68 MASS. EXPERIMENT STATION BULLETIN 355 



DEPARTMENT OF FLORICULTURE 

 Clark L. Thayer in Charge 



Breeding Snapdragons for Varietal Improvement and Disease Resistance. 



(Harold E. White, Waltham.) Snapdragon rust was much less virulent on plants 

 in the field this year. Heavy infection usually shows on susceptible varieties 

 by August 5 but this year it did not occur until about August 10, which is 10 days 

 later than normal. The cool temperature during the early summer months and 

 the heavy rainfall in the latter part of July apparently prevented normal dis- 

 semination and germination of the rust spores. 



Selection and hybridizing work is being continued with the most promising of 

 the rust-resistant strains developed at the Field Station. The loss of plants 

 through prevalence of wilt and blight diseases has interfered with pollination 

 work in the field. Therefore all hybridizing has been confined to the greenhouse 

 during the winter months, which has reduced the number of generations that 

 can be grown each year from two to one. 



Considerable variation has been observed in susceptibility' of the different 

 Field Station strains to the wilt and blight diseases, but sufficient data are not 

 available to determine how much of this is due to climatic conditions and how 

 much to heredity. 



A number of rust-resistant varieties of snapdragons sold for garden use have 

 been tested in the field over a period of two years. Many of these are highly 

 resistant to rust but several were observed to vary greatly in type of foliage, 

 habit of growth, and blooming quality, as compared with more susceptible varie- 

 ties. Out of some 25 strains tested at Waltham the following were found to be 

 the most desirable for garden use. 



Variety Flower Color Variety Flower Color 



Alaska W'hite Fair Lady Pink 



Buttercup Yellow Loveliness Light pink 



Campfire Bronze Maximum White. . . W hite 



Daffodil Yellow Opal Queen Salmon and apricot 



Dainty Light pink Orange Pink Orange-pink 



Salmon Pink Salmon rose 



Effect of Temperature on Forcing Lilies. (Harold E. White, Waltham.) A 

 rooting temperature of 60° F. has been found to be more favorable than a tem- 

 perature of 50° F. for Lilium longiflorum var. giganteum. This observation has 

 been substantiated over a period of two years. In 1937-38 the number of flowers 

 per plant averaged 5.10 for bulbs rooted at 60° F., compared with 3.79 for bulbs 

 rooted at 50°. A portion of the same case of bulbs, held in cold storage until 

 January 3, 1938, then potted and placed in 60° F. temperature, averaged 3.43 

 flowers per plant. Heavy watering of the soil during the rooting period did not 

 noticeably affect growth or flowering. A covering of hay over the bulbs on the 

 bench had neither favorable nor unfavorable effect. 



W^eekly records on the growth of the plants indicated that there was a stage 

 of rapid vegetative growth up to the 12th" or 13th week, followed by a period of 

 retarded growth for 3 to 4 weeks. At the end of the 14th to 16th week, another 

 stage of elongation in growth occurred. It would appear that this slowing down 

 in growth took place at the time of bud formation. 



Effect of Plant Nutrients, Soil Reaction, and Light on Gardenias. (Harold 

 E. W'hite, Waltham.) The use of fertilizers containing sodium nitrate as a source 

 of nitrogen resulted in an average production of 19.13 blooms per plant and 22.64 

 percent bud drop. Similar fertilizers with nitrogen in the form of ammonium 



