Vol. 51—1997 - NorthEastern Weed Science Society

19
cover the sta~es in the Northeast (1), (2), (3). In addition to the New England and
Mid-Atlanticlreports, that cover 12 northeastern states, Cornell University issues a
separate set ~f recommendations covering New York.
One commo feature of the 28 field crop recommendation reports is a table that rates the
effectiveness ,of individual herbicide treatments in controlling specific weed species in field
corn. The efficacy rating for a particular herbicide treatment to control a specific weed
species is developed by extension specialists based on experimental work and the
experiences qf farmers in the state.
Generally,1rating tables include five broad categories of control effectiveness: none,
poor, fair, g d and excellent. These ratings are associated with a range of percent
control of th, weed species. For example, a common range for a "good" rating is 80-90%
control. In some of the reports the ratings tables contain numerical entries of 0-10 that
correspond t~ percent controls of 0% to 100%. The ratings tables group herbicide
treatments according to their timing: preplant incorporated (ppi), pre-emergence (pre) or
postemergei' (pos). An individual herbicide treatment can be listed in more than one of
these catego .es, as appropriate. In most cases, ratings are published for individual
herbicide pr ducts. Products that contain the same active ingredient(s) are rated generally
as a single e try (such as Partner, Lasso, Microtech). In some cases, the rating tables
include tank-mix combinations of several products. None of the ratings tables contain any
non-ehemic~ techniques for weed species control in field corn.
Methods
As part of a project to develop a national corn weed control model, the National Center
for Food andAgricultural Policy (NCFAP) has created a database that contains all of the
individual w d control ratings for field corn from the 28 Extension Service reports. A
single data r ord in the NCFAP file contains an individual rating from an Extension
Service repo that is specific by herbicide application method and weed species. The
names of the products have been standardized in terms of active ingredient names. In
cases where Extension Service report includes products with different active
ingredients qn the same rating line, NCFAP created separate lines of data for the different
active ingredients, (Thus, a single rating for "Dual, Microtech or Frontier" means separate
records for metolachlor, alachlor and dimethenamid.)
The indiVidU~ ratings have been translated into numerical entries, basedon the midpoint
of the range or the control category. (A rating of "good" with an associated range of 80­
90% control has been entered as 85% in the database.) Each record includes an
identification of the timing of the treatment as POS, PRE or PPI.