Effects of long-wave UV light on Monilinia growth and identification of species

The effect of long-wave UV/dark period on mycelial growth of 46 isolates of Monilinia sp. collected in Spain and 16 isolates collected from other part s of the world was investigated. Typical isolates of M. laxa, M. fructigena , and M. fructicola were grown in the dark and identified by morphological characteristics. Long-wave UV/dark conditions reduced the growth rates of M . laxa, M. fructigena, and M. fructicola on potato dextrose agar. All isola tes of M. fructigena grew more slowly than those of M. fructicola. Typical and atypical isolates of M. fructigena and M. fructicola were placed in the ir respective species based on long-wave UV/dark growth rate data. M. laxa isolates were readily distinguished by the shea distance from their conidiu m to the first germ tube branch. The involvement of different photoreceptor s in photoresponses by M. fructicola and M. fructigena is discussed. Differ ences in mycelial growth under long-wave UV may be a useful tool to identif y Monilinia spp.