Abstract

Sprays of benomyl and dichlofluanid applied to red raspberries at flowering time decreased berry contamination and subsequent spoilage by Botrytis cinerea, but either had no effect on the prevalence of Mucorales or resulted in greater berry contamination and subsequent spoilage by fungi of this group. Mucorales, mainly Mucor hiemalis and M. mucedo, were more frequently the cause of spoilage when fruit was incubated at 21 than at 10 deg C. The total number of mouldy berries in a sample was decreased by pre-harvest fungicide sprays, although the differences from the unsprayed controls were not always significant. Comparison with unsprayed controls showed that pre-harvest benomyl sprays decreased the percentage of berries with B. cinerea mycelium arising from the proximal row of drupelets, but had no effect on B. cinerea developing elsewhere on the berry. This suggests that proximal drupelet infections originate from infected flower parts and are therefore reduced by the application of fungicides at flowering, whereas mycelium elsewhere on the berry may originate from the direct germination of spores on the berry surface and is less likely to be affected by pre-harvest fungicide sprays. It is suggested that neither benomyl nor dichlofluanid applied during flowering can entirely eliminate post-harvest spoilage of raspberries, because (a) latent infections by B. cinerea take place during the intervals between fungicide sprays, (b) some post-harvest rots are initiated by the direct germination of B. cinerea spores on the berry surface, and (c) fungi in the Mucorales are not controlled by either of these fungicides.