If the tress you've recently planted are also Prunus varieties, then they are at risk, unless you chose canker resistant varieties. There are treatments for bacterial canker which should really be applied in summer, early and late autumn, following pruning of badly affected parts of the tree.

thanks bamboo-my young ones are a few yards away in another field do you know if its airborn and should we remove the infected trees or treat them?-- bit of a panic as we'd just planted the new ones when we found the lesions

As Bamboo says the young ones are at risk. If the bark is ringed with canker they are dead. Spores are very resistant and spread easily. Cut off and burn any deceased branches. I have burnt the cuts and had some success, but very short lived.

Spread by water - which means when it rains, when the air is damp and moist, when it's foggy, when it snows....

thanks very much Bamboo and Doctor bob I think that the'll have to go so that these young ones hopefully survive