Stunted and yellowed Brussels sprouts were observed in many fields in San Mateo County in 1957. The affected plants grew very slowly after transplanting and interveinal yellowing or chlorosis developed shortly. As the plants developed, the older leaves cupped upward and developed small, necrotic spots near the margins. The plants seemed more severely affected while they were young, but tended to outgrow the trouble after a few months. The yields were drastically reduced and maturity was delayed.

James Quick, Soil Technologist, Agricultural Extension Service, Berkeley, the Kaiser Chemical Company, Natividad, and the Lazzarini Ranch, Pescadero, cooperated in the above reported tests.

The above progress report is based on Research Project No. 1591.