Question

Die back disease in citrus is due to deficiency of
a)Mo
b)B
c) Cu
d)Zn

Answer 1

The deficiency of nutrients causes many effects on plants. This condition may occur due dryness, water logging, and very alkaline and acidic conditions. Lack of nutrients like nitrogen, potassium, phosphorus, boron, zinc, etc., causes many different diseases.

Complete answer:
To answer this problem, first, we need to learn about the deficiency diseases of citrus plants. Dull green, yellowish, smaller leaves, the back of the twigs, the thin and bushy appearance of the uppermost part with a scattered bloom are the specific symptoms of deficiency diseases in the citrus. Deficiency is expressed by light green to yellow foliage over the whole forest.

Now, let us find the solution from the given options -

Molybdenum Deficiency in citrus is generally referred to as "yellow spot." Deficiency occurs when trees are unable to absorb enough Mo from acidic soil. The signs of deficiency occur on the leaves as large interveinal chlorotic spots in early summer.
Boron Deficiency in citrus (lime) is generally referred to as hard fruit or stony fruit. Trees deficient in boron develop twisted leaves. Mature leaves show thick, corky veins and midribs. The leaves have been twisted. Fruits of all ages exhibit signs of deficiency. A lot of fruit sets collapse in the first 3 or 4 months.
Copper Deficiency in citrus is variously referred to as exanthema, red rust, die-back, multiple bud or peach leaf conditions. Physiological disease caused by copper deficiency is often generally referred to as foliocellosis.
The most striking consequence of zinc deficiency in citrus is the characteristic irregular and chlorotic leaf spots, and small terminal growth leaves. The first leaf effects are the fading of chlorophyll in the mesophyll areas between the veins, in the main midrib veins and fringe bands adjacent to the remaining green veins.

Thus, the right answer is option C.

Note: Specific nutrient deficiency can cause many diseases in plants. The deficiency of nitrogen can cause symptoms like die back of twigs, thin and bushy appearance of the uppermost part with scattered bloom, etc. in citrus plants.