Last month we covered pests and now we are going to take a look at the most common diseases. Once again we have used both The Allotment Book by Andi Clevely and Allotment month by month by Alan Buckingham for reference. We highly recommend both books, especially if you are just starting out.
Just as with pests there are actions we can take to lessen our risk.
- Choose disease resistant varieties
- Keep your soil healthy, well drained and full of organic material
- Follow a crop rotation regime - See February 2024 blog
- Be vigilant and take action as soon as you think you might have an issue
- Remove and destroy diseased plants immediately to avoid spreading the disease to healthy plants
- Do not compost diseased plants
- Keep areas clear of dead plants and debris
- Avoid overcrowding
- Keep evenly watered to avoid drought stress
- Do not over, or under, feed
- Maintain healthy pH levels
Now to the specifics...
Canker - shows up as lesions that may encircle and kill complete stems. Causes death of bark and damage to tissue on trees and other woody plants. Prune back to healthy growth.
Mildew - Can be powdery or downy. Powdery, as the name suggests, leaves a grey, dust like substance on distorted foliage whilst downy shows as yellow areas on the top of the leaf with grey, fuzzy, patches below. Avoid overcrowding, and drought. Do not get the leaves wet when watering and pinch off infected parts.
Rots - caused by fungi and bacteria causing decay of plant tissue. Thrive in damp/waterlogged conditions and often after injury so prevention is better than a cure. Keep air circulation available, do not overcrowd or over water and be careful not to cause any damage to the plants. Remove affected plants and destroy.
Rust - Fungal disease that causes small dark spots on leaves and stems. Also has yellow, red or brown spores with pustules. Although ugly it is not disabling. Clear fallen leaves that are affected. This disease can seriously affect Mint in particular and the advice is to remove and destroy the plants, disinfect all tools used and replant in a new site.
Scab - Both fungal and bacterial disease causing rough patches on leaves, twigs, fruit and root crops. Superficial but may lay plants open to further diseases. Water and dress with manure on a regular basis and avoid over liming. Clear scab affected leaves and prune off infected shoots in the autumn. Although ugly, it does not prevent you from using the produce. Use it first and do not store.
Viruses - very common and can affect a range of plants. Signs are yellow spots, crinkled and or very small leaves, stunted growth and reduced yields. Spread by pests and by coming into contact with infected tools. Disinfect all tools, pots and seed trays used. Control pests as best you can. Destroy plants.
Wilt - A disease of the soil that can affect herbs, cane fruits and vegetables, especially tomatoes and cucumbers. Caused by poor drainage, overwatering or prolonged cold, wet weather. Affected plants are unlikely to recover but ensure soil or compost is never waterlogged and do not plant susceptible crops too early.