January 2007

Do you have tiny, black flies on or flying around your houseplants? These are fungus gnats. These gnats are 1/8th inch long black flies. They thrive in moist conditions. They are a nuisance and cause little damage. Control by not overwatering your houseplants and allow the soil to dry out between waterings.

Give your foliage houseplants a bath. Dust can reduce light penetration. Let them sit under a shower for a few seconds to remove dust.

Prune your Christmas cactus after blooming. This will encourage branching. Pinch off a few sections of each stem with your fingers. Root these sections in moist vermiculite or potting soil for new plants. The plant can be moved outdoors during the summer to a shady or semi-shady location.

Fertilize your poinsettia if you keep it past the holiday season. Apply a houseplant fertilizer once a month. In late February cut back each of the old flowering stems to 4 to 6 inches in height. This will promote new growth. Repot into a 2-3 inches in diameter larger pot in April. Make sure the soil is moistened and place the plant in a sunny window. When all danger of frost has passed and night temperatures are above 60°F, place the plant outdoors. The poinsettia should be in a shady location for two to three weeks to allow it to become acclimated to the new environment. Sink the pot in a sunny protected outdoor flower bed for the rest of the summer. Light shade during the afternoon is okay.

Brush snow and ice off of tree and shrub branches. Use a broom in an upward sweeping motion to reduce chances of breakage.

Did you know that snow is an excellent insulation for plants? The temperature below snow increases by about two degrees F for every inch of accumulation. The soil also gives off heat. The temperature at the soil surface can be much warmer than the air temperature. A study showed that the soil surface temperature was 28 degrees F under nine inches of snow while the air temperature was -14 degrees F.

The cicadas are coming! The 17-year periodical cicadas will be appearing in the Chicago area in spring 2007. Their last coming out party was in 1990.

• Full-grown cicada nymphs are brown, humpbacked and about three-quarters inch long.
• They commonly construct soil chimneys that extend from the ground up to three inches high and are about one-half inch in diameter.
• Within a few days, the nymphs break through the top of the chimneys or soil surface to crawl up trees, shrubs and other upright objects where they molt into adults.
• Adult periodical cicadas are about one and one-quarter inch long black insects with red eyes and orange-veined, clear wings.
• Males produce a high-pitched wavering song that sounds like a trill when many are singing together. They sing primarily during the sunny part of the day to attract females to them for mating.
• The males and the singing die after a couple of weeks, while females remain alive for two to four weeks longer to lay eggs.
• Eggs are inserted into tree and shrub stems that are up to two inches in diameter. Heavy egg laying will cause twigs to break, resulting in dead leaves at the end of branches.
• Control is directed at preventing egg-laying damage, as adult feeding is insignificant.
• Although pyrethroids and carbaryl (Sevin) will kill large numbers of adults, treated plants commonly experience about as much injury as untreated plants in landscapes. Mature trees and shrubs usually experience only minor damage.