SHUCK PROTECTIOlsr FOR EAR CORN". 



9 



The ears examined were of three classes. The first class had shucks 

 extending from 4 to 6 inches and the second class from 2 to 3 inches 

 beyond the tips of the ears ; the third class had practically no shucks 

 extending beyond the tips of the ears. The relation of shuck cover- 

 ing to infestation as it was found in these classes is shown in Table V. 



Table V. — Relation of the shuck covering of corn to insect infestation in 1916. 



> 



Number 

 of ears 

 exam- 

 ined. 



Percentage of ears- 



Kind of shuck covering. 



Attacked 



by 

 worms. 



Infested 



with 

 weevils. 



Affected 

 with 

 worm 

 mold. 



Extending 4 to 6 inches beyond tips of ears. . . . 



in 



■ 102 

 100 



72 

 87 

 96 



9 



22 

 100 



64 





77 





91 







[ 



Of the 111 ears with shucks extending from 4 to 6 inches beyond 

 the tips of the ears, 72 per cent had been attacked by worms, 9 per 

 cent had been infested by weevils, and 64 per cent had been affected 

 with worm mold. Of the 102 ears with shucks extending from 2 to 3 

 inches beyond the tips of the ears, 87 per cent had been attacked by 

 worms, 22 per cent had been infested with weevils, and 77 per cent 

 had been affected with worm mold. Of the 100 ears with practically 

 no shuck extension beyond the tips of the ears, 96 per cent had been 

 attacked by worms, 100 per cent Tiad been infested by weevils, and 

 91 per cent had been affected with worm mold. 



In the case of worms, 15 per cent fewer ears were attacked in the 

 4 to 6 inch extension shucks than in those havmg 2 to 3 inch exten- 

 sions, and 24 per cent fewer than where there was practically no exten- 

 sion. There were 13 per cent fewer ears infested with weevils in the 

 4 to 6 inch than in the 2 to 3 inch extension shucks and 91 per cent 

 fewer than in the shucks having practically no extension, while 13 per 

 cent fewer ears were affected with worm mold in the 4 to 6 inch ex- 

 tension shucks than in the 2 to 3 inch extension shucks, and 27 per 

 cent fewer than in those having practically no extension. 



These figures make it clear that length of shuck extension is a 

 controlling factor in the matter of ear damage. In addition, the 

 relationship between the length of shuck extension and the percentage 

 of ears attacked by worms is of special interest because, in connection 

 with the following evidence, it suggests a possible means of over- 

 coming the most serious obstacle in the way of making a perfectly 

 effective shuck protection for practically all of the ears. 



SHUCK EXTENSION AS A PREVENTIVE OF WORM DAMAGE. 



The foregoing discussion has made it clear that earworms may be 

 responsible (directly and indirectly) for much damage to corn. The 

 fact that earworms can and sometimes do cut holes through a 



