Insect Thresholds of Corn

Pest		Threshold	Reference
	western bean cutworm      field corn      sweet corn	1 plant in 7 with egg masses or injury 1 plant in 20 with egg masses or injury	UI CIS 302 (1993)
	western corn rootworm      seed corn        sweet corn	2 beetles per plant and less than half of plants have been pollinated 5 beetles per plant and less than half of plants have been pollinated Treat field NEXT YEAR at planting for larval control if infestation averages 1 beetle per plant THIS YEAR and field will be planted in corn	UI CIS 924 (1992)

Thresholds are not available for these pests: corn earworm; corn leaf aphid; cutworms, -army cutworm, -black cutworm, -redbacked cutworm, -spotted cutworm, -variegated cutworm, -western yellowstriped armyworm; earwig; garden symphylan; grasshoppers/crickets; oat bird-cherry aphid; seedcorn maggot; slugs; two-spotted spider mite; white grubs; wireworm.

References:  UI CIS 302 Western bean cutworm on beans and corn, UI CIS 924 Western corn rootworm.

Revised: August 12, 2008

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