IV. POTATO DISEASES ON LONG ISLAND IN THE 

 SEASON OF 1895.* 



Summary. 



(1). The most serious disease affecting potatoes on Long Island 

 are the early blight and late blight. These two diseases cause 

 considerable loss which could be prevented by spraying with 

 Bordeaux mixture. In an experiment at Floral Park five applica- 

 tions increased the yield 62 bushels per acre and three applica- 

 tions, 52 bushels per acre. Had late blight appeared the benefit 

 from spraying would have been still greater. 



(2), Paris green can be applied with Bordeaux mixture and is 

 then more effective than when applied alone, either dry or in 

 water. Plants sprayed with Bordeaux mixture and Paris green 

 were less injured by flea-beetles and Colorado potato-beetles than 

 were plants treated with Paris green only. 



(3). The expense of spraying is small as compared with the 

 increased value of the crop. With suitable apparatus it need not 

 be more than about |1.00 per acre for each application. 



(4), Beginning when the plants are from 6 to 8 inches high 

 spray thoroughly at intervals of about two weeks until five or 

 six applications have been made. 



(5). The internal browning of potatoes was observed on Long 

 Island in 1894. The cause of this trouble is not known. An ex- 

 periment made at Cutchogue shows that potatoes so affected are 

 considerably injured for seed purposes although the disease is 

 not transmitted from seed to crop. 



(6). A new stem-blight of potatoes has been observed on Long 

 Island and in Dutchess county. Some fungus destroys the stem 

 near the surface of the soil. It promises to become troublesome. 



(7). " Pimply " potatoes are caused by some insect which punc- 



♦jPublislied also as Bnlletin No. 101. 



