Q: What is happening to the earth with this maple leaf? As I was walking along the sidewalk, I saw it in the woods, but I thought it might be something that could be spread to nearby gardens.
A: This is a great example of gall bladder, which is a tissue deformity caused by insects, species, fungi, bacteria or nematodes. Gallstones often cause swelling or strange prognosis on leaves or stems, but sometimes the most obvious feature is such a change in color.
Responsible organ activity causes chemical changes in the leaf tissue, which in turn leads to tissue formation. For example, insect-infested ghouses provide their own small nests to feed the larvae, protecting them from predators or bad weather. (Surprisingly, the parasites, slightly larger than the dash on this page, still find their prey in these buildings and interrupt their life cycle. Isn’t that amazing?)
No matter how hard the gall may seem to us, it does not cause much damage to trees, shrubs, or shrubs that may last for many years. Oak trees are known for their wide variety of eye-catching gall, some of which are especially impressive when they fall from the roofs of our lawns or gardens. See if you can find something in those swollen red or brown lumps or something like a balloon. You may be bitten by a wise bird or other insect, however, or the culprit is gone for a long time and the plant flies away like an adult before the damaged leaf emerges.
If you have eye disease, you can cut down the most severe leaf blight on witch hazel (insect repellent), azaleas (fungi), oak seedlings (usually insects) and other easily accessible plants. Remember that the untouched parts of those leaves are still working to feed the plant, so do not avoid too much growth. Otherwise, I advise you to leave them alone and marvel at the complexities of the natural world. Gallstones can feed on singing birds and do not endanger the health of the plants. Like any other creature, people are hearing and declining over time, and gallstones can spread for a year and then disappear.
We have many websites with more information on gall, including shade tree gall and eye spot gall.
Q: My green hollyhock is shedding a lot of leaves, although all the rest of the growth looks good. What is the cause and can it be prevented?
A: The hollyhock is probably good and will do the natural thing for many greens in the spring. Even though we think green leaves always have leaves, they still shed leaves. In a single leaf-dropping event (like winter-hardy trees), the leaves retain their leaves for two or more years before being removed.
How old the leaves are before the leaves sprout depends largely on the type, but environmental factors can influence the process and can cause a plant to drop more leaves than average. One possible cause is stress, such as excessive soil or drought. Surprisingly, the opposite can happen in the same way.
For example, American hollyhows and oysters shed old leaves in the spring; Eastern white pine discards old needles during harvest. Probably a factor as to why they’re doing so poorly. Older leaves get more shade on the back of the trunk (also in the inner growth) and on the lower branches when the bush or tree is ripe. Look at the leaf on your holly and make sure you do not see large numbers of insects, but often large amounts of pests or diseases can be easily identified. As we move further into the growing season, the flow will slow down and stop.
The University of Maryland Extension Home and Garden Information Center provides free garden and pest information on extension.umd.edu/hgic. Click “Request Extension” to send questions and photos.