Mulberry weed seeds will lie in wait even after winter deaths
Q: These weeds are taking over in my garden [the reader sent a photo]. What can I do to control them?
A: I think we can see from the range of weed questions in this column that weeds are gaining ground in many of our gardens. The vining plant is an ivy-leaf morning glory, and the smaller weed is mulberry weed. Luckily, both weeds are annuals and will die with colder weather. Unfortunately, both are good re-seeders -- especially the mulberry weed. Try to pull, hoe or cut back as much of the weeds as you can to prevent more seed production. Spot-spraying with a contact weed killer can help, but it won't kill the seeds, which will simply lie in wait for next summer.
Royal Paulownia tree not ideal for shade
Q: Please identify this plant/weed [the reader sent a photo]. It came up on its own. It was very pretty through the summer.
A: I think it is a Royal Paulownia tree (Paulownia tomentosa). I am not sure why the leaf margin is puckered -- perhaps drought? This tree grows easily from seed and is a rapidly growing plant when young. Once it reaches 5-7 years of age, it produces lovely spikes of purple blooms. Unfortunately, I think every flower sets a viable seed, and it can easily spread. It is also fairly weak-wooded and so is not a desirable shade tree.
Sledgehammer can help control nutgrass
Q: I know you have talked about what to use to rid your yard of nutgrass before, but I can't remember what you said. Help!
A: Nutgrass is not easy to kill. Sedgehammer is an herbicide that gives decent control. Spot spraying with Roundup can help to suppress it as well, but that product will kill other vegetation, too.
Tough weeds threaten reader's zoysia yard
Q: Can you please identify this invasive plant [the reader sent a photo] and tell how to get rid of it and pine nutgrass that are in my zoysia grass? I just had the zoysia put down last year. It was very nice for one year, but now I am afraid these two weeds are going to take over. Any help would be greatly appreciated.
A: The weed in question is Virginia buttonweed. It is difficult to eradicate with herbicides. If you just have a spot or two in your new lawn, I would try to dig it out -- roots and all. It is a tough perennial to kill, so physical removal is best. Sedgehammer can give you control of nutgrass. It too is a tough weed to kill.
Yellow aster incurable plant virus
Q: Can you tell me what's going on with the new growth on the zinnias? It reminds me of rose rosette virus. Or could it be heat stress and dry conditions?
A: I think your zinnia is suffering from aster yellows. Aster yellows is a viral-like disease caused by a phytoplasma. An insect called a leafhopper that sucks the sap of plants can vector the disease. Various symptoms can occur from flower and leaf distortion to yellowing leaves with green veins. Growth slows down, and leaves may be smaller and more narrow than usual. Foliage is sometimes curled. Flowers can be deformed and exhibit bizarre tufts of deformed leaves. There is no cure for the disease.
Wait until spring to prune Encore azaleas
Q: My Encore azaleas are starting to bloom well now. They are getting too tall. I know you say to prune after bloom. Does that apply to these plants as well? If so, how much can I prune them?
A: While Encore azaleas are blooming nicely now, we do not prune them after bloom in the fall. Treat them just like a regular spring-blooming azalea and prune after bloom in the spring. If you prune as they head into the winter, you expose more of the plant to winter damage, should we have a cold winter.
Retired after 38 years with the University of Arkansas Cooperative Extension Service, Janet Carson ranks among Arkansas' best known horticulture experts. Her blog is at arkansasonline.com/planitjanet. Write to her at P.O. Box 2221, Little Rock, AR 72203 or email [email protected].
