ANNUAL REPORT, 1935 57 



Research work in cooperation with the Association of Official Agricultural 

 Chemists of North America has included modified methods for potash, active 

 water insoluble organic nitrogen, and soluble and available magnesium products 

 used in mixed fertilizers; other services of an executive and advisory nature 

 have also been rendered to this organization as in the past. 



DEPARTMENT OF FLORICULTURE 

 Clark L. Thayer in Charge 



Breeding Snapdragons for Varietal Improvement and Disease Resis- 

 tance. (Harold E. White, Waltham.) Field Station strains of rust-resistant 

 snapdragons crossed to the various California strains carrying resistance re- 

 sulted in considerable varied segregation for resistance. The Field Station 

 strain 3413-3 crossed with "Florists' Pearl and Shasta of the California group 

 resulted in the most uniform segregation for resistance. The F 2 generation 

 from selected crosses is to be carried on for further selection for bronze, red, and 

 pink types. 



The Field Station strains continued to stand up under resistance tests and 

 to breed true in the field. It has been observed for two years that certain of 

 the Station strains are more immune to Verticillium Wilt than others, and 

 very noticeably so when compared to commercial strains. Field plantings 

 have always been made on the same field where rust and wilt have been preva- 

 lent for the past four years. Seed which has been received from the California 

 Station where selections have been made for a wilt disease will be planted for 

 comparison with the Field Station strains. 



Seed of certain Field Station strains is being grown in quantity for trials 

 with various greenhouse growers; it is hoped that sufficient seed for this 

 purpose will be available in the spring of 1936. 



Propagation Studies on Geraniums. (Harold E. White, Waltham.) 

 The same experimental setup was used during 1935 to determine what effect 

 seasonal conditions in the field might have on the rooting of cuttings, and to 

 note whether the maturity of the plant was concerned in successful propaga- 

 tion by taking cutting material in August, September, and October. Approxi- 

 mately two thousand cuttings were taken in August, at least 80 percent of 

 which were lost through stem rot caused by the fungus Pythium. Similarly, 

 with the September and October lots of cuttings, heavy losses were experienced 

 because of stem rot. Sterilizing the sand with steam, treatment with potassium 

 permanganate and with bichloride of mercury did not noticeably check the rot. 

 Surface disinfection of the cuttings with potassium permanganate or bichloride 

 of mercury did not seem beneficial. 



Examination of the plants in the field revealed that, while cuttings might 

 not show any external symptoms of infection, the vascular system would show 

 a distinct brown discoloration. Cuttings with and without this brown dis- 

 coloration were placed in sand to root; the normal cuttings showed 8 percent 

 loss from rot as compared to 31 percent where the vascular system was dis- 

 colored. 



The fact that the percentage of rooting varied from 92 to as low as 10 under 

 various propagating conditions, indicates that probably the success or failure 

 of growers in rooting geraniums is due to the absence or presence of stem rot 

 rather than to the degree of maturity of plant material or to propagation 



