The genus Cinnamomum

168 Nguyen Kim Dao
through the Witches Broom Disease Project of Tra Mi cinnamon by a study group from
the Institute of Ecological and Biological Resources (IEBR, 1996). While the general
cause of witches broom disease is Mycoplasma (Phytoplasma), infections by viruses,
fungii, Azotobacter and insects are pre-disposing factors (Luc, 1999).
Preventative measures for this disease include soaking the seeds in warm water (70 °C)
containing an antibacterial medicine. To exterminate microorganisms, the chemicals
suggested are: Daconil – 0.14%; Viben – 0.07%; Anvil – 0.15%; Tilt – 0.006%;
Sconee – 0.02%; Formaldehyde – 0.37%; SEAL – 0.05%; Chloramphenicol – 0.25%;
or pulverized petroleum and soap at a ratio of 1:1 at the concentration of 5% (Luc, 1999).
The solution can exterminate thrips and does not influence the plant growth. The
diseases of cassia are more common in the south than in the north of Vietnam and the
south of China, because of the different weather conditions. The weather in the south
is hot, wet, and the rainfall and light regime is good for insect and disease development.
The incidence of diseases in private farms is lower than in state-owned farms because
the farmers have much experience in growing and tending cassia as it is an asset and
source of income for each family from one generation to another. Betrothal ceremonies
have often included the cassia gardens, so the gardens are cared for greatly. Effective
control measures suitable for small holders are not yet available. Witches broom disease
has spread from nursery to gardens. Here the most important protective measure is
phyto-sanitation. The seeds are selected from healthy mother plants and the land
should be cleaned. Supplying sufficient nutrients and minerals and additional lime can
be useful. Most diseases and pests occuring in the region can be effectively controlled
by simple treatments with suitable fungicides and insecticides.
Insect pests
There are 14 insect species that are harmful to cassia gardens and forests (Table 6.4),
two of which are serious pests: Liothrips sp. (thrips) and Anatkima insessa. Results from
experiments proved that thrips cause yellow leaves, curly leaves, stunted excrescence in
buds and treetops, and they transmit diseases from the exterior to the interior through
stinging and juice sucking. Insecticide application is seldom practiced by growers.
Physico-chemical Properties and Composition of Cassia Oil
Crude cassia oil has the following physico-chemical properties (Guenther, 1950):
Sp. gravity (15 °C) : 1.055–1.070
Optical rotation : 1°0 to 6°0
Refractive index (20 °C) : 1.600–1.606
Acid number : 6–15, in exceptional cases up to 20
Cinnamic aldehyde content : 75–90%
Solubility : Readily soluble in 80% alcohol
Boiling Point : 240–260 °C
Crude cassia oil is subjected to rectification by the importing countries (mainly the
USA). The rectification is done to remove adulterants such as rosin, kerosene and lead.
Only rectified cassia oil is permitted to go into the market. The rectified cassia oil has
the following physicochemical properties: