Over the years, I have met many people at Landis Arboretum, from locals stopping by to walk their dog to tourists passing through the area.
Teachers, artists, arborists, gardeners, lawyers, musicians, families — all sorts of people. Conversations typically begin with questions about plants, and the following are a few of the most frequently asked questions from my 25 years at the Arboretum.
Q) I have lichen growing on my trees, is it going to kill it?
A) No, lichen will not harm your tree. It is actually a symbiotic relationship between two organisms, a fungus and an alga. The fungus grows on the tree and collects moisture and minerals from the atmosphere, and the algae make food through photosynthesis. Together they provide what they need to exist. The tree bark is simply the site of growth but not a source of food. Sometimes stressed trees have more lichen on them because they have fewer leaves, so more sunlight is shining on the tree, allowing the lichen more opportunity to grow.
Q) Are moles eating my plants and grass?
A) This is a great question, and the answer is no. Moles are carnivorous animals that feast on worms, grubs and insects, not plants. The culprits are likely voles, which are herbivores and only eat plants. Both live in holes underground, which is probably why moles and voles get confused with each other. Moles typically tunnel while searching for food and leave mounds through the grass, but there will be no visible hole. Voles, too, have a hole, but no mound or tunnels. Voles can also damage trees and shrubs by girdling the base of the trunk and roots. The best control for voles is to use a repellent product and tree protection wraps around your plants, especially in the winter.
Q) How do I stop deer and other animals from eating my plants?
A) For larger game like deer, tall durable fences work really well. If fencing is not an option, you can make and apply a ‘Deer Be Gone’ product to put around the plants. The product is made by mixing rotted raw eggs, minced garlic, cayenne pepper, lemon juice, and water in a blender, then sprayed directly on the plants or around the perimeter of the garden bed.
Q) My lilacs look healthy, but aren’t flowering, what can be done?
A) There are a few reasons why this happens. First, lilacs can grow in both sun and shade, but require sun to flower well. If your lilac has been shaded out over time, consider moving the plant to a sunnier location or removing nearby branches to allow more light into the area. A second reason this occurs is because of pruning at the wrong time. Lilacs bloom on the previous season’s wood, so the only time to prune them without removing the next year’s flower buds is immediately after they bloom. Pruning at any other time of the year will remove flower buds.
Q) Why are my crabapple tree leaves falling off in the middle of summer? is my tree dying?
A) Most likely the culprit is fungus. Apple scab and cedar apple rust are two types of common fungi found on apple trees in our area that can cause premature leaf drop. Years with more rain make these issues more noticeable. Some years, the entire tree can be bare by mid-August, but do not worry: the tree will regrow leaves the following year. These are not life-threatening fungi, but it is best to remove the leaves from the property, which can greatly reduce the amount of inoculum in future years. If done annually, it can make a great difference after a while.