Major diseases of jackfruit include die back caused by Botryodiplodia theobromae, and fruit rots caused by Rhizopus artocarpus and Phytopthora palmivora. Die back results in discoloration and wilting of branches from the tip downwards. Fruit rots lead to soft rotting of young fruits. Management strategies include pruning, removing diseased plant material, and spraying fungicides like carbendazim, thiophanate methyl, and benomyl. Minor diseases include leaf spot caused by Phyllosticta artocarina and pink disease caused by Botryobasidium salmonicola, which can be controlled by spraying fungicides.
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
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.
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
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