You can't kill a JM just by using Spinosad - or any insecticide, for that matter. Japanese maples do have rather sensitive foliage and that can be damaged by many topical insecticides - it's called phytotoxicity and while it can burn foliage or cause leaf drop, it's not gonna kill the tree. Drooping, limp branches are not symptomatic of phytotoxicity. Something else is going on. Not sure what but posting photos of the problem could help.

It appears to be some delayed transplant shock - not fatal but not necessarily a good thing, either. First, you already know this but I'm going to repeat........planting a JM in June in a hot summer climate that is undergoing an extended drought is just not a great idea. Period. The tree is put at an immediate disadvantage by doing so. A reaction by the tree to this stressful situation should not be unexpected. Second, I know it seems counterintuitive, but pruning off the roots is exactly what you should NOT have done. Those fine feeder roots are how the tree accesses soil moisture and nutrients - the larger roots are only for anchorage. So the tree is now working on a second disadvantage - trauma to the rootball (JM roots are very sensitive to disturbance) and a lack of feeder roots. What I'd suggest you should have done is remove as much of the soil on the top of the rootball as possible to expose the burlap, cut any ties (and gently remove) and then unwrap the burlap surrounding the trunk and remove as much from the top of the rootball as possible, leaving the sides - with fine roots growing through - intact. Cutting off these roots has given the tree a major setback. In fact, the nursery I am associated with now nullifies their guarantee policy if removal of the burlap disturbs the rootball excessively......it is that much of a disruption to the plant, especially during the middle of the growing season. Finally, I'd want to know about your watering routine. Using an automated sprinkler system to water a newly planted tree is usually not a great idea. In fact, I discourage it. Most systems come on for a few minutes once or twice a day - this is not enough water for a new tree, particularly one of that size. And you can't tell just by looking at the surface of the soil or even down a couple inches if the soil is adequately moist down to a sufficient depth - it may appear adequately moist on the surface but be dry as a bone further down. Watering by hand, with the hose on a low trickle, for an extended period of time as often as necessary is a much better approach. The water needs to penetrate down into the soil profile at least to the depth of the bottom of the rootball and only low and slow will accomplish this sort of irrigation. A drip system or soaker could accomplish the same thing, but not a sprinkler system. So you've planted at possibly the worst time of year, you've cut off a major portion of the tree's feeder roots that supply its moisture needs and your watering program is not very suitable. Not a huge surprise the tree is reacting poorly :-) All you can do at this point in time is correct your watering practices and hopefully adequate water and cooler fall temperatures will encourage some new root development. I believe this to be recoverable but it may not be obvious until next spring and how well the tree leafs out at that time. Did it come with a warranty?

Yes, as long as the drainage is good, it should be fine. It is pretty much the equivalent of a couple of days of a constant downpour :-)) As long as the soil didn't puddle up and the water drained promptly, this is far less of a threat to the tree than it would have been to skip watering for a week or two!!

Vivian, that's my North Wind. :) I don't mind that you posted it. It's a phenomenal cultivar. I've had very good luck growing most JMs here in 5b. The exception would be the coral barks, or really any of the bright bark JMs. I had high hopes for Shidava Gold, but after a few years it, too, has lost the battle. It could be something else, but I suspect it's weakened by temperature lows here. All of Iseli hybrids, of course, thrive in zone 5. There's also a hybrid sold through Klehm's, called Northern Glow, that seems like a worthy cultivar. It has a slightly brighter green leaf than the Iseli hybrids. I've also had very good luck with the A. japonicum and A. shirasawanum cultivars, but many A. palmatum are doing well here, too, even without protection. Diana at Topiary Gardens Nursery is a wonderful resource-- her entire nursery is in rural 5a! If she can grow JMs at the rate and quality she does, I know we can. She grows many of hers out in the field, too, so she can give accurate reports of how much help (if any) each cultivar needs. If you want cold-tested JMs, give her a call. Her prices and shipping are extremely reasonable, too.