Potatoes

www.rhs.org.uk/advice
Leaf symptoms of potato blight : These first appear as brown or black patches
at the tips and margins of leaflets. Under suitable conditions the
patches enlarge and the leaflets curl and wither. In moist weather the
causal fungus is sometimes visible as a delicate white growth on the
margins of the patches, particularly on the underside of the leaves...

Chitting simply means encouraging the seed potatoes to sprout before planting.
* Seed potatoes are ready for planting out when the shoots are 1.5-2.5cm (0.5-1in) long.