Club root is a real bugger of a disease that can wreak havoc on your broccoli and other brassicas. Caused by the soil-borne organism Plasmodiophora brassicae, club root is notorious for its persistence in the soil and ability to spread easily.
The disease leads to swollen, distorted roots and wilting foliage, eventually stunting plant growth and reducing harvest. Club root favours acidic, moist soil conditions and can survive for years without a host.
Prevention
The best way to combat club root is through prevention, mate. Keep these tips in your gardening arsenal:
- Choose resistant varieties: Select broccoli and other brassica varieties which are resistant to club root. Look for them in seed catalogues or ask your local nursery for help.
- Raise the pH: Club root thrives in acidic soils. Test your soil pH and, if necessary, add lime to raise the pH to around 7.0, which can help suppress the disease.
- Good drainage: Ensure your garden has proper drainage, as club root prefers moist conditions. Consider raised beds or mounds if drainage is an issue.
- Crop rotation: Rotate your brassicas every 3-4 years to minimise the risk of club root buildup in the soil.
- Garden hygiene: Clean your gardening tools, shoes, and gloves regularly to avoid spreading the disease between garden beds.
Treatment
If club root has already made itself at home in your garden, don’t fret! Give these treatment options a fair go:
- Remove affected plants: Pull out infected plants, roots and all, and dispose of them in the rubbish, not the compost. This will help to limit the spread of the disease.
- Apply lime: If your soil pH is below 7.0, apply lime to raise it and create a less favourable environment for club root.
- Solarisation: This method involves covering the affected soil with clear plastic and letting the sun’s heat do its work. Solarisation can help reduce the club root population in the soil, but it requires a good amount of sunlight and warm temperatures to be effective.
- Biological control: Some commercially available beneficial microorganisms, like Streptomyces spp., have shown promise in suppressing club root.