1. Late last summer, despite ample water, the leaves on several limbs of my Japanese maple suddenly began wilting. Can I save the tree?

What you describe is a typical symptom of Verticillium wilt, a soil-borne fungal disease that affects the vascular systems of Japanese, Norway, silver, and sugar maples, as well as many other plants. Leaves will often turn yellow or brown and entire branches will die. In Diseases and Pests of Ornamental Plants, author Pascal P. Pirone states that in the early stages of the disease wilt symptoms are usually confined to single branches or to one side of the tree. Small plants or trees may die within a single season, but larger, mature trees may live for many years, or even recover from the disease under optimal conditions. Trees showing widespread and severe infection are unlikely to be saved. In cases where only a few branches are affected, the tree may be helped by regular watering and the application of a slow-release fertilizer around the base of the tree early in the growing season. Regular applications of fertilizer stimulate rapid growth and may result in the formation of a thick layer of sapwood that seals off the infected tissue. Diseased branches should be cut off well below the affected section and destroyed. Plants that are susceptible to Verticillium wilt should not be planted in soils known to be infected with the fungal disease.

2. Earwigs seem to be eating everything in my garden. Are there any synthetic or natural controls?

Earwigs are omnivorous-they eat plants, other insects, and decaying organic matter-but the damage they cause to garden plants is usually negligible. In fact, they are predators and often help control populations of far more destructive plant feeders such as aphids, nematodes, and mites. Night-feeding earwigs are sometimes blamed for injury that other pests have caused, because they like to hide in damaged plant tissues during the day. There's no reason to control earwigs unless you are sure they are responsible for unacceptable plant damage. In that case, you can keep them in check with insecticidal soap, which is available in most garden centers and hardware stores.

3. How do you grow strelitzias indoors?

The most commonly grown strelitzia is Strelitzia reginae, commonly called bird-of-paradise. It produces brilliant, birdlike orange and purple flowers on top of long stalks of glossy greenish-blue foliage. These subtropical plants need a rich, well-drained soil containing a lot of organic matter. Place them in a brightly lit spot with temperatures of about 68 to 75 degrees during the day and night temperatures about 10 degrees cooler. During the growing season, allow the soil to dry out slightly and then water them well. Feed them with a dilute liquid fertilizer every two weeks. The plants like their foliage misted daily and year-round humidity levels of about 35 percent.

In the winter, the plants need a resting period. Keep them at about 55 degrees, decrease watering, and stop fertilizing.

Plants need to be potbound before they will flower, so don't transplant them to a larger pot until the roots have filled up more than three-quarters of the soil area. Plants grown from seed take seven to eight years to flower. Those propagated by division take about four years.

4. How do I take care of a Moses-in-the-cradle plant?

Moses-in-the-cradle (Tradescantia spathacea; formerly Rhoeo spathacea), also called boat lily and numerous other common names, is a member of the spiderwort family. It is prized for its dark metallic green leaves that have glossy purple undersides. Small white flowers are borne within purple, boat-shaped bracts (the cradle) that are formed in leaf axils. Indoor Plants, by George B. Briggs and Clyde L. Calvin, suggests that the plants need full sun and moderate humidity, temperature, and water. The plant does not require pruning but should be fertilized four to five times per year from April to August.

5. I'm looking for a house plant that doesn't need sunlight but gives off lots of fresh oxygen. What do you recommend?

All plants give off plenty of oxygen, and some help to remove pollutants from the air. While no plant will grow without any light, there are many that can be grown under fluorescent lights. Unfortunately, few flowering plants will grow or thrive under standard artificial lighting, so unless you purchase and install professional-quality grow lights, you'll have to stick to foliage plants. Some plants that do well in low-light situations include: spider plant (Chlorophytum spp.), cast-iron plant (Aspidistra elatior), golden pothos (Epipremnum aureum), kangaroo vine (Cissus antarctica), grape ivy vine (Cissus rhombifolia), spotted evergreen plant (Aglaonema costatum), Chinese evergreen (Aglaonema commutatum), and snake plant (Sansevieria spp.). Many of these common indoor house plants can be purchased at your local garden center or greenhouse.

6. I've moved a big hibiscus that was outdoors all summer into our south bay window. It's still putting out blossoms, but the leaves are dropping.

Don't worry about the leaf drop. It's natural for a hibiscus to drop leaves when it is brought into dry indoor air. Mist it often to help it adjust. It will overwinter well as long as it isn't over-watered. This may be happening if the foliage turns from strong green to a ghostly green. If that occurs, take it out of the pot and let the root ball dry for a day or two before you put it back. Fertilize with a dilute, balanced mix once a month until the days begin to lengthen and new growth begins.

7. How do I propagate a gardenia using cuttings from a large gardenia bush?

In order to propagate the gardenia, use greenwood and semi-ripe cuttings taken as nodal stem-tip cuttings in late spring or early summer. Root one cutting per cell tray or pot. They tend to root in six to eight weeks and should be kept in humid conditions with temperatures between 68 and 77 degrees. They should flower in 12-18 months.

8. I have a Dieffenbachia at home and have found that it is causing a skin rash when I touch it. Is it possible that I am having an allergic reaction to my plant?

Commonly grown as house plants, Dieffenbachia species are actually tropical evergreen perennials in the arum family. They are distinguished by thick, clustered stems that become woody with age, draped with large, fleshy, spotted leaves. Many people are not aware that the base of the leaf stalks and stems contain a milky or yellowish sap that can cause contact dermatitis in susceptible individuals. To relieve skin irritation, wash the affected area thoroughly with soap and water; if the irritation persists, wear gloves when handling your Dieffenbachia. The plant also contains microscopic, needlelike crystals of calcium oxalate that if ingested by humans or pets can cause burning and swelling of the mouth and throat. People who experience severe reactions are sometimes unable to talk-hence one of the plant's common names, dumb cane. Before bringing any plant into a home that includes small children or pets, be sure to find out if it is potentially toxic.

9. Can you tell me how to germinate seeds from a plant commonly referred to as bat plant (Tacca chanteri and Tacca nivea)?

The seeds of Tacca-a genus of 10 or so herbaceous perennials from the subtropical forests of West Africa and Southeast Asia, grown for their handsome foliage and unusual flowers-should be sown in the spring on the surface of a porous soil mix at 70 to 80 degrees Fahrenheit. Keep the seed evenly moist. Bat plants can also be propagated in spring by dividing their rhizomes; be sure each section contains a bud.

The plants require a moist, warm environment, and if grown outdoors they will need some shade. Since they are not hardy-the minimum temperature at which they will survive is 55 degrees Fahrenheit-they are often grown in a greenhouse.

10. I recently purchased a Japanese persimmon, and a reference I consulted said it could produce parthenocarpic fruits. Does this mean it is self-pollinating?

Japanese persimmon (Diospyros kaki) is parthenocarpic, which means it is capable of producing mature fruits without benefit of fertilization, or sometimes even of pollination. The resulting fruits will then be seedless. If you planted your tree with other Japanese persimmons, however, cross-pollination will likely occur and the fruits will bear seeds.

The term “parthenocarpic” is derived from the Greek roots parthenos, which means “virgin,” and karpos, which means “fruit.” Notable examples of parthenocarpic fruits include navel orange, banana, and pineapple. Brian Capon, author of Botany for Gardeners, notes that not all seedless fruits are parthenocarpic. Some seedless grapes, for instance, develop after pollination and fertilization, but embryoes abort before seeds enlarge.

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