Physiological Disorders of Cauliflower and Cabbage:

Cauliflower and cabbage, both members of the Brassicaceae family, are prone to several physiological disorders that can affect their growth and yield. These disorders typically arise from environmental factors, soil conditions, or nutrient imbalances. Here’s a detailed overview of the physiological disorders for both crops:

Cauliflower

Buttoning:

• • Cause: Buttoning is the premature formation of small, hard, and compact heads rather than a large, tender curd. This disorder occurs when cauliflower is exposed to high temperatures or if there is a delay in sowing.
  • Symptoms: Small, underdeveloped heads that resemble buttons, often with poor quality.
  • Prevention: Plant in cool weather (ideal temperature: 15–20°C). Avoid delayed sowing or transplanting during hot periods. Choose heat-tolerant varieties.

Curd Discoloration:

1. • Cause: Discoloration of the curd is caused by exposure to sunlight, improper moisture levels, or nutrient imbalances, especially a lack of calcium.
   • Symptoms: Yellowing or browning of the curd, sometimes with a watery appearance.
   • Prevention: Ensure proper irrigation to avoid water stress, provide adequate calcium through fertilizers, and blanch the curds by tying the leaves around them to protect from sunlight.

Black Rot:

1. • Cause: Though not entirely a physiological disorder, black rot can be exacerbated by environmental stress, including high humidity and poor drainage.
   • Symptoms: Yellowing and wilting of leaves, followed by the development of black lesions, especially at the leaf margins.
   • Prevention: Ensure good air circulation, avoid waterlogging, and practice crop rotation to reduce the risk of this disease.

Tipburn:

1. • Cause: Calcium deficiency or rapid growth during periods of irregular watering or high temperatures.
   • Symptoms: Necrosis (death) of leaf tips, resulting in dry, brown spots.
   • Prevention: Apply calcium fertilizers, maintain consistent soil moisture, and avoid stress due to irregular irrigation.

Internal Hollowing:

1. • Cause: Internal hollowing is often due to erratic watering, excessive fertilization, or the plant being under stress.
   • Symptoms: Hollow spaces inside the curd, making it less desirable for marketability.
   • Prevention: Ensure uniform moisture levels, avoid over-fertilization, and provide adequate spacing to prevent overcrowding.

Lack of Head Formation:

• • Cause: Cauliflower plants may fail to form heads due to inadequate cold temperatures, poor nutrition, or damage from pests.
  • Symptoms: The plant grows vigorously without forming a central head.
  • Prevention: Plant in areas where temperatures remain cool, use balanced fertilization, and protect plants from pest damage.

Cabbage

Leaf Tip Burn:

1. • Cause: This disorder is due to a calcium deficiency, combined with environmental stress such as dry conditions or inconsistent irrigation.
   • Symptoms: The tips of older leaves turn yellow and dry out, leading to a scorched appearance.
   • Prevention: Provide consistent irrigation, apply calcium-based fertilizers, and avoid water stress.

Premature Flowering (Bolting):

• • Cause: Bolting can occur due to temperature extremes (especially high temperatures), nutrient deficiencies (especially nitrogen), or over-mature seedlings.
  • Symptoms: The cabbage plant flowers prematurely, leading to a poor-quality head.
  • Prevention: Maintain cool growing conditions (ideally 15–20°C), provide adequate nitrogen, and plant at the correct time to avoid heat stress.

Yellowing of Leaves (Chlorosis):

• • Cause: Nitrogen deficiency or poor soil drainage.
  • Symptoms: Yellowing of older leaves, starting from the tips, while the veins may remain green.
  • Prevention: Apply nitrogen fertilizers appropriately and ensure good soil drainage.

Head Splitting:

• • Cause: Cabbage heads can split due to irregular watering, which causes rapid growth and results in the head being too tight.
  • Symptoms: The head cracks open, making it unmarketable.
  • Prevention: Maintain uniform moisture levels and avoid periods of drought followed by heavy rain or over-irrigation.

Internal Corking:

• • Cause: This disorder is often caused by a calcium deficiency or water stress.
  • Symptoms: The core of the cabbage head becomes discolored and hard, leading to a poor-quality head.
  • Prevention: Maintain consistent moisture and apply calcium supplements.

Tipburn and Leaf Marginal Necrosis:

• • Cause: Calcium deficiency due to improper nutrient management or rapid plant growth during periods of stress.
  • Symptoms: Leaf edges turn brown, and the tips of older leaves die.
  • Prevention: Apply calcium-based fertilizers and maintain optimal irrigation practices.

Hollow Heart:

• • Cause: Often caused by irregular watering, inconsistent nutrient supply, or too much nitrogen.
  • Symptoms: The cabbage head appears normal externally but is hollow inside.
  • Prevention: Ensure regular irrigation, apply balanced fertilizers, and avoid excessive nitrogen.

Blackening of Leaves (Black Leg Disease):

• • Cause: Fungal diseases like Phoma lingam can cause blackening, especially in stressed plants.
  • Symptoms: Leaves become blackened at the base, and the stem may rot.
  • Prevention: Avoid overcrowding, maintain proper crop rotation, and use fungicides if necessary.