This year many of our customers have called to for advice on their boxwoods. It looks like the boxwoods have come back with a brown yellow discoloration on the newest growth tips with stems that are brittle and easily snap. There are two major issues that folks need to be aware of — an insect called the Boxwood leafminer (maggot) and record-breaking low winter temperatures and wind chills Chicago faced this last winter that reached a detrimental temperature of -60F.
Here are some of the symptoms for winter damage:
- The boxwoods look green and healthy last season and the discoloration only started with spring.
- The leaves looked yellowish brown (bleached) from the newest tips and is mainly on top or on the windward side.
Here are some of the symptoms for an infected Boxwood:
- You will see small blisters at the underside of the leaves caused by the larvae inside. If you peal the leaf, you will see small maggots inside.
- The leaves infested by larvae turn yellowish and appear spotted, as opposed to winter damage, where the tips are completed bleached.
Here’s what we recommend. If your boxwoods have experienced winter damage, apply a gentle acidifying fertilizer like Holly-Tone. The recommended application approximately 1 cup per plant spread. If you have and infection, the best options would be to apply a systemic insecticide that kills the larvae before they emerge as adults to lay new eggs. However the best time for this treatment is in March or April.