Causes of Potato Blight
Potato Blight is caused by the Phytophthora infestans fungus This fungus can also infect other members of the potato family, Solanaceae such as tomatoes. It spreads via airborne spores on the wind until it lands on a susceptible plant and the weather conditions are right for it to develop, warm and humid.
Good practice helps prevent potato blight
* Be sure to get all the potatoes out from the ground when you harvest, even the tiny ones if you can so you don’t leave a reservoir of infection on your plot.
* Ensure potatoes are well earthed up to protect tubers so preventing it spreading into them even if you get blight in the foliage
* Water from the base rather than spraying potatoes. If the weather is right but there is no rain, your artificial rain will give the blight a hold. Leaky hoses are a good way to water potatoes, unless you have hosepipe restrictions