ANNUAL REPORT, 1938 69 



sulfate gave 22.91 blooms per plant and 18.50 percent bud drop. The fertilizer 

 which gave the most favorable results supplied all nitrogen and phosphorus in 

 organic forms and produced 23.12 blooms per plant with only 14.60 percent bud 

 drop. 



The quantity of fertilizer applied per 100 square feet of bench area varied from 

 2 to 4 pounds, and the number of applications from 2 to 6 per year. When the 

 quantity and the frequency of application of fertilizers containing nitrate of soda 

 were increased, flower production was reduced and bud drop increased. Com- 

 parative applications of fertilizers with ammonium sulfate or organic materials 

 as sources of nitrogen did not decrease flower production or increase bud drop 

 as did sodium nitrate fertilizers. This difference in effect on production and bud 

 drop would appear to be due to the availability and accumulation of nitrate 

 nitrogen in the soil from the sodium nitrate. 



This opinion is further substantiated by the fact that the total bud drop for 

 the season was reduced to between 2.0 and 2.5 percent on a number of plants by 

 withholding fertilizers until November and December. At that time the plants 

 showed symptoms of nitrogen deficiency with a good set of buds but no develop- 

 ment. One group of plants received two applications of a chemical fertilizer. 

 The plants fed with organic materials produced 16 flowers per plant with only 

 2.33 percent bud drop, whereas those plants receiving chemical fertilizers produced 

 27 blooms per plant with 2.13 percent bud drop. Bud drop was proportionally 

 as high on nitrogen-deficient plants during November, December, and January 

 as on plants fed more heavily with fertilizers, indicating that soil fertility is not 

 the only limiting cultural factor concerned in loss of buds from gardenia plants. 



Further observations on the use of chemical fertilizers containing sodium or 

 calcium nitrate show that symptoms of iron chlorosis on gardenias are intensified 

 as the quantity and the frequency of application of fertilizers are increased. 

 Fertilizers with ammonia and organic forms of nitrogen, when applied in the same 

 quantity and frequency as the calcium or sodium nitrate mixtures, did not cause 

 chlorosis. One-year-old plants grown for a second season are chlorotic or normal 

 depending upon type of fertilizer treatment of the soils. 



Monthly pH determinations have been made on gardenia soils under different 

 fertilizer conditions. The data, compiled from records for two years, show no 

 relation between degree of acidity and severity of chlorotic symptoms of gardenia 

 plants. 



On the basis of experimental results it is concluded that chlorosis caused by the 

 inactivation of iron can be prevented under commercial cultural conditions 

 through the use of soils relatively low in nitrate nitrogen, and by the judicious 

 application of fertilizers so as to limit the accumulation of nitrate salts in the soil. 



Detailed results of experimental work with gardenias were published in the 

 Proceedings of the American Society for Horticultural Science, 1937. 



Propagation Studies with Geraniums. (Harold E. White, Waltham.) The 

 use of fungicides on geranium stock plants in the field as a means of producing 

 disease-free cuttings proved to be of little value. A 2-2-50 and a 4-4-50 Bordeaux 

 mixture and a 4-50 wettable sulfur spray were applied twice in June, Julv, and 

 August, and once in September. Moderate to severe burning of the foliage re- 

 sulted from the use of all these materials and the rooting of cuttings was not 

 increased very appreciably. 



Cuttings taken from stock plants grown in greenhouse benches rooted con- 

 sistently better with less loss from stem rot than cuttings taken from field-grown 

 plants. An average of 9 cuttings per plant was obtained on inside bench-grown 

 stock as compared with an average of 3 cuttings on field plants. The excellent 

 results of propagation from greenhouse-grown plants as compared with field- 



