Vegetable Brassicas

Agronomically, the key to top performing crops is balanced plant nutrition. High brassica yields are obtained on fertile soils where water is not limiting. Good soil structure is essential for strong root development.

It is important to produce a complete crop canopy as soon as possible after planting and then to maintain productive leaf areas for a long period, in order to maximize growth.

Good nutrition is an essential pre-requisite for a high quality brassica crop and influences all aspects of quality: appearance, size, weight, shelf life and importantly taste and nutritional content.

Through its influence on growth and development, crop nutrition influences all aspects of vegetable brassica appearance including size, weight, compactness and colour.

Crop nutrition influences characteristics such as dry matter, cell wall strength and moisture control which all affect storage quality and shelf life of all brassica vegetables.

Good nutrition is an essential pre-requisite for improved brassica sugar content, resulting in sweeter and tastier crops.

Brassica vegetables all contain various health promoting compounds including vitamin C and glucosinolates. A good balanced crop nutrition programme is needed to achieve good levels of these compounds.

Tipburn is generally related to calcium and/or boron deficiency. Tipburn is a major concern in head forming brassicas, because it develops approaching maturity, or during storage, leading to loss of quality and marketability.

Hollow stem is a physiological disorder in cabbage, cauliflower and broccoli - frequently linked to calcium and boron deficiency or over-supply of nitrogen.

Black petiole or black midrib is an internal disorder of cabbage, which occurs as the head approaches maturity. It is thought to be caused by an imbalance of potassium and phosphate and excess nitrogen.

Clubroot is caused by a soil-borne fungus and affects all brassica species.

Deficiencies should always be checked by using leaf tissue analyses, as many of the symptoms resemble each other.

Black speck is a brassica disorder that consists of very small to moderate size discolored lesions on the midrib and veins of the leaves.

The aim of a brassica producer is a high yielding high-quality crop that satisfies the end-user. There are a large number of agronomic factors which can influence this, many are within the control of the grower under given growing systems and climatic and soil conditions.

Soil and leaf tissue analyses should be used to assess nutrient imbalances.

A correct balance between macronutrients and micronutrients is essential to obtain the best results possible from vegetable brassicas. A deficiency of any single nutrient is enough to limit crop yield and the availability of each nutrient needs to be related to the crop requirements. A review of nutrient uptake and offtake reveals which nutrients are required at which growth stages together with the role of each nutrient.