Diseases of clove

PAT401

1. COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), ViaVaigai Dam, Theni-625 562 DISEASES OF CLOVE STUDENT COURSE TEACHER Miss. SUMITHRA.S Dr. PARTHASARATHY. S ID NO : 2015021128 Asst.professor ( Plant pathology)

2. MAJOR DISEASES DISEASES CAUSAL ORGANISMS 1. Leaf spot ,twig blight and flower bud shedding Colletotrichum gloeosporioides 2.Leaf rot Cylindrocladium quinquiseptatum 3.Sudden death Valsa eugeniae 4. Seedling wilt Rhizoctonia sp., fusarium sp., colletotrichum sp., 5. Sumatra or die back Ralsonia syzygii , Endothia sp., and phytopthora sp. , 6. Little leaf Phytoplasma

3. 7. Grey blight of clove Pestalotia palmarum 8. Leaf spot of clove Alternaria citri 9. Sooty mould of clove Phragmocapnius sp. 10. Alagal spot of clove Cephaleurous sp. 11. Black root rot Rosellinia pepo 12.Die back Cryphonectria cubensis

4. 1.Sudden death Occurrence : The clove crop of the zanzibar , on which the economy of the islands is largerly based, and which provides nine-tenths of the worlds supplies, is seriously threatened by the sudden-death disease. In 1950 , it was estimated that at least half of the clove trees in zanzibar island had already been killed by this disease, and that in island of Pemba for many years.

5. Sudden death Pathogen : Causal organism : Valsa eugeniae ( Nutman & F.M.Roberts ) Pathogenic character : The perithecia are produced in large numbers.The ascospores are formed during the rainy season are washed down to the soil where the infect the roots.

6. Taxonomic position Kingdom : Fungi Phylum : Ascomycota Class : Sordariomycetes Order : Diaporthales Family : Valsaceae Genus : Valsa Species : Valsa eugeniae

7. Symptoms On mature trees, slight chlorosis occurs on the leaves which results in a sudden and rapid leaf fall followed by wilting of the plants. Complete death of the plants occur within a few days.Death of the trees caused when the roots are unable to absorb water. Major fungal disease that affects the absorbing roots of mature clove trees.

8. Management Cut off the branch cleanly below the infected area and paint the cut surface with copper oxy chloride paste . There is no easy cure for sudden death disease, which is spread by water borne spores,but clove trees affected are sometimes injected with repeated injections of tetracyclin hydrochloride.

9. 2.Sumatra or die back Occurrence : Since the early 1960’s ,an apparently infectious disease of cloves has been spreading throughout W.Sumatra , one of the main clove producing areas of Indonesia. Distribution : Indonesia,Java,Srilanka,Brazil,SouthAfrica , Taiwan,Philippines,Malaysia etc.,

10. LOSSES Sumatra disease is considered to be the single most important threat to clove production in indonesia ,where cloves are used in the manufacture of kretek cigarettes.clove provide an important supplementary income to many small holders in Indonesia . Annual losses in Indonesia were estimated to be $25 million in 1985.

11. Pathogen Causal organism : Ralstonia syzygii subsp. syzygii Pathogenic character : One of the xylem restricted or xylem limited bacteria,which lives in the xylem cells or tracheary elements of plants.

12. Taxonomic position Kingdom : Bacteria Phylum : Proteobacteria Class : Betaproteobacteria Order : Burkholderiales Family : Burkholderiaceae Genus : Ralstonia Species : R.syzygii

13. Transmission R.syzygii subsp syzygii is transmitted by insect vectors that feed on xylem sap. Primary spread : Insects 1.Hindola fulva ( sumatra ) 2.Hindola striata (java) Secondary spread: Contaminated tools

14. Symptoms It is a bacterial disease that generally leads to the death of clove trees within 3 years. It causes yellowing leaves that may wilt or drop from the tree. Greyish brown streaks may appear on new wood of diseased clove trees.

15. Management Insecticide like aldicarb and carbofuran granules have provided effective control. Antibiotic therapy has been used to extend the productive life of infected trees but with some phytotoxicity . Inject an antibiotic called oxytetracyclin into trees to slow the decline of infected clove trees.

