Question

Die-back symptoms in citrus are observed due to the deficiency of

• A. Copper
• B. Boron
• C. Potassium
• D. Calcium

Hint:

Mnemonic for Copper: Cu = Cutting back (Die-back).
Also remember "Exanthema" and "Reclamation disease" are associated with Copper.
Citrus is an indicator plant for Copper deficiency!

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to identify the specific micronutrient deficiency that leads to the "Die-back" condition in citrus trees.
Detailed Explanation:

• Copper (Cu) Deficiency in Citrus:
Copper is essential for several enzymatic processes, including photosynthesis and lignin synthesis.
In citrus, a severe deficiency of copper leads to a disorder called "Die-back" or "Exanthema."

• Symptoms of Die-back:
The young twigs start dying from the tip backward (hence "die-back").
Large, dark green, and often distorted leaves are seen on the lower branches.
Pockets of gum may form between the bark and the wood (gumosis).
Fruit may show brown stains and often drop prematurely.

• Role of Copper:
Since copper is involved in the formation of cell walls (lignification), its absence causes the structural weakening of young shoots, leading to their eventual death.

• Other Deficiencies:
Boron: Causes fruit cracking and hard fruit.
Potassium: Causes leaf scorching and small fruit.
Calcium: Causes terminal bud death and "cup-shaped" leaves.

Step 2: Final Answer:
Die-back in citrus is a characteristic symptom of Copper deficiency.