We have a number of Canary island pines, and a substantial number of them are showing chlorotic mottling of needles, caused by ozone. Response to ozone is strongly affected by the genetics of the individual tree, so that in a stand, one or two trees may show symptoms, while others look perfectly healthy. My understanding is that P. canariensis is grown from seed, which perpetuates this unpredictable response to ozone pollution. Does anybody know of a nursery that has been vegetatively propagating ozone-resistent trees?