Chile peppers (Capsicum sp.) are a widely cultivated crop that is a staple in the diet of many cultures worldwide and is used as a vegetable, spice, ornamental, and medicinal plant (Bosland and Votava, 2012). There are five domesticated species: C. annuum L., C. baccatum L., C. chinense Jacq., C. frutescens L., and C. pubescens Ruiz and Pav., with C. annuum providing most of the commercial production in the world. In New Mexico, the chile pepper industry has cultural and economic significance with New Mexico having the largest area of chile pepper production in the United States (USDA, 2017).
A relatively new disease affecting chile pepper production in New Mexico is powdery mildew incited by L. taurica (Lév.) Arn. Powdery mildew is a major foliar disease that can cause serious economic losses (Palti, 1988). It is widely distributed in chile pepper production areas with confirmed existence from dry regions of Asia and the Mediterranean to more humid regions (Palti, 1988). It was reported in the North-Central Mexico states of Chihuahua, Zacatecas, and Aguascalientes in 1999 (Velásquez-Valle and Valle-Garcia, 1999). Since its introduction into the southwest region of the United States, losses to powdery mildew have varied year to year, with severe infection early in the season causing heavy yield losses (Murray, 2000). Application of fungicides may manage the disease; however, effectiveness depends on early detection and thorough coverage of the plant, which can be difficult (Goldberg, 2004). The most economically and environmentally sustainable management of powdery mildew is through resistant cultivars. In this study, a wide range of germplasm was evaluated for resistance to powdery mildew.
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