If your lawn has slipped a bit after having been the fall showplace of the neighborhood, don't worry. Most of your neighbors are in the same boat: weeds. What you and they are encountering is the fall outbreak of chickweed and henbit, which started sprouting in late September and continues to this day. You want to tackle these problems now, whether you renovated your lawn in late summer or you've waited until now to control all weeds on the lawn.

There are two distinct lawn management programs here, so let us first focus on the previously renovated lawn and how to dispose of the weeds that have just surfaced.

The good news is that both weeds are easily controlled. The bad news is that these weed seeds will sprout randomly on the lawn up to mid-March of next year, so there's no reason to delay attacking the weeds.

The star-shaped weed growing close to the surface of shaded, north-facing lawns is common chickweed. You'll find a tiny white flower in the center of the star. Leaves are glossy, rounded on the sides and taper to a point. Checking further, you'll find that the stems holding the leaves are opposite each other, and quite hairy.

While chickweed favors shaded soil, henbit is found mostly on lawns in full sun; if your lawn faces south, you're almost certain to find some henbit sprouting there right now.

Catch henbit early to prevent seed formation and germination of more seeds. Unlike chickweed, henbit grows upright. It's easily seen. Flowers are a pale purple, but hopefully you won't see them just yet. Leaves are rounded on the sides and toothed at the ends. Stems are always square shaped, short at the base of the plant and long at the top, and stems are always opposite each other on square stalks. The weed will take over large areas of the sunny lawn over the winter if left alone.

If the weeds are few, dig them with a weeding tool. Take care with the henbit because the least jarring will release the funnel-shaped seeds and assure more henbit over the winter.

If the weed count is such that hand-digging is impractical, you can rely on herbicides to put the weeds away. Use the hose-end sprayer, but spot-treat the weeds; don't treat the entire lawn unless weeds are everywhere.

For chickweed, use Ortho Chickweed and Clover Killer, which contains Mecoprop. One application will kill it in a week.

For henbit, use 33 Plus or Rockland 3-Way Lawn Weed Killer. Spot-treat the weed, but don't spray within 18 inches of the dripline of trees and shrubs. Make sure no rain is in the forecast, too.

Remember that additional chickweed and henbit are likely to surface if these weeds dotted the lawn last winter. You can spot-treat future weeds whenever you find them surfacing on the lawn; because they are winter weeds, herbicides function well at all times.

Next, there are lawns in dire need of renovation. Because of one problem or another, it was impossible to renovate the lawn back in August and September. The weeds continued to proliferate through the fall, with the exception of crabgrass, goosegrass, Bermudagrass and quackgrass, which succumbed to the first frost. If this is the picture of your lawn right now, you want to drop everything this weekend to put the lawn in order; your goal is to catch up with your neighbors by Easter of next year.

Here is your lawn calendar for the next month: Don't cut the lawn now. If there is no rain forecast, spray lawn weeds today or tomorrow with a liquid weedkiller, either 33 Plus or Rockland 3-Way Lawn Weed Killer. If there are trees on the lawn, don't spray within 18 inches of the driplines. Use a hose-end sprayer on large lawns, spraying only where there are weeds. On small lawns, use a hand-pump sprayer with a plastic tank. Afterward, don't cut the lawn for two weeks.

Over the Thanksgiving weekend, install the grass-catcher on the mower, adjust the wheels to cut at the second lowest cutting height, then cut the lawn, dead weeds and all.

Next, remove all debris and thatch from the lawn. On small lawns, you could bear down hard with a bamboo get out to rake all debris; move north-south, then east-west.

On large lawns, rent a power rake from the rental store, adjust the machine to comb the lawn to a depth of a half-inch, then dethatch the lawn north-to-south, then east-to-west. Finally, use the bamboo rake to remove the debris from the lawn.

Over the Dec. 12-13 weekend, or in the following week, apply grass seed to the entire lawn (overseeding). Here, the seeding rate is half that for starting a new lawn. Seeding rates and settings for the rotary Spyker or Cyclone spreader is as follows: bluegrass, 1 pound per 1,000 square feet, spreader setting 3; fine fescue, 2 pounds, setting 6; perennial rye, 4 pounds, setting 7; tall fescue, 3 pounds, setting 6 1/2. Apply the seed uniformly with the spreader.

If you have bare spots, go over these areas twice with the spreader, in effect seeding at the full rate since no grass is growing there. If possible, rake the seed into the top quarter-inch of soil to put the seed in immediate contact with soil. However, no seed will start germinating until mid-March.

Having seeded, fertilize with Milorganite at the rate of 20 pounds per 1,000 square feet. This means a setting of 9 on the rotary Spyker or Cyclone lawn spreader.

Other chores to be tackled:

Tree trunks in full sun in late afternoon should be "whitewashed" with lime and water over the next two weeks to prevent damage to the trunk in late February. Add 2 measuring cups of ground limestone to a quart of water in a bucket, stirring all the while so the granules stay in suspension. Use a wide paintbrush to paint this whitewash on the trunk from the soil line to where the first limb crotch. All trees are candidates for whitewashing, but the smooth-bark trees are the ones most often victimized, mostly American beech, European beech, yellow birch, flowering cherries, maples, pear, white pine, weeping willow, flowering fruit trees and red oak. If you have ever had splitting of the trunk bark before, this is southwest injury or sunscald. Once the cambium tissue dies, a canker usually develops within a few years because water cannot be replaced by conduction through damaged wood tissue. Whitewash your trunks now and you won't have to worry about the problem.

For your wisteria that failed to flower last summer, fetch your steel shovel, go just inside the dripline and thrust the shovel vertically into the soil to sever all lateral roots growing in the top eight to 10 inches of soil. The more roots cut, the more likely the wisteria will flower next summer.

Prune all phlox to the ground, even a bit below the soil line. Pick up all foliage cut away as well as debris littering the flower bed. The cleaner the area, the less likely you'll have disease on the phlox next spring.

Clean up the iris bed, but for a different reason. Debris houses the iris borer eggs laid by the female in late September. By having a spotless iris bed, you eliminate chances of having iris borers next May.

Start lowering the cutting height of your lawn this weekend. Over the next two weeks, you want your bluegrass lawn to be cut to an inch, the other grasses (fine fescue, tall fescue and perennial rye) to 1 1/2 to 2 inches. Bag the clippings for these final cuts of the year.

Jack Eden hosts "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500 AM).