Integration of biological and chemical control of brown rot of stone fruits to reduce disease incidence on fruits and minimize fungicide residues in juice

Brown rot is a major disease of stone fruits caused by Monilinia spp. It can reach high incidence that leads to considerable losses during storage. Our work aimed at the evaluation of innovative biological and integrated approaches to control brown rot of apricots and peaches, and of their influence on the presence of fungicide residues both in the harvested fruits and derived peach juices. In this work, we report the results of a two-year field investigation carried out in 5 different farms in Southern Italy. Plant health management strategy was based on two treatments performed in the last thirty days before harvest. Two biocontrol agents (BCAs), the yeast Rhodotorula kratochvilovae strain LS11 and the commercial biofungicide Serenade Max ® (based on Bacillus subtilis strain QST 713), were applied alone (biocontrol) or in combination with low doses of the fungicides (25% of full dosage, integrated control) cyprodinil (30 days before harvest), and boscalid (7 days before harvest). The highest protection was recorded in conventional (fungicides applied at full dosage) and integrated control treatments, both on apricots and peaches. In the integrated control, residues of fungicides in fruits and in peach juice were significantly lower compared to those of the conventional control in both fruit species. Our data show that biological and integrated control based on two key treatments at thirty and seven days before harvest can be considered as effective and safer control strategies of brown rot of stone fruits. Furthermore, the applied strategies can dramatically reduce and even set to zero the level of fungicide residues in derived fruit juices.