Question

Red rust of tea disease is caused by which organism?
a. Cephaleuros
b. Synchytrium
c. Mucor
d. Fusarium

Answer 1

Hint: Red rust is a parasitic thalloid green algal disease. When a tea plant is affected by this disease it destroys leaves of the plant and inhibits formation of new shoots and also damages fruits of the plant.

Complete answer:
Red rust is a condition in which algae grows on stems or leaves. On leaves the effect can be parasitic and epiphytic while on stem it is mostly parasitic. When algae gets favourable conditions, it penetrates into the leaf tissue below the epidermis layer and starts damaging the internal tissues. Algae is orange and yellow in colour, that's why we call it “rust”. The algae do not grow on petiole of leaf. Algae do not penetrate inside the host cell but it gets its nutrition through diffusion and hence hosts get deprived of nutrition and get dry and turn up to brown colour.
This condition can be treated in two ways:
To cut down all infected portions from the plant. With the help of spraying Bordeaux mixture.
By increasing the vigour of the branches because it is considered that lack of vitality of the branches is directly linked with the virulence of the disease.
Now, algae which is responsible for this red rusting is Cephaleuros which have parasitic life cycle on tea plants and grow on leaves and stem leaving brown and orange patches on the leaf. The algae also infect other plants as well like coffee, mango, guava, etc.

Note: Red rust name is given to the disease due to colour of the algae and patches formed due to the algae which is orange-yellow colour. There is no rusting as such.