engleski

The sensitivity of Botrytis cinerea Pers. Fr. to new botriticides in the vineyards

Botrytis cinerea, the cause of grey mould, is a fungus well known for the fast development of resistance to fungicides for its control. The problem of resistance of B. cinerea is especially pronounced in the protection of vineyards because grey mould is one of the economically significant grape vine diseases. In the continental part of our country the disease inflicts damages of 50 to 60%, and in the Mediterranean part 3 to 5%, which continue in the wine making process. In order to overcome the problem of resistance there are continuous world efforts to develop new active agents. New agents, in addition to having a good efficacy against B. cinerea should enable the control of biotypes, which are resistant to existing fungicides. Their mode of influence should not be such that it selects new resistant biotypes. Within such research methods are being developed for testing the sensitivity of B. cinerea. By performing tests in field trials during the pre-registration phase of fungicide testings it is possible in B. cinerea populations to detect biotypes that are naturally resistant to the active agent that has not been applied yet. These can be signs for the rapid appearance of resistance if the active agent were to be applied intensively. During the last 5 years new active agents have been developed in the world, of which pirimetanil and ciprodinil from the anilinopirimidine group were acknowledged in Croatia in 1997, and fenhexamide (hidroxianilide) in 1998. Until then the palette of botriticides was based on agents from the dikarboximide group, the use of which is limited to twice during vegetation due to resistance. Dikarboximide-resistance was scientifically proven in Croatia in 1993. In 1998 and ’ 99 The Department for Plant Pathology conducted trials in which the state of field populations of B. cinerea was tested in vineyards in which the mentioned agents had been applied intensively, but also in vineyards in which they had never been used. The tests were performed in vitro. Since there are as yet no published methods for testing the sensitivity to fenhexamide, the same test was applied for this purpose and assessed as appropriate. Biotypes of B. cinerea that are naturally resistant to pripimetanil, ciprodinil and fenhexamide were determined both in vineyards with the performed intensive control and in vineyards in which these agents had never been applied. The obtained results are a warning sign for the application of the mentioned agents, but there is still no danger of the appearance of practical resistance.

Botrytis cinereea; cyprodinil; fenhexamide; grapevine; Pyrimethanil; resistant biotypes

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