Washington, D. C. September 13, 1923 
FURTHER STUDIES WITH PARADICHLOROBENZENE FOR PEACH BORER 
CONTROL 
WITH SPECIAL REFERENCE TO ITS USE ON YOUNG PEACH TREES. 
By Outver I. Snapp, Entomologist, and CuarLtes H. ALDEN, Scientific Assistant, 
Fruit Insect Investigations, Bureau of Entomology. 
CONTENTS. 
Page. Page. 
Introduction. ......--)------2--+0----2+-022-- 1 | Laboratory experiments—Continued. 
| Experimental results in the field...........-.- 2 Mortality of peach-borer larvee exposed 
| Efiect of paradichlorobenzene on the trees... 6 to paradichlorobenzene....... Bats}. 14 
| Results from winter and spring treatments. . 10 Effect of temperature and moisture on 
Correct method of applying paradichloro- the effectiveness of paradichloroben- 
OTRO Ce spt dope < crerera' aya) <1 Aa aint Bim ae o's 4 12 DONC Y Feces ho a ctoptd ee ps pane ete aoe 15 
Laboratory experimenits....................- FS | UML on onc alon aa canlnae sets oem Acae eee 18 
Rate of evaporation of paradichloro- 
DEHZERDCLYSUQIS: «0225 oc no. sai weet asese 
INTRODUCTION. 
The use of paradichlorobenzene for the control of the peach borer 
(Aegeria exitiosa Say) on trees 6 years of age and older has rapidly 
increased in popularity among peach growers since the appearance of 
the report by E. B. Blakeslee ‘ on his experiments on this new method 
of control of this most destructive enemy of the peach. 
Peach growers throughout the area of distribution of the peach 
» borer east of the Rocky Mountains have already adopted the treat- 
ment to a large extent, and in certain important peach-growing areas 
where the borer is excessively troublesome the employment of para- 
dichlorobenzene has become rather, general. Thus in Georgia dene, 
during 1921, 250,000 pounds of the chemical were used, and possibly 
more was required during the season of 1922. 
The experimental results obtained by Blakeslee showed that this 
chemical is safe when properly employed for the control of the peach 
borer on trees 6 years of age and older. In certain cases, however, 
injury to trees younger than about 6 years occurred. Since the peach 
borer is often very destructive in young orchards, it is highly desir- 
» able, if possible, to use the chemical on trees of all ages. Further 
experimentation by the Bureau of Entomology and several of the 
agricultural experiment stations, notably those of New Jersey, Mary- 
1U.S8. Dept. of Agriculture Bulletin 796, Use of Toxic Gases as a Possible Means of Control of the 
Peach-Tree Borer. 1919. 
46631 °—23——1 
