Knowledgebase

Cornus sericea Artic Fire Red Osier #874844

Asked June 26, 2024, 4:18 PM EDT

I’m not sure what’s affecting my red osier dogwoods. There are random wilting leaves and yellow leaves. I don’t see aphids but had them last year. Leaves are also being chewed? Planted in shade and looked great up until last week. Plants are about 3 years old.

Queen Anne's County Maryland

Expert Response

The chewing symptoms are minimal and fortunately not concerning, so they can be ignored. If you want, inspect the leaf undersides to see if a caterpillar-like larva called a sawfly is present, since dogwoods do have that one primary leaf-chewing pest. If found, just remove them by hand, as insecticide use would not be necessary.

The rest of the symptoms suggest under-watering or drought stress. Have the shrubs been monitored for watering needs, now that our region is approaching (or already in) drought status? As a rough guideline, a thorough soaking of the root zone might be needed about once a week in hot, dry weather. More detailed watering guidance can be found on the linked page.

Miri
Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied June 27, 2024, 11:42 AM EDT

What do I do about black sooty mold dripping onto my Nellie Stevens holly? I have quite tall mature American beech throughout my 2 acres of woods. Virtually every beech has numerous aphids on numerous limbs and I can’t possibly spray horticultural oil on them. I’ve been told they won’t die (my biggest fear) but the sooty mold and sticky honey dew is dripping onto anything below, including my 6’ Hollies. I have about 10 of them and don’t know what to do. Spraying them with horticultural oil is possible but surely it will be a season long problem,  what do I do and how often do I do it? My property has recently been Baywise certified (Chesapeake Bay), and I want to keep it that way without losing any trees and native shrubs.

The Question Asker Replied July 02, 2024, 9:33 PM EDT
The beech will not need treatment for the aphids, and the sooty mold should rinse/weather away in time on its own. You're right -- horticultural oil is sometimes labeled for the removal of sooty mold (though that's not its primary function), although we would not spray while temperatures are above 85 degrees, which of course may add to the hassle of making repeat applications. If you have a garden hose whose spray will reach the lower beech branches, you could blast the twigs and foliage undersides with plain water to knock off most of the aphids, at least for the time being, which will reduce the honeydew abundance for a time.

Miri
Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 03, 2024, 9:37 AM EDT

Loading ...