WILT-DISBASES OF TOBACCO. 



255 



tests in 1911," the number of examples were somewhat increased. Here are added some observa- 

 tions of 1912, made on tobacco seedlings received from 1 1 sources and set on the trial grounds. The 

 conditions of the experiment and the results are given in table 34, omitting only the dates of planting 

 (February 14 to March 30). 



TABLE 34. Effect of Occurrence of Disease in Seed-bed on Planted-out Tobacco. 



The plats i ib and 86 are perhaps the most interesting. Naturally, sources of error were not 

 wholly excluded. The factors which may have influenced the result are: 



(a) The soil was not wholly free from the slime-disease, 

 (fr) The persistent drought. 



(c) A toa-toh plague, especially for I to 9; the latter had toa-toh in the seedlings. 



(d) The fact that the seedlings from all sorts of ground, loose red earth to low white clay, were planted out on the 



same piece of clay ground. 



(e) The small number of plants. 



All things taken together, it is plain that the dying in the field tobacco was more prevalent 

 according as more sick seedlings occurred in the seed-beds. 



(8) ON THE ASSERTED NON-SUSCEPTIBILITY OF NICOTIANA RUSTICA FOR THE SLIME-DISEASE. 



Two ways stand open for him who would obtain a race of resistant Deli tobacco : The first looks 

 to the discovery of fine sound specimens on slime-sick soil ; the second to the crossing with less sus- 

 ceptible or wholly resistant varieties of tobacco. Upon the first method more later. 



In order to cross the Deli tobacco with immune sorts we must first have these, and if obtained, it 

 remains to be seen whether the desired peculiarity is transmitted in full measure to the descendants 

 and is constant in the cross. If this should fall out according to wish, then comes the question 

 whether the type obtained is of a sort that the planters will try, or whether it must be further im- 

 proved, retaining at the same time the desired resistance. 



Tests were also made on a number of ornamental tobaccos, seed of which was received from 

 Haarlem, viz., Xicotiana affinis, .V. atropurpurea grandiflora, N. colossea, N. glauca, N. sanderae (in 6 

 colored varieties), and .V. silvestris. Both the Djatti and the tobacco strains were tried and all of the 

 inoculated plants became diseased. Nicotiana latissima is also subject. 



The finer sorts of foreign tobacco of the species N. tabacum, so far as tested in Deli, are badly 

 attacked by the slime-sickness, so that the chance of obtaining a reistant variety from these seems 

 not better than from Deli tobacco. 



Of the coarser sorts it has been announced in literature (Uyeda) that one, namely, the Boer 

 tobacco (A f . rustica), is non-susceptible to the slime-disease. There were obtained, therefore, from 

 the Agricultural Institute at Pusa in India, where this tobacco is commonly cultivated, seeds of 

 different varieties to the number of 20, which varieties were tested by inoculation, only one of 200 

 plants remaining sound. The details are given in table 35. 



