Leaf Blight. Oil palm. Curvularia eragrostidis. Bird's eye spot Rubber. Drechslera heveae. Anthracnose. Shimul. Colletotrichum capsici. Wilt. Raintree, Cherry ...
Major Nurseries Diseases of Agroforest trees in Bangladesh and their management
K. M. Golam Dastogeer PhD Dept. of Plant Pathology BAU, Mymensingh
Agroforest Nursery In Bangladesh • To date, actual forest coverage in Bangladesh is less than 7 percent (SHED 1998) • Agroforestry means a mixed cultivation of trees and crops (fruit trees, timber trees, bamboo, vegetables, spices, medicinal plants etc.) • Over 69’000 families are involved in the nursery sector, either as nursery owners, part or fulltime labourers or as associated actors like input suppliers.
Common Nursery diseases in BD Disease
Host Plant
Cause
Seed rot/Germination failure
Eukalyptus, Koroi, Shimul, Jam, Teak
Aspergillus sp., Fusarium sp. Macrophomina phaseolina, Botryodiplodia theobromae, Curvularia
Damping off
Eukalyptus, Koroi, Narikeli, Pine, Sissoo etc.
Pythium sp., Phytophthora sp., Corticum sp., Fusarium, Sclerotium sp. Rhizoctonia sp. Phoma sp. etc.
Root Rot
Rubber, Gamar, Teak
Fusarium solani, Fusurium sp.
Dieback
Keora, Kadam
Chaetomella raphigera, Rhizoctonia solani
Leaf Spot
Rubber, Jali bet
Corynespora cassiicola, Guignardia calami
Disease Leaf Blight
Host Oil palm
Bird’s eye spot Anthracnose
Rubber Shimul
Wilt
Raintree, Cherry and other berrey Jackfruit
Canker Butt rot Heart rot
Cause Curvularia eragrostidis Drechslera heveae Colletotrichum capsici Verticillium sp., Fusuruim sp. Nectria haematococca Fungi
Oak, Sal, Teak, Mahogoni, Pine etc. Many deciduous trees Fungi
Important Nursery diseases Disease: Damping off Pre-emergence: seedlings are attacked by fungi and are killed in the soil before emerging out or germination.
Post-Emergence: Seedlings are attacked by fungi on the hypocotyls or roots or both while still in cotyledon stage. Seedlings may collapse on ground.
Disease Cycle • Phytophthora sp. survives in the soil as resting spores called oospores. • Oospores are formed in infected roots and are eventually released into the soil following breakdown of the rotted roots. • Optimum conditions for germination of oospores, infection, and disease development include temperatures of 65° to 75°F and nearly saturated soils. • Under these conditions, the oospores germinate to produce sporangia, which release the infective motile zoospore stage
Disease cycle of Phytophthora
Factors affecting damping off • High MC • Acidity PH >5 • High OM • Clay soil • Dense population • Excessive fertilizer esp. N2
Management • Good drainage • Fine texture soil • Soil amendment with saw dust, sand, ash etc.
• Maintain soil pH 5.00 to 6.0…Liming? • Moderate density of seedlings. • Balanced fertilization
• In case of regular high incidence of damping-off, the disease can be prevented by steam sterilization of nursery soil or drenching soil with 2% formalin or application of fungicides
(thiram,
captan, copper oxychloride). • Soil drenching with BAU-Biofungicide (3.0% solution).
Disease: Root Rot Host : Gamar Pathogen : Fusarium solani Symptoms: ►Reduced growth and dull green color of leaves compared to deep green color of normal foliage. ►This is followed by death of apex of the shoot and gradual dying out of the leaves. Such death occurs in irregular patches in the nursery. ► Small light brown spots appear first on secondary roots which turn brown as decay progresses. ► At advanced stages of the rot only the woody tissues of the roots remain.
Control: • Maintain nursery hygiene
• Application of fungicide, Zineb @ 100g/m2 or 0.5% as soil drench in areas of dead, dying and surrounding healthy
seedlings. • BAU-Biofungicide ( 0.3% ) as soil drenching.
Disease : Root Rot Host : Teak Pathogen : Pseudomonas solanacearum Symptom: ►Root rot appears as gradual death and dying up of leaves beginning from the lower ones. ►Rots first appear in fine feeder roots, then move into the main tap root where brownish to blackish discoloration develop in the pith and surrounding woody tissues. Management ►Raising teak nursery on sites having well draining soil. ►Avoiding water logging condition.
