Recent seasons have brought extreme temperature fluctuations and erratic rainfall patterns, increasing the occurrence of physiological disorders in vegetables. Two common disorders affecting broccoli and cauliflower are hollow stem and tipburn.
Hollow Stem
Hollow stem, sometimes referred to as boron deficiency, is particularly prevalent in summer when higher temperatures accelerate plant growth. Broccoli and cauliflower have high boron requirements, making this deficiency frequent. As plants grow, internal splits in the stem cause hollow, necrotic areas. Symptoms include brown, water-soaked lesions on broccoli florets and cauliflower curds, significantly reducing shelf life as the product begins rotting from the inside.
Hollow stem is often triggered when soil dries out following extended rainfall and is more likely with excessive nitrogen levels. While nitrogen is crucial for stimulating growth, overuse can dilute essential elements like calcium and boron, which are vital for cell wall strength and elasticity. This imbalance leads to tissue breakdown and stem splitting.
Hollow stem on broccoli
Hollow stem on cauliflower
Tipburn
Tipburn, also known as calcium deficiency, is another common physiological disorder affecting all brassica crops. Calcium uptake and transport within plants are challenging, particularly during humid and warm growing conditions. When plants grow rapidly but evaporate less, calcium cannot move quickly enough from roots to growing tips, resulting in deficiencies in the inner leaves. Affected areas become necrotic, papery, and highly susceptible to secondary infections. Leaves may also appear cupped, reducing the product’s shelf life.
Internal tipburn on cabbage
Tipburn on wrapping of cauliflower
Prevention and Varietal Selection
Choosing the right variety for the season is critical to minimising the risk of hollow stem and tipburn, as some varieties are more resistant to these disorders than others.
Sakata’s F1 hybrid broccoli Ares is specifically designed for warmer growing conditions where hollow stem is a major challenge. This variety matures quickly, producing perfectly dome-shaped, dark green heads that fit seamlessly on punnets. Ares is suitable for sowing in spring, summer, and autumn, making it a versatile choice for various growing conditions.
By understanding the causes and selecting resistant varieties, growers can better manage these physiological challenges, ensuring healthier crops and extended shelf life.