191 



Sooty Blotch or Fly Speck (Phyllachora pomigena 

 (Scnw.) Sagc). 



A fungous growth known as sooty blotch or fly speck has 

 been common for many years, occurring on the surface of 

 apples. With us it aifects Greenings more commonly, some- 

 times discoloring the fruit to quite an extent. It was for- 

 merly believed that there were two species of fungi, — one 

 causing the blotch, the other fly speck, — but it is now gen- 

 erally recognized that one species of fungus causes both. 

 Both of these forms occur on the surface of the fruit and 

 do not penetrate the cuticle, and they can easily be removed 

 by washing. 



Sooty blotch forms large, irregular, olive-brown areas on 

 the fruit, while fly speck occurs as minute dark-colored dots 

 scattered over the surface. The trouble appears to be more 

 abundant in the shade and where there is considerable mois- 

 ture. The fungus does not injure the fruit other than to 

 affect its market value, and it can usually be controlled by 

 spraying late in the season with Bordeaux mixture. 



Apple Blight^ Fire Blight^ Twig Bligilt^ etc. (Bacil- 

 lus amylovorijs (Burr.) DeToni.). 

 This blight has been common for many years on apples, 

 pears and quinces, and is often severe in some parts of the 

 United States. It is caused by a minute organism (bacil- 

 lus), and it is generally recognized that infection takes place 

 at the period of pollination. The blight is characterized by a 

 blackening and shriveling of parts of the twigs or branches, 

 and the leaves droop and turn bro^vn, but do not fall. The 

 organisms under certain conditions multiply very rapidly in 

 the nectaries of the flower, and are readily transferred to 

 other flowers by bees. From the nectaries the bacteria gain 

 entrance to the tissues of the small branches, causing them 

 to collapse. In most cases direct infection probably occurs 

 by means of insects, abrasions, etc. The blight organism 

 also occasionally causes what is termed blight canker. The 



