Question

Whip-tail's disease in cauliflower is noted due to deficiency of
(a) Manganese
(b) Magnesium
(c) Molybdenum
(d) Nitrogen

Answer 1

Hint: Symptoms of whiptail disease in young plants are chlorosis of leaf margins (the whole leaves may turn white). Another symptom includes the under-development of leaf blades. Only the midribs may develop when the deficiency becomes more severe.

Complete answer:
Whiptail disorder is caused due to deficiency of a chemical element called molybdenum. Mainly, the leaf blades do not develop properly and become strap-like under this condition. Due to severely deformed growing points, no marketable curd is formed. This condition in cauliflower is mainly due to deficiency of molybdenum which occurs in acidic soils below 4-5 pH. Young seedlings with molybdenum deficiency exhibit stunted growth and severe leaf deformations. Leaf-blades are severely reduced and become cupped upwards. Leaf margins also display chlorosis and slight necrosis.

Additional information:
- Molybdenum is important for yield as:
It increases growth (especially of broccoli and cauliflower), inner quality (sugar and vitamin C content), and shelf life.
- Factors leading to molybdenum deficiency:
Acid soils
Low pH
Low levels of soil organic matter
- Other nutrient deficiency in cauliflower are:
Browning: It is a common problem in cauliflower. The stem becomes hollow and the curd becomes brown in this condition. Additionally, the affected curds develop a bitter taste. It occurs due to a deficiency of boron.
Buttoning: One of the symptoms of this disorder includes small curd or ‘button’ while the plants are small and consequently the curd gets open. This disorder is mainly caused due to the deficiency of nitrogen.
Blindness: Under this condition, the terminal bud remains under-developed or gets broken or eaten away by the insects.
Internal tipburn: It is a nonpathogenic internal disorder and is mainly associated with the death of leaf tissue.
So, the correct answer is ‘(c) Molybdenum’.

Note: Molybdenum deficiency can be controlled by limiting the soil which reduces the acidity and increases the soil pH up to 6.5. It can also be controlled by the application of 1-2 kg/ac of sodium or ammonium molybdate.