S. H. WITTWER 



373 



by the auxin level (2). In Table 2 the number of fruit showing blossom- 

 end rot is listed for both treated and control groups. It is somewhat 

 surprising that with all varieties the incidence of the disorder was less 

 as a result of treatment. This can hardly be ascribed to any direct effect 

 of the applied growth substance but likely exists because nontreated 

 plants grew more vegetatively (less correlative inhibition (30) from early 

 fruit development), and in subsequent periods of drought their water 

 requirement was less. 



Fruit Set in Beans. — Snap beans are frequently grown in environments 

 not favorable for fruit set. Factors which have been reported as associated 

 with blossom drop are hot dry weather, rapid fluctuations in temperature 

 and moisture (4,8), and, more recently, insects (14). The most striking 

 results obtained through the use of growth substances for improving 

 pod set have been obtained in weather with daily maximum temperatures 

 above 90°?. and no rainfall (14,32,36,43,55). Data obtained from spray 

 treatments of CIPA to Stringless Greenpod beans grown under such 

 conditions of high temperatures and no rainfall are presented in Table 

 3. Results with growth substances on snap beans have not always been 

 so extreme. In repeated tests under more normal temperatures (Table 3) 



TABLE 3 

 Effects of hormone sprays on yields, pod size, and seed content of snap beans 



Sprays 



USED 



Midsummer crop 



(Mean maximum 



temperatures during 



flowering 98 ± 3° f.) 



Fall crop 



(Mean maximum 



temperatures during 



flowering 80 ± 7° f.) 



Yield of pods Averages for Total Averages for 



IN grams total PODS YIELD TOTAL PODS 



per 500 plants harvested in grams harvested 



Weight Seed per 500 Weight Seed 

 Early Total (Grams) Number plants (Grams) Number 



*p-chlorophenoxyacetic acid. 



