ANNUAL REPORT, 1942 41 



Resistance to other diseases, such as Verticillium Wilt and Powdery Mildew, 

 has not been conclusively determined, although in some seasons a few strains 

 have appeared somewhat less susceptible to these diseases than commercial 

 varieties. 



Soilless Culture of Carnations. (Harold E. White, Waltham.) The use of 

 gravel as a cultural medium has been continued for demonstration purposes and 

 for comparison of the responses of carnations to various nutrient formulas. Four 

 formulas were used, which gave the following number of blooms per square foot: 

 Ball's, 14.80; New Jersey, 15.77; Ohio 2 WP Modified, 19.33; Ohio 2 WP Modified 

 plus Yi formula weights of phosphate and potash, 18.61; soil plot (checks), 17.44. 



Plants grown in soil and transplanted to gravel require considerable time for 

 adjustment and development of a root system adapted to the gravel medium. 

 The most critical cultural period for the plants is after they are transplanted from 

 soil to gravel. Keeping the gravel too wet soon after planting will cause heavy 

 losses of even the most vigorous plants; and, contrary to what has been claimed, 

 observations show that weak plants give no better results in gravel than in soil. 



A commercial grower should not find it difficult to grow carnations in gravel as 

 far as manipulation of the nutrients is concerned; but the costs of installation at 

 present are very high and it is impossible to obtain fertilizer salts or pumps for 

 the duration of the war. 



Cultural Requirements of Freesias. (Harold E. White, Waltham.) Freesia 

 corms pre-cured for 2 to 11 weeks prior to planting lost from 3 to 24 percent of 

 their original weight — a greater loss than in the two previous years because of 

 differences in moisture content of the 1941 crop. 



Corms planted August 17 to 25 required 173 days to flower; those planted Octo- 

 ber 20, 133 days; while those planted on November 1 flowered in 123 days. 

 Freesias bloomed earlier when grown in benches than when grown in bulb pans. 

 Increasing the growing temperature to 60°F. in mid-November hastened the 

 blooming of early planted corms by 3 to 4 weeks. 



Disease Resistance and Heredity of Carnations. (Harold E. White, Waltham.) 

 Microscopic examinations and germination tests of pollen from 25 varieties of 

 carnations were started in September and continued through October and Novem- 

 ber. In the early September tests pollen from the four varieties, Johnson's Crim- 

 son, Olivette, Barbara Brlgham, and Peter Fisher, responded satisfactorily with 

 60 to 70 percent germination. Subsequent tests made at weekly intervals on 

 pollen from these same varieties yielded very poor results. Freshly collected 

 pollen dried in a temperature of 72°F. for 1 to 3 days and other samples exposed 

 to sunlight for 6 hours failed to germinate. Microscopic examination of pollen 

 did not reveal any morphological peculiarities which could be associated with 

 poor germination responses. A few imperfect or shriveled pollen grains were 

 common to all varieties but were not numerous enough to be considered a factor 

 in causing poor germination. 



The size of pollen grains in the different varieties did not vary greatly, ranging 

 from 45 to 49 microns in diameter. A number of giant grains similar to those 

 characteristic of tetraploid plants were found mixed with pollen of normal size. 

 Typical pollen characteristics were spherical shape, external markings of extme 

 being punctate with distinct pores. 



Only 5 out of 23 varieties produced seed with self-pollination. Seed production 

 was low, varying from 10 to 21 seeds per capsule. On the basis of observations 

 made on germination and fertilization, it would seem that the ability of pollen 

 to germinate is influenced by environmental conditions present at the time it 

 is formed. 



