GRAPEVINE TRUNKS DECLINE ASSOCIATED WITH MACROPHOMINA PHASEOLINA

Macrophomina phaseolina fungi were isolated from infected grape branches and it was identified using morphological and molecular characteristics. M. phaseolina colonies were observed on PDA medium with a distinct color gradient between dark gray and black, and formed microsclerotia after 4-5 days. Molecular identification of the ITS 1,4 region of the two M. phaseolina isolates (grape1 and B66) was deposited in the NCBI database with accession numbers OQ802810 and PQ587052, which showed 99-100% identity with reference sequences in NCBI. The phylogenetic tree showed a clear evolutionary affinity between grape1 and BS6 isolates with minor differences due to environmental or geographical diversity. Chlorite susceptibility test revealed three growth patterns (dense, feathery, restricted). This reflects variation in their resistance or sensitivity and in the optimal temperature for fungal growth, with the maximum development of the two M. phaseolina isolates occurring at 30C. In contrast, growth was poor at low temperatures (15-20C) or at high temperatures (35 C). The pathogenicity test showed that the two M. phaseolina isolates caused clear disease symptoms, represented by general deterioration and wilting of the inoculated branches.