22 MASS. EXPERIMENT STATION BULLETIN 441 



These varieties were selected for selfing and crossing because of their inherent 

 resistance to Fusarium dianthi. A large number of seedlings are being studied 

 for their reaction to the disease and other characters. Two additional wilt dis- 

 eases, Verticillium wilt ( Verticillium cinerescens Wr.) and bacterial wilt (Phylo- 

 monas caryophylli Burkh.), have been found in eastern Massachusetts. 



Toxic Effect of Wood Preservatives on Plants. (L. H. Jones.) Pentachlor- 

 phenol as a wood preservative is frequently used with range oil as a diluent. It 

 may be easily and rapidly applied to lumber with a paint brush. When such 

 treated lumber was covered with soil, no injury to plants was observed, even 

 when their roots were in contact with the wood. However, when such treated 

 lumber is used above ground, grave injury to seedlings may result from volatiliza- 

 tion of the oil by high light intensity and high temperature coupled with poor 

 ventilation. The injury is in the nature of a scorching due to the dissolving action 

 of the oil on the epidermis. The injury is most severe where the treated sides of 

 flats are higher than emerging seedlings. If the plants can grow higher than this 

 source of the volatile substances, they are not affected by the gases. 



Veneer wood plant bands strongly impregnated with range oil caused grave 

 injury to plants when no ventilation was provided. 



Miscellaneous Studies. (E. F. Guba, Waltham.) 



Control of Seed Decay and Damping-off of Vegetable Seedlings by Seed-borne 

 Chemicals. Studies have been continued to provide the vegetable growing 

 industry with the latest information on the subject. During the year, zinc oxide, 

 Semesan, Phygon, cuprous oxide, Arasan, Fermate, and Spergon were tested in 

 comparison with no treatment. No one material was satisfactory with all vege- 

 tables; but for all the vegetables tested, one or more materials gave good results. 



Celery Dermatitis. Many celery growers are poisoned from handling celery, 

 especially by contact with spoiled celery caused by Erwinia carotovora (Jones) 

 Comm. s.a.b. The relationship of other spoilage organisms is being investigated. 

 A clinic was conducted by Dr. Francis M. Rackemann of Boston and his staff, 

 in cooperation with the plant pathologist, which was attended by several celery 

 growers. Studies are in progress in cooperation with Dr. Rackemann to learn 

 the answers to various aspects of the problem. 



Resistance to Potato Late Blight. Potato seedlings resistant to late blight, 

 originated by Dr. F. J. Stevenson of the U. S. Department of Agriculture, were 

 compared with standard susceptible varieties. Mohawk and Green Mountain 

 vines were completely destroyed before September L The vine growth of all 

 seedlings remained free of late blight up to October 2, when the tubers were dug. 

 Seedlings B 69-16, B 70-5, and B 61-3 showed a trace of late blight tuber rot, 

 and tuber infection was severe with seedling B 76-43. Seedling B 69-16 performed 

 the best of the entire lot in every respect. 



DEPARTMENT OF CHEMISTRY 

 Walter S. Ritchie in Charge 



Factors Affecting the Vitamin Content of Milk and Milk Products. (Arthur 

 D. Holmes.) During the past year three studies conducted under this project 

 have been completed. All the products studied were produced locally, the ice 

 cream and mare's milk being produced at the University. The various samples 

 of goat's milk were obtained from prominent goat dairies located at widely 

 scattered points in the State. 



