The document discusses Rhizopus artocarpi, a fungus that causes jack fruit rot, including its symptoms such as soft rotting of young fruits and inflorescences, distribution in various Pacific islands, taxonomy as a species of the fungus Rhizopus in the order Mucorales, and management through cultural controls like pruning and sanitation or chemical controls like fungicide sprays. Warm, humid conditions favor the fungus's development and it can be spread by wind, rain and insects.

1. COLLEGE OF AGRICULTURAL TECHNOLOGY
Affiliated to Tamil Nadu Agricultural University, Coimbatore
Kullapuram, Via Vaigai dam, Theni-625 562
JACK FRUIT ROT
STUDENT COURSE TEACHER
Miss. KOWSALYA M Dr. PARTHASARATHY S
ID. No. 2015021065 Asst. Prof., (Plant Pathology)

2. JACK FRUIT ROT
Rhizopus artocarpi
Occurence and distribution:
It is reported from Cook Islands, Fiji, French
Polynesia, Niue, Samoa and Solomon Islands.

3. Symptoms
• Young fruits and male inflorescences are badly
attacked by 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 fall off early.

4. • In the first stage of attack the fungus appears as
greyish growth with abundant mycelia which
gradually becomes denser forming a black
growth.
• The fungus gradually advances until the whole
fruit or the entire inflorescence rots and falls off.

5. Symptoms

6. Taxonomy
• Kingdom : Fungi
• Order : Mucorales
• Family : Mucoraceae
• Genus : Rhizopus
• Species : Rhizopus artocarpi

7. Pathogen character

8. • Colonies very fast growing and more than 2cm high,
reddish grey brown.
• Sporangiophores 1-3.5 cm tall, 34µm thick, non septate,
brownish black.
• Sporangia borne singly at top of sporangiophore, mostly
100-200 µm diameter.
• Usually collapsing when mounted on a slide, white at first,
becoming black, containing many sporangiophores.

9. Lifecycle

10. Favourable condition
• Warm, humid, rainy conditions favour 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.

11. • 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.

12. Management
CULTURAL CONTROL :
• Prune the trees so that air travels freely through the
canopy and the fruit dries rapidly after rains.
• Carry out hygiene measures: remove infected fruits of
all ages from the trees and any that have fallen to the
ground.

13. After harvest :
• Harvested fruits with care, avoiding bruising it or
creating wounds. Similarly, transport the fruit with
care.
• Avoid storing fruit in warm, poorly ventilated,
buildings with high humidity; if possible, store the fruit
below 10 ͦ C. Rhizopus does not produce spores at 4ͦ C.
Remember, one fruit in a consignment can cause the rot
of many others in a few days.
• Make sure the packing shed and boxes/bins are clean,
removing any plant material on which Rhizopus could
produce spores.

14. CHEMICAL CONTROL:
• Spray young fruits with Mancozeb 0.25% or Copper
oxychloride 0.25% or Dicloran 0.2% or Pristine 0.2%
at interval of 3 weeks during the months of January,
February and March.