I live in Victoria, and have an oldish (40-50 years) apple tree in my yard (no idea what species - it's big - not a dwarf or semi-dwarf and apples are large). It's a beautiful tree, and I'd like to keep it healthy, but I really don't care about apple production or quality. Everything I read on the web about pruning and spraying apple trees seems to relate to improving the fruit. I'm trying to find out what is absolutely necessary to keep it healthy. Does it really need to be sprayed 2 or 3 times a year, and if so, for what and with what? What should my goal be in pruning? What are the dangers of letting it go "natural" - ie. not spraying unless/until I see a problem and pruning only occasionally to keep the shape? Any advice greatly appreciated.
Spray with a lime and sulphur mix... late Feb... no spray.. less vigor, less fruit, more bugs, more birds? Prune for shape, strength and remove criss-crossed limbs... or touching limbs, unfettered growth, may harm the health of the tree, ie: crotch split..... more desease... water spouts/shoots, you get the picture I hope. Fertilize in the spring... hope this helps...
Letting it go natural is no danger, but just as you suggest, take care of any issues you can such as: pruning out rubbing limbs, pruning diseased limbs a foot back from any symptoms (such as a canker or blight), giving a natural fertiliser (i.e. some compost mixed with wood ashes spread beneath the tree), and spraying fungicide if defoliation or severe leaf lesions warrants it.
