Effect of Diaporthe/Phomopsis Species Isolated from Soyabean and Abutilon theophrasti on Soybean Seed Germination

Twelve isolates of Diaporthe/Phomopsis species from soybean (six isolates) and Abutilon theophrasti (velvetleaf) (six isolates) were studied for their pathogenicity to soybean and their effect on soybean seed germination and seedling survival after artificial seed inoculation. The following criteria were taken into consideration: number of germinated and rotten seeds, seedlings with necrosis, germ length and length of necrotic lesion. All tested Diaporthe/Phomopsis isolates caused seeds rot. P. longicolla isolates from soybean plants (PL1 and PL2) and isolates from velvetleaf (AbPL1 and AbPL2) exhibited statistically significant decrease in germ growth. These germs were only 1.0– 1.8 cm long. No relation between length of germs and length of necrosis was found. The highest percentage of decayed seedlings was determined in the isolates AbPL1 and 2 as well as in PS 1 and PL 1 20 days after inoculation. Results of our research showed that Diaporthe/Phomopsis species from velvetleaf could be more pathogenic on soybean than isolates of the same species from soybean.