2014 Apple Tree Die-Off
It seems that these past couple years provided a “perfect storm” resulting in a lot of apple tree die-off this spring/summer throughout the state, and particularly in the northern part. The “perfect storm” included:
Drought of 2012
- Heavy crop of 2013 (this came as a result of the light 2012 crop due to frost)
- Brutal 2013-2014 winter
Symptoms across the state have included tree death (whole or in part), slow leaf emergence, and leaf drop. The problem could become worse as the summer progresses due to increased water demand as the weather warms up and the tree produces a crop. Dr. Patricia McManus, Professor of Plant Pathology at UW-Madison recommends the following action to lessen the stress on your trees (her comments are in italics; I’ve added my own notes in regular type):
1. Avoid a heavy crop on already stressed trees. If the crop is heavy, remove a portion. This can be accomplished through picking some of the immature apples now. Thin out throughout the tree and save the best apples.
- 2. Irrigate if we get a dry spell. On trees that leafed out and then collapsed, it’s likely that either there was root damage, or damage to the vascular cambium. In either case, water conduction is compromised, so you don’t want to compromise trees further with drought.
- 3. Do not apply nitrogen in an attempt to stimulate trees. This will increase leaf growth, but on trees with a compromised vascular system, you don’t want more leaves competing for water. It is best NOT to fertilize this year.
4. Control weeds and especially grass within the drip line of trees, since grass is a big competitor for water. If the tree is located in a lawn, make sure that you water much more than what the grass will take up.
5. It’s drastic, but if trees are dead from the tips down, then prune way back into living tissue and retrain a new canopy. I’m not sure, however, that this is much better than just replanting an entire new tree. But if you do replant, avoid the old hole, or amend the planting hole with fresh soil to get away from replant fungi. Mark the dead branches for removal, and prune in late winter.
If you have further questions, feel free to stop by the office or give me a call at 715-672-5214.
Mike Travis, Agriculture Agent