Friday, July 20, 2007
I still get calls about this 'disorder' if you want to call it that. Honeycrisp foliage has this propensity to turn a mottled yellow by mid-July on some trees, and it is endemic to wherever Honeycrisp is grown. Weak trees with a light crop are most likely to exhibit the symptoms. Annual, moderate bearing -- with good fruit thinning every year -- should minimze it. Keep the nutrient status of the trees up to snuff too. I have written about this before way back in 2000, and here is a good picture of what the Honeycrisp 'yellows' looks like. The disorder should not be confused with potato leafhopper injury, which looks similar. But you'll get the 'yellows' with no PLH in sight. Studies have shown that it is likely caused by an inability of the tree to mobilize starch. So, don't worry about it too much if you have it, but it is a sign that you may want to make sure the trees are in good health. Oh, and check out the video. Ciao.