Question

Lesions on leaves, stems ,and fruits with raised, brown, water soaked margins seen in
A. Smut
B. Rust
C. Canker
D. None of these

Answer 1

Hint:- Lesion is a region of damage in an organ or tissue caused by infections or wounds. In plants lesions usually represent microbial infections and damages. Characteristics of different microbial attacks vary and can be differentiated based on the type of lesion formed. Lesions can also be formed due to tumor formation in plants.

Complete solution:
Canker or the Citrus canker is a bacterial disease infecting the citrus plants. The bacteria can enter the plant parts through openings of stomata or any wounds. The infection is usually more affecting in younger plants. Citrus canker infection is a latent infection. An infected plant may appear healthy for a long time. Bacteria are present in older lesions and bacteria-containing fluid oozes out from the lesions. This infective fluid reaches other healthy plants spreading the infection. The disease is also spread by air currents and raindrops. Rainwater containing bacterial fluids accumulated in the plant parts can enter through the natural openings of the plants. Xanthomonas axonopodis is the causative agent of the disease. The canker lesions are seen in the stem, leaves, and also in the citrus fruits like lemon, grapes, etc.
Smut disease in crops is caused by smuts which are multicellular fungi that produce a large number of spores called teliospores. Economically significant crops like wheat, barley, sugarcane, maize, etc. are affected by smuts. Smuts affect the reproductive system of the crops and produce abnormal tumor-like outgrowths called galls which on bursting releases a large number of teliospores.
Rust disease is caused by pathogenic rust fungi. They are obligate organisms that affect only living plants. Fungi coming under order Pucciniales are the causative agents. They are large in number and affect a wide range of crops and plants. The fungi appear as rust-colored spores in plants and also form yellow colouration, stunted growth, and fruiting bodies in infected plants.

So, the correct answer is option C.

Note:- Citrus canker can cause canker outbreaks. Once canker infection is detected in an area the eradication of whole citrus plants in that area of cultivation will be required. The area after eradication is used for cultivation only after certain months or years as the bacteria may remain in the soil for some time.