Efficacy of Fungicides for Control of Colletotrichum gloeosporioideson Dendrobiums

Abstract

Dendrobium clone hybrid plants, one-year-old, were potted in hard coco on 10 Sept. 2009. Plants were fertilized weekly with 150 ppm Peters Professional 20–20–20 water soluble fertilizer (The Scotts Company, Marysville, OH). The experimental plants were inoculated with conidia spores of Colletotrichum gloeosporioides. Twelve plants per treatment were arranged in a completely randomized design. Fungicide treatment were sprayed until runoff using a compressed air hand pump sprayer on 10 Mar. to 10 May 2010. The foliage was allowed to dry and the conidia spore inoculum was applied using a spray bottle. Colletotrichum gloeosporioides lesions were counted on 17 May 2010. Plants were rated on a scale of 1 to 10, where 0 = no disease and 10 = plant defoliated. Treatments were: Control, Pageant 38% WG at 6.0 oz per 100 gal, Pageant 38% WG at 12.0 oz per 100 gal, Cleary’s 3336 4F at 6.0 fl oz per 100 gal, Pentathlon LF at 32.0 fl oz per 100 gal, Heritage 50 WG at 4.0 oz per 100 gal, Insignia 20% WG at 4.0 oz per 100 gal, and Insignia 20% WG at 8.0 oz per 100 gal. All fungicide treatments gave some control of C. gloeosporioides. Pageant at 12.0 oz and Insignia at 8.0 oz provided excellent control followed by Heritage and Cleary’s 3336.