Coryneum Microstictum on Rose from Oregon

SUMMARY

On specimens of Coryneum microstictum on cankered rose canes from Oregon the conidia measured essentially the same as those on rose from the eastern part of the United States; those from Canada and England were somewhat smaller. Composite measurements of conidia from all these sources (10.8-23 μ × 4.6-9 μ) accord well with those previously published by others for this species on rose, which are also variable.

Culturally the fungus from Oregon resembled that from eastern United States, although it was separable in color. It was also similar to an authentic culture of C. microstictum var. Mali. These three cultures produced a noticeably less restricted growth than two cultures of C. Beyerinckii from different sources (Oregon and Europe) included in the same comparison, and also shown to be separable from each other.

In culture conidia of C. microstictum from Oregon were often larger than those direct from the cankers, and some were much longer with as many as seven cells. They were similar to the conidia from the other culture of this species from eastern United States.

Conidia of the two cultures of C. Beyerinckii differed from each other. In the one from Oregon they were few-celled and relatively shorter, whereas in the one from Europe they were usually longer and sometimes contained as many as seven cells.