High temperatures and humidity in southern New Mexico could bring on problems in chile with powdery mildew, a yield-reducing disease that damaged crops in 1996 and 1997. Powdery mildew fungus causes plant leaves to curl, exposing chile pods to sunburn injury. The amount of damage depends on when powdery mildew strikes said Natalie Goldberg, plant pathologist with New Mexico State University's Cooperative Extension Service. But if the disease is delayed until August or September, our losses are generally reduced. In fact, when the disease occurs very late in the season, it may actually provide a little bit of a benefit in defoliating the plants in time for red chile harvest.
Growers can take several steps to prevent crop damage, starting with thinning their chile.
Powdery mildew attacks the lower leaves of chile plants first. The disease causes a small lesion on the upper sides of leaves and a grayish powdery growth on the undersides. It gradually works its way up the plant as the disease develops. Sulfur is the only fungicide registered for powdery mildew in chile. Growers who can get the sulfur on early on the undersides of leaves and lower part of the plant canopy can see some reduction in disease severity.