Cassava Farms in Disease Control

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Disease Control,in Cassava Farms,IPM Field Guide for Extension Agents. Weston Msikita, International Institute of Tropical Agriculture Plant Health Management Division. Cotonou B nin,Braima James, International Institute of Tropical Agriculture Plant Health Management Division. Cotonou B nin,Emmanuel Nnodu, National Root Crops Research Institute Umudike Umuahia Abia State Nigeria. James Legg, International Institute of Tropical Agriculture ESARC Kampala Uganda.
Kerstin Wydra, International Institute of Tropical Agriculture Plant Health Management Division. Cotonou B nin,IITA 2000 Francis Ogbe, ISBN 978 131 176 2 National Root Crops Research Institute Umudike Umuahia Abia State Nigeria. Printed in Nigeria by Wordsmithes Printers Lagos,What are the objectives of this guide 4. Introduction 4,What are the common cassava diseases 6. Why are cassava diseases important 18, When are cassava diseases likely to cause severe losses 20.
How can I best control diseases in cassava farms 22. Summary 25,Disease Control in Cassava Farms,IPM Field Guide. What are the objectives of Introduction,this guide. Many diseases are caused by very tiny living, This field guide has been prepared to help you things called pathogens Pathogens are so tiny. to that you cannot see them even with the aid, recognize common cassava diseases and of hand lenses Examples of pathogens are vi. specify their causes ruses bacteria and fungi When a pathogen. specify how the diseases damage cassava attacks a cassava plant it multiplies and. plants spreads inside or on the plant As it spreads. identify the sources of cassava diseases it destroys the plant The plant will show signs. and understand how cassava diseases spr symptoms of attack Damage symptoms of. ead and cassava diseases appear on the leaves Fig, combine appropriate practices to control ure 1 stems Figure 2 and storage roots.
cassava diseases and grow a healthy crop Figure 3 of the plant Cassava diseases are. of cassava recognized by their symptoms such as dis. coloration of leaves sores on the stems,and discoloration of storage roots. Some other diseases which you may notice in,cassava are caused by nonliving things Ex. amples of such diseases are wilting due to Figure 1 Cassava plant damaged by Figure 2 Cankers of cassava. drought and poor plant growth because of cassava mosaic disease anthracnose disease on stem. poor soils,Figure 3 Cassava storage roots damaged by cassava. brown streak disease,Disease Control in Cassava Farms. IPM Field Guide, What are the common cassava leaves The virus multiplies and occurs.
cassava diseases in large numbers in the leaves and stems Cas. The common diseases of cassava are cassava sava mosaic disease is also spread by planting. mosaic disease cassava bacterial blight cas stem cuttings from plants infected with the. sava anthracnose disease cassava bud necro disease. sis and root rots Some of these diseases at Other crops attacked Cassava mosaic dis. tack the leaves and stems of cassava plants ease attacks only cassava. Cassava leaves,while others attack the storage roots. with chlorotic,Leaf and stem diseases pale patches. of cassava,Common leaf and stem diseases of cassava mosaic. are cassava mosaic disease cassava bacterial disease. blight cassava anthracnose disease cassava,bud necrosis and brown streak disease. Cassava mosaic disease,Cassava mosaic disease is caused by a virus.
which occurs inside cassava leaves and stems,Damage symptoms The leaves of cassava. plants with the disease are discolored with,Cassava leaf with. patches of normal green color mixed with,chlorotic pale. light green yellow and white areas Figure 4,spots caused by. This discoloration is known as chlorosis The,cassava green.
chlorotic patches can be confused with cas,sava green mite feeding damage Figure 5. When cassava mosaic attack is severe the,leaves are very small and distorted and the. plants are stunted The disease symptoms,are more pronounced on younger plants Fig. ure 1 usually under 6 months than on older,plants Figure 6. Method of spread The main sources of the Bemisia, virus which causes cassava mosaic disease are whitefly as.
cassava plants with the disease and the white seen enlarged. fly Bemisia tabaci Figure 6 The virus occurs under the. in the saliva of the whitefly During feeding the microscope. insect injects saliva containing the virus into,Disease Control in Cassava Farms. IPM Field Guide, Cassava bacterial blight leaves It multiplies and occurs in large num. bers in the leaves and stems Cassava bacterial,Cassava bacterial blight is caused by a bacte. blight is therefore spread by planting stem,rium which occurs inside cassava leaves and. cuttings from plants with the disease symp,toms Dead cassava stems and leaves with the.
