IIU Repout of the Botanist of the 



ON THE potato. 



(Solanmn tuberosum.) 



Altliongh a Rhizoctonia^ disease ol potatoes has long been com- 

 ninn in Europe, especially in Germany, where it is known under 

 the names " Grind " and '' Pockenkranheit," there isj so far as 

 we are able to ascertain, no record of the occurrence of Rhizoc- 

 tonia on the potato in America. Yet our observations indicate 

 that potatoes in the United States may- be quite generally in- 

 fested by a species of Rliizoctonia, as the subsequent discussion 

 will demonstrate. 



The occurrence of this fungus upon potatoes was first brought 

 to our attention by Messrs. F. A. Sirrine and F. M. Rolfs, who 

 reported having found it on potato stems collected in the vicin- 

 ity of Jamaica on Long Island, In the latter part of July -the 

 writers visited Long Island and examined several potato fields 

 in the vicinity of Jamaica and Floral Park. A little Rliizoctonia 

 was found on the potato stems in all of the fields examined, but 

 it was impossible to determine whether the plants had suffered 

 any injury from its presence. Unfortunately, the potato tops 

 were nearly all dead at that time, the varieties grown in that 

 locality being almost all early varieties. A few tubers were 

 examined but nothing found. On this visit we also had the 

 opportunity of examining some diseased potato stems collected 

 on Staten Island by Miss Emma Sirrine, and found them infested 

 with Rliizoctonia. A few days later Mr. Rolfs found it at Matti- 

 tuck, Outchogue and East Hampton, in the eastern part of Long 

 Island. Here it occurred on late potatoes, and, in one instance 

 at least, there was good evidence that it had killed a consider- 

 able number of plants. It was also found at Wading River. 

 There has been much complaint about the premature dying of 

 potatoes on Long Island the past season. What part Rliizoctonia 

 played in this trouble is not certainly known, but probably it 

 was not an important one. Later, the Rhizoctpnia was found on 

 potato stems in many fields about Geneva, -Phelps, Lodi and Oaks 

 Corners. 



'Rliizoctonia solani Ktthn. 



