What do you guys think?

[Basswood]

I have a small collection of bonsai in training. One of which is a Kousa dogwood from what was a 8’ tree that is having issues. The burned tips and the shoots that were hardening off have gone limp and wilting. I’m kind of stumped on what it is.

I have two possible culprits that match up time wise. I made an application to all my trees of permethrin and oil. I didn’t measure the rates and sprayed everything since my quince had aphids. I know my rate was on the high side. So possibility 1 is chemical burn. But all trees were sprayed with only 2 having similar symptoms (second is a Carpinus to a lesser extent).

The second one that lines up right is a new overhead misting irrigation I installed. For awhile the emitter was hitting the dogwood pretty close and direct. This was going off twice a day, 6am and 4pm, for 40 minutes. The carpinus is on a different watering schedule. I have reduced the watering schedule to 25min twice a day and also moving the dog. The dogwood is in fast draining bonsai media that would be difficult to overwater.

All the trees will get an additional 20min of watering from a fan sprinkler that does the grass at 5am.

Normally they are on a pretty regimented fertilizing program of high N every two weeks or so, I’ve been slacking on that this year.

1 of my two linden is showing similar symptoms, but that one is on a different watering schedule.

 

[The Green One]

Looks like oil injury.

Less than 85F using a summer hort refined oil at .5% rate, I still make sure there are GOOD drying conditions, and absolutely ZERO Sulfur in the spray tank.

"If the oil cannot dry, the plants can fry"

And measure of course.

Pick off the damaged leaves and start anew?

 

[Basswood]

Pretty much damaged the whole canopy. I figured I’d leave it since I’m sure they’re still photosynthesizing for the tree. Didn’t expect oil to effect the shoots as well the way it did.

It was sprayed in the evening before dark.

 

[The Green One]

Yep.

I spray oils mid-morning through early afternoon on "clear to partly cloudy" dry days.

The only sprays I do in the evening before dark are Serenade on my veggie garden.

Re check your chart too, on plants sensitive to Oils.

 

[Basswood]

Thanks. Didn’t think of kousa to be sensitive, though I mostly treat them at dormancy with oil. Honestly I don’t use oil except occasionally as a surfactant at .5g per 100g during warm months. Thought I’d be in the clear bring it was the evening. Never actually saw oil damage except on blue spruce.

 

[The Green One]

You can get Phyto on non-sensitive plants as well with oils, when it's too hot and/or poor drying conditions Jzack.

At least this did not happen at a clients home.

 

[Basswood]

Yeah I’m not so concerned about it and new it was a possibility. I got lazy. Oh well, I’m sure the tree will be fine. Actually looked like auxiliary buds on effected branches were pushing.

 

[evo]

My money would be on the watering mist. Rule out the oil by making spot applications on unaffected leaves. Dogwoods are sensitive to watering issues

 

[Basswood]

The only difference in watering schedule changes to years prior is misting instead of an overhead fan sprinkler. I have used the same durations and frequencies.

It’ll be hard to find a leaf to test unfortunately.