Whilst watching the TV programme Coast last weekend I was reminded of the horrors during the Great Famine in Ireland during the mid 1800's or perhaps better known as the Potato Famine? It was said that approximately one third of Ireland's population were dependant on the Potato crop for food and as Potato Blight ravaged their crops resulting in over 1million people dying and another million emigrating - cutting the country's population by up to 25% causing devastating effects.
Phytophthora infestans is the fungus responsible for Blight and can affect both Potatos and Tomatoes alike - brown patches develop on the leaves, and the fruits of the tomato start to go brown in patches until the whole fruit shrivels and unless the affected leaves of potatoes removed in time, the fungus will get into the soil and wipe out your whole potato crop as it did in Ireland (although maybe on slightly smaller scale!). The fungus seems to strike predominantly in moist or wet weather in mid to late summer and does not take long to take hold.
With potatoes, I've found that if you remove all the foilage above ground, then usually the potato tubers will carry on and develop okay without being affected. Obviously there is the option to spray the plants but I prefer not to. With tomatoes, many people will opt for growing them under cover or if grown outside the best thing is to remove as many of the diseased leaves and fruit as quickly as possible and in many cases plants will recover. ONE IMPORTANT THING - do NOT compost any of the diseased plants or fruits - dispose in a rubbish sack. If this goes into your compost, the disease is much more likely to become a real problem especially where the compost is added to planting areas where you will grow potatoes or tomatoes the following year.
TIPS TO AVOID BLIGHT:
- Do not to grow these two crops in close proximity to one another.
- Try operating a good crop rotation system which helps avoid pests and diseases getting established.
- Ensure the plants are correctly spaced out.
- Try growing more blight resistant varieties if this is a problem.
- For potatoes; earth up the tubers well - this will offer greater protection for your crop.