DISEASE: ROOT ROT Host: Rubber Pathogen: Fusarium spp. Symptoms: • Yellowing of leaves followed by drying out of seedlings due to rotting of root. • Collar region predisposed by water logging condition in nursery beds or polyethylene bags containing the seedlings.
Control:
• Avoiding water logging condition of polybag or nursery soil. • maintaining better soil aeration by way of breaking and crust formation on top layer of soil.
• Application of Dithane M 45 @ 50g/16 lit. of water and applied as soil drench at the onset of early disease symptom.
Disease: Dieback Host : Rubber Pathogen: Botryodiplodia theobromae Symptoms: ►The symptom first appears as pale green discoloration of the leaves of the grafted shoots. ►Later turn yellow and finally dry out and die.
Control: ►Germinated seeds should be planted in polyethene bags, instead of nursery beds, where grafting should be done. ►Upon successful grafting, transplanting will be done on the polyethene bag directly.
Disease: Dieback Host: Keora Pathogen : Chaetomella raphigera
Symptoms: ►At first symptom appear as a rot either at the tip or at the middle or lower part of the stem. ►A light brown transition zone of infection is seen in the stem tissue of affected seedlings. ►As rot progresses the portion of the stem further dies up. Control Measures ►The disease can be controlled by spraying Dithane M 45 @ 30g/16 litres of water at the early stages of disease incidence. ►Two or three weekly treatments proved to successfully control the disease.
Disease : Dieback Host : Kadam Pathogen : Rhizoctonia solani Symptoms: ►The disease starts as rot at one or more spots on leaves. ► Such rots gradually develop and coalesce to form bigger necrotic areas killing both young and old leaves simultaneously. ►Seedlings with affected leaves exhibit healthy roots. Control: ► Application of a foliar fungicide such as copper oxychloride, Dithane M 45 @ 0.2% should be good enough to control the disease.
Disease: Leaf Spot Host : Rubber Pathogen : Corynespora cassiicola Symptoms:
►The symptoms first appear as yellowish brown spots which thereafter turn to pale gray. ►Later, spots enlarge and coalesce to give rise to large necrotic areas.
Control: Application of Dithane M 45 (0.2%) may effectively control the disease.
Disease : Bird’s Eye Spot Host : Rubber Pathogen : Drechslera heveae Symptoms: ►At the early stage light brown discoloration which ultimately results necrotic spots with pale centre and dark brown margins develop on leaves. ►This results in premature defoliation, and dieback may occur. Control : • Shading the nursery plants reduces the disease incidence. • Maintain seedlings in vigorous condition through adequate balanced nutrition. • Application of Dithane M 45 (0.2%) may effectively control • the disease.
Disease : Leaf Spot Host : Jali bet (Calamus tenuis) Pathogen : Guignardia calami Symptoms: ►The disease starts as light brown spots on leaves which later on coalesce to form large irregular spots. ► In severe case, the leaf spots is such that most of the leaves may be killed so that the affected seedlings dry out. Control: ► Generally 2 to 3 weekly applications of Dithane M 45 @ 50g /16 litres of water and applied at the onset of early symptom expression .
Disease : Leaf Blight Host : Oil palm Pathogen : Curvularia eragrostides Symptoms: ►The leaf blight appears as small, irregular, light brown spots or patches on the leaf tips or on the edges of leaf blades first on the young leaves and then on older ones. ►The lesions gradually enlarge and their centers dry out and turn gray. ►Distinct demarcation between healthy and diseased zone will be formed. Control: Five foliar sprays at weekly interval with Benlate (0.5%) applied on every 400 seedlings raised in polyethylene bags.
Major Plantation Diseases
1. Disease : Dieback Host: Keora Pathogen : Cystospora sp. Symptoms: ►The plantations reveal a high proportion of side branches dying or top dying condition. ►The condition was most severe in Chittagong division slightly less in Barisal and the least in Noakhali coastal plantations. ►Dying branches showed a clearly defined transition zone of progression of infection in most of the branches. A fungus was consistently associated with the transition zone of infection.
Control : Application of Dithane M 45 @ 0.2% .
2. Disease : Massive Mortality Host : Keora
Symptoms: ►Death of leaves, twigs, branches and ultimately the whole tree. ►All trees in some plantations die in progressive succession. ►Dying trees show gradual yellowing of leaves followed by total leaf fall. ►The dead branches also break-off because of strong wind action
Causal Factor: ►Sudden heavy siltation in coastal plantations covers all the pneumatophores at and around the basal area of keora trees. ►Thus the aerenchyma of the pneumatophores become deprived of free oxygen supply. ►Lack of oxygen resulting in the death of the roots, death of the leaves, twigs, branches and ultimately the whole trees. Control: Development of a barrier (either a canal to divert sand or a narrow embankment to stop sand against the progressively advancing line of siltations is recommended.
