76 MASS. EXPERIMENT STATION BULLETIN 369 



Glass Container Research. (C. R. Fellers and K. R. Newman.) This study, 

 sponsored by the Glass Container Association of America, has thus far been 

 limited to a determination of head-space and dissolved gases, particularly oxygen, 

 in bottled citrus, apple, and tomato juices. In general, oxygen disappears from 

 bottled juices in 15 to 25 days at room temperatures. Ascorbic acid losses parallel 

 the oxygen loss, indicating a direct oxidation of the former. Coincident with 

 oxygen disappearance is the development of undesirable color and flavor changes 

 in the beverage. The presence of large amounts of oxygen in the head space 

 intensifies and accelerates flavor and color defects. Methods of oxygen removal 

 at the time of filling the containers are now being studied. 



DEPARTMENT OF HORTICULTURE 

 R. A. Van Meter in Charge 



Powdery Mildew on Garden Phlox. (Harold S. Tiffany, Waltham.) Prelim- 

 inary tests were conducted for the control of powdery mildew {Erysiphe cich- 

 oraceariim) on garden phlox {Phlox panicidata) , from the standpoint of plant 

 tolerance and residue as well as disease control. No plants were sprayed until 

 an appreciable amount of the mildew was evident throughout the plantings. Ma- 

 terials for control were then applied at ten-day intervals up to the flowering period. 



Hammond's Copper Solution (1-150) resulted in fairly complete control and 

 left no residue on the plants. Bordeaux mixture (2-2-50) gave equally good control 

 but left objectionable residue. Neither of the other materials tested gave sat- 

 isfactory control. 



Propagation of Hybrid Lilacs. (Harold S. Tiffany, Waltham.) Late taking 

 of lilac cuttings has been widely believed to offer a very low percentage of rooting. 

 Four hundred internodal lilac cuttings {Syringa vulgaris, varieties Souvenir de 

 Ludwig Spaeth, Marceau, Congo, Charles the Tenth, Jan Van Tol) were taken 

 on July first, a full month after the wood was in prime condition for taking. 

 Forty cuttings of each variety were given a constant temperature of 75° F. by 

 electric cable, and forty were kept at room temperature of the benches. Each 

 forty cuttings of the same variety were further divided into tens, receiving (a) 

 Hormodin powder No. 3; (b) Rootone; (c) Hormodin A (60 BTI units for 24 

 hours); (d) no treatment. Five of each ten cuttings were terminal, and five had 

 terminals removed, to test the theory that terminal leaves transfer a higher 

 percentage of growth substances to the base of the cuttings than do other leaves. 

 The cuttings were all placed in a medium of one-third peat and two-thirds sand; 

 cheesecloth tents were provided; and the cuttings were watered fairly heavily. 



Varietal response to the various treatments was pronounced. While bottom 

 heat at 75° F. definitely hastened rooting of some varieties this effect was not 

 consistent with others. Treatment with a growth substance was effective with 

 some varieties; others rooted better with no treatment. At the end of thirteen 

 weeks, 53 percent of the cuttings had produced good and excellent root masses. 

 The ratio of terminal cuttings rooted was one-third higher than of those without 

 terminals. With the exception of six plants lost, the potted plants produced ex- 

 cellent root systems and strong winter buds. Further trials will be made in 1940. 



Factors Influencing the Rapidity of the Growth of Nursery Stock. (Haiold S. 

 Tiffany, Waltham.) The fertilization of evergreens, in order to provide maximum 

 quality growth, represents a problem on which comparatively little research 

 has been done. In view of the importance of such material to ornamental plant- 

 ings, investigations have been started b\- the establishment of fourteen plots 



