SEM observations of 12 species of the genera Triticum, Hordeum, A\•ena, Secale, Panicum, Setaria, Bromus and Glyceria contribute to a better understanding of the exine sculpture and lead to the description of 4 types. No fundamentally new features were revealed and the scope of SEM may be limited to that context. A higher degree of reliability in the identification of the pollen types may be achieved if all available Ll\1 and SEM characters are combined and if the ecological differences of those wild grass species ranging within the pollen size of cereals are taken into consideration as an exclusive factor. Finally the existence of a taxonomic patterning of the exine sculpture is confirmed.

Yeasts are potential antagonists of microorganisms in the phyllosphere. Due to their osmotolerance, they should also be able to colonize apple flowers. In field experiments, we applied yeast agents against fireblight at two different sites in the southern part of Germany. They showed efficiencies 0–20% below Plantomycin (streptomycin). Co‐culture experiments in liquid basal media with synthetic nectar resulted in suppression of Erwinia amylovora by yeast. This effect could not be confirmed with population studies of yeasts and E. amylovora in flower clusters. Field and laboratory experiments indicated that yeasts have antagonistic properties against fireblight but further research is needed to investigate this potential.

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