frequent irrigation, the usual man- agement practice in the production of hand-picked tomatoes, is not necessarily best suited for the new varieties developed for one-time mechanical harvesting. In addition to the need for determinate maturity, dry fields allow much more efficient operation of mechanical harvesting equipment. These studies were conducted to determine how dry the soil can become before affecting yield, maturity, and soluble solids content of the new varieties-and whether a plant or soil moisture index can be developed as a guide to irrigation of the growing crop, as well as the final water cutoff date. Research has previously shown that irrigation practices do affect the relative maturity of the crop and can directly influence yields obtained in a single harvesting operation.

D. W. Henderson, Associate Irrigationist, furnished the calibration curve used to convert readings on the moisture meter to tension.