Studies on the Mycoflora of New Zealand Barley Seeds (Hordeum Vulgare L.)

Abstract

The seed-borne fungal flora of 32 samples of New Zealand barley seeds was studied using the following detection methods:- the modified filter paper method, heat treatment method, benomyl agar method and rose bengal agar method. The heat treatment method was the most efficient for detecting the pathogens Drechslera teres and D. sorokiniana. Seventy-three species of fungi belonging to 44 genera were identified; 20 of these have not been recorded previously on New Zealand grown barley. Alternaria alternata, Cladosporium spp. (including C, cladosporioides and C. herbarum}, Sporobolomyces roseus, Drechslera teres, D. sorokiniana and Epicoccum nigrum were frequently recorded. A non-pathogenic albino strain of A. alternata was isolated. The pathogens of barley that were isolated were D. teres, D. sorokiniana, Fusarium culmorum and F, graminearum. Drechslera graminea was not recovered. Alternaria alternata, Cladosporium spp., D. teres, D. sorokiniana and E. nigrum were found to decrease gradually at different rates on the barley seeds during 8 months of storage in a silo while storage fungi, Aspergillus and Penicillium increased steadily, indicating poor storage conditions of the grains in the silo. Drechslera teres could survive up to 5 years on the barley seeds in the laboratory. Hence the use of old barley seeds cannot be recommended as a control measure to eliminate D. teres. In the laboratory test with 3 fungicides, the systemic mixture 'Vitaflo 200' gave effective control of Drechslera spp. while 'Baytan F17' did not perform so well because the active ingredient in this fungicide has little fungicidal effect on mycelial growth and spore germination in vitro. Nine species of fungi were described: an albino Alternaria alternata, Drechslera erythrospila, D. sorokiniana, D. teres, Drechslera sp., Fusarium avenaceum, F. culmorum, F. graminearum and Myrothecium leucotrichum.