95% of growers had satisfactory to excellent weed control
  • Over 40% of all acres were band sprayed
  • Microrates give less crop injury and increase yields

Steps to Successful Weed Control

  • Effectively kill weeds with preplant tillage
  • I.D. weed seedlings in the cotyledon stage
  • Proper sprayer calibration
  • Select the correct herbicides
  • Select the herbicides rates needed
  • Use preemerge Roundup usually 1 quart/acre
  • Use layby herbicides
  • Cultivate and rotary hoe effectively

Strategies for Successful Microrate Use

  • Always include Betanex, Betamix or Progress
  • Always use Upbeet
  • Always use MSO or a basic blend adjuvant
  • Always use Stinger
  • Use a grass herbicide as necessary
  • Start applications 14-21 days after planting
  • Always use 3 applications, 4 if needed
  • Increase rates of Betanex, Betamix or Progress as beet size increases.
Beet SizeBetanex or BetamixRate Progress Rate
Cotyledon to 4 leaf 8 oz. 5.7 oz.
4-leaf and larger 8-12 oz. 8.6 oz.

Banding Microrates Saves Money

Herbicide Application MethodMicrorate Cost Applied 4 Times
* 7" band $29 $61 savings
11" band $45 $45 savings
Broadcast $90

Growing Degree Days – Sugarbeet Leaf Stage Predictor

Coming to an Internet site near you – www.crystalsugar.com (Pest Alert Section) – will be a growing degree-day (GDD) calculator with a sugarbeet leaf stage predictor. Here is how it will work:

There will be an input box with a drop down menu to choose the weather station nearest the field of interest. The choices will be Felton, Hillsboro, Eldred, Mayville, Northwood, Warren and Humboldt.

There will be an input box to enter planting date month. A drop down menu will have the choices April, May and June. There will be an input box to enter planting date day. A drop down menu will have the choices 1, 2, 3…31.

After these three boxes are filled there is a compute button for the calculator to add all the growing degree-days between the planting date and the day before the request. The computer will then determine cumulative GDD.

Right underneath the calculator part of the screen will be a table of leaf stages, a short description of those leaf stages and the number of growing degree-days for the crop to reach that stage. It should be noted that in reality, from leaf stage 2, a pure leaf stage, for example V 3.0, does not exist, because when three leaves are present, the fourth is present and partially unrolled. The table really should be thought of as having all tenths between all stages. The table shown has some examples of decimal fractions between the various leaf stages to indicate all the detail.

Use this calculator to keep track of the growing degree-days since planting and get a very good estimate of crop stage. Note that one could also put in a date when the field is at some leaf stage and predict when it will be at some other leaf stage.

It should be noted that the number of growing degree-days between planting and emergence and the various leaf stages were gathered between 1991 and 1993. The research was done by Carlyle Holen and Dr. Alan Dexter, NDSU and U of MN.

Growing degree-days should be a more reliable predictor of leaf stages than calendar days. Growing degree-days can more accurately account for plant development over a wide range of temperatures. For example, if this spring is unusually wet and hot, the growth may be greater than average and the interval between microrate applications should be only 5 days. If conditions are unusually cool sugarbeet growth will slow and the interval between applications could be more than 7 days.