The following are highlights and updates about samples and questions recently received in the Plant & Insect Diagnostic Clinic:
Cicada Killer Wasps continue to buzz, alarm, annoy or entertain (depending on your point of view!). The season will wrap up soon, so if you haven't controlled the burrowing females by now, consider letting them go for the year. See our online article for more information.
Those tiny crickets called ground crickets or pygmy crickets are back. If they're bothering you, see our article from last year.
This is the time of year that magnolia scale symptoms look the worst on infested plants. Honeydew, sooty mold and stunting combine to make the plants look unthrifty. See the photo below. Late August is the time to treat infested plants with a contact insecticide or systemic for crawler control. See the newsletter from August 27, 2008 for more details.
Corn rootworm beetles move from corn fields to gardens at this time of year and feed on everything from dahlia flowers to silks of late-planted sweet corn. Control is very difficult. Consider tolerating the feeding, screening or repeated insecticide application. See the Clinic website for more information.
We have received a couple of samples this week of hosta petiole rot (also called hosta crown rot) caused by Sclerotium rolfsii. This hard to control fungal disease is dreaded by most hosta gardeners. This fungus can also affect a wide variety of plants and can survive years in the soil. For more information and pictures please see this pamphlet.
Magnolia scales (on stems) and sooty mold (on leaves).
Northern corn rootworm beetles feed on roses and other flowers in town in late summer after they wander away from the corn fields.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on August 10, 2011. The information contained within may not be the most current and accurate depending on when it is accessed.