Downy and Powdery Mildew of Lettuce: Comparison of Chemical Management Tools in 1997

• Main Authors: Matheron, Michael E., Porchas, Martin
• Other Authors: Oebker, Norman F.
• Language: en_US
• Published: College of Agriculture, University of Arizona (Tucson, AZ) 1997
• Subjects: Agriculture > Arizona; Vegetables > Arizona; Lettuce > Arizona; Lettuce > Diseases
• Online Access: http://hdl.handle.net/10150/221600

Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development of downy mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for management of these diseases in 1997. A very low level of downy mildew occurred during this trial; however, all treatments significantly reduced the number of leaf lesions compared to nontreated lettuce plants. Powdery mildew was quite intense at crop maturity and was significantly lower, compared to nontreated lettuce, on plants treated with Microthiol Special, BAS 490 + Bravo Weather Stik, Quadris, and two additional treatments not usually found to reduce this disease.