Effects of toxin from a crude extract of E. turcicum on disease symptoms
development in sweet corn
The fungal isolate DI, previously tested as a virulent strain, had been
grown on PDA for 8 d before transferring 5 discs (0.5 cm diameter) to each
flask containing potato dextrose broth (PDB), and incubated on a rotary shaker
at room temperature for 2 wk. The cultures were then filtered through Whatman
paper No.1 via vacuum pump. The cultures were mixed with 10% ethyl acetate
and were shaken thoroughly. The cultures stod for 30 min to separate toxin
from suspension. The suspension was separated into two parts; the top part was
taken to be extracted, using a rotary evaporator at 55o C with a pressure of 200
lb and speed of 50 rpm, repeated three times. The crude extracts were then
dissolved with deionized water and mixed with methanol at the ratio of 9: 1 and
then mixed with hexane at 2: 1. The extracts stood for a period of time to let the
solution separate. Once again the top part was mixed with hexane (1: 1). The
crude extracts (toxin) were then tested for their effect by dropping the fungal
toxin on the leaves of sweet corn variety Hibrix3 (2-wk-old), then incubated in
a moist chamber. The results of E. turcicum toxin on the leaves were recorded
at 3 d after application.