9 



fnngiis used and to the natural resistance of the plants. The cotton 

 plant inoculations described in Bulletin 17 were all made in the green- 

 house and it is now believed that the negative results were due either 

 to the slow growth of the plants or to the fact that they were natu- 

 rally resistant. 



THE FAILURE OF SOIL FUNGICIDES. 



Careful experiments have been made with a large number of sub- 

 stances applied to the soil in the hope of killing the fungus, but all 

 the results obtained up to the present time indicate that there is no 

 hope of success from the use of any fungicides sprayed on the plants 

 or applied to the soil. 



Fields uniformly infected with the wilt disease were selected, and 

 over twenty different substances were applied in amounts as large as 

 it was thought safe to use. In many cases the expense of their appli- 

 cation in such quantities was so great as to make their use impracti- 

 cable had they proved efficacious. In other cases, as in the use of 

 materials containing copper, continued applications in such large 

 quantities would be likely to injure the soil. 



The following were among the fungicides tried, nearly all of which 

 were tested in duplicate or triplicate (in different localities): 



1. Bordeaux viixture, 1,200 gallons per acre, applied to the soil ten days before 

 planting. 



3. Bordeaux mixture, 1,300 gallons per acrje, applied to the soil before planting 

 as above, and also sprayed on the plants and soil at intervals during the summer. 



3. Bordeaux mixture, 1,300 gallons per acre, with the addition of a small quan- 

 tity of molasses to increase the solubility of the copper. 



4. Bordeax mixture and.sulpliiir, i>reY)ared by adding to each barrel of a mix- 

 ture containing the ordinary amounts of copper sulphate and lime 6 pounds of 

 sulphur and (i pounds of lime that had been boiled together one hour. This was 

 mixed with the soil in the row ten days before planting. 



5. Bordeaux mixture, 3,600 gallons per acre. This is equivalent to 546 pounds 

 of copper sulphate per acre, but the cotton grew well here until attacked by the 

 wilt disease. To all appearances neither the cotton nor the wilt fungus was 

 affet^teil by this very heavy application, which was on a rather small plot (3.")0 

 square feet). 



6. Copper carbonate, applied in solution to the soil just before planting, at the 

 rate of 136 pounds per acre. 



7. Copper acctatf, applied in solution to the soil just before planting, at the 

 rate of 102 pounds per acre. 



8. Lime (fresh stone lime) was applied to infected land in September. 1899, at 

 the rate of 3, 4, 5, and tons per acre. The lime was harrowed in as soon as it 

 had become slacked. An equal area was left untrea ed, and cotton was planted 

 in the usual way in 1900. Lime was also applied to other infected fields in the 

 spring, shortly before planting, at the rate of 3.000 and 4.00:) pounds per acre. 



9. Sulj>linr (flowers of sulphur) was applied to the soil before planting, at the 

 rate of 400 and 600 pounds per acre, 



10. Lime-sulphur mixture, consisting of 30 pounds of lime, 30 pounds of sul- 

 l)hur. and 00 gallons of watrr. The lime was slackcnT and boiled with the sulphur 

 one hour. It was applied at the rate of 6i)0 and 9it0 gallons per acre. 



