44 Journal of Agricultural Research voi. xvii, no. » 



This observation may be repeatedly noted in infested soils, and it was 

 with the idea of explaining this condition particularly that the investi- 

 gation on the influence of environmental conditions upon the disease was 

 begun in 191 4. 



Sorauer (25) in 1895 made some observations upon the rootrot on 

 cyclamens, and concluded that heavy manuring, too abundant watering, 

 and too high temperatures favored the attack by the parasite. 



Peglion (20), who first reported the disease on tobacco in 1897, also 

 believed that too much manure and water were controlling factors in 

 producing the disease. 



Campbell (5) believes excessive quantity of humus in the soil predis- 

 poses the tobacco plant to disease, and also that an acid condition of the 

 soil weakens the plant and predisposes it to disease. 



Buttaro (4), probably following the lead of other European authors, 

 also writes that the disease on tobacco is favored by abundant organic 

 matter, excessive humidity, and high temperatures. 



Benincasa (/) concludes that in some years the disease appears only 

 slightly or not at all, and states that its development is favored by too 

 much organic matter, excessive v/atering, and generally damp weather. 

 Benincasa, at about this time, began to study the relation of moisture 

 and different kinds of soils to the development of the disease. He con- 

 cluded at this time that porous soils give the best results and in 1911 

 he discussed the subject in more detail. 



Cappelluti-Altomare (6) concluded that the disease could be checked 

 by limiting the amount of watering and by not reducing too greatly the 

 light and air supply of the seed beds. He also advises against sowing 

 the seed too thickly. 



Galloway (11, pp. 174-178) reporting on the wilt of violets, caused by 

 T. hasicola, advises against the use of decaying vegetable matter in the 

 propagating beds. His statement that — 



plants affected may make a good growth in summer and show no evidence of trouble 

 until September or October, when they will wilt more or less during the day and 

 revive at night. 



is especially pertinent to the investigations in this paper. 



Clinton and Jenkins (9) suggest that excessive fertilization, soil reac- 

 tion, and soil moisture, the latter in particular, may be important sec- 

 ondary factors determining the extent of the injury by T. hasicola. 

 They also state that the cold, wet weather of early spring helps along 

 the trouble in the seed beds, particularly when they are not properly 

 ventilated. 



Clinton {8) is quite convinced that the character of the season, 

 especially the moisture and possibly unusually cold wet spring weather, 

 and the character of the soil and subsoil — fineness, liability to become 

 water-soaked, drainage, amount of humus, especially in the shape of 

 manure — have much to do with determining whether or not the fungus 



