I started a hedge row of Donald Wyman Lilac bushes about 4 summers ago. In the past two seasons, they have been 'stressed' and rebloomed in July/August. They have shoots with dense small leaves that sprout up and don't look like the mature lilac leaf. I have been told that they have been overwatered. We have had more than 4 inches of rain above the normal amount in Nebraska this year, and although I have moved the sprinkler heads to avoid watering them, they appear stressed again this summer. Are they 'gonners'? Should I attempt to cut out the 'sprouted' shoots that are heavily leafed? Will they recover in the coming years if the rains subside? They are approaching 4-5 feet now, and are substantial, but certainly not fully grown. I welcome any suggestions and words of encouragement.
Donald Wyman Lilac
Certified GKH Gardening Expert
It sounds like you may have grafted plants and the rootstock may be trying to reassert itself. Check near the soil to see if you see a graft collar. This will look like a bark scar that goes all the way around the tree. If you see a graft collar, make sure to remove the suckers as they are not the same variety as you bought.
Stress can come in many forms for a plant. Overwatering is a common stress, but not the only kind. If rainfall is the only water it is getting, I am certain that overwatering is not the problem. 4" more than usual is not enough to be overwatered Actually, if there is a large tree nearby, it could be underwatered as the tree could be taking all moisture. Lack of moisture or poor soil are other possibilities as well.
I would not say they are "goners". Have the soil tested and start using a rain gauge to see how much water they are actually getting and they will recover quickly. Chances are, even if you do not do this, they will adapt on their own to their conditions.