to present the data on the experiments of 1924 (Table IX, p. 29) and the conclu- 

 sions from the results of the two years' experiments. 



"In all tests during the last two years, kahmat has controlled onion smut just as 

 weU as formaldehyde. It is superior to formaldehyde, however, not on account of 

 its fungicidal properties but on account of its comparative safety when used in con- 

 centrated solutions or when used in very dry soils. Under these same conditions 

 formaldehyde frequently causes serious injury. 



"The claim of the manufacturers that the percentage of germination is increased 

 S+u^ ^T ^^^P^*^ ^"^^Id seem at first to have some support in the data presented. 

 Ot the 14 comparisons between treated and check rows, 10 show that there were more 

 seedhngs on the treated than on the untreated rows. This does not necessarily 

 mean, however, that kaUmat stimulated germination of the seeds; it may have 

 merely killed off some organisms which naturally destroy the seedhngs before they 

 reach the surface of the soil. 



'"^^^u^^^ u°^^®^*^°^ *° ^^® ^^^ °^ kahmat is that it is rather expensive at present. 

 It may be obtained for about SI. 00 per pint. In larger quantities, however, it 

 k m'k^ J -^ ^^ obtained at a lower price. If any considerable demand for it 

 should be developed, the cost of production wiU be lowered or other substances em- 

 bodying the same protective principle will appear on the market. 



Of the formulas tried, probably the 1-50-4000 could be recommended as giving 

 excellent control and as being economical of labor and material. This would require 

 about five quarts of kahmat per acre of onions when the rows are thirteen inches 

 apart. In extremely dry soil the same amount applied in greater dilution might 

 have some advantage." 



Uspulun. This is a patented German chemical preparation marketed in the 

 form of a purphsh gray powder, readily soluble in water to form a purple solution. 

 The active fungicidal principle is orthochlorphenol. In prehminary greenhouse 

 experiments 1 per cent, and 2 per cent, were tried in the formulas 1-50-3000, 1-50- 

 4000, 1-50-5000, 1-100-3000, 1-100-4000 and 1-100-5000. Fair control was 

 secured with all formulas but the best with 1-100-3000. In the field experiments 

 of 1924 the formulas of 1-50-3000 and 1-100-3000 were each used on one row 70 

 feet long. The percentage of control was just as high as that secured by kahmat or 

 formaldehyde. There was no e\adence of seed injury or stunting and the percentage 

 of germination was higher than on the check rows. The results were sufficiently 

 promising to warrant the further testing of this substance. The results will be 

 described more in detail after further tests under different conditions. 



Germisan. Tliis is also a German patented disinfectant marketed in the form 

 of a powder but to be used in solution. It has been tried only in our field experi- 

 ments of 1924 and in the formulas 1-50-3000, 1-50-4000 and 1-50-5000. All form- 

 ulas gave increased germination and good control of smut. The weakest formula 

 gave just as good control as the others. These results look promising, but we hesi- 

 tate to make any recommendations until the material has been tried under other 

 conditions. 



The other chemical solutions tried gave a percentage of control much lower than 

 formaldehyde. 



Dry Chemicals. If some effective and comparatively cheap substance could be 

 found wliich could be applied as a dry powder it would present certain advantages 

 over solutions: (1) it would ehminate the labor of drawing barrels of water to the 

 field, (2) it would make the drill easier to push because of ehmination of the weight 

 of the water, (3) it would ehminate the danger of clogging the seed spout and pack- 

 ing wheel with mud, and (4) machinery for apphcation would probably be simpler 

 and cheaper. 



A number of these dry preparations have been tried by the writers but only one 

 up to the present has given a high enough percentage of control to encourage further 

 trials. This is a powder prepared especially for tliis kind of work by the Corona 

 Chemical Division of the Pittsburgh Plate Glass Company and furnished to the 

 writers under the label "Corona 640." In the preliminary greenhouse tests, this 

 gave better control than any of the others and was, therefore, selected for the field 

 tests of 1924. This was in badly infested soil but at the end of the season the row 

 to which this material was apphed contained as many healthy onions as any of the 

 rows treated with the other preparations. There was also an increase in the number 



24 



