apple disease mystery

Discussion in 'HortForum' started by justalittlegardenobsessed, May 25, 2011.

  1. justalittlegardenobsessed

    justalittlegardenobsessed Active Member

    Likes Received:
    Vancouver, BC
    I have an apple tree issue which no one has been able to solve. Ive tried many nurseries, gardening websites, poured over disease and nutrient deficiency files, and sent the leaves to a plant pathologist, without success. Any suggestions (including other contacts or resources) would be extremely welcome.

    I have a total of eight oblique cordoned apples. Most are 5-6 years old. Seven are in an unheated greenhouse because I thought it would help prevent them from getting diseases. Six of the apples in the greenhouse are in the ground, which is cheap, crappy, sandy soil which previously grew grass. One is in a pot, with much better soil.

    The remaining apple is a Liberty step over apple which is outside the greenhouse in better soil. Ironically this apple is the healthiest. It has no foliage issues, and although it is the youngest tree, it bloomed the most and produced a healthy apple last year. It has 4-5 blossom clusters this year and has set some apples.

    However, the apples inside the greenhouse, both in the soil and in the pot, get pale yellow areas and then brown spots on their leaves. The leaves are also somewhat contorted. Most are scab-free or scab resistant varieties (Liberty, Jonafree, Florina.) But all of them have the same symptoms.

    I don't think they are apple scab, according to this description of scab symptoms, anyway:

    "Leaf spots appear in spring as small olive-green lesions on the upper and lower leaf surfaces. As spores form, lesions develop a velvety brown appearance. Later, lesions are more elongate and often follow veins, but the same velvety brown look is present. As leaves age, they turn yellow (except for the scab lesions) and fall from the tree."

    Mine don't look start out as olive-green lesions, they don't ever look velvety brown, and the leaves don't turn yellow and fall off.

    A plant biologist checked out the leaves and said she could find no signs of fungal spores. She thought it was probably a nutrient deficiency but could give me no other suggestions.

    The confusing thing is if its a nutrient deficiency, why is it appearing on all the greenhouse plants both the plants in the ground and in the pot, which has better soil?

    The trees are still growing. But most are not producing blossoms. The Liberty tree produced one blossom cluster this year. The tree in the pot, which is the youngest of the trees, and had the fewest symptoms, produced five blossom clusters.

    I tried giving the trees Miracle-Gro (I know that's not very sophisticated but I didn't know what else to try) on both the leaves and the roots but that didn't seem to help. I've attached some pictures of the symptoms.

    Thanks kindly for any help you may be able to provide.

    Attached Files:

Share This Page