In vitro susceptibility test of Cladosporium cladosporioides isolates from Argentinian tomato crops against commercial fungicides

MACHUCA, LAURA MACHUCA; ACUÑA OJEDA, MARIA FLORENCIA; ALFARO, ESTEBAN; SPAGNOLO, LORENA CECILIA; OBREGÓN, VERÓNICA GABRIELA; IBAÑEZ, JULIA MAGALÍ; MURGUÍA, MARCELO CÉSAR

Journal of Horticultural Sciences

Society for Promotion of Horticulture

Lugar: Bengaluru; Año: 2023 vol. 18 p. 432 - 438

0973-354X

Tomato cultivation is an important agricultural activity in northeast of Argentina, and disease control isindispensable for its production. The purpose of the current study was to identify two fungi isolated from tomatoplants cultivated in greenhouses, with symptoms of leaf mould disease and a strain of the genus Cladosporiumfrom a culture collection, and evaluate their in vitro susceptibility to four commercial fungicides. Macro andmicroscopic examination, molecular characterisation and sequence analysis were applied for identification. Brothdilution and spread plate methods were used to determine the minimal inhibitory concentration (MIC) and minimalfungicide concentration (MFC). The active ingredients of the products were azoxystrobin+difenoconazole,trifloxystrobin+tebuconazole, chlorothalonil and metalaxyl-M+mancozeb. The results were processed using theKruskal-Wallis method. The isolates were identified as Cladosporium cladosporioidesa-c; consequently, lesionsfound on tomato plants did not correspond to Cladosporium fulvum. There was a significant statistical differencebetween the obtained values. Qualitatively, the three strains had a similar behaviour for chlorothalonil(MIC values: 0.25 - 0.5 μg/ml, MFC values: 4 μg/ml).In all cases, tests with metalaxyl-M+mancozeb yieldedhigher values than those achieved for chlorothalonil (MIC values: 8 μg/ml, MFC values: 8- 32 μg/ml).trobilurin-formulated fungicides were less effective against C. cladosporioidesa-b (MIC values: 16-256 μg/ml,MFC values: >64 μg/ml). C. cladosporioidesc was the most sensitive isolate. The information about the presenceof a non-frequent fungus and its fungicide susceptibility, would be useful for establishing control strategiesand enhance production.