Damage symptoms Initially damage by cas bacterium also serve as sources of the disease. sava bacterial blight appears as water soaked if they are not destroyed after root harvest. dead spots lesions The lesions occur be,The disease is spread naturally by raindrops. tween leaf veins and are most evident on the,which splash the bacterium from infected. lower surfaces of the leaves Figure 7 The le,plants to healthy plants Insects for example. sions are small not completely round in shape,grasshoppers become contaminated with the. and have a few angles at their edges These,bacterium and spread it to healthy cassava.
angular lesions later join together into larger,plants Farm tools that are used to cut in. patches killing the leaf blade as they enlarge,fected cassava plants should be cleaned after. The leaf blade turns brown with the water,use to prevent the bacterium on them from. soaked area at the leading edge of the brown, spreading to other plants Figure 7 Cassava leaf with angular Figure 8 Cassava leaf blighting caused. patch This damage symptom is known as leaf, blighting Figure 8 Severely blighted leaves Other crops attacked Cassava bacterial leaf spots of cassava bacterial blight by cassava bacterial blight.
wilt Figure 9 die and fall causing defoliation blight attacks only cassava. and shoot tip die back Figure 10 or com,plete death of the shoot Leaf blighting starts. from the leaf blade and moves towards the,petiole The petiole retains a horizontal posi. tion before leaf fall Figure 9 This is unlike,cassava anthracnose damaged leaves whose. petioles droop before leaf fall Figure 12,Drops of brownish gum may occur on the. leaves petioles and stems of plants infected,with cassava bacteria blight.
The damage symptoms of cassava bacteria,blight are more evident in the wet than in the. dry season The disease is more severe in,young plants than in older ones. Method of spread The main sources of the, bacterium which causes cassava bacterial Figure 9 Leaf blighting and wilting Figure 10 Cassava shoot tip die back. blight are cassava plants with the disease The caused by cassava bacterial blight caused by cassava bacterial blight. bacterium enters cassava plants through,wounds and scratches on the stems and. Disease Control in Cassava Farms,IPM Field Guide,Cassava anthracnose disease Cassava bud necrosis.
Cassava anthracnose disease is caused by a Cassava bud necrosis is caused by a fungus. fungus which occurs on the surface of cassava which occurs on the surface of cassava stems. stems and leaves and leaves, Damage symptoms Cassava anthracnose Damage symptoms The disease appears as. disease appears as cankers sores on the patches of brown or grey fungal matter cover. stems and bases of leaf petioles Figure 11 ing the stem The fungal matter sometimes. Cankers weaken the petioles so that the leaf covers buds eyes on cassava stem cuttings. droops downwards Figure 12 and wilts The Figure 14 The affected buds die which re. wilted leaves die and fall causing defoliation duces the sprouting ability of stem cuttings. and shoot tip die back or complete death of, the shoot Soft parts of cassava stems become Method of spread The main sources of the. twisted under severe attack by the disease fungus that causes bud necrosis are cassava. The disease usually starts at the beginning of plants with the disease Dead cassava stems. the rains and worsens as the wet season and leaves with the fungus also serve as. progresses sources of the disease if they are not de Figure 11 Cankers of cassava Figure 12 Cassava shoot with wilted. stroyed after root harvest The fungus spreads anthracnose disease at the bases of leaves caused by cassava anthracnose. Method of spread The main sources of the by wind however planting of infected stem cassava leaf petioles disease. fungus that causes cassava anthracnose dis cuttings is the main method by which the dis. ease are cassava plants with the disease The ease spreads. fungus spreads by wind carrying spores from, cankers on the stems or by planting stem cut Other crops attacked The fungus that. tings with cankers The fungus enters causes bud necrosis causes leaf spots on a. cassava plants through wounds and feeding variety of plants including grasses cereal. punctures made by the bug Pseudotheraptus crops banana and mango. devastans Figure 13 Dead cassava stems and,leaves with the fungus also serve as sources of. the disease if they are not destroyed after,root harvest p.
