22 MASS. EXPERIMENT STATION BULLETIN 417 



This preliminary work indicates that frenching of tobacco leaves inoculated 

 with a mosaic virus may be induced by a high soil temperature; or else there was 

 associated with the mosaic virus a frenching virus, the effects of which are ap- 

 parent only at soil temperatures of 90° and above. 



Soil temperature had a marked effect on the development of uninoculated 

 tobacco plants. Growth was slow at temperatures below 65°, and increasingly 

 rapid at the higher temperatures. The uninoculated plants showed no evidence 

 of frenching at any of the temperatures. 



Effect of Soil Temperature on Certain Forage Grasses. (L. H. Jones.) Seed- 

 lings of brome grass {Bronius inermis Leyss.), meadow fescue {Festuca elalior L.), 

 perennial rye grass {Lolium perenne L.), and timothy {Phleum pratense L.) were 

 established at a soil temperature of 65° P., which after 18 days was altered to 

 produce a range of temperatures from 50° to 90° at 10-degree intervals. Fescue, 

 rye, and timothy, according to values of growth and dry matter produced, had 

 an optimum soil temperature of 70°; brome grass did best at 90° and poorest at 

 50°; rye and timothy did well at 50° and poorly at 90°; and fescue did well through 

 the whole range of temperatures employed. 



Creosote Injury to Plants. (L. H. Jones.) Wherever creosote fumes are evolved 

 in confined spaces, such as cold frames, there is certain to be serious injury to 

 plants. Creosoted lumber covered with soil has not been harmful to seed ger- 

 mination or the growing plant in any of the experiments. However, when the 

 creosoted wood was above the soil line and consequently above leaves, as in a 

 seeded flat, injury occurred, appearing first as a rolling of the leaves, usually 

 upward and inward. Continuous exposure to the fumes eventually killed the 

 plants. Air temperature and sunlight intensity are probably contributing factors, 

 not only in causing an evolution of creosote fumes, but also in making the plants 

 more susceptible to injury from the fumes. 



Creosoted paper used flat on the soil as a collar for the protection of cabbages 

 against maggots did not produce injury unless there was poor air drainage or 

 failure to remove frost protectors in the presence of sunlight. If the stems are 

 soft when the maggot protectors are applied, it is possible that the plants can be 

 harmed by creosote coming in contact with such tender tissue. 



If creosote fumes are evolved in a sunlighted chamber, types of injury similar 

 to those obtained with illuminating gas result. With tomato plants epinasty, 

 early senility, and abscission were frequent results of exposure to fumes of creo- 

 sote for a limited time. Longer exposures caused immediate leaf death more 

 often to leaves of medium age than to the oldest or youngest leaves. 



Weathering of treated wood may reduce the intensity of the injury, but cabbage 

 plants showed considerable injury from wood known to have been creosoted six 

 years previously. 



Causes and Control of Decay of Squash in Storage. (E. F. Guba, Waltham.) 

 In previous work with gourds, less shrinkage from decay after harvest occurred 

 when the plants were protected with a fungicide during their growing period in 

 the field. This year the effort was applied to Blue Hubbard squash. The control 

 plots gave as good yields of mature squash and as low a percentage of immature 

 infected squash as did the plots dusted or sprayed with fungicides. 



Decay found among the small immature squashes was essentially due to 

 Choanephora cucurbitarum (Bark & Rav.) Thax. brown rot. and Macrospotium 

 cucumennum E. & E. black spot rot. Some bacterial wilt rot, due to Erwinia 

 tracheiphila was evident among the mature squash at harvest. 