3. Disease : Bamboo Blight Host : Bhaluka and Bhaijja Pathogen: Sarocladium oryzae Symptoms: ►Blight appears on young growing culms (generally 1- 5 meters in height) in August, the disease being at its worst by mid November. ►Blight starts as death and decay of culms sheath and then of culms at nodes which progresses both up and down the nodes of growing culms. ►The nodes of the young culms breaks at the point of maximum decay. ► Sometimes, death and decay may totally destroy the whole of a culms. ►One year old truncated bamboo shows the presence of light brown transition zone of advancing infection on the rind of the culms. ►Splitting of such portion of the culms would reveal the presence of fine thread like whitish mycelia of a fungus.
Control:
►The bamboo blight can be controlled to a large extent by improving cultural practices such as removal of blighted culms, burning debris in situ in clumps in April. ►Adding new soil in and around clumps in April-May before the onset of monsoon. ►The application of Dithane-M 45 as a soil drench or spray (0.2%) is advisable.
4. Disease : Mistletoes in Plantation Host : Gamar, Teak and Malakana Koroi Symptoms: ►Angiospermic parasitic bushes having green foliage and small branches in rather dense clusters are seen to grow on various parts of the crown of the affected trees. ►The parasite produces flowers and fruits. ►The parasites prepare food through photosynthesis as they have green foliage and engulf the host branch and ultimately kills the portion of host branch.
Parasite/ : Scurrula gracilifolia, S.parasitica and Dendrophthae falcata
Control: • Mechanical control through pruning is the most effective method for removal. • Growth regulators such as ethephon provide a degree of temporary control but repeated applications are required. • Severely infested trees should be removed and replaced with less susceptible species to protect surrounding trees. • Alternatively, gamar/teak should be planted in mixture with evergreen species having leading canopy in which case infestation by the parasite of partially shaded gamar canopy would be very minimal.
5. Disease : Root Rot of Pyinkado Host : Pyinkado Pathogen: Ganoderma lucidum Symptoms: ►The first symptom appears as pale green color of the foliage of the upper portion of the crown. ►Then gradually progresses as light yellow, then yellow and ultimately dries up and fall off. ► The bark become very much permeated by white mycelia of the pathogen and reaches the collar region causing a complete girdle. ► Then the foliage start drying up. Later, the twigs and branches dry up. Ultimately the death of the crown results.
Pyinkado
Control: ►Disease can be effectively controlled by the use of 2% formalin in water as soil drench during the early stage of symptom expression. ► Digging out a trench of about 25 cm in width and of 1m in depth around an infected pyinkado tree will arrest further spread of the pathogen to neighbouring trees through rhizomorph.
► Raising mixed plantations of pyinkado and trees resistant to attack by G. lucidum will also help to reduce the build up of infection by the pathogen. ► Teak (Tectona grandis) is known to be resistant.
6. Dieback Host: Jackfruit Cause: Nectria haematococca Symptom: ►First dieback appears as pale green of the leaves, then progressively change to light yellow, yellow to reddish yellow. ► The older leaves fall off first followed by younger ones. ► After the leaves fall off, the branches die. ► At first small, young branches die which is followed by the older ones.
Control: ►It can be controlled by applying Cupravit, or Dithane M-45 (0.2%). ►Irrigation during dry season. ► Removal of infected parts along with a small portion of diseased parts.
7. Canker Host: Jackfruit Cause: Nectria haematococca ► The cankers on jackfruit trees start as blackening of bark generally at the bases of small dead branches. ► The dead area gradually expands followed by light brown discoloration. ► The canker affected portion fails to add any new growth, and a depression usually develops. ► On the bark of the dead area small, rounded, reddish-yellow fruit bodies of Nectria haematococca develop profusely during the monsoon.
Control:
►It can be controlled by applying Cupravit, or Dithane M-45 (0.2%). ►Irrigation during dry season. ► Removal of infected parts along with a small portion of diseased parts.
Acknowledgement: Most information presented in these slides has been copied and in some cases modified from a presentation document kindly supplied by Professor Dr. Ismail Hossain, Department of Plant Pathology, BAU, Mymensingh-2202
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