That's herbicide damage.

Source may be drift from applied weed killer.

Or may be herbicide carryover in organic matter such as composts or manure.

See this http://smallfarms.oregonstate.edu/sfn/f09Herbicide

Thanks for the link to the article, Jean001a. No herbicides were used in the yard. I now suspect the store-bought bag of manure may contain a herbicide. I'm going to conduct some tests to verify this.

LOOKS LIKE SOME CHEM AFECTED PLANT.....

I conducted a test by planting some seedlings into several soil mixes. The problem occurs only with mixes containing a store-bought manure. I'll be contacting the company producing the product to see what they have to say.

Jim

bookdesign, interesting.....I'll be curious to hear what the manufacturer has to say about your issue (that is if they even bother to reply ).

Harry