Effect of early contamination by <em>Botrytis cinerea</em> on the development of Grey mould on Muscat d’Italie in Tunisian vineyard

Abstract

Grey rot, caused by Botrytis cinerea, is nowadays the most damaging disease of the Tunisian vineyard. The fungus attacks berries at the maturation stage and causes important economic losses. The protection of vineyard against this disease is very difficult due to the fungus characteristics. In fact B. cinerea is in the border of parasitism and saprophytism, in pre-veraison it usually survive as saprophyte then it attacks berries before their maturation. The purpose of this study is to highlight the role of pre-veraison’s contamination by B. cinerea on the development of the Grey rot on the berries after veraison. The results revealed that at the pre-veraison stage, B. cinerea grows as a saprophyte. The fungus’s rate presence is low on the barks (less than 10 %), very high on the floral buds (between 5 and 27 %) and relatively high in the immature berries (about 20 %). The quantification of bunches pollution, showed that the rate of contaminations by B. cinerea is very high (more than 70 %). On the other hand, the mapping out showed up that outbreak of the disease happened after veraison on Muscat d’Italie. Also, the rate of berries’ rot, were different each year, in relation to the climatic conditions and plant’s physiology. We found that the rate of rot inside bunches is relatively high (between 15 and 40 %) due to condia on stem or B. cinerea latent. The statistical analysis showed significant relationships between the rate of latent B. cinerea and the appearance of the disease after the veraison stage. Also, the scoring of conidia observed in the air showed a big activity of the fungus during flowering and the maturation of berries