ON CLADOSPORIUM HERBARUM : THE QUESTION OF ITS PARASITISM, AND ITS RELATION TO “THINNING OUT” AND “DEAF EARS” IN WHEAT

Summary. The only types of Cladosporitun found occurring on our four cereals were strains of C. herbarum , not different species. Five strains of C. herbarum , tentatively termed “prevalent strains” of wheat, barley, oats, cabbage and broccoli, were isolated from these plants respectively. The bud‐spore forms, or so‐called Hormodendron stages, of these strains do not differ in parasitic capacity from the normal Cladosporium forms; they do not cause perforation of leaves. None of these strains of C. herbarum , and they may be regarded as typical of the species, is parasitic in any stage or form on brassicas or cereals; they are all “semi‐parasitic,” establishing themselves on, and thereafter hastening the death of, dying tissues. C. herbarum is not the cause of “thinning out,”“premature ripening (whiteheads),” or “deaf ears” in wheat.