16. 3.Leaf spot,twig blight and flower shedding Occurrence : The disease was reported from kerala and when the flowers are seriously affected there is heavy shedding and the losses are huge. Symptoms: Necrotic spots of variable size and shapes are noticed on the leaves. Severely affected leaves wither, droop down and dry up.

17. In nursery seedlings die back symptoms are seen. Twigs are infected as the symptoms extend from the leaves through petioles. The affected branches stand without leaves or only with young leaves at tips. Flower buds are attacked by spreading infection from the twigs. Shedding of flower buds occurs during periods of heavy and continuous rainfall.

18. Pathogen Causal organism: Colletotrichum gloeosporioides ( Penz . & Sacc ) Pathogenic characters : The mycelium is greyish white, thin and sparsely septate . Acervuli are glabrous, rounded and elongated or irregular in shape with setae. Conidia are cylindrical with obtuse ends, one celled and are formed on aseptate,hyaline .

19. Taxonomic position Kingdom : Fungi Phylum : Ascomycota Class : Sordariomycetes Order : Glomerellales Family : Glomerellaceae Genus : Colletotrichum Species : C.gloeosporioides

20. Favourable condition The organism has a wide host range. Heavy and continuous rainfall favour the infection and disease spread. Primary spread : Dormant mycelium and ascospores from infected debris. Secondary spread : Wind borne conidia

21. Management Destroy weed, clerodendron,growing in clove gardens as it serves as the colleteral host. With the initiation of the disease spray the crop with bordeaux (4:4:50) mixture or mancozeb (0.25%) and repeat at 14 days interval particularly in rainy season.

22. 4. Leaf rot Symptom: It is noticed in the nurseries as well as in the main field both at young and mature stages. Infection starts as dark spots at the leaf margin and spreads sometimes with no definite pattern. Rotting may be in the whole leaf or at the tip resulting in defoliation.

23. Pathogen Causal organism: Cylindrocladium quinquiseptatum Host plants : Eucalyptus grandis Eugenia maculata Eugenia globulus Pimenta dioica

24. Taxonomic position Kingdom : Fungi Phylum : Ascomycota Class : Sordariomycetes Order : Hypocreales Family : Nectriaceae Genus : Cylindrocladium Species : C . quinquiseptatum

25. Management Seedling and young plants can be sprayed with systemic fungicides Carbendazim 0.1%. Prophylatic sprays with bordeaux mixture 1% also prevents the disease. Removal of the affected seedlings.

26.   5.Seedling Wilt Losses : The mortality of seedlings due to seedling wilt in the nursery was reported to range from 5-40 %. Causal organism: Cylindrocladium  sp., Fusarium  sp., Colletotrichum  sp., Rhizoctonia   sp.,and   Trichoderma  sp

27. Symptoms Seedling wilt is found mainly in nurseries and causes five to 40% death of seedlings. Leaves of affected seedlings loose natural lustre , tend to droop and ultimately die. The root system and collar region of the seedling show varying degrees of, discolouration and decay.

28. Management Since the infected seedlings promote spread of the disease they are to be removed and destroyed . The remaining seedlings should be treated with carbendazim 0.1% both as spray and soil drench. the nursery is drenched with Copper oxychloride 0.25 %. Alternatively the foliage may be sprayed with bordeaux mixture 1%.

29. 6.Little leaf Symptoms: The affected trees exhibit symptoms of complete repression. The trunk shows numerous protuberances. The branches grow at acute angles with the trunk giving a cone-shaped appearance to the tree. Leaves are reduced in size, internodes are short and primary and secondary branches are arranged closer to each other.

30. The disease also affects seedlings in the nursery. Presence of short internodes and clustering of small, crinckled leaves is also observed. Pathogen:   The disease is caused by Phytoplasma .  Management:  The disease can be kept under check by spraying tetracyclin .

31. 7.Black root rot Black root rot caused by Rosellinia pepo , a new disease of the clove tree in Brazil. Symptoms : Wilting, chlorosis and death, with dry leaves remaining attached to the branches for sometimes. Especially on older plants,only the part of the tree exhibited such symptoms,with leaves falling and leaving the plant defoliated.