Blight Spirit

Whilst the rest of Europe seemingly bakes during record breaking temperatures, the British weather has been, well, rather British. 

June's hot, extremely dry conditions have been replaced by something rather more familiar - wet and miserable - which has created perfect conditions for potato blight (Phytophthora infestans). Blight strikes when the temperatures over two consecutive days reach over 10 degrees Celsius, and each day has at least 10 hours of relative humidity of 90% or over. July has had that in spades. 

For potato crops (and tomatoes; both are members of the nightshade family Solanaceae) this can prove to be catastrophic. 

The symptoms start with a browning of the edges of the plants leaves, which very quickly reduce the leaves to a brown, crispy tatter. The rain washes the blight spores on to the soil, which can reduce the potatoes to rotting masses of tubers. Hence the need for earthing up the rows of potatoes; that, as well as stopping the potatoes turning green and inedible, reduces the risk of the blight spores reaching the tubers. 

(an unfortunate sight, but we must persevere) 

I learnt a trick a few years ago: cut the foliage off the infected plants, leave the tubers in the ground for a couple of weeks to allow the spores to die off. Dig up the crop and hopefully, if unspoilt, eat, store and enjoy. 

Commercial potato crops are sprayed at great expense to both the farmers and the environment, but this option is not available to the gardener. Being organic means that this would be out of the question anyway. 

Instead, it's about growing more blight resistant varieties. The best blight resistant potato we grew was Sante, but that seems to have disappeared, so we are looking out for something similarly resistant. 

We are keeping our fingers crossed and shall report back when the crop is ready to be lifted. 

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