152 BULLETIN 1476, U. S. DEPARTMENT OF AGRICULTURE 
PLOWING AS A MEANS OF CONTROL 
Recent field experiments conducted by the bureau in the Lake 
Erie region have demonstrated the value and necessity of plowing 
under cornstalks and stubble as a means of corn-borer control. The 
effectiveness of plowing depends upon turning under the corn refuse 
and other plant debris so completely that none of it remains upon 
the soil surface. It requires also that the material shall not be 
dragged to the surface by later cultivation. 
Clean plowing is the best practical method of control for applica- 
tion to fields containing high stubble or stalks in case it is im- 
practicable to cut the stalks close to the ground and dispose of them 
by feeding or burning. Existing methods of cutting stalks or break- 
ing them off at the soil surface, raking them into windrows, and 
burning them are less effective than clean plowing alone, except where 
such raking and burning are followed by plowing under the 
remaining debris. 
In the Bono-Reno area of northwestern Ohio during May and 
June, 1926, the number of borers per acre remaining in cornfields 
which had been poled, raked, and burned, or disked for small grain, 
was nearly twice as great as the number remaining in fields where 
cornstalks or stubble had been plowed under. 
In disked corn-stubble fields where small grains were seeded the 
previous fall or in the spring, 89 per cent of the original borers 
remained alive in the corn remnants and other plant debris on the 
soil surface. 
Studies made in five plowed fields of Lucas County, Ohio, revealed 
that on an average 75 per cent of the borers were killed by the 
operation, although no special effort was made to plow under cleanly. 
Two of these fields contained standing stalks and three were in high 
stubble. 
Similar field work at Silver Creek, X. Y., showed an average of 
97 per cent of the borers killed in three fields where standing stalks 
were poled down and then plowed under. In three fields where 
high stubble was plowed under, an average of 78 per cent of the 
borers were killed. 
Less than 10 per cent on an average were killed by winter condi- 
tions, predators, parasites, and disease. 
In the region previously mentioned an average of 59 per cent of 
the borers were killed by poling, raking, and burning the standing- 
stalks in four fields. Many living borers were found in pieces of 
stalks not burned properly, as well as in stalks not broken off during 
the poling process, and in stalks missed by the rake. Fourteen per 
cent of the borer population were left in small pieces of corn husk, 
leaves, etc., which it was not possible to gather with the type of rake 
ordinarily used for such purposes. 
DISKED CORNFIELDS SHOW VERY POOR RESULTS 
In four fields of high stubble where oats were seeded after disking, 
without previous cultivation, only 11 per cent of the borers were 
killed. Therefore, the seeding of small grain on disked corn stubble 
or stalks is a dangerous practice under corn-borer conditions, since 
it leaves so many of the borers alive. The growing grain also pro- 
vides shade and ideal protection from the wind for the borers left in 
such fields during the late spring. 
