Sunday, February 17, 2008

Winter Watchfulness for a Healthier Landscape

Winter no longer seems like the season we once knew. Instead of skating and sledding, we frequently find ourselves outdoors hiking in tee-shirts or just soaking up the sun. These weird and wacky days of winter offer us a welcome opportunity to get a jump on gardening chores, with the added bonus of preventing problems before they begin.

Perhaps the first chore worth exploring is watering. As many parts of the country experience some degree of drought this year, often combined with unseasonably warm temperatures, we find our landscapes suffering from stress (as though the holiday season isn't stressful enough!), especially evident among evergreen trees and shrubs such as hollies, boxwood, and azaleas, and evergreen herbs and perennials, as well as trees and shrubs planted last fall.

While water should be conserved whenever possible, it is important to realize that evergreens do not enter a dormant phase, but continue to use and lose water through their needles and leaves. In the absence of rain, keep root systems moist and healthy by carefully and judiciously watering about once a week. Failure to supply water can result in the death of sensitive transplants and perennials, and the continued stress on other evergreens can easily lead to insect infestations.

Another solution, especially for broadleaf evergreens, is to apply one of the antidessicant sprays available at garden centers. The antidessicant, sometimes called an antitranspirant, provides a waxy film on the leaf surface to minimize moisture loss, allowing plants to cope more easily with drier soils and cold winds. Sprays should only be applied when the air temperature is above freezing. Antidessicants can also protect foliage from the damaging effects of “winter burn” and, as a bonus, from various forms of fungal disease.

Deciduous trees and shrubs also deserve your attention in late winter, especially when it comes to pruning, one of the most important of all gardening skills. Prime candidates include fruiting and flowering trees, including apples, crabapples, cherries, and ornamental species such as crepe myrtles, as well as wisteria, grape vines and roses. Winter provides an excellent opportunity to assess the condition of these trees, shrubs, and vines, allowing you to prune branches, while the plants are dormant.

With older trees, the primary goals are to increase the amount of light reaching into the tree’s interior and improving air circulation, which will help to minimize disease and pest problems in the future. Look for limbs which may be growing too close together, crossing or rubbing against one another, and carefully remove them with sharp, clean pruning sheers or a saw.

It might even be advisable to keep a small bucket near at hand filled with a dilute solution of bleach and water. Dip your pruning sheers or saw into the solution in-between pruning each new branch or tree to prevent any possibility of transmitting disease pathogens.

Younger trees or trees which grow quickly, such as the infamous and over-planted Bradford pear, often require diligent pruning to help establish an attractive shape or form, and to provide a healthy structure or “scaffolding.” Thin out potentially weak branches, again with an eye to facilitating the penetration of light and air. And, with both older and newer trees, eliminate any suckers, damaged or diseased limbs, and branches which hang dangerously low over sidewalks.

One of the most important winter chores is bug hunting. By locating and eliminating pests during the winter, you will be preventing a measurable amount of caterpillar damage during the traditional spring feeding frenzy.

Among the easiest pests to locate are the egg masses of tent caterpillars. Although people are most familiar with the tell-tale tents these odious creatures spin between the branch forks of cherry trees in early spring, their egg masses are actually quite distinctive – and disgusting. Look for shiny brownish-black, bubbly masses which are often wrapped completely around the small twigs and thin branches of wild and ornamental cherries, as well as apple and crabapple trees, and, to a lesser degree, on some other species like beech and willow. Sometimes these masses are mistaken for galls or some other disease. Make no mistake: each egg mass contains between 150 and 400 eggs. When feasible, try to prune off small twigs to capture the entire egg mass and destroy them through burning or crushing.

Gypsy moths await hatching in early April in fuzzy, felt-like light tan egg masses, generally found on the trunks of oak trees and other hardwood species, although they are also found in sheltered locations, including secluded corners of sheds, carports, stacks of firewood, picnic tables and other outdoor furniture.

These egg masses contain from several hundred to one thousand individual eggs. It is important when removing egg masses to thoroughly scrape them into a container for disposal. Some bug hunters favor using a coffee can filled with soapy water, which will be flushed later on. Do not simply scrape egg masses onto the ground where they may still hatch.

Fall cankerworms are sometimes best known as "loopers," "inchworms" or "measuring worms." The brownish-grey egg masses are deposited in neat, single-layered masses of 100 or so eggs in uniform rows on the branches and twigs of hardwood species including oaks, ash, maples, and hickories. Eggs can be crushed in place or scraped off for disposal.

Bagworms are most often found on junipers, cedar and arborvitae, as well as spruce, pine, and Leyland cypress. The distinctive, albeit camouflaged egg cases are roughly carrot-shaped, tannish-brown, and can reach up to two inches in length, hanging down from stems like a bag or sack. The case itself is actually quite natural-looking, as the crafty bagworm weaves its silk together with the dried needles and small twigs of the host plant to help blend in. However, careful inspection will easily locate these brownish dry casings against the lush green of the surrounding vegetation. Incidentally, each bagworm egg case may contain as many as one thousand eggs. On smaller shrubs it is quite possible to handpick all of the egg cases and eliminate any possible infestation in spring.

Of course, you may not be able to locate or reach all of the egg masses or cocoons, but removing as many as you can will go a long way to controlling pest populations without pesticides. In the cases cited above, destroying just one egg mass might be the equivalent of destroying up to one thousand voracious caterpillars.

Also, during the course of the year, you can continue your good work of controlling pests naturally by encouraging other pest predators to set up housekeeping in your yard, often by simply setting up a bluebird house or providing some other sources of habitat.

The last word in preventing problems is sanitation. Begin by cleaning out any leaves, broken branches, and other debris which may have become lodged in your shrubs and other evergreens. Much like pruning, a quick cleaning will increase the air circulation and amount of light reaching the interior area of plants, ensuring their continued health and vigor.

Next, clean up underneath trees and shrubs, removing leaves and other accumulated material which might potentially provide a hiding place for small nibbling rodents, and a unwanted habitat for various insect pests which may be overwintering in leaf litter. Collect these materials, and add them to your compost bin.

Copyright 2008, Joseph M. Keyser

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