WHITE SPOT: A NEW EMERGING DISEASE IN CORN
A WHITE SPOT DISEASE, earlier described as Phaeosphaeria Leaf Spot was first observed in Brazil in 1982. Later on, the disease was reported in South and Central America, South Africa, and Asia. Early stage of infection is characterized by the presence of small, pale green spots on the leaf surface (Figure 1). Advanced symptom of the disease includes bleached lesions causing blight of the whole leaf (Figure 2). Similar type of disease was first observed in Bukidnon in 2014 after a week of continuous light rain and foggy weather condition. Since then, severe infection is commonly observed in corn fields with mid-elevations (350-955 masl) throughout the growing season. Aside from field corn, the disease also affects sweet and waxy corn.
Several pathogens have been reported as causal agents of the white spot disease, which include Pantoea ananatis; Phaeosphaeria maydis (anamorph: Phoma maydis); Sclerophthora; and Phyllosticta sp., Phoma sorghina, Sporormiella sp. disease complex. The use of resistant varieties if available, application of fungicides such as mancozeb (e.g. Dithane) or pyraclostrobin (e.g. Cabrio) and removal of infected crop residues after each cropping season are among the practical means of white spot disease management.