We have had 721 Growing Degree Days (base 32) here. On May 4th. And today I spotted the first crabgrass of the season. It is tiny--about an eighth of an inch tall. It is in last year's highly crabgrass infested lawn between the sidewalk and street, on my street, where the owner does not use crabgrass control. Nearby (few miles) soil temperature was about 57, but I will have to check soil temp again. Was warm (max about 77) and dry for two weeks and then had two light rain showers in last four days. I suppose that any lawn that had fairly thick grass would be cooler and not have much chance of crabgrass emergence yet. What is your situation?