LEAF BLIGHT, TARO – NIGERIA: (KATSINA) ************************************** A ProMED-mail post <http://www.promedmail.org> ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
Date: Wed 18 Nov 2015 Source: Daily Trust [edited] <http://www.dailytrust.com.ng/news/agriculture/disease-killing-cocoyam-farming-in-katsina/120164.html>Disease killing cocoyam in Katsina ———————————- Cocoyam [taro] farming in Katsina State is gradually being phased out as agricultural research institutes are yet to provide the farmers with a solution to the leaf blight disease affecting the crop for about 5 years now [see ProMED-mail post http://promedmail.org/post/20101216.4451]. Katsina, particularly its southern part, was a major producer of cocoyam which was transported to the north-eastern states and Niger Republic.
A farmer said, “With the growing devastation of the leaf blight disease, we can no longer continue with cocoyam farming. We are yet to find a lasting solution to the leaf blight affecting the crop.” He stressed the need for agricultural institutions to come up with new improved seedlings of cocoyam and a reliable solution to the disease.
An agricultural expert and agro-allied product dealer said the disease can be managed with appropriate systemic or non-systemic fungicides. “Resistant varieties are the most effective method of controlling the disease. Symptomatic leaves should be removed to reduce the spread to the tubers. Cocoyam should be planted in well-draining soils,” he advised.
[Local] markets are now dominated with potatoes, yam and cereals with a few bags of cocoyam already affected by the disease.
[Byline: Idris Mahmud]
— Communicated by: ProMED-mail <[email protected]>
[Taro [_Colocasia esculenta_] leaf blight caused by the fungus-like organism _Phytophthora colocasiae_ was 1st reported in Java in the early 1900s. Since then, it was found in various parts of Asia and the Pacific, and in 2010, it was also reported for the 1st time from Africa (see ProMED-mail post http://promedmail.org/post/20100715.2365). Both leaves and tubers of the crop are used, and taro blight results in yield losses of 30-50 per cent or even total crop losses. The disease also reduces the quality of the harvest.
Symptoms include purple-brown water-soaked lesions on leaves oozing a clear yellow liquid; lesions enlarge and eventually destroy entire leaves in 10-20 days, leading to reduced photosynthesis and vigour of the plant. Disease development and spread are favoured by free water collecting on older leaves, high temperatures and high humidity. The pathogen can be spread by wind, splashing rain and mechanical means (including insects and human activities). Spores survive in plant material for several weeks, and, therefore, infected planting material (seed tubers) is a common means of pathogen spread over long distances and between seasons.
Varying levels of disease intensity in different areas have led to the suggestion that different strains of _P. colocasiae_ may exist, in addition to differences in the genetic background of local taro varieties. Some of these strains appear to be able to infect some other aroid crops (for example _Alocasia_ species) as well, but further information is needed on whether non-aroid crops like yam (_Dioscorea_ species) and cassava (_Manihot esculenta_) could be affected by these pathogens.
Disease management using an integrated approach has been successful in the Pacific, including cultural methods (such as crop rotation, intercropping), fungicides as sprays or treatments for seed tubers, phytosanitation and use of cultivars with reduced levels of susceptibility. Programmes specific to different areas for the assessment of taro blight resistance levels of local cultivars have been set up by some countries.
In Nigeria, a resistance breeding programme has been established in 2011 by the National Root Crops Research Institute (NRCRI; see ProMED-mail post http://promedmail.org/post/20110422.1253). However, breeding of resistant crop varieties, followed by field testing and eventual multiplication for release to farmers usually takes many years.
Maps Nigeria: <http://worldatlas.com/webimage/countrys/africa/lgcolor/ngcolor.htm> Nigerian states: <http://media.premiumtimesng.com/wp-content/files/677x533xnigeria_map_m_104046032.gif.pagespeed.ic.A4Q8ve7feg.png> Africa (overview): <http://www.lib.utexas.edu/maps/africa/africa_pol97.jpg>
Pictures Taro leaf blight symptoms: <http://www.pestnet.org/Portals/32/Images/Disease/1067-Taro%20leaf%20blight/1067a-TLB.jpg>, <http://www.ediblearoids.org/portals/0/taropest/lucidkey/taropest/media/Html/Fungi/Pcolocasiae/Phytophthoracolocasiae20GJ.jpg> and <http://www.extento.hawaii.edu/kbase/view/files/pictures/Img0007.jpg> (compared with healthy leaf) _P. colocasiae_ zoospores: <http://www.forestryimages.org/images/768×512/5390071.jpg>
Links Information on _P. colocasiae_: <http://www.extento.hawaii.edu/kbase/crop/type/p_coloc.htm> and <http://www.ediblearoids.org/portals/0/taropest/lucidkey/taropest/media/Html/Fungi/Pcolocasiae/Pcolocasiae3.htm> Taro leaf blight, disease and impact: <http://www.fao.org/DOCREP/005/AC450E/ac450e06.htm#b2-4.2%20Taro%20Leaf%20Blight>, <http://www.apsnet.org/edcenter/intropp/lessons/fungi/Oomycetes/Pages/TaroLeafBlight> (with pictures), <http://www.papuaweb.org/dlib/tema/ubi/paiki-1996-taro-leaf-blight.pdf> and <http://www.spc.int/tarogen/Documents/Misc_Publications/TLBimpact2.pdf> _P. colocasiae_ disease cycle: <http://www.ediblearoids.org/portals/0/taropest/lucidkey/taropest/media/Html/Fungi/Pcolocasiae/lifecycle.jpg> _P. colocasiae_ taxonomy: <http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=232219> NRCRI: <http://www.nrcri.gov.ng> – Mod.DHA
A HealthMap/ProMED-mail map can be accessed at: <http://healthmap.org/promed/p/1321>.]
[See Also: 2014 —- Leaf blight, taro – India: (HP) http://promedmail.org/post/20140904.2747184 2011 —- Leaf blight, taro – Nigeria: update http://promedmail.org/post/20110422.1253 2010 —- Leaf blight, taro – Africa: 1st rep. West Africa http://promedmail.org/post/20101216.4451 Undiagnosed disease, taro – Cameroon http://promedmail.org/post/20100715.2365] ………………………………………….sb/dha/je/ml *##########################################################* ************************************************************ ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Donate to ProMED-mail. Details available at: <http://www.isid.org/donate/> ************************************************************ Visit ProMED-mail’s web site at <http://www.promedmail.org>. Send all items for posting to: [email protected] (NOT to an individual moderator). If you do not give your full name name and affiliation, it may not be posted. You may unsub- scribe at <http://ww4.isid.org/promedmail/subscribe.php>. For assistance from a human being, send mail to: <[email protected]>. ############################################################ ############################################################
List-Unsubscribe: http://ww4.isid.org/promedmail/subscribe.php
|