Jack Fruit Diseases

Soft rot or fruit rot

Disease symptoms:

• Young fruits and male inflorescences are badly attacked by the fungus and only a small percentage of the fruits reach maturity.
• Female inflorescence and matured fruits are not usually attacked.
• The disease is a soft rot. A large number of the affected fruits falls off early. In the first stage of attack ·the fungus appears as greyish growth with abundant mycelia which gradually becomes denser forming a black growth.

Survival and spread:

• The fungus gradually advances until the whole fruit or the entire inflorescence rots and falls off.

Favourable conditions:

• Warm, humid, rainy conditions favour the development of rot. Wind, rain and insects dislodge and spread the tiny

Dieback

Disease symptoms:

• The most of die-back becomes evident by discolouration anddarkening of the bark some distance from the tip.
• The dark area advances and young green twigs start withering first at the base and then extending outwards along the veins of leaf edges.
• The affected leaves turn brown and their margins roll upwards.
• At this stage, the twig or branch dies, shrivels and falls.
• There may be exudation of gum from affected branches. Such branches are often affected by shoot borers.
• Infected twigs show internal discolouration

Survival and spread:

• Infected twigs may cause the spreading of die back

Favourable conditions:

• Relative humidity above 80 percent and temperature of 25-31°C and rains

Leaf spot

Disease symptoms:

• Produces dark brick red spots on both the surface of leaf which upon maturity become greyish studed with dark colour, pin headed fruiting bodies of the fungus.

Survival and spread:

• The fungus overwinters on old leaves . Young rapidly expanding leaves are infected.

Favourable conditions:

• Temperature of 25°C and Relative Humidity 95-97%

Rust

Disease symptoms:

• Rust generally develops late in the summer, and in years when disease is severe, it can cause the trees to defoliate in a matter of a few weeks. If this happens on a regular basis, the overall growth of the trees can be reduced and yields can be affected.
• Another consequence of defoliation is that if it occurs early in the summer, the trees will put out new growth that is then at risk of being damaged by early frosts. On the other hand, if defoliation occurs in the fall, the trees may go dormant earlier than usual, which then protects them from early frosts.
• Initially, symptoms of fig rust are visible as small, yellowish spots on the upper surface of the leaves. As these spots (or lesions) grow larger, they turn a reddish-brown color but remain relatively smooth.
• On the lower surface of the leaf, the lesions are a reddish-brown color and have a slightly raised, blister-like appearance. Heavily infected leaves often turn yellow or brown, particular y around the edges, and drop prematurely.

Survival and spread:

• The fungus mainly survives through teliospores (thick walled, resting spores) on leaves left in the orchard or on the soil surface.
• The disease spreads by wind-borne uredospores from infected tree.

Favourable conditions:

• Temperature ranging from 25.5 to 30.5° C with relative humidity of 86-92°c favours high intensity of rust.

Pink disease

Disease symptoms

• It is widespread in tropical and subtropical areas.
• Disease appears as a pinkish powdery coating on the stem.
• Pink colour represents profuse conidial production of fungus.
• Young woody branches of the affected trees lose their leaves & show die back symptoms.
• Pink encrustation is seen on the lower shaded side.

Disease cycle

IPM for Jackfruit

To know the IPM practices for Jackfruit, click here.

Source: NIPHM; Directorate of Plant Protection, Quarantine & Storage