296 Proceedings of Inc ,na Academy of Science 



of cultivated sorghum and the consequent spread of the sorghum midge, 

 wild corn almost disappeared throughout its range, due to the ravages 

 of the insect. The existence of the plant in large areas along the Ohio 

 river in Kentucky was unsuspected until announced by the writer a year 

 ago." The occurrence of wild corn as a serious weed problem along the 

 Ohio and Wabash rivers in Indiana is an important economic problem. 

 That the species is persisting is probably explained by the fact that 

 Indiana is so far north as to be out of the range of the sorghum midge. 

 Although a native of a warmer climate, the plant seems to be thoroughly 

 acclimated in its northern home. 



Controlling wild corn is far from an easy job. In Posey County 

 the only successful control method practiced is thorough cultivation, in- 

 cluding regular hoeing as soon as the weed is large enough to be rec- 

 ognized. One difficulty is that chance seedlings spring up throughout the 

 growing season in spite of the most diligent hoeing. Some farmers 

 reduce the damage considerably by delaying planting in the spring until 

 after most of the wild corn seeds have sprouted. The young plants are 

 then destroyed by plowing and preparing the seed bed for corn. There 

 seems little hope for controlling the weed by crop rotation since corn is 

 practically the only crop the farmers will grow on the overflow land. 



A solution that suggests itself is the introduction and acclimatiza- 

 tion of the sorghum midge. If this could be done, the wild corn would 

 probably soon disappear since the midge prevents the production of 

 viable seeds and wild corn is an annual plant, depending entirely upon 

 seeds to reproduce. The introduction and acclimatization of the sor- 

 ghum midge is a dangerous experiment, however, since the insect might 

 attack the sorghum crop, which is worth about $1,000,000 annually in 

 Indiana. 



Surface cultivation in the fall in order to induce the germination 

 of the seeds of wild corn seems to offer little hope as a remedy since 

 most of the infested land is subject to overflow during late spring and 

 early fall, and seeds are scattered over the fields during each overflow. 



Since wild corn is an annual, it is possible that if all the plants 

 were kept from seeding throughout a single season, the pest would dis- 

 appear, providing none of the seeds remained viable in the soil during 

 the second winter. Large scale co-operation of this type among fai-mers 

 is theoretically possible but pi-actically almost impossible. Until further 

 knowledge is secured, late planting and thorough cultivation will have 

 to be depended on as the best control measures available. 



In addition to the economic phase of the subject, wild corn presents 

 a problem of considerable interest to the plant ecologist. 



-Chicken Corn, an Unusual Weed, Found Growinr^ in River Lowlands in Kentucky. 

 Weekly News Letter. U.S.D.A. June 29, 1921. 



