Environmental Entomology (1988) 17, 911-914

Jim M. Story, Keith W. Boggs and William R. Good (1988)
Optimal timing of 2,4-D applications for compatibility with Urophora affinis and U. quadrifasciata (Diptera: Tephritidae) for control of spotted knapweed
Environmental Entomology 17 (5), 911-914
Abstract: Field studies were conducted in 1983 and 1984 to determine the optimal timing of 2,4-D ((2,4-dichlorophenoxy) acetic acid) applications for compatibility with two seed head flies, Urophora affinis Frauenfeld and U. quadrifasciata (Meigen), introduced for control of spotted knapweed, Centaurea maculosa Lamarck, in Montana. Application of 2,4-D at the spring rosette stage had no effect on the adult emergence of either fly species in either year. Application of 2,4-D at the flower-bud and flowering stages had no effect on the emergence of U. quadrifasciata but significantly reduced the June emergence of U. affinis during both years except for the 1984 application at the flowering stage. Integration of the two fly species and the herbicide, 2,4-D, at the rate of 2.25 kg (AI)/ha, for the control of spotted knapweed is possible if the 2,4-D is applied during the spring rosette stage in May.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
control - general
Research topic(s) for beneficials or antagonists:
resistance to pesticides

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Centaurea stoebe micranthos (weed)		U.S.A. (NW)
Urophora affinis (weed bioagent)	Centaurea stoebe micranthos (weed)		U.S.A. (NW)
Urophora quadrifasciata (weed bioagent)	Centaurea stoebe micranthos (weed)		U.S.A. (NW)