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Diseases of nutmeg
1. COLLEGE OFAGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562
DISEASES OF NUTMEG
STUDENT COURSE TEACHER
Miss. SOWMYA S P Dr. PARTHASARATHY S
ID NO : 2015021123 Asst.professor ( Plant pathology)
2. Major diseases
Diseases Causal organism
Leaf spot and shot hole Colletotrichum gloeosporioides
Fruit rot Colletotrichum gloeosporioides
Botryodiplodia theobromae
Thread blight
Marasmius pulcherima
Marasmius equicrinus
3. Leaf spot and shot hole
Causal organism : Colletotrichum gloeosporioides
Teleomorph stage : Glomerella cingulata
Distribution :
It has worldwide distribution.
4. • Single celled conidia, hyaline slightly curved
with oil globule.
• Asexual fruiting body acervuli.
Pathogen
5. Favourable conditions
• Optimum temp - 25-28 °C, pH range of 5.8 to
6.5 and high humidity.
• Spores are released from acervuli when there
is an abundance of moisture.
• Colletotrichum is inactive in dry season.
6. Mode of spread
• Primary spread – Through dormant mycelium
and ascospores from infected debris.
• Secondary spread – Through wind borne
conidia.
7. Taxonomic position
• Kingdom : Fungi
• Phylum : Ascomycota
• Class : Sordariomycetes
• Order : Incertae sedis
• Family : Glomerellaceae
• Genus : Colletotrichum
• Species : C. gloeosporioides
8. Symptoms
• The initial symptoms of the disease appear as sunken spots
surrounded by a yellow halo.
• Later, the central portion of the necrotic region drops off
resulting in shot hole symptoms.
• Die back symptoms are also observed in some of the
matured branches.
• On young seedlings, drying of the leaves and subsequent
defoliation are observed.
10. Management
• Collect and destroy the infected plant debris.
• The disease can be controlled by spraying 1%
Bordeaux mixture two or three times during
rainy season.
12. Taxonomic position
• Kingdom : Fungi
• Phylum : Ascomycota
• Class : Dothideomycetes
• Order : Botryosphaeriales
• Family : Botryosphaeriaceae
• Genus : Botryodiplodia
• Species : Botryodiplodia theobromae
13. Pathogen
Inside the pycnidia, conidiogenous cells
produce hyaline thin walled pycnidiospores
which become brown, thick walled, two celled
with longitudinal striations.
15. Symptoms
• On immature fruits, the symptoms of the disease appear as
splitting and rotting of fruits which ultimately drop
prematurely.
• In case of fruit rot, the infection starts from the pedicel as
dark lesions and gradually spreads to the fruits, causing
brown discolouration of the rind resulting in the rotting.
• In advanced stages, the mace also rots emitting a foul smell.
19. White thread blight
The first is a white thread blight wherein fine
white hyphae aggregate to form fungal threads
that traverse along the stem underneath the
leaves in a fan shaped or irregular manner
causing blight in the affected portion.
20. Horse hair blight
• The symptoms of this disease appear as fine black silky
thread of the fungus form an irregular, loose network on
the stems and leaves.
• These strands caused blight of leaves and stems.
• However, these strands hold up the detached, dried
leaves on the tree, giving the appearance of a bird’s
nest, when viewed from a distance.
22. Management
• Follow phytosanitation and shade regulation
practices.
• With the initiation of the disease spray the crop
with Bordeaux mixture .
23. Other minor diseases
• Die-back (Diplodia spp.)
• Dry rot (Stigmina myristicae)
• Root rot (Fomes noxius and F. lamaoensis)
24. References
• Singh.V.B, Kriti singh- Spices, New age
International publisher.
• Saha.L.R, Handbook of plant diseases, 2002,
Kalyani publishers, New Delhi.
• http://tnauagriportal.ac.in
