Lamb et al. When a fungus is homothallic and self-fertile, one needs to obtain crossed fruiting bodies such as perithecia, and to distinguish them from selfed fruiting bodies. Most incubations in Israeli x American crosses and Israeli x Canadian strains were at 25, with two or more replicate plates, but some further replicates were crossed at 17.5, producing no differences in cross-fertility results but a longer maturation time. Mature perithecia were dissected in 2M sucrose solution and the asci were viewed at x 80 to see the ascospore colour segregation ratios.
Strains often become less self-fertile with time, especially with repeated subculturing.
El-Ani et al. Most American and Canadian strains were reisolates of Olive's original ones, from ascospores from selfed crosses. The strains crossed here, their genotypes and their cross-fertility results are given in Tables 1 to 3. At least 20 perithecia per dish were examined from each cross, mainly from near the line where the two strains met, or from either side of the visible fertility barrier where one was formed. In the latter case, there were usually many selfed perithecia on either side of the barrier.