2OO 



BACTERIA IN RELATION TO PLANT DISEASES. 



98 per cent germinations and exposure for 5 minutes in water at 140 F. (60 C.) or below 

 may be recommended as not injurious to wheat. 



Barley dipped for 30 minutes in copper sulphate water (i pound to 4 gallons) gave 86 

 per cent of weak germinations; and when exposed for i hour, 47 per cent. 



Wheat exposed to potassium sulphide (i ounce to i gallon for 75 minutes gave 100 per 

 cent germinations. Barley treated in the same way for 75 minutes gave 90 per cent germi- 

 nations. Oats treated in same way gave 96 per cent germinations; but exposed for 19 

 hours gave 42 per cent weak germinations. 



According to Cranefield (1901), formalin used as weak as 2.5: 1,000 (i pound [pint] to 

 50 gallons of water) for 20 minutes may injure oats used for seed. The experiments cover 

 20 varieties of oats and the germination of over 25,000 seeds. The amount of injury varied 

 greatly in different varieties, and was more noticeable in planted seeds than in those used in 

 the germinating chamber. 



Longer exposures than 20 minutes at the standard strength (i pint to 50 gallons) did 

 not much increase the injury. The early growth from the treated seed was retarded and at 

 no time did the treated quite equal the untreated in height. 



When more concentrated solutions of formalin were used the injury was progressively 

 greater, e.g., i pint to 50 gallons of water, 91 per cent germination (check 94.5) ; i pint to 

 25 gallons of water, 74 per cent; i pint to 20 gallons, 73 per cent; i pint to 10 gallons, 31 

 per cent; i pint to 5 gallons, 12 per cent. 



In 1901, Windisch published many experiments on lupins, peas, horse beans, soy 

 beans, corn, flax, rape, lucern, and clover, showing the effect of formaldehyde on germina- 

 tion. Each of these was in duplicate. The following are some of his conclusions : 



Per cent of Germinations. 



No injurious action was observed on lupins, peas, horse beans, soy beans or maize, 

 when the 0.02 per cent formaldehyde solution was used. 



Hiltner, in some root-nodule experiments, exposed soy bean seeds for 3 minutes and 

 for 10 minutes to i :ioo mercuric chloride water, then carefully washed it away and planted. 

 The plants came tip badly, but this was not ascribed to the germicide. 



According to Dr. Windisch, winter wheat endured a soaking for 24 hours in 0.02 per 

 cent formaldehyde, and in 0.04 per cent without lessening the power of germination. It 

 also endured 0.08 per cent formaldehyde for 24 hours and gave a germination of 88.5 per 

 cent at the end of 14 days. Exposure to 0.12, however, gave only 9.25 per cent germination 

 at the end of 14 days, and exposure to 2 per cent gave o per cent germination at the end of 

 14 days. Even the diluted solutions delayed the germination somewhat. 



F. ~L,. Stevens (1909) reports that treatment of oats with a solution of i ounce formalin 

 to 0.5 gallon of water reduced germination to 37 per cent, while a solution of i ounce to i 

 gallon of water for 24 hours gave a germination of 73 per cent to 96 per cent, according to 



