Researches on incidence, bioecology and control of turcicum leaf blight (Exserohilum turcicum (Pass) Leonard. and Suggs) and maydis leaf blight (Helminthosporium maydis nisik.)diseases in corn fields in Adana province of Turkey and response of cor

ABSTRACT PhD THESIS RESEARCHES ON INCIDENCE, BIOECOLOGY AND CONTROL OF TURCICUM LEAF BLIGHT (Exserohilum turcicum (Pass) Leonard, and Suggs) AND MAYDIS LEAF BLIGHT (Helminthosporium maydis Nisik.) DISEASES IN CORN FIELDS IN ADANA PROVINCE OF TURKEY AND RESPONSE OF CORN VARIETIES TO THESE DISEASES Veli ÇETİN DEPARTMENT OF PLANT PROTECTION INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor : Prof. Dr. N. Kemal KOÇ Year: 1999, Pages: 131 Jury : Prof. Dr.N. Kemal KOÇ : Doç. Dr. Abuzer SA?IR : Doç. Dr. Ali ERKILIÇ Problems in corn areas in Adana province have increased in parallel to enlarging corn growing areas. Two leaf blight diseases, which caused by Exserohilum turcicum (Pass.) Leonard and Suggs, and Helminthosporium maydis Nisik., have high importance level among these problems. In vitro characteristics, incidences in Adana province, overwintering features and control measures of these diseases and responses of corn varieties were researched between 1994 - 1998. The largest colony in diameter of E. turcicum was obtained in modified PDA, which has less decstrose and that of H.maydis was obtained in oat agar. The conidia number for both species was the biggest in peptone decstrose agar. The optimum pH range for colony development was 5 to 9 for both diseases. Temperature request was different for optimum colony development; 25°C was the best for E.turcicum and 30 °C was the best for H. maydis. Duration of illumination did not effect E. turcicum growth while H. maydis growth decreased in parallel to getting decrease of illumination. Maydis leaf blight was found more important then Turcicum leaf blight in Adana province. Both species were not able to overwinter under ground. Moreover, duration of survivance of conidia was decreased where they were allocated deeper in the soil. They could only overwinter where they were on plant which has not been harvested or on plant debris on the soil surface. All cultivars and hibrits tested against to Turcicum leaf blight under natural conditions were found resistant in 1994. According to results of the tests carried out under artificial inoculation conditions, they found as 16 resistant, 2 moderately resistant, 4 moderately susceptible, in 1996 and 16 resistant, 3 moderately resistant, 5 moderately susceptible in 1997. Against to Maydis leaf blight, they found as 6 resistant, 3 moderately resistant, 9 moderately susceptible and 1 susceptible, in 1995, 5 resistant, 5 moderately resistant, 6 moderately susceptible and 7 susceptible in 1997. Maneb, mancozeb, metconazole, prochloraz, propiconazole, cyproconazole and çaptan were controlled these diseases, but carbendazim and triadimenol was not effective in greenhouse conditions. Key words : Corn, E.turcicum, H. maydis II