Diseases of Jackfruits

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1. Diseases of Jackfruit

2. Introduction Jackfruit ( Artocarpus heterophyllus ) is consumed as fruit as well as vegetable. The trees are supposed to be hardy but even then the following diseases become a limiting factor in its cultivation. Jack fruit is a minor and less exploited crop which is rarely grown as monocrop . Usually it is grown as mixed crop. Jack fruit is said to be rich source of carbohydrate and even some vitamins like Vita A. The plant genus Artocarpus comprises roughly 50 species of tropical trees native to the Pacific and South and Southeast Asia, several of which produce edible Fruit.

3. Diseases Major Diseases 1. Die back; ( Botryodiplodia theobromae ) 2. Fruit rots a. Rhizopus artocarpus b. Rhizopus nigriocans C. Phytopthora palmivora Minor Diseases a. Leaf spot- Phyllosticta artocarina b. Pink disease- Botryobasidium salmonicolor & Corticium Salmonicolor

4. 1. Die back ( Botryodiplodia theobromae )

5. SYMPTOMS Discoloration and darkening of the bark from the tip downwards. It advances and young green twigs start withering from the base towards veins of leaf edges. Infected leaves turn brown with their margins rolling upwards. Infected twigs or branches shrivel due to necrosis and fall down, there may be exudation of gum from affected branches which may then attacked by shoot borers causing internal discoloration of the twigs. On infected twigs, erumpent aceruvuli of Colletotrichum gloeosporioides can be seen.

6. CAUSAL ORGANISM: Botryodiplodia theobromae Characteristics : Pycnidia are asexual fruiting body, up to 5mm in diameter. Conidia are asexual spores, thin walled at first and become thick walled, septate mycelia is present. Primary source of inoculum: Dormant mycelia. Secondary source of inoculum: Soil and airborne conidia.

7. Management Pruning of infected twigs followed by spraying of carbendazim 0.1% or thiophonate methyl 0.2 % or chlorothalonil 0.2% is recommended. Controlling shoot borer, & shot hole borers by suitable insecticides is also important in reducing die back disease.

8. 2. Fruit rots a. Rhizopus artocarpi

9. SYMPTOMS The young fruits are badly attacked by the fungus & only a small percentage of the fruit reach maturity female inflorescence & matured fruits are not usually attacked . The disease is a soft rot a large no. of the affected fruits fall off early . In the first stage of attack the fungus appears as a grayish growth with abundant mycelia which gradually becomes dense forming a black growth.

10. Pathogen The fungus gradually advances until the whole fruit or the entire inflorescence rots & falls off . Causal organism:Three species of plant-pathogenic fungi of the genus Rhizopus can cause this disease in the tropics: Rhizopus oryzae, Rhizopus artocarpus , and Rhizopus stolonifer . No jackfruit varieties are reported to have significant resistance to the disease.

11. Management Prune the tree to encourage good ventilation and to reduce relative humidity in the canopy. Remove and destroy diseased fruit from trees and the ground. Clean up decaying organic debris within and around the tree. Ensure that water does not pond around the tree’s root zone. Control weeds around young trees. Intercrop jackfruit with trees that are not susceptible to infection by Rhizopus. Avoid wounding the fruit. Wash fruit after harvest in clean water and dry thoroughly before packing or transporting. Do not pack fruit with symptoms, destroy them. Avoid storing fruit after harvest in hot, poorly ventilated containers.

12. Chemical Control Spraying of the young fruits with capton 0.2% or Bordeaux mixture 1.0% or copper oxy chloride .025%. An interval of three weeks during the months of Jan – Feb & March is effective in controlling the disease.

13. Phytophthora rot : Phytopthora palmivora Symptoms: Infection takes place through whole or wounded skin in rough skinned verities & through wounds in smooth skinned verities. Water socked lesions occur 48-78 hours after inoculation. They enlarge to form light brown spots with sporulating hyphae near the edge affected fruits develop soft rot. The damage caused to the bark of crown roots and or bark of the trunk is called Phytophthora gummosis collar rot or foot rot.

14. Epidemiology Sporangial production rain water was the best and P . palmivora thrives best at 25- 28°C. A soil pH of 5.4-7.5 favours the disease. Management: Spraying with Benomyl 1g/ lt completely control the rotting

15. MINOR DISEASE A. Leaf spot- ( Phyllosticta artocarina )

16. Symptoms It produces white spots with broad dark margins on leaves. Pestalotiopsis clastica also causes leaf spots. It is characterized by dark brick red spots on both the leaf surfaces in mature spots the centres become grayish with erupted dark acervulus, The margins of the spots turn dark brown.

17. Management The disease is effectively controlled by spraying Carbendazim 0.1% or Thiophanate methyl 0.2% or Difolatan 0.2%.

18. B. Pink disease ( Botryobasidium salmonicolaor & Corticium Salmonicolor )

19. Symptoms  It is widespread in tropical and subtropical areas.  The disease appears as a pinkish powdery coating on the stem.  Pink colour represents profuse conidial production of fungus.  Young woody branches of the affected tree lose their leaves & show die back pink encrustation is seen on the lower shaded side, and show die-back.

20. Management The affected branches should be pruned and the cut end should be pasted with Bordeaux paste or Copper Oxychloride