Ouch. It's getting quite warm for some of that. I'm assuming that you have bluegrass or fescue - both of which - but especially fescue - if over-fertilized, will be more susceptible to brown patch. If it were me I would spot treat with a liquid selective herbicide like Weed-B-Gone or something that is labeled for use on the weeds you want to kill. You should wait for the coolest day possible, and spray carefully, knowing that it could also kill the grass. Also, with warmer temperatures, spray can volatile and drift to non-target plants (i.e. trees, flowers, shrubs) very easily.

Purchasing lawn care products(other than a few like post emergents like Bayer and OOrtho products and and Scotts starter fertilizer with seed-safe preemergent)greatly limits the products available and the cost. Try to find a Feed and Seed store in your area. They can be a great source of advice and information on the products available. Below is a copy of a chart published by CSU which might help you in selecting a product based on AI. I personally do not use pendimethalin products because of it's increased likelihood of damage to the roots of turf grasses. At the recommended application rate it only gives 8 weeks of protection--probably due to increased likelihood of root damage at heavier application rates. Table 1: Preemergence herbicides for annual grass control and expected level of control. Herbicide Name Trade Name CrabgrassFoxtail Goosegrass Barnyardgrass Field Sandbur benefin Balan G-E F G NA benefin/trifluralin Team E G G-E NA bensulide Betasan G-E P-F G-E NA corn gluten meal Many G NA NA NA dithiopyr Dimension E G-E G-E NA oxadiazon Ronstar G E NA G pendimethalin Pre-MPendulum E E G-E G prodiamine Barricade E G G NA siduron Tupersan F-G P-F F-G NA E=excellent, G=good, F=fair, P=poor, NA=information not availableExclusion of chemicals or product trade names does not imply criticism, nor does inclusion imply any endorsement, by Colorado State University or the author. Read all label directions before using any pesticide. * Colorado State University Extension turfgrass specialist and professor, horticulture and landscape architecture. 10/97. Revised 12/14. Hope that helps you make your decision.

Pendimethalin stains horribly. I don't like the idea of everything, including me, being stained yellow. I'm sure it washes off eventually, but I'd rather not deal with it. Also, while I'm sure that Pendimethalin is a great pre-emergent, I don't think it's known so much for killing mature, growing crabgrass. Dithiopyr kills up to stage three or stage four crabgrass. Also, I believe it's supposed to last longer. Dithiopyr stays active for about two months, preventing and killing crabgrass for the whole time. It can also be put down again in early to mid June to pretty much get through the whole season. However, in the end, it's a personal choice. When I was starting out with our new lawn, every forum I went to, I was inundated with posts suggesting Dithiopyr over Pendimethalin and singing it's praises. I don't typically blindly follow forum advice, but I've always been a firm believer that, where there's smoke, there's fire. I did my own, independent research and everything I've read seems to pan out. I'm sure either product works fine for what it's supposed to do. For me, it's just that Dithiopyr seems to do it just a little bit better.

Thanks, mishmosh. I started working on this lawn last fall when I redid the area over by the wood fence. It came in good then the cold hit (central connecticut) and I began noticing all the dying crabgrass near it. This past spring I reseeded those areas and got 50/50 grass vs. annual grass weeds & crabgrass. Some other areas just outside of view in those pictures are mostly crabgrass and are looking pretty rough now. I am getting there and your recommendation will help in the spring. Thanks!