dying lilac bushes

Asked July 29, 2013, 10:25 PM EDT

I planted four new lilac bushes in May. They were doing great until about 2 or 3 weeks ago. The leaves are curling up and turning brown. They have holes eaten in them. They also have little grayish/white spiders spinning webs on them (one spider per leaf). I'm not sure that the spiders are actually killing the leaves. What do you think is harming my lilacs, and what can I do to save them?

Umatilla County Oregon

2 Responses

Are you here in Umatilla County, Oregon? With the heat we have been experiencing the last few weeks - you may have had water stress to these young plants. We often see spider mites on drought stressed plants.
If you are here locally, you can drop a plant with some of the insects off at our Pendleton or Hermiston Extension office and we will take a look and see if we can identify the problem further. Meanwhile be sure and deep water these plants three times a week during these hot days. http://extension.oregonstate.edu/umatilla/ visit our website for directions to our offices.

Thanks so much for your reply. Yes, I live in Pendleton. I actually brought some leaves into the Pendleton office last week, but no one was in who could help me. The lilacs seem to be doing better. I've been hosing off the spiders, and your advice about deep watering three times a week is helpful. Three of the four plants have new leaves growing on them. I'm pretty sure I don't have spider mites. After I emailed you my question, I found larger spiders on some of the leaves. They were black with white dots. I think the little specks I was seeing were just baby spiders. Interestingly enough, this morning I found a little "colony" of eggs underneath one of the leaves. The eggs are all neatly lined up. I put the leaf with the eggs on it in a jar. If I have any more questions, I'll email you again. Thanks again for your advice.