The genus Cinnamomum

250 M. Anandaraj and S. Devasahayam
Major diseases
Stripe canker
Phytophthora cinnamomi, which causes severe damage to forest trees and avocado, was
first recorded on C. verum causing stripe canker (Rands, 1922). Symptoms start as
a vertical stripe on the stem with amber coloured exudate at the advancing margins,
which hardens later. This disease is reported to be severe in ill-drained soils and causes
up to 42% damage. This fungus also affects C. camphora, C. culitlawan and C. sintok
(Rands, 1922; Ciferri and Fragoso, 1927). The fungus, P. cinnamomi, from pineapple
was also pathogenic on cinnamon, but with reduced virulence. The fungus produces
only chlamydospores characterised by non-papillate sporangia. Papillate sporangia can
be obtained by incubating a non-sterile percolate of field soil (Mehrlich, 1934). Control
measures include improving soil drainage conditions, phytosanitation and wounddressing
with tar. The disease is reported to spread along the west coast of Sumatera
(Van Hall, 1921; 1924). This fungus has also been recorded on cloves in Malaysia
(Lee, 1974; Purseglove et al., 1981).
P. cinnamomi has also been recorded on C. camphora (Chang, 1993a) and C. osmeophleum
from Taiwan, causing yellowing and wilting followed by death of plants from root rot.
P. cinnamomi is heterothallic and both A1 and A2 mating types have been recorded in
Hualing, whereas only the A1 mating type was recorded in Chia-yi. Isolates from
C. camphora were of the A1type (Chang, 1992a,b; 1993a). There is no report of this
fungus on cinnamon in India. P. cinnamomi has been isolated from clove trees in India,
which caused sudden death of the trees (Anandaraj, unpublished).
Foot rot
Foot rot is a major destructive disease of Chinese and Vietnamese cassia (C. cassia),
caused by the fungus Fusarium oxysporum. This fungus attacks and destroys the vascular
system by infecting through the roots. The disease is prevalent during the post-rainy
season when the weather is humid and warm. Application of Trichoderma is effective in
checking the disease incidence, especially in nurseries (Dao, this volume).
Witches broom
Witches broom disease affects more commonly cassia seedlings in nurseries and young
trees in fields, though old trees are also infected. The Tra Giae hamlet of Vietnam
(Tra Mi District, Quang Nam Province) is a hot spot area for this disease. Witches broom
disease is caused by a phytoplasma. Preventive measures recommended for avoiding
the disease include soaking the seeds in warm water (70°C) containing an antibiotic
before sowing. Not much is known about the mode of transmission, vector and other
aspects of the disease. Phytosanitation is advocated to keep the incidence low (Dao, this
volume).
Leaf spot and dieback
Leaf spot and dieback disease in cinnamon is caused by Colletotrichum gloeosporioides.
Symptoms in young seedlings include small brown specks on leaf lamina which later
coalesce forming irregular patches. In older leaves, these small specks coalesce and