Vol. 51—1997 - NorthEastern Weed Science Society

18
EF ICACY RATINGS FOR FIELD CORN HERBICIDES:
A NATIONAL SUMMARY
L. P. Gianessi and M. B. Marcelli 1
ABSTRACT
The N tional Center for Food and Agricultural Policy (NCFAP) created a national
datab ,compiling 1996 data from 28 weed control guides for field corn (Zea mays).
Herbi de performance in weed control for field corn was summarized for 42 states.
Mean, tandard deviation, minimum and maximum were calculated for the efficacy of a
total 0 78 treatments applied to 87 weed species across the U. S. The 78 treatments
includ d applications of herbicides alone or in combination using different methods of
applic tion. Each treatment average shows the rating for a specific weed, herbicide and
applic tion method in the U. S. as a whole; minimum and maximum show the variations
amon states. This variation in weed control might result from differences in: planting
time, ming of weed emergence, precipitation, temperature, soil, etc., affecting herbicide
perfo ance in different states.
Introduction
Each ear, state extension services release weed control guides for field crops. These
guides are meant to inform the states' growers of the range of choices available to control
specifi weeds for each crop. The guides also advise growers on the expected
perfo ance of available herbicide treatments to control specific weeds in each crop in the
state. e weed control guides provide information on newly registered herbicides, new
comb' ation products and any changes in performance of the available treatments.
In 199 ,weed control guides for field crops were contained in 28 reports issued by state
coope ative extension services. Twenty-four of the weed control guides are specific for
an in vidual state. Four of the weed control guides cover more thanone state: Pacific
North est (three states), New England (six states), Mid-Atlantic (six states) and one
report for Montana, Utah and Wyoming. Thus, the 28 reports cover 42 states. (The six
cote inous states not covered by an annual state weed control recommendation report
are 0 ahoma, Texas, Nevada, Arizona, New Mexico and Louisiana.) Three reports
1 Seni r Research Associate and Research Associate, National Center for Food and
Agric tural Policy, 1616 P Street, NW, First Floor, Washington, DC 20036