What can you recommend to kill hairy bittercress and to prevent it next year?
I used crabrass preemergent + fertilizer three weeks ago. Now I have "hairy bittercress" in a large section of my 1-acre lawn (see picture #1). Pictures #2 and #3 I think are the same weed, but I am not sure because the growth is lower and more clover-like. What can you recommend to kill the hairy bittergrass and to prevent it next year? If pictures 2 and 3 are something else, please help with it also.
The weeds in your photo look like chickweed. Both hairy bittercress and common chickweed are winter annuals. Seeds germinate from late summer through fall. Weeds overwinter and continue to grow in early spring. Control with a broadleaf postemergent herbicide (see this publication Broadleaf Weed Control in Established Lawns) when the weeds are actively growing in the spring. You can also control both with a preemergent applied in early to mid-September before it germinates. However, you would not be able to sow grass seed in the fall.