Coconut diseases Lecture By Allah Dad Khan Provincial Coordinator IPM KPK MINFAL
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This document summarizes several coconut diseases, including their symptoms, causes, and management strategies. It describes diseases such as bud rot and nut fall caused by fungi like Phytophthora spp. that results in yellowing and wilting fronds. It also discusses lethal yellowing phytoplasma that causes premature fruit dropping and yellowing of the crown. Control methods include removing infected plant debris, using appropriate fungicides, planting resistant varieties, and avoiding wounding palms.
Coconut diseases Lecture By Allah Dad Khan Provincial Coordinator IPM KPK MINFAL
- 2. Coconut Diseases A Lecture To ToT trainees ( FFS) By Mr. Allah Dad Khan Provincial Coordinator IPM KPK MINFAL Pakistan
- 3. Symptoms Chlorosis of youngest open leaves; leaves rapidly turning necrotic; necrotic spots on leaf bases; unopened spear leaves can be pulled away from the plant easily; removal of unopened spear leaves reveals soft, pink-red tissue with foul smell; leaf necrosis spreading through central crown leaves; woody parts of plant may have water- soaked, pink lesions with dark borders; infected inflorescences abort nuts Cause Oomycete Comments Palms between 14 and 40 years old most susceptible; disease occurs in all coconut growing regions; diseases emergence favored by high rainfall Management Control of the disease is reliant on good sanitation practices and the use of appropriate systemic fungicides; remove all infected debris and dead trees from plantation and destroy; irrigate trees early in the day to allow surfaces to dry off during the day Bud rot and nutfallPhytophthora spp. Fusarium solani Fusarium moniliforme Graphium spp.
- 4. Symptoms Older fronds turning yellow and gradually wilting and drooping; fronds collapsing and dying; internal tissue of lower stem discolored; overall reduction in vigor Cause Fungi Comments Fungi may enter through wounds on trunk or pruning wounds Management Spacing trees widely limits the chance of infection through root grafts; avoid damaging tree trunks with tools and machinery; remove any dead or severely damaged trees from plantation immediately, including any that have been killed by natural processes; if a site is known to be infected with the disease, the ground should be fallowed for at least 1 year prior to a new plantation being established Ganoderma butt rot Ganoderma spp.
- 5. Symptoms Small, yellow-brown spots on leaflets which develop gray centers and dark green borders; lesions coalesce to form large necrotic patches; tips of leaflets turning gray; canopy has blighted appearance Cause Fungus Comments Fungi will colonize young, wounded or weakened tissues; disease emergence favored by high rainfall and high humidity Management Disease usually only merits control in coconut nurseries as infection of mature coconut palms are rare; appropriate broad spectrum protective fungicides should be applied Gray leaf blight Pestalotiopsis palmarum
- 6. Symptoms Oldest leaves of palm turning yellow and wilting; reddish-brown rot in bole tissue; destruction of root system Cause Fungus Comments Some grasses such as Bermuda grass have been reported as alternative hosts fro the fungi Management Any infected trees must be uprooted and burned; area can only be replanted once soil is treated for the disease Marasmiellus cocophilus
- 7. Symptoms Soft, yellow rot on trunk; affected areas are dark and turn black as they mature; a reddish-brown liquid may ooze from rotting regions and spill down trunk Cause Fungus Comments Fungi enter the trunk through wounds Management Avoid wounding palms with machinery and tools to reduce disease incidence; disease can be controlled with applications of the fungicide benomyl where registered; infected trees should be removed and destroyed as soon as possible Stem bleeding disease Chalara paradoxa
- 8. Symptoms Abnormal bending or ribbing of the leaflets, flaccidity of the leaves, general yellowing followed by marginal necrosis of the leaflets. Abnormal shedding of buttons, reduced leaves and crown, gradual reduction in yield. Root (wilt) Disease Tanjavur wilt
- 9. Symptoms Decay of finer nuts, withering, yellowing, drooping and drying of outer whorl of leaves and exudation of reddish brown fluid at the base of the trunk. Control Measures Practice growing banana as intercrop in coconut. Root feeding with Calixin (2ml in 100ml water) once in 3 months. Tanjavur wilt
- 10. Symptoms Blackening and shriveling up of distal ends of the leaflets in the central spindle and younger leaves which later break off in bits. Gradual weakening of the tree resulting in decline yield. Leaf Rot
- 11. Symptoms Newly formed nuts more rounded than in in previous years; nuts exhibit scarring on the surface; chlorotic spots on leaves; stunted inflorescences with tip necrosis; leaves begin to decline in size and number; death of palm Cause Viroid Comments No vector has been identified Management There is currently no known method of controlling the disease Cadang-cadang Coconut cadang-cadang viroid (CCCVd)
- 12. Symptoms Some varieties which have the disease may show no symptoms, others exhibit partial yellowing of leaves which begins to spread to leaf tip; necrosis of petioles causing leaves to die and hang from palm canopy Cause Virus Comments Transmitted by leaf hoppers Coconut foliar decay Coconut foliar decay virus (CFDV)
- 13. Symptoms Premature dropping of fruit; fruit with brown-black water-soaked appearance; necrosis of inflorescences; flower stalks turn black; lower, older leaves turning yellow; entire crown turning yellow; yellow leaves turn brown, dry out and hang from canopy Cause Phytoplasma Comments May be transmitted by leaf hoppers Management The most effective method of managing the disease is to plant resistant coconut varieties such as Malayan dwarf or Maypan; antibiotic treatment is effective but not usually practical for large scale plantings Lethal yellowing Lethal yellowing (LY) phytoplasma