The document discusses 3 main diseases that affect cinnamon plants: leaf spot caused by Colletotrichum gloeosporioides which causes leaf spots and dieback; canker caused by Phytophthora cinnamomi which causes irregular vertical stripes on the bark; and grey blight caused by Pestalotia palmarum which causes small yellow-brown spots on leaves that later turn grey. The diseases are described in detail including symptoms, pathogens, conditions that promote spread, and recommended management practices such as removing debris, spraying fungicides, and soil application of sulphur.
3. 1. Leaf spot and dieback - Colletotrichum gloeosporioides
• First it is observed in many parts of Kerala which is serious
both in nurseries and grownup trees.
Symptoms
• Small spots develop on leaf lamina which gradually enlarge
and coalesce to form irregular patches.
• Leaves dry up and the pathogen spreads to the stem resulting
in die-back symptoms.
4. • Young seedlings are killed.
• In mature trees, small specks appear which increase in size
resulting in necrotic blotches. Light to deep brown concentric
zones develop on the spots during alternate dry and wet
conditions.
• Shot hole symptoms are rarely noticed.
6. Pathogen
• Pathogen produces single celled conidia, hyaline,
slightly curved with oil globule.
• Asexual fruiting body is acervuli.
7. Favourable conditions
• Heavy and continuous rainfall favour the infection
and disease spread.
• The organism has a wide host range and the infection
is by air-borne conidia.
8. Mode of spread and survival
• The fungus is soil borne and survives as facultative
saprophyte in the infected plant debris .
• The fungus mainly spreads from field to field through
irrigation water.
• The secondary spread is through wind borne conidia.
9. Management
• Collect and destroy the infected plant debris.
• With the initiation of the disease, spray the crop with
Bordeaux mixture (5:5:50) or copper oxychloride
(0.3%) or combination of mancozeb (0.25%) and
carbendazim (0.1%) and repeat at 14 days interval.
10. 2. Canker – Phytophthora cinnamomi
Symptoms
• Irregular and vertical necrotic stripes (1-5 cm) appear
on affected plants.
• The cankers are sunken with zonations and separated
from the healthy tissue by a black line.
12. Pathogen
• The hyphae are broad, hyphal swellings typically
spherical (42 µm).
• Sporangiophore are thin (3 µm) and occasionally
branched. Sporangia are broadly ellipsoidal or ovoid
(33 x 57 µm), papilla absent.
13. • Oogonia (40 µm) have smooth walls and become
yellow or golden with age. Antheredia amphigenous,
long and measure 21-23 x 17 µm. Oospores hyaline,
nearly filling the oogonium and thick.
Favourable conditions
• The optimum temperature for growth of the fungus is
24-28o C.
15. 3. Grey blight – Pestalotia palmarum
• Reported in India by karunakaran et al.
• Foliar damage upto 90 %
• Most serious disease spread in all cinnamom growing
areas.
16. Symptoms
• Initially small yellow brown spots appear on the
leaves.
• Small brown spots which later turn grey with a brown
border.
17. Pathogen
• Conidia produced inside the black acervuli amidst
sterile setae.
• Conidiophores hyaline, short and bear five celled
conidia
• Middle three celled are dark coloured .
• End cells are hyaline with 3 to 5 slender elongated
appendages at the apex of the spore.
18. Mode of spread
• Primary and secondary spread through conidia from
infected plants.
Management
• Spray Copper Oxy Chloride or Bordeaux mixture
0.1% during winter season and Summer season.
• Top dressing with fungicides with application of
potassium.
19. References
• Gupta S.K., Monica sharma and R.C.Sharma,
2017, Diseases of vegetables, ornamentals and
spice crops, scientific publishers, New delhi,
page no – 170 to 173.
• www.researchgate.net
• www.plantdiseases.com
• www.apsnet.org
• www.ecoursesonline.iasri.res.in
