Thousands of readers have discovered firsthand in the past week, lawn renovation is not as difficult as some make it out to be.

To be sure, you don't take kindly to being out in 90-degree temperatures trying to put the weeds in limbo, but you also know that the sooner the weeds meet their Waterloo, the sooner the new lawn will be in place. This week, major happenings continue on the renovated lawn.

On the 60-40 lawn with a weed population less than 60 percent and a minimum of 40 percent good grass, you're nearing the end of the first phase of your fall lawn program. You applied the weed killer last weekend, followed by the midweek application of a crabgrass killer. One look at your lawn tells you that things are proceeding as you expected.

The good news is that you're on vacation this weekend. Don't cut the lawn or do anything to it. By Wednesday, however, the second and final application of your crab grass control product should be made. Repeat the scenario used for the initial application last week. Just be sure to check the forecast before committing yourself to the chemical treatment; if the chance of rain runs 20 percent or more, a day or two delay in the second treatment won't make a difference. Three or four days after next week's crab grass treatment, cut the lawn with the bagging attachment in place. The cut should be at the same height as before, around two inches.

Looking ahead, 99 percent of the weeds will be dead to the roots by Aug. 17-20, at which time preparations will begin for dethatching the lawn surface. Think of it like ridding dandruff from the scalp and you'll get the picture of the dethatching operation. I'll give details next week.

Then there is the disaster lawn, which has suddenly come to life thanks to your feeding of last week and follow-up soaking.

Why did you fertilize when you had plans for killing the lawn anyhow? You applied plant food so the weeds would resume growing and resume their production of sugar. Weed killing compounds function in different ways, but the substance you're about to use functions only when the weed is manufacturing sugar and exporting it to other parts of the plant, including the roots.

Glyphosate (phonetically, gly-fos-ate) is the product you're about to use on the lawn. It moves in the plant only when sugar is moving out of the leaves to all parts of the plant. Since the weeds are now actively growing thanks to your feeding of the lawn, the weeds are making sugar, so your application of glyphosate now or in the next few days will work miracles.

When should you make the application? Today is fine, tomorrow, or first thing next week.

Meanwhile, shop for the glyphosate. If your lawn is 1,000 square feet or less, buy a quart container of Security liquid concentrate Blot-Out or Ortho liquid concentrate Kleenup; both products are identical, so buy whichever is cheaper. For lawns over 1,000 square feet, your best buy is a quart container of Monsanto's 41 percent Roundup, which retails for about $45 and is often discounted to $40. Monsanto also has a second glyphosate product (18 percent Roundup L&G), but it's not as economical as the 41 percent compound.

Check the weather. If showers are in the forecast, wait. Rain on the day before the application will boost the chemical's performance.

The only hangup with the application is the method. With Blot-Out or Kleenup, you can use the hose-end sprayer. With Roundup, you can't.

Here are the scenarios for treating the disaster lawn:

Blot-Out or Kleenup. The hose-end sprayer will treat 500 square feet. Add 16 ounces of the chemical to the jar, but do not add water. Screw on the cover, making sure the control knob is in the off position. Make sure the deflector is in place. Spray the contents of the jar over a 500-square-foot area. To make things even easier, add an ounce of Rockland spray indicator to the jar along with the chemical; the blue-green dye will mark the lawn where you spray, virtually assuring a perfect application. Only one treatment is needed to kill everything. For the next 500 square feet, refill the jar of the sprayer and repeat the application.

Incidentally, the Kleenup label cautions you against using an ordinary hose-end sprayer when Ortho distinctly wants you to go out and buy their lawn and garden sprayer ($9) or their spray-ette ($8). If you have a hose-end sprayer that works, use it, but you don't have to buy the Ortho sprayer.

Roundup 41 percent. The hose-end sprayer is out. If you use a hand-pump sprayer with a plastic tank, add 2 2/3 ounces of Roundup to a gallon of water, a teaspoon of the spray indicator and pump up the sprayer. The dye will mark the area sprayed. Go over everything once with a misting spray; it will treat about 1,000 square feet.

Lacking the pump sprayer, use a plastic trash can. Move the can onto the lawn, then add 10 gallons of water, 2 2/3 ounces of Roundup and an ounce of spray indicator. Stir things with a stick. Wear rubber gloves so you don't get dye under your fingernails, then use a two-gallon sprinkling can dipped into the solution to apply to the lawn. The dye will mark everywhere you treat the lawn. Apply all 10 gallons of the solution to the lawn, one application for everywhere. The mix should suffice for almost 1,000 square feet.

During and for 24 hours after the application, banish everyone from the lawn, pets included. Flush the hand-pump sprayer with soapy water, pumping the soap through the nozzle to wash away traces of the chemical. Bleach and water (one to 10 parts of water) will clean out the sprinkling can. Clean the hose with a rag dipped in the bleach-and-water mixture. Finally, be careful where you walk, because the chemical on the soles of your shoes will kill good grass after you exit the treated lawn. Wear rubbers, removing them when you last exit the lawn, then wash in soapy water.

Here are some questions that may be raised:

What should you do if you mistakenly spray a desirable plant? Have a sprinkling can handy with clean water; douse the plant with water.

The lawn has trees. Will the glyphosate harm the trees? No. Bacteria in the soil will attack the chemical sprayed on bare soil, degrading the product in the process. Only if you sprayed tree leaves with the chemical could any harm come to the tree.

Can glyphosate be saved for future use? Yes, but store the container indoors in the fall so the mixture never freezes. All garden products should be stored in a locked cabinet. Jack Eden hosts "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500 AM)