Other crops attacked The fungus that,causes cassava anthracnose disease affects. other crops as well as cassava for example,coffee pepper and pawpaw. Figure 13 The bug Pseudotheraptus Figure 14 Cassava stem with fungal. devastans on cassava leaf patch arrow of bud necrosis disease. Disease Control in Cassava Farms,IPM Field Guide, Leaf spot diseases then serve as sources for spread of the dis. Cassava leaf spot diseases are caused by fungi, There are three different types namely white Other crops attacked Not much is known. leaf spot brown leaf spot and leaf blight about the host crop range of cassava leaf spot. Damage symptoms Cassava white leaf,spot disease appears as circular white or.
brownish yellow spots on the upper leaf sur,faces Figure 15 The spots sometimes have. purplish borders around them, Cassava brown leaf spot disease appears as Figure 15 Cassava leaf with white leaf spot. small brown spots with dark borders on the disease. upper leaf surfaces Figure 16 The brown,spots occur between leaf veins and their sizes. and shapes are limited by the distance be,tween these veins The dead tissue in the cen. ter of brown spots may fall to give the leaf,surface a shot hole appearance Under se.
vere attack the infected leaves become yellow,dry and die prematurely. Cassava leaf blight disease appears as light,brown lesions on the upper surfaces of the. leaves The lesions are not limited by veins, therefore they are usually larger than brown Figure 16 Cassava leaf with brown leaf spot. leaf spots The lesions may enlarge to cover disease. most of the leaf surface and cause leaf blight,ing Figure 17 The blighted leaves lack water. soaked areas which are typical of leaf damage,by cassava bacterial blight Figure 8 Leaf.
blight lesions also lack the dark borders of,brown leaf spots and they do not develop into. shot holes on the leaf surface,Method of spread The main sources of the. fungi that cause leaf spot diseases are infected,cassava leaves on the plant or those fallen on. the ground The fungi spread to new plants, from these sources by wind or rain splashes Figure 17 Cassava leaf with leaf blight disease. Leaf spot fungi can occur on weeds which,Disease Control in Cassava Farms.
IPM Field Guide,Stem and root diseases,Cassava brown streak disease. Cassava brown streak disease is caused by a,virus Presently the disease is reported only. from cassava growing regions in East and,Southern Africa. Damage symptoms Damage symptoms of,cassava brown streak disease appear on the. leaves stems and storage roots of cassava,plants On the leaves the disease appears as.
patches of yellow areas mixed with normal,green color Figure 18 The yellow patches. are more prominent on mature leaves than, on young leaves The damaged leaves do not Figure 18 Cassava leaves with chlorotic pale. become distorted in shape as occurs with patches of cassava brown streak disease. leaves damaged by cassava mosaic disease,Figure 1 On the stems the disease appears. as dark brown streaks Figure 19 with,dead spots on leaf scars These streaks are. most prominent on upper green portions of,the stems The diseased plants may show.
shoot tip die back Cassava brown streak dis,ease distorts the shape of the storage roots. and may cause cracks and discoloration in,the storage roots Figure 20. Method of spread The main sources of the,virus that causes cassava brown streak are. cassava plants with the disease The disease is,spread through the planting of stem cuttings. from diseased plants The virus is also believed,to be spread from plant to plant by insects.
Other crops attacked Cassava brown Figure 19 Cassava stem with Figure 20 Cassava storage roots. streak disease is not known to attack other streaks of cassava brown streak discolored by cassava brown streak. crops disease disease,Disease Control in Cassava Farms. IPM Field Guide,Cassava root rot diseases,Cassava ro. 7 IPM Field Guide Disease Control in Cassava Farms 6 Figure 6 Adults of Bemisia whitefly as seen enlarged under the microscope Figure 5 Cassava leaf with

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