Characterization and Control of Pestalotiopsis spp. the Causal Fungus of Guava Scabby Canker in El-Beheira Governorate, Egypt

Abstract

During 2013-2014 growing seasons, forty three isolates of Pestalotiopsis spp. were recovered from guava leaves and fruits showed scab symptoms from different regions in EL-Beheira governorate. Five Pestalotiopsis species were recognized according to the morphological characteristics of fungal colony (Colony color, Size and number of acervulii) and conidia (length, width, and color of median cells, length and the number of apical and basal appendages); they were P. psidii, P. microspora, P. clavispora, P. neglecta and Pestalotiosis spp. All the isolates recovered were pathogenic to the cv. Balady of guava fruits. However, P.psidii isolates were the most highly pathogenic followed by P. neglecta, P. clavispora, P. microspora and Pestalotiopsis spp, respectively. RAPD-PCR analysis using five random oligonucleotide primers revealed DNA fingerprints and considerable variations were revealed with primers tested.  Bar primer showed a common band for all Pestalotiopsis isolates and species at 500bp, while BAQ, 18 and A9B4 exhibited banding pattern similar for all isolates of the same species which were different from that of the other species. Scab disease control of infected fruits by chitosan as a natural product was tested. The in vitro 2.5% chitosan application significantly inhibited the growth of Pestalotiopsis spp. tested by 86.53% on agar plates. The in vivo tests on fruits, the chitosan treatment to artificially infected fruits reduced the development of symptoms at the different chitosan concentrations, i.e., 1.5%, 2% and 2.5%. The 2.5% chitosan was the most effective concentration for scab disease control in guava fruits. It is the first report of identification five different Pestalotiopsis  species affecting guava fruits and leaves in EL-Beheira Governorate, Egypt. Also, the study supported the view that chitosan offers a safe alternative to synthetic fungicides in postharvest scabby control and could be considered as a potential agrochemical of low environment impact.