Euonymus Scale does not infect Weigela. Actually this plant is mostly free from insect problems. Sometimes it gets Mealybug but I never see it on this plant. Oil will kill Scale and Mealybug if applied properly. That is the plant gets drenched. One application is not usually enough. If you do have scale, and I suggest sending some to your local extension service to find out, you need to know what scale you have. You then Oil when the crawlers are active for best control. Scale can stay on a plant for a long time after it is dead, this often fools people into thinking they did not kill it. If it is scale see if it comes off easily and what color it is underneath. Brown or black usually means it is dead.

I don't see any scale insects. Do I need to put in my high powered eyeballs?

grasswhisperer, the spotting appears on the lower leaves and the plant seems to have been pruned since (a leaf half way up has been cut in half). This leads me to think that the spotting is an effect of the spray treatment; and the plant is growing out of it.
A rolled leaf on the lower left appears show some mechanical damage; not an insect in my opinion.

you ASSUMED wrong.. there are no scale... so you applied a remedy that was not needed .. that is pollution ...

now that you have pix posting abilities.. please do so before applying more remedies ...

no rhiz.. no need for the binoculars.. i see no scale ...

when did you apply the oil .... and did the leaf damage appear after???

with 8 weeks near 100 and total drought.. many of my shrubs are showing leaf damage... what was your ambient summer weather ...

and arent the leaves going to fall off in a week or two... no need to do anything else this year ... other than perhaps a little extra cleanup of those leaves.. never hurts to insure they dont winter over

was it planted this year.. what was your watering protocol this summer .... was it properly and deeply watered all season long???

most scale.. in my experience anyway.. is on the branches.. not on the leaves .....

if you are referring to the white on the branches.. i would suggest they are too perfectly spaced to be an erratic insect ...in other words.. its part of the design of the bark ...

scale is rather rare.. BUT FOR EUONYMOUS .... which is why i got rid on mine ... once the host is gone.. you will rarely if ever see scale again .... of 500 or so conifers i brought into the property in 11 years .... if i found scale on 2 of them... that is it ...

the family has had weigela for my entire 52 years.. and i cant ever recall a single bug issue ...

my vote is sun scorch or drought.. or lack of water when needed ...

good luck

ken

Well clearly I've come to the right place. Thank you all for your insight. I am a novice who would love to learn more.

We are in eastern Mass - I noticed this near the end of the summer/early fall - not sure how long it was like this. This Weigela was planted 3 springs ago. I've pruned back each year since.

As far as water - beyond fostering during the first year of planting, I have only watered when plant looked stressed, which, this past summer, I don't recall happening. Despite typical warm temps we also got a decent amount of rain now and then. In short, I did not notice the plant suffering (although I now realize that does not mean it was sufficiently hydrated.)

Well it certainly seems based on feedback this is not from a pest. And to answer the question - I only applied the oil when I noticed this spotting. That is - the oil did not cause the spotting.

Also - I should add that this spotting is not on the entire plant - only on 1 isolated area (a few branches). when I first noticed, I thought it was scale back for vengeance from the euonymous, but now I've learned that's not the case.

I look forward to any more advice, but for now I will do nothing.

Thanks!