244 THE CEREALS IN AMERICA 



hvndtweed (Convohult4s arvensis "L.), imported, and the hedge bindweed or morning 

 glory (Coftvo/vulus sejitufM (L.) Willd.), native. Both are perennial vines, with ex- 

 tensive underground stems, wliicii n:ake them practically impossible to eradicate. 

 They may be greatly reduced by thorough cultivation. Where they are a serious 

 jjest, it is desirable to cultivate the field two years in maize, in order to reduce theii 

 injury to succeeding grain and grass crops. Good results have been obtained by 

 using sorghum or rye as a smother crop. They do their chief injury by Avinding 

 themselves about the cultivated plants. When a badly infested field is to be 

 planted to maize, it is desirable to delay plowing until the w-eather is favorable for a 

 rapid growth of maize. By this time the bindweeds will have started in the un- 

 plowed land. By plowing and immediately planting, the maize will get well started 

 before the bindweeds have recovered from the plomng. The land should be kept 

 harrowed, so as to prevent, as far as possible, the gro^vth of other weeds, until both 

 maize and bindweeds have a good start. If the bindweeds are now cut off with a 

 hoe, and the land thereafter kept cultivated in the usual manner, no further serious 

 inconvenience will be experienced from the bindweeds. 



319. CocKLEBUR is also a branching annual, belonging to the Aster and Daisy 

 family. It grows from one to two feet high, and is especially distinguished for its 

 large spiny burs, which are so serious an inconvenience by clinging to the bodies of 

 our domestic animals. Each bur contains two seeds, only one of which grows the 

 first year, the other remaining dormant until the second year, unless the plant of the 

 first seed has been destroyed, when, as shown by McCluer, the second seed may ger- 

 minate. The plants usually grow in such limited numbers that those which escape 

 destruction through ordinary methods of cultivation may be pulled by hand. 



320. Spanish Needles, Stick-Tights, Beggar's Ticks. — These are 

 branched annuals belonging to the Aster and Daisy family (Compositae), growng 

 two to four feet high, with browTi, thin, flat seeds, two to four do^vnwardly barbed 

 awns. These weeds do their principal damage by the seeds adhering to animals 

 and clothing. Reasonably careful cultivation will destroy them. 



321. Fungous Diseases. — The more important fungi which 

 attack the growing maize plant are as follows : 



(i) Maize smut {Ustilago zeae (Beckm.) Ung.). 



(2) The bacterial disease of dent maize {Bacillus cloacae Jordan). 



(3) The bacterial or wilt disease of sweet maize {Pseudomonas stewarii). 



(4) Maize rust {Puccitiia sorghi Schw.). 



(5) The leaf blight fungus (Helminthosporium graminum Rab.). 



The maize smut is the only disease that has assumed any 

 widespread economic importance. 



322. Maize Smut differs from the smut of the other cereals in its mode and 

 source of infection, making its appearance upon any partot the plant above grouna; 

 although the ears and tassels are the portions chiefly infected. Formerly it was 

 thought that inf«ctiau was largely by means of smutty seeds. It is now pretty well 



