Prevalence and fungal isolates associated with Korogwe leaf spot disease (KLS) of sisal
O. G. MTUNG'E (1), L. Luo (1), X. Liu (1), R. B. Mabagala (2), Y. Diao (1), Y. Meng (1), J. Li (1). (1) China Agricultural University, Beijing, China; (2) Sokoine University of Agriculture, Morogoro, Tanzania
Sisal (<i>Agave sisalana </i>Perrine) is a hard fibre producing plant grown mainly in tropical and subtropical countries. Korogwe leaf spot disease of sisal is characterised by chocolate brown concentric scab like eruption that was first observed in 1951 in Korogwe District, Northern Tanzania. The disease causes difficulty in fibre extraction leading to darkened, low quality fibre. To date there is no report of its distribution within and out of Tanzania sisal fields. The actual cause of the disease has not been confirmed, and the isolated pathogens have been poorly described in few reports. A total of 64 affected leaf samples from 5 sisal farms located in Guangxi and Hainan provinces in the Southern China, and 13 farms located in the North Eastern Tanzania were collected in July to September 2013 for pathogen isolation and identification. Result showed that the disease is wide spread to all locations visited in a varying severity. Incidence up to 100% was recorded in some fields. Through a combined fungal morphological identification and ITS sequence analysis, a total of 11 fungal species in 110 isolates from both China and Tanzania were identified. Among these, <i>Fusarium</i> <i>equiseti</i> had the highest frequency of occurrence covering all locations, followed by <i>Alternaria alternata,</i> <i>A. tenuissima </i>and <i>Phoma herbarum.</i> The findings suggest the possibility of association of a disease with several fungal pathogens in combination with other factors.
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