Response of some Commercial Strawberry Cultivars to Infection by Wilt Diseases in Egypt and their Control with Fungicides

Abstract

Isolation trials carried out from naturally infected strawberry plants by wilt diseases grown in three Counties at Qalubiya Governorate resulted in the presence of four fungi with different frequencies. These fungi were identified as Fusarium oxysporum, Verticillium dahliae, Rhizoctonia solani and Pythium sp. Pathogenicity test using the four fungi showed that only F. oxysporum and V. dahliae were able to cause the typical symptoms of wilt. Evaluation of six strawberrycultivars against F. oxysporum and V. dahliae under greenhouse conditions revealed that cvs. Festival, Florida and Sweet Charlie were less susceptible. While under field conditions they exhibited low percentages of final disease severity and low values of area under disease progress curve (AUDPC), low values of relative area under disease progress curve (rAUDPC) and low rates of infection (r-values) during the two tested growing seasons of 2010/11 and 2011/12. On the other hand, cvs. Fortuna and Camarosa exhibited the opposite results in this respect. Six fungicides were evaluated on the susceptiblecv. Camarosa under greenhouse conditions and for two successive seasons under field conditions (2011/12 and 2012/13) where the most effective fungicides were Uniform, Tachigaren and Topsin-M in controlling wilt infection. The highest yield increase percentage was recorded in cv. Camarosa during the two growing seasons (2012/13 and 2013/14) under protective trial by Uniform fungicide.