A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>
Date: Fri 23 Mar 2012
Source: AllAfrica, Nairobi Star report [edited] <http://allafrica.com/stories/201203231358.html>
KEPHIS team identifies Bomet disease
The Kenya Plant Health Inspectorate Service [KEPHIS] has announced a breakthrough in the cause of a mysterious disease that has destroyed over 1000 acres [400 ha] of maize crop in Bomet county [Rift Valley province; see ProMED-mail post 20120117.0114] since last October . The disease became of concern to farmers, especially after conflicting diagnosis on its cause.
KEPHIS have [now] identified the disease as leaf stripe of maize caused by a fungus called _Cephalosporium acremonium_ [see note below]. The pathogen is seed borne, but can also survive on maize plant debris and [become] soil borne. "The disease is widespread particularly on the earlier maize crop. Its impact on the younger crop is less," says James Onsando, KEPHIS.
Onsando says the disease starts with chlorosis and drying up of the upper leaves from the midrib and progressing to the margins. "The drying progresses downwards showing blighting of the leaves. In some cases, browning of the nodes was observed and in some cases excessive tillering," he said. Within weeks the whole plant rots away as the disease spreads fast.
He says the disease has been exacerbated by drought, stem borer infestation, thrips damage, and maize streak virus. He has advised farmers in the affected areas to practise crop rotation for at least 2 to 3 seasons to reduce the disease level with non-grass crops like sweet potatoes. KEPHIS is conducting further research to develop management strategies for the disease.
[Byline: Ibrahim Oruko]
[It appears that there has been some confusion in the report above:
the fungus _Sarocladium strictum_ (previously _Cephalosporium acremonium_, _Acremonium strictum_) has been reported to cause cephalosporium stalk, kernel, and ear rots as well as black bundle disease of maize. The pathogen also causes acremonium wilt of sorghum.
Leaf stripe disease as well as late wilt of maize is caused by _Cephalosporium maydis_.
_S. strictum_ appears to infect plants growing in unfavourable conditions, but details of its epidemiology remain uncertain. The fungus may not be a primary parasite and has been reported to produce compounds with toxic effects on host tissues. In China, _S. strictum_ has been reported to cause yield losses of up to 66 percent, depending on host cultivars, and a small number of resistant varieties were identified. In Africa, it has been reported as an important pathogen on several maize cultivars from Cameroon causing leaf chlorosis, leaf and stem necrosis, wilting and stunting of plants, as well as failure to produce kernels resulting in serious yield losses.
The related _Hymenula cerealis_ (previously _Cephalosporium
gramineum_) causes leaf stripe of grassy species including a range of cereal crops.
The leafhopper transmitted _Maize streak virus_ mentioned above (MSV; genus _Mastrevirus_) is widespread in sub-Saharan Africa, including Kenya. A number of MSV-resistant maize cultivars have been developed for use in the region.
<http://www.ogiek.org/photo-gallery/kenya-map-big.jpg> and <http://healthmap.org/r/21SF> Kenya provinces:
_S. strictum_ diseases of maize:
<http://www.flickr.com/photos/cimmyt/4911001203/> (kernel rot) and <http://krishisewa.com/disease/dm/dm3.jpg> (black bundle) _C. maydis_ wilt and leaf stripe of maize:
Cephalosporium stripe of wheat:
Information on _S. strictum_ diseases of maize:
<http://cat.inist.fr/?aModele=afficheN&cpsidt=13647073> (Cameroon), <http://www.cabdirect.org/abstracts/20103247115.html?freeview=true>
Information on cephalosporium wilt and black bundle diseases of maize
<http://krishisewa.com/disease/dmaize2.html> and <http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7348.1970.tb06432.x/abstract>
Cephalosporium leaf stripe of cereals:
_S. strictum_ taxonomy and synonyms:
Other fungal taxonomy via:
List of major diseases and pathogens of maize:
Undiagnosed disease, maize - Kenya: (RV) 20120117.0114
Rough dwarf disease, maize - Kenya: 1st rep. 20110204.0407
Cephalosporium stripe, wheat - USA: (IL) 20080609.1829
Maize streak mastrevirus - Kenya (West) (02) 20010417.0761 Maize streak mastrevirus - Kenya (West) 20010414.0743]