WeedCast Predictions Save Farmers
Colorado wheat field.
Corn farmers in the Morris area of west central Minnesota see a glimpse of
the future whenever they click on their computer's mouse or leaf through their
local newspaper for weed forecasts.
For example: from late April until early July 1996, the Morris Sun weekly
paper carried charts showing height predictions for 11 common weeds. The last
forecast for weed seedling emergence made by using weather data from the Morris
area was posted on the Internet on July 1. It showed from 90- to 100-percent
sprouting of pigweed and lambsquarters for farms in the area. The information
helped area farmers plan their weed control strategies.
"We're working to expand the forecasts nationwide," says Frank
Forcella. He is the Agricultural Research
Service agronomist who developed the weed forecasting computer model,
called WeedCast, that generates the predictions.
"Right now, we just share the model's results on the Internet or in the
local newspaper. We're working on putting the model itself on the net so
farmers everywhere can type in their local weather data and get predictions for
"We're also considering adapting the model to user-friendly software
that would be distributed by us or a private company," Forcella adds.
The forecasts can be used with other farm management aids, such as the
WeedSim model developed by the University of Minnesota in conjunction with ARS.
That model advises farmers if and when to use herbicides and mechanical weed
control based on predicted weed dormancy, emergence, and speed of growth.
In tests at Morris, Forcella and his colleagues have grown corn and soybeans
with fewer herbicides because predictions reassured them that the weed numbers
wouldn't harm yields. Their profits were $20 an acre more than where standard
weed control practices were used. Occasionally, there were slightly more weeds,
but never enough to affect yields in the current or following year.
When combined with information on yield losses from weeds and delayed
planting, WeedCast predictions help determine the best compromise date for
seedbed cultivation to substantially destroy weeds, instead of using herbicide
Forcella has worked closely in development and implementation of these
models with weed scientists and agricultural economists at the University of
Minnesota, in cooperation with their counterparts in most of the Corn Belt
states. Minnesota's Agricultural Utilization Research Institute also helped
fund this research. -- By Don Comis, ARS.
Forcella is at the USDA-ARS North Central Soil Conservation Research
Laboratory, Morris, MN 56267, phone (320) 589-3411 ext. 127.