EFFECT OF DIFFERENT FUNGICIDES IN THE CONTROL OF Botrytis cinerea Pers. in vitro AND in vivo IN STRAWBERRY (Fragaria×ananassa Duch.)

The aim of this study was to determine the effect of seven fungicides on Botrytis cinerea growth and control of gray mold in strawberry plants. Thus, the mycelial growth, germination and sporulation of an isolate of B. cinerea obtained from rotted strawberry collected from a strawberry farm located at Dlalha in Gharb-Loukkos region (Morocco) was tested in vitro in presence of seven fungicides currently used in the control of fungal diseases of strawberry crop. Additionally, the in vivo assay was conducted to evaluate the efficacy of these chemical products in repressing Botrytis development on strawberry plants versus different incubation and sampling time. Among the fungicides tested, Fenhexamid, Pyrimethanil were found to be most effective showing complete inhibition of mycelial growth even at lowest tested concentrations and during the four weekly intervals of incubation, Pyrimethanil, Pyraclostrobin + Boscalid, Thiram and Fenhexamid at ½ Recommended dose (RD) gave better result for sporulation inhibition than Cyprodinil+Fludioxonil (80.37%), Chlorothalonil (81.3%) or Mepanipyrim (58.87%) at the recommended dose. The effectiveness of Chlorothalonil was prevalent in inhibiting conidial germination (100%), while the other fungicides were less efficient with an inhibition percentages varying from 76.33 to 85.66% in presence of Cyprodinil+Fludioxonil, ranged from 79 to 79.66% respectively at ½ RD, ¾ RD of Pyraclostrobin+Boscalid. The pulverisation of strawberry plants with the mixture of Cyprodinil and Fludioxonil or Pyraclostrobin + Boscalid in the in vivo assay decreased the disease development to 92.56% and 92.74% respectively. Coformulations application provided an efficient and prolonged control against B. cinerea survival and development on leaves. In contrary, a colonization percentage of 59.49% was noted after Mepanipyrim sprays. Moreover, the plants showed increased fresh weight after treatment with Fenhexamid (8.3 g), Cyprodinil+Fludioxonil (8.1 g) and the mixture Pyraclostrobin+Boscalid (7 g). Moreover, strawberry weight was notably improved with an average ranged from 13 g and 17.7 g. In conclusion, with careful use of fungicides, mixing site-specific fungicides with multisite fungicides, the effective life of fungicides for gray mold control can be extended.