JANUARY 20, 1997
Gardening: Starting a new year in the garden
by Mary Robson, WSU Area Extension Agent
Ahh, January! The calendar says winter, and the gardener's rhythm may have slowed after the holidays, but there are still lots of plant-related activities to engage the senses, intrigue the mind, and stretch the body. Winter offers many mild days for pruning, transplanting, and installing new plants in the garden. How can we get these mild days to coincide with weekends?
Now, when trees are leafless, is a good time to inspect trunk, branches, and bark for disease or insect problems. Get acquainted with the normal, healthy appearance of the plants, and become aware of oddities and deviations from normal. On stone fruit such as cherry, plum, or peach, cankers may have affected the plant. Bacterial canker is a common stone fruit problem. (Lilacs may also show symptoms of bacterial blight). Look for depressed, sunken areas, perhaps with gumming of sap around the depression. Cankers look as if a giant thumb has pressed into the wood, or perhaps a giant finger: they are generally longer than they are wide. The elongate area may also appear blackened as well as sunken. Prune out any wood affected with cankers. If the tree is affected severely on a major area such as the main trunk, saving the tree may be impossible.
Apple anthracnose is another tree fruit disease that can be seen through wood and bark symptoms. In advanced cases, the bark looks as if it has been firmly raked with a very narrow iron comb; anthracnose leaves stringy parallel fibers in the wood. (Others symptoms also show in the leaves when the tree has foliage.) Prune out wood affected with anthracnose.
Removing dead or diseased wood, for all woody plants, helps improve plant shape and health. Prune on days when the temperature is above freezing. For specific information on fruit tree pruning to improve crop production, contact your local Cooperative Extension office for bulletin PNW-400, Training and Pruning the Home Orchard. This Washington State University publication costs $1.00, plus individual handling and mailing costs that may be applied in individual county offices. In King County, the bulletins office is at 206-296-3900. In Pierce County, call 206-591-7170 between 9 a.m. and 3 p.m., Monday through Friday. In Snohomish County, call 206-338-2400.
On milder days, when temperatures are above 40 and it's not raining, dormant oil spraying, to help in management of some insect problems, can also be done in January. Applied during the dormant stage of the tree, they can help to suppress overwintering stages of scales, as well as mite eggs, and aphid eggs. The oil seems to suffocate the insects in these stages and does give some control. Lime-sulfur is also often used to control these insect stages. (Lime-sulfur may also be effectively applied later in the season for disease control.) Dormant oil does not serve to manage disease problems such as brown rot and apple scab, which have to be dealt with at a later growth stage of the tree as it begins to leaf out.
Lime-sulfur, however, does seem to give some partial control to powdery mildew problems on roses if applied during the dormant season. Another valuable effort during January is to rake and dispose of all fallen leaves when pruning and caring for trees, shrubs, and roses. If a thorough garden clean-up wasn't done earlier, there is still time to exercise necessary garden sanitation. Don't compost any diseased plant residues.
Peach growers with peach leaf curl problems should get the first fungicide spray on the trees early in January. The infection lives over on the bud scales, the wrappings for the buds, and it begins to affect the trees very early before the buds swell. Bordeaux mix and lime-sulfur are registered for peach leaf curl; apply 3 times, waiting three weeks between applications, beginning in very early January. The peach cultivar "Frost" has some resistance to peach leaf curl as a mature tree but is susceptible to infection in the first 3 or 4 years of its life. Some peach growers in western Washington report good results in controlling peach leaf curl by sheltering the trees from rain during December, January, and early February. Rigging a shelter or tarp isn't practical unless the trees are fairly small and it's a limited planting.
Visit nurseries to look for bareroot fruit trees, grapes, raspberries, and currants to plant this month. January offers nearly perfect conditions for planting and transplanting if you wait for a day when the ground isn't too soggy for digging, and when the temperature is above freezing. Mulch newly-planted areas with 2-3 inches of any organic material, even fallen leaves, keeping the mulch well away from the crowns and trunks of the plants.
As buds begin to swell on shrubs, clip branches of quince, plum, early cherries, forsythia, and winter jasmine for indoor bloom. It's not necessary or even advisable to smash the stem ends with a hammer. Keep clippers sharp, and make a clean cut. Immerse the boughs deeply in tepid water for 24 hours before arranging them in vases. Remove any foliage underwater, and change water often when keeping boughs indoors.
Yes, it's winter, and the gray days will be with us for weeks yet, but careful observation will show snowdrop shoots emerging, some early buds swelling, and signs of life and growth stirring through the garden--and the gardener.
Visit WSU's Agriculture Site on the World-Wide Web at http://www.cahe.wsu.edu.