Evaluation of Lecanicillium longisporum, Vertalec for simultaneous suppression of cotton aphid, Aphis gossypii, and cucumber powdery mildew, Sphaerotheca fuliginea, on potted cucumbers

The commercial preparation of Lecanicillium longisporum, Vertalec^® was evaluated for simultaneous suppression of cotton aphid and cucumber powdery mildew on potted cucumber plants. Vertalec was applied onto cucumber plants that had been infested with either cotton aphid, spores of Sphaerotheca fuliginea or both. Irradiation-inactivated Vertalec (II Vertalec) was also applied to an identical series of cucumber plants as a control. The Vertalec was highly pathogenic against adult aphids with an LT₅₀ of 6.9 days. II Vertalec did not affect aphid survival. Application of either active or II Vertalec significantly suppressed spore production of S. fuliginea compared to the water control. For dual control assays, Vertalec applications were made one day after infestation of both aphid and S. fuliginea onto potted cucumbers. Fifteen days after the Vertalec treatments, the numbers of surviving aphids and the production of powdery mildew spores were significantly reduced compared with the water control. The presence of aphids also suppressed S. fuliginea spore production. Our results suggest the potential of a dual role for Vertalec as a microbial control agent of aphids and powdery mildew in cucumber.