Status and future prospects of research on diseases of enset (<i>Ensete ventricosum</i>) and their management

Abstract

The production of enset in Ethiopia is limited by a number of constraints of which diseases play a major role. The most important disease is bacterial wilt (BW) caused by Xanthomonas campestris pv. musacearum. Cultural practices such as crop sanitation, avoiding the use of contaminated tools and destruction of infected plants are commonly used to manage BW. Since these practices do not offer adequate or complete BW control, research efforts have been made to develop BW resistant enset varieties. However, no success was registered as all enset clones evaluated did not have adequate level of resistance. Currently, efforts are being made to introduce transgenic resistance and bio-intensive integrated disease management options. Enset is also affected by many other diseases of lesser economic importance caused by fungi, nematodes and viruses. Fungal foliar diseases include leaf spot diseases caused by Phyllostica sp., Pyricularia sp., or Drechslera sp. which commonly affect suckers, seedlings and young plants. Leaf spot diseases in older plants are caused by Cladosporium sp., Deightoniella sp. or Mycosphaerella musicola. Wilt and root rot caused by Sclerotium rolfsii or Fusarium oxysporum are also encountered but rare. In general however, fungal diseases are of minor economic importance as adult enset plants tolerate them. Among the common parasitic nematodes that attack enset are the root lesion nematode caused by Pratylenchus goodeyi, the root knot nematode caused by Meloidogyne spp. and the leaf nematode caused by Aphelechoides ensete. Survey of enset nematodes indicated that Pratylenchus goodeyi was the most prevalent followed by A. ensete and Meloidogyne spp. Finally, a new virus with bacilliform particles causing chlorotic streak and severe stunting of enset has been described. The virus tentatively named Enset leaf streak virus has a double stranded DNA genome of 7163 base pairs and belongs to genus Badnavirus, family Caulimoviridae. No other virus including Banana streak OL virus reported from banana in Ethiopia have yet been reported on enset. A nationally coordinated effort assisted by further research should be made to develop integrated management strategies for enset BW by using traditional and new technologies. At the same time, the incidence and extent of damage caused by the other enset diseases should be quantified, and the diseases be prioritized and management options developed before their re-emergence as major threat to enset production due to factors such as climate change.

Keywords/phrases: Bacterial wilt, Disease management, Fungi, Nematodes, Viruses