Spring is a gardener's favorite time of year. We get back to play in our beloved gardens once again. We happily dig, weed, prune and plant. The weather is delightful, just right for working in the yard, aerating, fertilizing and mowing.
Unfortunately, spring is also the aphid's favorite time of year. Last week, two alert gardeners brought in the first aphids of the season for identification. These were not the run-of-the mill tiny, green aphids. They were big, black giant willow aphids. Do not let the name fool you. These large pests that look like ticks attack other trees besides willows. My office visitors had found them on their blue spruce.
Usually, aphids are small critters. They have soft bodies. With long mouth parts, they pierce stems, leaves and other tender plant parts to suck out plant juices. They come in a multitude of colors, not only green and black, but also brown, yellow and red. Some are woolly, such as the woolly apple aphid. The main identifier for aphids is the tubes on their backsides, called cornicles.
Most adult aphids are wingless, but in spring, many will have wings to facilitate travel to different host species. As in the case of the giant willow aphid, aphids usually feed in large colonies. Females can produce live young without mating. This allows for many generations of aphids in a year. Aphids can mature from the newborn stage to reproducing adults in only seven days. As adults, they can produce 80 "babies" in a matter of a week. Populations can boom.
Aphids in moderate numbers rarely cause significant damage to healthy plants. The sticky honeydew that they exude as they suck out plant juices can be an annoying problem. It can take the finish off a car and cover anything located underneath an infested tree or plant with a messy goop. An additional concern is that aphids carry and transmit viral diseases that adversely affect a large number of plants.
Aphids aren't difficult to control. To control the giant willow aphids, I recommended that the gardeners hose them off weekly for a few weeks. As the hot weather hits, the aphid populations will start to decline. Hosing affected plants effectively controls most aphids. I squish the aphids on my roses with my fingers. Since natural predators help control aphid populations, avoid using chemical sprays, except as a last resort. Insecticidal soaps work quite well. Horticultural oils are another alternative, but pay attention to labels to avoid damaging sensitive plants or discoloring blue evergreens.
For more information on gardening, 887-2252 or skellyj@unce.unr.edu, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu. "Ask a Master Gardener" at mastegardeners@unce.unr.edu.
-- JoAnne Skelly is the Carson City/Storey County Extension Educator for University of Nevada Cooperative Extension.
