SWEET PEA DISEASES AND THEIK CONTROL 139 



Of still greater importance in the control of the sweet pea aphis 

 is a little fly scientifically known as Aphidius testaceipes. The 

 adult female of this fly possesses a long sharp-pointed ovipositor 

 which is used to pierce the body wall of the louse and of depositing 

 its eggs within the aphis. The egg upon hatching in the body of 

 its host, gives birth to a small legless larva which begins at once to 

 feed upon the interior organs of the louse, the latter of which soon 

 dies and remains attached to the part of the plant upon which it 

 was feeding. After a time, the larva pupates and then cuts out a 

 circular hole on the top of the mummied body of the aphis, emerg- 

 ing as a winged fly. The two sexes mate, and the female is again 

 ready to deposit her eggs in the bodies of other living lice. 



Besides the lady beetles and Aphidius flies, there is also a fungus, 

 Empusa aphidis, which parasitizes the sweet pea louse. It may 

 be possible to cultivate the fungus and use it to inoculate broadcast 

 the aphids. 



The sweet pea aphis is not only a pest by itself in that it sucks 

 the plant juices, but it also acts as a carrier and transmitter of the 

 pathogen which causes mosaic. The sweet pea aphis is not only 

 an outdoor pest but it often causes great damage to greenhouse peas. 

 If we are to succeed at all in controlling many of the diseases 

 previously mentioned, it is essential that we keep in check the 

 sweet pea aphis. 



Anthracnose, Glomerella rufomaculans (B.) V. Sch. and Sp. 



The symptoms of a disease known as Anthracnose are diverse. 

 Sometimes it is manifested in a wilting or dying of the tips, which 

 become whitish and brittle and readily break ofl^. At other times 

 the dying works downwards and involves the entire branch. Fre- 

 quently also, such infected leaves become brittle and soon drop. 

 Examination of an infected leaf with a hand lens shows that it is 

 peppered with minute salmon-colored pustules. At the time of 

 blossoming the fungus makes its attack on the peduncle at the point 

 of union with the buds, in this case, producing bud-drop, the bud 

 hangs wiltingly from the peduncle, or the fungus attacks both the 

 flower bud and the peduncle, in which case both dry up but do not 



