Bentgrass does not like the world at three inches. When you mow it down you might be creating false crown. Because it doesn't like much of anything over .5 inch mowing height the crown of the plant grows at a eleveted level. When the height is lowered you remove to much of the canopy. Unless you have a reel style mower you will never be able to maintain bentgrass. You are competing against roots under the tree in the front. Think about a landscape bed or running a trencher along one side of the tree

Corn gluten meal is a very effective preemergent for anything propogated by seed. The key is timly application. Basically you make an application in the early fall for cool weather weeds and another in early spring for summer weeds such as crabgrass and perhaps your bent grass. The application rate is 20lbs. per 1,000 sq. ft. of lawn. In addition, since CGM is 60% protein, it acts as an excellent fertilizer as it contains 9% nitrogen. However, CGM is ineffective on perennial weeds that are not spread by seeds an in fact fertilizes them.

Cultural Control: Removing Plants and Tubers Tubers are key to nutsedge survival. If you can limit production of tubers, you�ll eventually control the nutsedge itself. To limit tuber production, remove small nutsedge plants before they have 5 to 6 leaves; in summer this is about every 2 to 3 weeks. Up to this stage, the plant hasn�t formed new tubers yet. Removing as much of the plant as possible will force the tuber to produce a new plant, drawing its energy reserves from tuber production to the production of new leaves. Continually removing shoots eventually depletes the energy reserves in the tuber, because the nutsedge will have to use 60% of its reserves to develop the first plant and 20% for the second. However, mature tubers can resprout more than 3 times. Even though these newer sprouts start out weaker than the previous ones, plants can develop from them and produce new tubers unless you remove them. The best way to remove small plants is to pull them up by hand or to hand hoe. If you hoe, be sure to dig down at least 8 to 14 inches to remove the entire plant. Using a tiller to destroy mature plants only will spread the infestation, because it will move the tubers around in the soil. However, repeated tillings of small areas before the plants have 6 leaves will reduce populations. If you find nutsedge in small patches in your turf, dig out the patch down to at least 8 inches deep, refill, and then seed or sod the patch. Here is a link that might be useful: Nutsedge

If you add zeolite to your yard it will help get rid of all kinds of burrs and weeds. They thrive in poor soil and zeolite provides a wide range of nutrients that desirable plants need. We are out in the country and had a terrible problem with burrs and weeds. But a couple applications of zeolite has gotten rid of most of them in our lawn. Zeolite is available at feed stores and most garden supply stores in 50 lb bags. Just spread it according to the directions on the package and let nature take it's course. Now if we could just get rid of the f%*@^!g fire ants we could all go barefooted like we did when we were kids... Cheryl