36 Florida Agricultural Experiment Station

 LITERATURE CITED

 1. GADDUM, L. W., and L. H. ROGERS. A study of some trace elements
 in fertilizer materials. Fla. Agr. Exp. Sta. Bulletin 290. 1936.
 2. PURVIS, E. R., and R. W. RUPRECHT. Cracked stem of celery caused
 by a boron deficiency in the soil. Fla. Agr. Exp. Sta. Bulletin 307.
 1937.

 3. SCRUGGS, F. H. Annual fruit and vegetable report. Fla. State Mkt.
 Bureau. Season 1937-38.

 4. TAYLOR, J. J. Annual report of the State Chemist of Florida for the
 year ending December 31, 1937.

 5. TOWNSEND, G. R. Manganese sulphate sprays for vegetable crops.
 Fla. Agr. Exp. Sta. Press Bulletin 487. 1936.

 6. TOWNSEND, G. R. Zinc sulphate sprays for vegetable crops. Fla.
 Agr. Exp. Sta. Press Bulletin 488. 1936.
 7. WANN, JOHN L. Florida truck crop competition. II. Intrastate.
 Fla. Agr. Exp. Sta. Bulletin 238. 1931.