Economic injury levels for Spodoptera frugiperda (Lepidoptera: Noctuidae) on silage corn in Maryland
1993
Pereira, C.J. | Hellman, J.L.
The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a serious pest of corn in Maryland. To estimate the relationship between number of larvae per plant and plant weight at two plant growth stages for single-cultivar stands of silage corn, field experiments were conducted in 1988 and 1989. In 1990, single- and mixed-cultivar stands at mid-whorl were compared. Significant reductions in plant weight as a function of larval density (5, 10, 15, and 20 second instars per plant) were observed for artificial infestations at mid-whorl and late-whorl stage corn. No relationship between larval density and plant weight was detected for the mixed-cultivar stand infestation at mid-whorl stage. Using the observed relationships of plant weight and number of larvae per plant, crop value of $988/ha, and management cost of $37/ha, economic injury levels were set at two second-instar fall armyworms per plant for mid-whorl infestations during 1988, 1989, and 1990 and for late-whorl infestations in 1988 and 1989.
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