The name is absent

Table 1. Total Adjusted Returns per Acre for Integrated Alfalfa Management Practices, 1983 to 1987

End-Of-Season Harvest Practice

Fall Cut                  Winter Grazed                    Unharvested

application is a common weed control alternative for
Oklahoma alfalfa growers and has been found to be
an effective weed pest control alternative (Wilson).
Winter grazing may assist in reducing annual cool-
season weed populations in established alfalfa by
inhibiting weed growth.

Little research has focused on the interaction be-
tween end-of-season harvest options with insect and
weed controls, though research has documented in-
teractions between insect and weed pests (Berberet
et al. 1987). Some annual weeds are Ovipositional
sites for the alfalfa weevil and larval feeding damage
may be increased with higher populations of certain
weeds (Ben Saad and Bishop). In contrast, Norris et
al. found that effective weed control in alfalfa
resulted in higher populations of the Egyptian alfalfa
weevil. The higher insect populations led to reduced
alfalfa yields, but reductions were not as great as
when neither insect nor weed pests were controlled.
An Illinois study also showed that yield reductions
were greatest when neither insects nor weeds were
controlled (Kapusta et al.).

RESEARCH DESIGN AND DATA

This research was designed to address effects on
economic returns from interactions of cultivar selec-
tion and end-of-season harvest options along with
pest control alternatives. Alfalfa production data
were collected from Oklahoma’s South Central Re-
search Station (Dowdy). The experimental design
was a split-plot in strip configuration with four
replications of three alfalfa cultivars. Two cultivars
(WL318 and Arc) had been selected for their
tolerance to alfalfa weevils and resislance to some
aphid species and alfalfa pathogens, while the third
(OK08) had no selection for pest resistance.

Subplots positioned in strips across the main plots
consisted of three alternative end-of-season harvest
options. The three options consisted of late-fall har-
vest (November), winter grazing (December and
January), and unharvested. Insecticides and/or her-
bicides were applied annually without consideration
of insect and weed populations in a 2 x 2 factorial
design on subplots within each cultivar-by-harvest
combination. The resulting pesticide treatments in-
cluded insecticide only, herbicide only, both insec-
ticide and herbicide, and neither insecticide nor
herbicide. Alfalfa was irrigated to maintain high
forage productivity throughout the growing season.

Yields were recorded from four or five harvests
annually during the second through sixth years of
stand life for the study area. Weed content of forage
was estimated at each harvest, which allowed es-
timating alfalfa yield separately from total forage
yield and adjusting total harvested forage when
weeds were present.

At the end of the five-year study, alfalfa was
Valuedbasedontheaveragepricefrom 1982 to 1987
in Oklahoma. Alfalfa value was discounted for weed
content based on sale data from HAYMARKET in
Oklahoma (Ward 1987). Total value for alfalfa
produced per acre was adjusted for harvest and
pesticide treatment costs, though no adjustment was
made for seed cost differences among cultivars.
Variable costs for insecticide and herbicide applica-
tions and for late-season harvesting were based on
1987 estimates. Cattle grazing costs were assumed
bome by the livestock enterprise and not the alfalfa
enterprise. The value of grazed alfalfa was also
assumed to be attributable to the cattle enterprise in
the form of weight gain and thus was not associated
with the alfalfa enterprise. Adjusted value of alfalfa

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