Suspicious leaf drop, scale insects, saving seeds
LEAF DROP WORSE THAN NORMAL
Q: My Sonic Bloom weigela gets some dead-looking branches every year. I usually cut them below the dead leaves. I have already cut out a lot. Should I, or is this normal leaf drop? It has had the second bloom and there were lots of blooms, a little smaller than usual. The shrub has full sun until early afternoon, and then it has indirect sun the rest of the day. A sprinkler head is close by, running for 30 minutes twice a day, two days per week. (It takes that to add an inch of water to the lawn.)
A: I really like the re-blooming series of Sonic Bloom weigela.
The pictures you sent are not normal leaf drop. You can take one of the dying branches in to your local extension office for a disease diagnosis. This late in the season, I would just do some general cleanup, removing dying canes. Weigela is a cane-producing plant and often benefits from annual pruning — after it blooms in the spring. I noticed that some of the stems that have damaged leaves are large and woody. To increase vigor, prune out some of the older, woodier canes next spring after the first bloom. Remove the cane fairly close to the soil line. This should encourage younger, more vigorous canes. Monitor for more dieback; but taking in a sample now would not be a bad idea.
SCALE INSECTS NEED DEALING WITH
Q: My Chinese holly bush was recently diagnosed with scale insects. I have not watered much, could that be a cause? Should I water every day?
A: Water was getting to the critical point until Oct. 4 and 5, when we finally got rain.
I don’t think extra water would help combat scale. Scale insects suck sap out of the foliage and stems, and heavy infestations can cause the plant to decline. The systemic insecticides are very effective in late winter/early spring when the plants are moving energy up into the tops of the plants, but in the fall and winter, there is more movement to the roots than the tops. You could use a dormant oil when it stays cooler, if you can spray enough under the leaves, where the scale insects are. Then use a systemic insecticide next spring.
HOW TO RECREATE THIS YEAR’S YIELD
Q: Can you please tell me the best way to save seeds from my zinnias to plant next spring? I’ve had the prettiest color and yield this year.
A: Don’t deadhead the blooms, but let some of them completely ripen on the stems. Some people put a small paper bag around them to catch them, but that isn’t necessary. Once they look completely dry, snip off the blooms and lightly crush them to separate old petals from seeds. Then store the seeds in an envelope in a cool, dry place until next spring. Once the soil warms up, scatter the seeds, and they should grow. If they are open-pollinated zinnias, you should get similar colors. If they were a hybrid variety, you will have different results, but you should still have pretty blooms.
CARSON KNOWS WHAT APP DOESN’T
Q: I found this tree growing within the common property behind our house. It is about 12 feet tall. My LeafSnap app did not identify it. I know you will be able to.
A: I am pretty sure the tree is a royal paulownia or princess tree (Paulownia tomentosa). The leaves can be huge when the tree is young. It is a very fast-growing tree, which makes it somewhat weak. It also freely seeds itself, so beware. I do love Picture This as a plant ID app, but do be aware that apps aren’t infallible — although no person is either.
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 jcarson@arkansasonline.com.