Studies on a species of Monosporascus isolated from Triticum

A species of Monosporascus isolated from darkened stem bases of Triticum in Libya is compared with the two known species of the genus: M. cannonballus and M. eutypoides. The isolate resembles M. cannonballus in the type of ostiole developed but M. eutypoides in having mainly two-spored asci. It differs from M. eutypoides in having a reduced ostiole but this may be a response to growth in culture as this species has only previously been reported from infected tissues. In addition to having mainly two-spored and not one-spored asci, the isolate differs from M. cannonballus in that the spores pass through a stage in which a reticulum is visible when viewed by SEM. SEM photographs of the spores of both M. cannonballus and M. eutypoides, to which species this fungus is tentatively referred, are included. On germination the ascospores of the Triticum isolate produce 5--10 germ tubes. A growth curve for cultures is provided showing that the optimum temperature for growth is in the range 25--35 degrees C. Subcultures held at 48 degrees and 55 degrees C for five days failed to grow when transferred to 30 degrees C but ones held at 45 degrees for the same period grew normally when the temperature was reduced to 30 degrees C. The appearance of the colonies at different temperatures is also described.