Red clover looks sick in a lot of fields this year. "Why?" is one of the most often asked questions here in the department.
First, we must not overlook the effect of the early growth followed by the hard freezes in March. This unusual condition started a chain reaction that made the insects and diseases more important in reducing stands. The early start, followed by the freeze, caused unseasonable maturity or false dormancy. Thus, many stands stopped growing at 6" to 10" heighths. Many stands were thinned and some killed by this freeze.
Where the first harvest has already been made, the second growth looks fine and is making a remarkable recovery.
Thompson, Warren C. and Taylor, Norman L., "What's Wrong With the Red Clover This Year?" (1967). Agronomy Notes. 213.