Ash Whitefly Chilled but Still Around
QUESTION: For the last few years my pomegranate tree has been loaded with what I was told were ash whiteflies. This year there are none. I am delighted, but I wonder why they have gone away?
ANSWER: Happily, reports like yours are coming in from many areas of the Southland. Some experts believe that the freezing temperatures we experienced last December wiped out the ash whiteflies in many of the colder zones. However, there are also reports from some of the milder areas that are experiencing infestations for the first time. The University of California has been releasing a predatory wasp that may eventually control the ash whitefly.
The ash whitefly is not to be confused with the poinsettia whitefly that has caused Gov. Pete Wilson to declare the Imperial Valley a disaster area.
Diseased Rhubarb Must Be Dug Up, Destroyed
Q: What causes some of my rhubarb plants to rot, while others remain healthy?
A: Rhubarb plants are subject to crown rot which first appears as spots at the base of the leaf stalks. It progresses from stalk to stalk until the entire plant dies. Dig up and destroy the diseased plants; plant any new plants in a different location.
Dwarf Meyer Lemon Too Big for 10-Inch Pot
Q: I have a three-year-old dwarf Meyer lemon tree that I grow in a 10-inch pot. It originally produced several lemons. Since then it has blossomed but the tiny young lemons turn yellow and drop off. Why no fruit?
A: You have planted the tree in a container that is entirely too small. It’s amazing the tree has survived. A 10-inch pot would provide almost no room for the tree to develop a root system. The tree can barely produce foliage, let alone fruit. A dwarf Meyer lemon will grow and produce fruit in a container, but the container must be large--at least 25-gallon soil capacity (half-barrel size). You can try transplanting the tree to a larger container, however, the tree may be root bound; spread the roots out when transplanting.
Spray Water on Cactus to Remove Mite Webs
Q: My Christmas cactus is covered with webs and parts of it shrivel and drop off. What causes this and what can I do?
A: The webs are most likely produced by red spider mites that flourish in dry conditions. A Christmas cactus can tolerate more moisture than many cacti. Spray it with water frequently until the problem is controlled.
Prune Camellias for Shape After Flowering
Q: I have pretty, young healthy camellia plants. Do they need pruning? If so, when should I do it?
A: Young camellia plants only need to be pruned to sufficiently shape the plants and to remove any weak or dead wood. This pruning should be done immediately after the plants have flowered.
Don’t Be Concerned by Pyracantha Berry Crop
Q: Last year my pyracantha was loaded with berries. This year there are few, although the plant is very healthy. Why?
A: Many pyracantha varieties tend to be alternative bearing--a large crop of berries one year and a small crop the next. As long as the plant is healthy, there’s probably nothing to worry about.
Some Chemicals Still OK for Oxalis Control
Q: My once beautiful dichondra lawn is being devastated by oxalis. The EPA has banned the better oxalis controllers. How can I control it? I hope you can help before I give up on my lawn.
A: A survey of several local nurseries reveals that the most popular oxalis control has indeed been banned. It used to be combined with fertilizers and sold as a dichondra food. The nurseries report that there are still some individual chemicals that are approved for dichondra lawns that will control oxalis. Consult your local nursery personnel for specific chemical controls.
Incidentally, the nurseries also report receiving a number of complaints about oxalis in dichondra lawns and their sales of dichondra sod are down considerably.
Chinese Cabbage Ought to Be Planted in Fall
Q: How can I keep my Chinese cabbage plants from going to seed rather than forming heads?
A: You don’t say so, but I suspect you planted your Chinese cabbage in the spring when the long days promote seed formation. In the Southland, Chinese cabbage should be planted in the fall or early winter.
