New York Agricultural Experiment Station. 25 



effect July 1, 1912, provides that agricultural seed containing more 

 than three per ct. of foul or foreign seeds shall not be offered for 

 sale in the State unless the percentage of impurity be plainly marked 

 on the container. Of the 124 samples examined officially under this 

 law, 19 contained more than the permissible three per ct. of foreign 

 seeds. During the year analyses were made, also, of 1,140 seed 

 samples sent in by farmers and others. 



Persistence of potato late-blight. — Experiments reported in Bulletin 

 No. 367 seem to show that the potato late-blight fungus is unable 

 to over- winter in the soil. Hence, so far as late blight is concerned 

 there is no risk in planting potatoes where potatoes blighted or 

 rotted the previous season. However, there are other kinds of 

 potato blight (also scab) which do persist in the soil and rotation 

 of crops is helpful in controlling these. 



Disinfection of seed potatoes. — It has been discovered that, in the 

 disinfection of seed potatoes by means of formaldehyde gas as 

 heretofore recommended, the tubers are liable to injury unless the 

 quantity of potatoes treated equals ten pounds or more per cubic 

 foot of space in the disinfection chamber. The property of ad- 

 sorption is responsible for this. The injury takes the form of sunken 

 brown spots. Liability to injury is increased by sprouting of the 

 tubers and by raising the relative humidity of the air. 



Further, it has been found that Rhizoctonia sclerotia on potato 

 tubers are not all killed by the standard treatment with formaldehyde 

 gas or formaldehyde solution recommended for scab. The formal- 

 dehyde is unable to penetrate to the center of the larger and more 

 compact sclerotia. Corrosive sublimate, on the contrary, is highly 

 efficient in destroying Rhizoctonia. 



Accordingly, it is recommended that when it is desired to treat 

 seed potatoes for Rhizoctonia the corrosive sublimate treatment 

 should be employed. Also, the formaldehyde gas treatment should 

 be used only in those cases in which it is impracticable to use one or 

 the other of the standard liquid treatments. Details of this investi- 

 gation are given in Bulletins Nos. 369 and 370. 



CHEMICAL DEPARTMENT. 



Under the head of " Inspection Work," mention has been made 

 of the analyses, performed by this department, of fertilizers, feeding 



