LONG TERM STORAGE FOR FIVE IMPORTANT CEREAL PHYTOPATHOGENIC SPECIES

Abstract

Fusarium head blight (FHB), spot blotch (SB) and common root rot (CRR) are consistently of the most important cereal diseases globally, but few publications have appeared on preservation. We have stored seventy FHB, SB and CRR fungal isolates of five species (Fusarium culmorum, F. verticillioides, F. solani, F. equiseti and Cochliobolus sativus) in sterile distilled water and freezing in two independent experiments for 36 months. Fungi were tested for viability, purity and morphological stability. The storage treatments included fungal inoculum consisting of spores and hyphae suspended in sterile distilled water at 4°C and mycelial cultures on Petri-dishes with potato dextrose agar (PDA) by freezing at -16°C. The first experiment included 70 isolates was tested six times, after 6, 12, 18, 24, 30 and 36 months of storage. The second experiment with 16 isolates, out of the tested 70 isolates, was tested over periods from 1 to 36 months. The 70 three-year old water-stored and frozen cultures did grow when sub-cultured on PDA. Moreover, viable 16 cultures were recovered from the two storage methods having 100% revival at each time point for up to 3 years. All tested isolates were found to be pure, and maintained their original morphological features. Survival of cultures was not affected with preservation procedure, time in storage or taxonomic classification. The two techniques were found to be easy and reliable for preservation of important cereal fungi for up to 36 months. To our best knowledge, this is the first research reporting the possibility of preservation for FHB, SB and CRR causal agents by cold water and freezing for three years.