Protective and Curative Activity of QoI and DMI Fungicides Against Botrytis cinerea on Strawberry

Strawberry is considered to be an essential strategic crop due to its great economic value. Grey mold disease, induced by Botrytis cinerea, is a major constraint to strawberry production worldwide, causing considerable economic losses. Protective fungicides considered essential tool in management strategies. Recently, fungicides ineffectiveness observed widely in many countries due to the evolution of resistance in B. cinerea which poses an ongoing threat to strawberry production. Therefore, this investigation carried out to test the following fungicides Speedcide (difenoconazole DMIs), Tilt (propiconazole DMIs) and Tazer (azoxystrobin QoIs) against B. cinerea and to evaluate the fitness penalties of B. cinerea resistant isolates.the results indicated that among the collected isolates 13 (43.33%), 15 (50%) and 18 (60%) were resistant to difenoconazole, propiconazole and azoxystrobin. The assessment of fitness penalties of resistant isolates revealed that all the tested isolates were able to infect and develop lesions on strawberry leaves. Tilt (Propiconazole) had the strongest inhibition activity, as a protective and curative treatment with mean 91.89 and 71.45%, respectively. Finly, the application of Tilt fungicide inhibited spore germination on the leaf surface and proved its effectiveness against both resistant and sensitive isolates.