Rhizopus Rot of Jackfruit

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. Jackfruit, Artocarpus heterophyllus, is a popular

garden species prized for its edible flowers, fruit, and

seeds for fresh consumption or cooking. Jackfruit trees

can reach over 60 ft in height and bear fruit that can be 2

feet or more long and weigh as much as 70 pounds.

Rhizopus rot is a common fungal disease of jackfruit

flowers and fruit. Rot is more likely to occur in

high-rainfall areas or during and after stormy periods.

When warm, humid, wet weather coincides with the

flowering and fruiting season, rhizopus rot can cause

total loss of fruit in jackfruit trees.

Symptoms

At first, soft, watery, brown spots develop on the flowers

and fruit. Subsequently, a powdery, fuzzy-looking

mass of black spores and white fungal mycelia covers

the jackfruit surface. The pathogen engulfs the young

fruit, resulting in the characteristic black, rotten,

shrunken, and sometimes mummified fruit remains. Fruit

symptoms can appear on the tree or can develop on fruit

that are in storage or transit.

Cause

Three species of plant-pathogenic fungi of the genus

Rhizopus can cause this disease in the tropics: Rhizopus

oryzae, Rhizopus artocarpi, and Rhizopus stolonifer. No

jackfruit varieties are reported to have significant resistance

to the disease.

Epidemiology

Warm, humid, rainy conditions favor the development

of rhizopus rot. Wind, rain, and insects dislodge and

spread the tiny fungal spores. When deposited on moist

fruit surfaces, the spores germinate and infective mycelia

grow into the tissues. The infection produces a layer

of black spores on the fruit surface to start secondary

cycles of infection and disease. Although wounds can

predispose the fruit to infection, unwounded flowers and

young fruit are also susceptible. Rhizopus can survive

on decaying plant litter or in the soil to initiate new infections.

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.

Keep ripe fruit from contact with the soil or decaying

organic material. 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. Where disease

is severe, protect fruit with periodic sprays of copper

fungicides or other products registered for use on jackfruit

in Hawaii.

References

Morton, J. 1987. Jackfruit. In: Fruits of warm climates.

Julia F. Morton, Miami, FL. p. 59–64.

Sangchote, S., J. Wright, and G. Johnson. 2003. Diseases

of breadfruit, jackfruit and related crops. In:

R.C. Ploetz (ed.), Diseases of tropical crops. CABI

Publishing, Wallingford, Oxon, UK. p. 135–145

Scot Nelson

University of Havaii at manoa

              

  health