Abstract:
To clarify the pathogen of anthracnose on
Zinnia elegans Jacq., according to Koch's law, the diseased leaves were collected for the pathogen isolation and pathogenicity testing. After the pathogenicity test, based on their morphologic characteristics, the isolates were proved to be closely related to
Colletotrichum species. To further investigated the pathogen, molecular identification based on the phylogenetic analysis of
ACT (actin gene),
CHS (chitin synthase A gene),
GAPDH (glyceraldehyde-3-phosphate dehydrogenase), ITS (ribosomal internal transcribed spacer),
SOD2 (manganese-superoxide dismutase),
GS (glutamine synthatase)
, CaM (calmodulin) and
TUB2 (beta-tubulin) was conducted and the pathogen was identified to be
C. siamense. Furthermore, the antibiotic activity of nine fungicides to this pathogen was tested
in vitro and it was found that the EC
50 values of trifloxystrobin + tebuconazole 75% water dispersible granule (WG), triflumizole + tebuconazole 35% suspension concentrate (SC), chlorothalonil 75% wettable powder (WP), azoxystrobin 250 g/L SC, prochloraz 50% WP, difenoconazole 10% WG, prothioconazole 10% SC, fluazinam 500 g/L SC and bromothalonil 25% WP were 0.152, 0.407, 2.48, 252, 0.0342, 0.556, 317, 0.00291 and 27.4 mg/L, respectively. Among them, fluazinam 500 g/L SC and prochloraz 50% WP showed the strongest fungicidal activities.