S. H. WITTWER 



371 



1949. In the three years temperatures became optimal for fruit set on 

 the twenty-seventh, the twenty-first, and the tenth of June, respectively. 

 Price data compiled from the combined reports of the Detroit and 

 Benton Harbor Farmers' Markets revealed an abrupt drop of over 50 

 per cent in the fresh market price of tomatoes on August 13 in 1947, 

 August 9 in 1948, and July 26 in 1949. 



10 



15 



20 



25 



30 



Figure 3. Averaged day to day night temperatures during the month of 

 June in East Lansing, Michigan. Fruit setting on field tomatoes was delayed 

 until June 10, June 21, and June 27, for the years 1949, 1948, and 1947, 

 respectively. (Optimum range for fruit setting 59-68°F.). 



Hormone spravs for greenhouse tomatoes have been used as supple- 

 mentary (33) to other grower practices for improving fruit set, size, 

 and yield. In the greenhouse temperatures are controlled so that some 

 pollination and fertilization occurs even in very dark weather if flowers 

 are sufficiently "vibrated." Resulting tomatoes usually contain seeds. 

 The importance of time of application on the greenhouse crop has 

 recently been emphasized (17,21), and present evidence indicates that 

 pre-anthesis treatments with growth substances greatly inhibit flower 

 bud development and are notorious for causing complete seedlessness 



