14 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 



11 days before sowing, with the beds tightly covered during the 

 interim, appears to have been entirely harmless and very effective 

 against the disease. Burns found the sulphuric-acid treatment used 

 by the writers at Halsey, three-sixteenths ounce per square foot 

 applied at time of sowing, as effective as the formaldehyde and non- 

 injurious. Spaulding, 1 reporting tests made in 1907 and 1908, also 

 obtained excellent results with acid, which was not tested by Jones 

 and Gifford. He in addition obtained good results in preliminary 

 tests with copper sulphate and with sulphur. 



Acid was also used at an unnamed locality by Gussow, 2 with 

 excellent results. 



Charcoal, an amendment rather than a disinfectant, is reported by 

 Retan 3 to be of value against damping-off. in the clay soil at Mont 

 Alto, Pa. 3 and to result in the increased size of pine seedlings. A layer 

 3 inches deep was spaded into the soil. Annual treatment with this 

 amount would, of course, be impracticable. However, Retan states 

 that the effect of such charcoal addition is permanent. Further 

 experience seems necessary to confirm the permanent value of char- 

 coal for preventing damping-off on this and other soils. A single test 

 by the writers of a lighter application of charcoal at the Cass Lake 

 nursery proved unsuccessful. 



SOIL-DISINFECTION TESTS SUMMARIZED. 



The writers' experience with soil disinfectants at the different 

 nurseries, as well as the experience of other experimenters, has been 

 so varied that it is rather difficult to correlate the results. Correlation 

 will be made easier by reference to Table III, in which are summed 

 up all of the successful tests of treatments of coniferous seed beds of 

 which the writers have been able to learn. In the tests at Halsey, the 

 Kansas sand hills, Garden City, Lincoln, Cass Lake, Dundee, Glen- 

 view, and East Tawas, the experimental treatments were applied by 

 the writers or their assistants, with the cooperation of those in 

 charge of the nurseries. At Fort Bayard the tests were conducted by 

 Mr. H. C. Turner, at Monument by Mr. W. H. Schrader, at Porvenir 

 by Mr. H. D. Burrall, at Pocatello by Mr. Arthur P. Say, in Vilas 

 County, Wis., by Mr. W. D. Barnard, at Providence by Prof. H. H. 

 York, at Morrisville under the direction of Mr. John Foley^and at 

 Haugan by forest officers, following recommenda-ions made by the 

 writers. 



i Spaulding, Perley, 1914. Op. cit. 



2 Gussow, H. T. Diseases of forest trees. In Com. Conserv. Canada, Kpt. 1st Ann. Meeting, 1910, p. 

 136-137. 1910. 



3 Retan, G. A. Charcoal as a means of solving some nursery problems. In Forestry Quart., v. 13, no. 1, 

 p. 25-30. 1915. 



