Deformed Lilac Leaves Maybe a Sign of Problems

Q. My lilac bush had some leaves on it that suddenly look
like they are deformed. What is the problem?

A. Deformed or crinkled leaves can indicate several things.
If the edges of the leaves were damaged, scorched, the interior of the leaf
will continue to grow while the dead margin will not. This can cause leaf
deformity called cupping.

Stink bug

Feeding damage by some bugs on leaf
buds before they open can cause crinkled or deformed leaves. These include the
stink bug group of insects such as the leaf footed plant bugs. Look for bugs on
the
bottom of the leaves or crawling on stems.

Leaf deformity can be caused by “weed
killer” sprays that drifted on the foliage during windy or hot weather. Some
herbicides, like dandelion killers for lawns, cause leaf deformity if it comes
in contact with leaves as they are enlarging or expanding.

Squash bugs, one of the stink bug types

Bottom line, most likely the damage
is temporary and as more leaves develop they should be normal. However, if you
inspect the plant and see these types of insects apply an insecticide for
ornamental plants and spray leaves and stems during early morning hours. Spray
the undersides of leaves because this is where most the bugs hang out.

Make sure the plant gets enough
water. This is a plant that likes compost and wood mulch, not rock mulch.
Lilacs do not like rocks covering the surface of the soil. Every year apply 1/2
cubic foot of compost on top of the mulch and water it in. Use a high
phosphorus fertilizer that promotes flowering of woody plants.