Answer: The "Modified Leader" method is probably the best route for a home grown apple tree. It starts out with one leader, but as that central trunk becomes stronger it is allowed to form several tops. This helps the tree sustain the weight of the fruit. Eventually, you'll want to prune the leaders so they arch downward, which will make it easier to pick the apples as well as allow sunlight and air to get into the central part of the tree.
As far as when to prune, I would suggest waiting until the very coldest part of the winter is behind you, but the weather is not warm yet. It's a time you're anxious to get into the garden and there are many pleasant days when it's fun to do this. The tree will still be dormant with no leaves, so it's a good time to be able to stand back and make a good judgment about just what needs to go or stay.
When you prune, the first thing you do is remove damaged, broken and diseased branches. Next, remove any branches that rub or touch each other. When that is done, stand back and STUDY from all angles. Then carry out the suggestions above for the 'modified leader' method.
If you do a fair amount of pruning it will produce a big, flush of growth in the spring, therefore be on the lookout for
suckers and water sprouts (vigorous vertical shoots) and take them out when they appear. When you cut, cut quite
close to the nearest branch or trunk leaving just barely a "neck". Do not leave stumps as they will be a weak point on the tree and invite disease and insects. Remember that pruning off too much at any given time will probably stress your tree. So don't go "overboard".
Here is the Web site for The Virtual Orchard: http://orchard.uvm.edu. There might be some additional information there which would be of help.
It's a fact of nature that in order to grow tree fruits, you need to commit to the time and energy required to protect them. To avoid scab problems, your apple trees can be sprayed with Bordeaux (lime-sulfur). This fungicide must be applied early and thoroughly to protect new growth. Apply according to label directs; as the buds break until the leaves are fully expanded. Do this at prepink, pink, calyx, and first cover. Since the fungus overwinters in fallen leaves and fruit, be sure to thoroughly clean up and dispose of plant debris in the fall months.
For apple maggots, you can make sticky-traps to hang in your tree; use red balls or old plastic Christmas tree ornaments coated with petroleum jelly to trap the females. (They lay their eggs in developing apple fruits and the eggs hatch into little worms burrow their way through the fruit. The brown trails are the tunnels where they've been.) Again, be sure to dispose of, or bury any fruit that has fallen on the ground.
I'd also suggest visiting your local Cooperative Extension office for detailed control measures. Good luck!
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