Integrated management of Botrytis cinerea in protected raspberriesto minimize fungicide residues in the fruit

Abstract: Botrytis is the major cause of post-harvest fruit rotting and can cause significantreduction in yield. Generally fungicides are applied during flowering and early fruit to controlbotrytis. This results in fungicide residues in the fruit and retail surveillance has shown that morethan 50% of UK produced fruit contains fungicide residues. This is no longer acceptable to themarket and so alternative approaches to disease control must be explored to enable raspberryproducers to significantly reduce this incidence of residues. Raspberries suffer from rain damageand, to meet the quality requirements of major multiple retailers, much of the crop is now grownunder protection. This new growing environment provides opportunities to reduce reliance onpesticides.In 2006 a 5-year HortLINK project was initiated to develop sustainable methods ofintegrated management of pests and diseases of protected raspberry to produce quality fruit withminimal risk of detectable pesticide residues at harvest. Here only the results with control ofBotrytis are presented.In the first three years fungicides and alternative products were evaluated for control ofBotrytis fruit rot in replicated field trials. However, none of the fungicides or alternative productswas effective in reducing the incidence of Botrytis fruit rot. The greatest reduction in Botrytis wasachieved by improved cool chain management of the fruit post-harvest i.e. rapid removal of fieldheat at 1-2°C followed by increased cooling at 2-3°C in the two days prior to marketing. Thisresulted in a significant reduction in fruit Botrytis assessed 6 and 8 days after harvest comparedwith the standard post-harvest management at 4-5°C.In the fourth year of the project a management system for Botrytis based on good crophygiene and cane management together with early season (pre-flowering) and post-harvest use offungicides, rapid fruit cooling after harvest and high quality cool chain marketing of the fruit wascompared for control of Botrytis with the growers’ standard programme in two large scale trialson commercial farms. A combined analysis of the data from both sites indicated there were nosignificant differences in percentage marketable fruit or percentage with Botrytis rot between theintegrated management system and grower standard system. The management system will befurther evaluated in 2010.