[welshpete]

all 5 varieties of potato's developed scab this year can any one tell me why'
varieties as follows: pentland crown, dessiere, charllote, kers pink, maris peer
the ground was fertilized with chicken manure from a friend's manure heap prior to planting,
help needed please

[Yorkie]

Welcome to the site 

Scab is often caused by too much dryness or too much lime.

Was the manure fresh or well rotted?

[operabunny]

This has been mentioned on a few threads - it does seem as though people in areas that had a really dry spring have had worse scab than usual.

[Ice]

As has been said, too dry or too much lime is the culprit.  It might look unsightly but it is entirely cosmetic and doesn't affect the eating quality at all.

[welshpete]

thanks for replies

Yorkie ; the manure was well rotted.

we did have a dry spring,but we did manage to water every 2-3 days