Carbaryl is still available:
I use it for chemical thinning in advance of thinning apples by hand.
“Carbaryl ( Sevin ) applications made within 30 days after petal fall have a pronounced thinning effect on most apple varieties. Sevin does not thin pears. It is a broad-spectrum material that acts as a stomach as well as contact poison and controls various fruit insects, including organophosphate-resistant pests such as white apple leafhopper. It is one of the low-hazard insecticides and can be used up to one day before harvest on most fruit crops … in home orchards. Sevin is very toxic to bees and, therefore, should not be used just before bloom. It is also toxic to certain predator mite species.”
Cooley, Daniel R., et al., ed. 2015-2016 New England Tree Fruit Management Guide. UMass Extension. 11 May 2018 <http://fruit.umext.umass.edu/tfruit/2015-16netfmg/2015-2016NETFMG.pdf>.