|Hello, Four years ago we bought two varieties of columnar apple trees from Monrovia (six trees total) through our local nursery. I don't know the exact variety names. We planted them in January and they bore fruit the very first year. We were very pleased with them, they were very pretty when they blossomed. But one of the trees got a big ugly scab on its trunk. This fall the tree died and we dug it up, but I notice that all the other trees have multiple small scabs. I am afraid they will die too. I am thinking of digging them all up and starting over with a fresh batch of six trees, but I don't know if it is the soil that made them sick or if the first tree just|
|Unfortunately, in order to remain healthy, most apple trees need to be on a regular spray schedule. If your trees are developing calluses or growths on the trunks and branches, they may have developed a disease called scab. The fruits will have lesions on them and the foliage will develop olive-green splotches before turning brown. If you noticed these problems with the fruit and foliage, it's likely your trees have scab. You can avoid the problem in the future by using a lime-sulfur (Bordeaux) as directed on the label. If you did not notice these symptoms on the foliage and fruit, then your tree may be showing signs of mechanical damage (lawn mower, weed whacker, etc.) If this is the case, the wounds will heal over (creating a callus) and there's no other treatment required other than keeping lawn equipment a safe distance away.
If you decide to replace your trees, the most disease resistant columnar apple trees are Golden Sentinel and Scarlet Sentinel. Golden Sentinel produces a striking display of white spring flowers followed by very large and attactive solid golden yellow fruit. Sweet, juicy and delicious. Disease resistant and productive. Scarlet Sentinel has large, delicious, greenish-yellow fruit with an attractive red blush. Dense clusters of white flowers are followed by abundant, closely spaced fruit. Very productive and disease resistant and non-branching. It's the most dwarfing of the Columnar varieties.