Determination of reactions of citrus species and varieties to Alternaria alternata f.sp. citri isolates a causal agent citrus brown spot

In this study, the host range of Alternaria alternata f.sp. citri isolates, cause of brown spot disease on citrus, was determined by use of spore inoculation and by reaction to toxins released during mycelial growth.33 citrus cultivars, grown in Çukurova Region for a long time or new in region, were tested to 13 different isolates of the fungus.Robinson, Dancy, Minneola Tangelo, Fortuna ve Lee mandarin varieties very susceptible to the fungus while Fremont, Hernandina, Clemantin resistance. Sweet orange and lemon cultivars were generally resistance. Rio Red and Star Ruby grapefruit were sensitive to its spore suspension, while Hernandina was to its toxins.Among the tested mandarin varieties in vivo Dancy, Fortune, Nova, Minneola Tangelo were found highly sensitive, Robinson and Ortanic were found medium and low sensitive respectively, the other tested varieties had no infection symptoms. Only 4 orange varieties (Cara Cara, Moroblood, Valencia Midknight and Valencia) were shown low sensitivity, the others had no infection symptoms. The tested lemon varieties had no infection symptom at all. The most sensitive variety was Riored among the grapefruit varieties. While Star Ruby variety had shown medium sensitivity and Henderson were shown low sensitivity.