Summer die back, little leaf and gummosis of citrus are diseases of citrus plants due to deficiency of which of the following nutrients?
Verified Answer
A. Boron
B. Copper
C. Zinc
D. Molybdenum
Explanation:
Summer dieback, little leaf, and gummosis in citrus are characteristic symptoms of Copper (B) deficiency. Copper is essential for enzyme activity, photosynthesis, and lignin formation. Boron (A) deficiency affects fruit development. Zinc (C) deficiency causes 'little leaf' and 'rosette' but typically without gummosis or severe dieback. Molybdenum (D) deficiency causes 'yellow spot' in citrus, not these symptoms. Hence, (B) is the correct answer.