APS Homepage

Poster: Biology & Disease Mgmt: Chemical Control


Greenhouse characterization of hydrazone-copper mixtures as low copper treatments to control early and late blight on tomato
C. AVILA-ADAME (1), D. Young (2), J. Webster (2), O. Brian (2), D. Ouimette (2) (1) Dow AgroSciences LLC, U.S.A.; (2) Dow AgroSciences LLC, U.S.A.

Copper-based fungicides remain critical tools in crop disease management programs to control a broad spectrum of fungal and bacterial plant pathogens. However, because of the high rate required to control plant pathogens, there is concern regarding their potential negative environmental impact. Certain salicylaldehyde benzoylhydrazone (SBH) compounds bind copper and show strong synergism with copper when tested for inhibition of fungal growth under in vitro conditions. Experiments were conducted to characterize synergism for Cu-hydrazone mixtures in controlling Phytophthora infestans and Alternaria solani on tomato under greenhouse conditions. Treatments included a SBH alone, three copper materials, and Cu-SBH mixtures. The SBH alone was weakly active against both pathogens with 26 and 33% disease control at 400 micromolar for P. infestants and A. solani, respectively. The copper materials, which included Cu(OH)2 in the form of KocideĀ® 2000, CuSO4, and CuCl2, provided a similar level of disease control (p > 0.3) when applied alone. The copper-SBH mixtures at various molar ratios produced synergistic interactions in nearly all combinations and were superior to the commercial fungicide KocideĀ® 2000 at equivalent rates of copper.