TOBACCO INVESTIGATIONS. 33 



Organic matter, of course, can be economically applied to the soil in the 

 form of a cover crop, as has already been mentioned, or as manure. This 

 latter method is the more costly if all manure has to be bought, but some 

 manure should be applied from time to time to get the best development 

 of tobacco, apparently, although it is true that many growers are at 

 present using commercial fertilizers and cover crops alone with good 

 success. 



The increased growth on acid phosphate in conjunction with applications 

 of organic matter is conspicuous and rather difficult of explanation, aside 

 from the points brought out in the discussion of the question of soil 

 reaction. The tobacco jjlant uses very little of the available phosphoric 

 acid of the soil, and certainly for direct fertilization effect, or as a food 

 material, the plant needs only a small amount of the phosphoric acid 

 available. It might be well to caution against the use of very large 

 amounts of acid phosphate on our heavier soils year after year, as there 

 is a tendency for this material to darken the leaf, and also, on account of 

 the sulfate or sulfuric acid contained in it, to injure the burn. In our 

 experiments, however, this has not occurred as yet. 



Miscellaneous Observations. 



Other Root-rots. 



While making an examination of the roots of plants from a field which 

 had presented an unthrifty appearance all season (1916), but on which very 

 little root-rot (Thielavia) could be found, it was observed that certain of 

 the plants showed a peculiar discoloration of the root stock just below the 

 surface of the ground. The only organism isolated was a species of Acti- 

 nomyces, which was characterized by Dr. P. J. Anderson of this depart- 

 ment as differing, apparently, from the ordinary forms found in our soils. 

 No connection has been established as yet between the presence of this 

 fungus in soils and its relation to the tobacco plant. No infection experi- 

 ments have been made, but a study of this organism, if found again, is 

 projected. Forms of Fusarium were also isolated from this and other 

 material, but their role is problematic. 



"Mammoth" Types of Cuban and Connecticut Havana Tobacco. 



From time to time there have appeared in the fields of Connecticut so- 

 called "mammoth" plants of Cuban and Connecticut Havana tobacco. 

 Beinhart and Hayes first experimented with the mammoth Cuban type 

 found in Connecticut on the plantation of the Windsor Tobacco Corpora- 

 tion by its manager, Mr. J. B. Stewart, from whom the type takes its 

 name, "Stewart Cuban." This mammoth type was first grown com- 

 mercially in 1914, and was found to cure in a very satisfactory manner. 



At present the Stewart Cuban, or a very similar mutant, is being growTi 

 not only in Connecticut, but in Massachusetts as well to a limited extent. 



