Q: This is a picture of our dogwood tree with white growths on it. Your help is welcome.
A: Your dogwood tree has a healthy case of scale insects. Scale insects attach themselves to the host plant and suck out the plant saps or saps. This particular scale is commonly referred to as Japanese maple scale but can attack other small ornamental trees, including dogwoods. You can use a systemic insecticide on the tree; or wait until fall and use a dormant oil that completely covers the tree after the leaves fall. This oil can suffocate scale insects, but oil products will burn plants when the weather gets hot. So if you use dormant oil, wait for fall.
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Q: I have lots of phlox that always do well in a flower bed around the pool. Full sun all day. This year some of them have a white powdery substance on the leaves, both the top and bottom, and they have only recently broken the ground. Is this some type of powdery mildew and if so is it easily treatable? [The reader sent a photo.] Thanks for your help.
A: Phlox is one of the plants that are particularly sensitive to powdery mildew. Some years weather conditions are better for the disease than others. While some species are hardier than others, under “perfect” conditions they can all get it. Warm spring weather paired with high humidity are perfect for this powdery mildew. I’ve heard that the taller varieties are more susceptible than the shorter varieties, but I’ve seen powdery mildew on some plants each year while others never had it. You have several options. Keep plants as dry as possible after sunset—that means watering or using drip irrigation early in the day. Also, make sure the plants aren’t overcrowded, as this can reduce airflow and worsen the disease. If the disease was only on a leaf or two you could remove it, but that’s not the case here. You will now need to spray with a fungicide and repeat this about every 10-15 days for at least three applications. When temperatures get very high, the disease tends to slow down. Products containing chlorothalonil, myclobutanil, or propiconazole should all provide control. There are many different products to choose from; Common names include Daconil, Ortho Max Disease Control, Fertilome Liquid Systemic Fungicide, Spectracide Immunox, and Banner Max. This fall, make sure you do a good clean by removing all parts of the spent plant and the mulch around it remove to start next season clean.
Q: On a guided nature hike around Pinnacle Mountain, we were told that violets, as described in Saturday’s column, were a bird’s-foot violet. The leaf looks like a splayed bird’s foot. The flower has a dark purple petal with all other petals being much lighter. do you know more about it
A: There are several species of wild violets, all belonging to the Viola genus. Bird’s foot violet is Viola pedata. It has very distinctive, thin-lobed leaves, in contrast to the almost heart-shaped or rounded leaves of the more common wood violet – Viola sororia, which is highly invasive in native landscapes. The flowers on the bird’s forage violet may be solid purple or have one petal much darker than the others.
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Q: I just found some strange orange growths on my cedar. It looks like orange jelly with tentacles. I’ve never seen anything like it. Is that something I should be worried about?
A: I had several questions about it and sent in a few pictures. What you see is the fruiting body of cedar apple rust. This disease requires two host plants to complete its life cycle – usually a cedar and an apple tree, but it could also be a quince or hawthorn tree. On a cedar, especially during spring rains, the galls on the cedar produce gummy orange growths with tentacle-like projections. Once they dry out, they shrivel up into brown, gnarled galls. Depending on the weather, they may rehydrate a few times in the spring. When the spores leave the cedar and fall onto an apple tree, the apple tree will develop yellow spots bordered in orange. Once you see the disease, it’s too late to control it. Unless the apple tree is very small, the disease will rarely cause permanent damage, but the tree’s fruit will also sometimes be spotted.
Janet Carson, who retired after 38 years with the University of Arkansas Cooperative Extension Service, is one of Arkansas’ best known horticulturists. Your blog is up arkansasonline.com/planitjanet. Write to her at PO Box 2221, Little Rock, AR 72203 or email her [email protected]