The phylloplane microflora of ripening wheat and effect of late fungicide applications

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Abstract
SUMMARY: Flag leaves and ears of spring wheat cv. Timmo (in 1980) and winter wheat cv. Maris Huntsman in 1981 and 1982 were colonised by a variety of micro‐organisms whose numbers increased rapidly between anthesis and harvest. The predominant mycoflora were yeasts, yeast‐like fungi and filamentous fungi which included Cladosporium spp., Verticillium lecanii, Alternaria alternata, Fusarium spp. and Epicoccum nigrum. Although similar species were isolated, their relative abundance on flag leaves and ears differed. The fungicide captafol was most effective as a protectant and significantly decreased populations of fungi on flag leaves and ears for 6 and 4 wk respectively, compared to untreated controls. Benomyl and Delsene M (carbendazim + maneb) were the most effective of the systemic sprays and formulations. In general, fungicides affected populations of yeasts, yeast‐like fungi and Cladosporium spp. most while Alternaria was tolerant of all treatments. Yields of winter wheat were increased in two seasons by an average 0–2 t ha‐1 (2–4%) following a single late fungicide treatment at G.S. 50 or 60 and 0–41 t ha‐1 (5‐1%) when this was combined with an early spray against foliar diseases (G.S. 38–40). Individual treatments increased yield by up to 12% with little difference between applications at G.S. 50 or 60. The yield benefit came mainly from increased 1000‐grain weights. Germination of the treated grain was increased only slightly.