Adam Colbenson

We'll no I wasn't being funny. If you knew just what you were actually breathing everyday I doubt you would call them diffuse. In any case yeah, maybe wear a respirator everyday at the sawmill, if you want to live to be 90.

On that note, you might as well wear a respirator everywhere you go. Those diesel fumes you inhale at the bus stop, the 2nd hand cigarette smoke you breathe, the random airborne bacteria or fungus you inhale... They'll all kill you eventually

The studies I've seen show that black locust has similar nutritional value and toxicity as alfalfa. Perhaps individual ungulates have more or less tolerance for the toxins, and perhaps you have a crazy horse that likes to chew on fence posts. For the most part it seems that as long as the animals vary their diets and don't eat black locust alone, they'll be just fine.
Experience talking (not scientifically justified).

If you're looking to optimize the soil under your tree, and get rid of your leaves every year, here's your solution: Use the leaves (shredded or whole) as mulch under the trees they came from. (Warning: for leaf transmitted diseases). Leaf decomposition (leaf mold) is literally the best thing for trees ever. Forget fertilizing, forget foreign compost, every nutrient the tree needs from the soil, is returned through composition to the soil, from the leaves. It's like the spider that eats her own web to provide the nutrients for her new web. Forget that turf, dedicate the area under your tree, to your tree, in the form of a leaf mold pile of previous years leaves. Yeah it's not aesthetically perfect, but it is naturally perfect.
Adam

Add finished organic compost to the soil surface under the trees canopies as often as annually. Apply non allelopathic mulch over the compost. Then release the hogs! They clean up infected debris and in return provide perfect fertilizer.
Happy pick'ns

I agree that learning these skills for yourself is a great asset. But consider the risks to yourself. Making a mistake in a high angle situation can lead to injury or death to yourself, or massive health problems to the trees. Please climb per OSHA standards for your own sake and prune per Anzi standards for the trees sake. Most people don't know these standards or have the equipment or skills to do this successfully. Those arborists who only want to remove the trees are only out to optimize profit. Disregard them. Your trees are valuable, and so are you! Adam

If you want to grow a timber stand of perfect (and highest profit) sawlogs in a minimum of 20 years. Start formative pruning your saplings and don't quit till they're 16 feet tall. Then fence them off and let your hogs loose in the stand. Pig Shit is perfect organic fertilizer for them. Make sure to prune off any limbs larger than 1" and lower than 16', not exceeding 1/4 of the total canopy per year. Then log them between 20-50 years of age for optimal profit.

Call a nearby Tree Care company who employs a Board Certified Master Arborist and have them send out a consultant to assess your apple trees and your desire for the trees. Then either proceed with a work agreement with them, or hire someone less educated, or do nothing. Just don't prune them yourself.