“Ask the Plant and Pest Professor” is compiled from phone and email questions asked of the Home and Garden Information Center (HGIC), part of University of Maryland Extension, an educational outreach of the University of Maryland.
Question #1: I have established cherry laurels in a landscape bed in the front of my house. They have always been very healthy until this summer when I began to notice some branches that have brown leaves. Upon closer examination I noticed this white-fungus looking stuff on these stems. I am concerned that this will spread and cause further damage. What is this and what can I do to stop it?
Answer#1: We have been hearing from many homeowners with similar concerns about their cherry laurels. What you are noticing is not a fungus but a type of scale insect called white prunicola scale. This is an insect that sucks sap from twigs and branches. This can cause dieback, which is usually preceded by leaf yellowing, browning and premature leaf drop. The white substance you describe is the covering that is cast off by the male scales. If you look closely you may see round, orange objects which are the egg-bearing females. To control this pest prune out any dead or heavily infested branches. Then use a soft brush dipped in water to scrape off the remaining scale, as best you can. Spray with a horticultural oil, according to label directions, in the dormant season (November – March) or after the eggs hatch and the crawlers are present (this is when the insect is the most vulnerable to sprays). The timing for this is June, July or September.
Question #2: Why do I have toadstools or white mushrooms in my lawn? I first noticed them when it began to warm up in the spring, but I still see them. What can I do to get rid of these mushrooms?
Answer #2: A mushroom is the spore-bearing or fruiting structure of a fungus. The fungus feeds on decaying wood buried in the soil. The source of organic matter can be dead tree roots, buried logs, stumps or even buried wood or lumber. When conditions are right these fruiting bodies form. The mushrooms are an important part of the natural world. They are not harming your lawn. There really is not a practical or permanent way to prevent them. If needed you can rake them up and dispose of them.
Question #3: I garden every year but the last several years our organic vegetable garden has been infested with harlequin bugs. I even stopped growing most of the greens these bugs love. Word around the community garden is that gardeners have not been having problems with them this summer. I’d like to plant cabbage and kale again soon do you think it is safe to do so?
Answer #3: Insect populations ebb and flow and can be difficult to predict. In general we are getting fewer questions about garden pests this season. However, you should still be prepared just in case you see them. You can find detailed information about preventing and controlling harlequin bugs on the “Grow It Eat It” section of our website. Also look for the photo of the egg cases. If you should find any on your plants you should crush them to prevent large populations from building up.
To ask a home gardening or pest control question or for other help, go to https://extension.umd.edu/hgic Or phone HGIC at 1-800-342-2507, Monday through Friday, 8 a.m. to 1 p.m. Follow us on Facebook and Twitter.
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