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		Crab Grass Control
				Crab grass can be a scourge in any fine lawn and is its most troublesome weed. If you've never had it, you don't want it. If you have had it, you'll go to great lengths to rid your lawn of this utterly unsightly nuisance. Even if one has not had crab grass before, one's neighbors may have it, or one's neighbor's neighbors. Crab grass plants produce a prolific number of seeds and like broadleaf weed seeds, they are easily transported by wind and birds.
			As crab grass and its cousin, barnyard grass, grow in the summer and fall, they crowd out desireable bluegrasses and fine fescues. When they die off at the first hard frost, they leave enough bareness on the soil for seeds of winter annuals like common chickweed to grow and prosper, which further crowd out the fine grasses. When these annuals wither and die the following year (after dropping zillions of seeds) the crab grass seeds deposited the previous year begin the cycle all over again. But now its worse because now there is more bareness and more seeds.
			I have consulted on lawns that were 70%+ crab grass and have seen pictures of that same lawn, when it was brand new 4 - 7 years earlier, and in a 100% crab grass free condition. What happened was that crab grass was left to its own volition. It doesn't have be that way.
			What Can and Should You Do? - The most effective cure for crab grass is to prevent it in the first place by applying a pre-emergence crab grass preventer in the spring. This granular product combined with water forms a barrier on top of the soil that prevents crab grass seed germination. Timing the application is critically important. The gereral rules mentioned by product manufacturers are: Before temperatures are routinely in the 70's; When forscythias are in full bloom; Before dandelions reach puff-ball stage. In the Vineyard climate, the above are often somewhat opposed to one another. If one year's infestation which one begins to see in late July and August is light, I'll generally look at nos. 2 and 3 above and go with one application. If the previous year's crab grass was heavy, I'll recommend 2 applications about a month apart - one at the beginning of the above period and another at the end. Prevention Guarantees? Can't be done. As mentioned the timing is critical but so is the amount of follow on water to create the barrier. Not enough and it never forms properly. Too much and the barrier breaks down and is washed away. An additional problem is that while maybe 80% of crab grass seeds germinate within the "typical" time frame of spring, the balance may not germinate until summer through fall. Crab grass prevention, therefore, should be viewed as a multi-year or ongoing project. Combating it can be labor and materials' intensive if the infestation is heavy. But conversely, on some lawns this year, we hand pulled the few plants that appeared and need do nothing more than a single pre-emergence application next spring. Other Solutions? Once formed, crab grass can be killed with a spray. Two applications about a week apart are generally required if the plants are larger than 2". The area should remain dry for 48 hours after spraying. A benefit of spraying is to eradicate the plant in August before it has a chance to drop seeds. The disadvantage is that depending of the area of infestation, one might be left with a large bare spot(s) of dead crab grass and nothing else.