Archivio Journal of Plant Pathology

Abstract:

In the spring of 2014, a disease of garlic (Allium sativum) was observed in more than 30 plots in Jabal Akhdar (Sultanate of Oman), which was characterized by premature yellowing and wilting of the leaves followed by plant death. Upon uprooting, white cottony mycelium and black sclerotia were observed on the outer layer of the bulbs, roots and surrounding soil. The infection appeared to progress from the outer layers of the bulbs to the inner ones so as to involve the whole organ. Disease incidence ranged from 20 to 100%. On potato dextrose agar (PDA), fungal isolates with whitish/grayish mycelium and small-sized sclerotia typical of Sclerotium cepivorum were consistently recovered from symptomatic bulbs and roots. The sequence of the internal transcribed spacer (ITS) region of the ribosomal DNA (Al-Sa'di et al., 2007) of three fungal isolates using ITS1 and ITS4 primers produced in all cases a nucleotide sequence 510 bp long (accession Nos GCC3471-73) which, when compared with sequences from database revealed 99.8% nucleotide similarity to a previously published sequence (accession No. FJ460433) of the garlic isolate H-292 of S. cepivorum from Hungary. The disease was reproduced in healthy garlic bulbs planted in inoculated soil with an incidence ranging from 30 to more than 65%. To the best of our knowledge, this is the first report of the association of S. cepivorum with white rot of garlic in Oman.