16 



BULLETIN" 796, U. S. DEPARTMENT OF AGEICULTUKE. 



TWO-YEAB OECHAKD TEEES. 



The effect upon two-year orchard trees proved less serious, al- 

 though much too great to make their fumigation practicable. On 

 August 18, 191_6, 20 Belle of Georgia trees were treated in an orchard 

 at Vienna, Va. These trees were in their second season from plant- 

 ing and were consequently two years older than the nursery trees. 

 The soil was exceptionally stiff clay loam. With one or two excep- 

 tions these trees were vigorous and normal. Table V gives the date 

 of application, dosage, and the results of later observations on the 

 effects of the fumigation. 



Table V. — Effect of stated doses of para-dichlorotenzene on 2-year-old Belle of 

 Georgia peach trees, Vienna, Va., 1916-11. 



Tree 

 Nos. 



Condition 

 of trees 

 before 



treat- 

 ment. 



Dose. 



Date of 

 applica- 

 tion. 



Condition of trees on specified dates of examination. 



Mar. 14, 1917. 



July 24, 1917. 



1 

 2 

 1 



Normal.. 



...do 



...do 



Weak. . . 

 ...do 



Normal.. 

 ...do 



Weak. . . 



Normal.. 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



...do 



Jounce... 

 ...do 



J ounce. . 

 ...do 



1916. 

 Aug. 18 



...do 



...do 



Moderateinjury, notserious 



Slight injury, not serious 



do 



Fully recovered, normal growth. 

 Do! 



2 



.do 



Dead.... 





1 

 2 



f oimce. . 

 ...do 



...do 



...do 



Slight injury, not serious 



Severe injury, girdled 



Do. 

 Dead. 



1 



2 

 1 



1 ounce. . 



...do 



2 ounces . 

 ...do 



3 ounces. 

 ...do 



4 ounces.. 

 ...do 



5 ounces.. 



...do 



6 ounces.. 

 ...do 



8 ounces.. 

 10 ounces. 



...do 



...do 



...do 



Severe injury, three-quarters 

 girdled. 



Slight injxiry, not serious 



do 



Partly recovered, normal 



growth. 

 Fully recovered, normal growth. 



2 



...do.... 



...do 



...do 



do 



...do.... 

 ...do 



...do 



...do 



...do 



...do.... 

 ...do 



Severe injury, girdled 



Dead. 



1 

 2 



1 



Slight injiiry , not serious 



Severe injury, three-quarters 



girdled. 

 Severe injury, girdled 



Fully recovered, normal growth. 

 Partly recovered, normal 



growth. 

 Dead. 



2 

 1 



Traces injury, not serious 



Severe injury, serious 



Fully recovered, normal growth. 

 Partlv recovered, normal 



2 



1 

 2 

 1 

 1 



Traces injury, not serious 



Slight injury, not serious 



Traces injury , not serious 



Moderateinjury, notserious 



Severe injury 



growth. 

 Fully recovered, normal growth. 

 Subnormal, stunted. 

 Fully recovered, normal growth. 



Do. 

 Rubriormal, stuilterl. 









It will be noted by reference to Table V that for all doses up to 

 and including 5 ounces the injury to one tree is recorded as " slight " 

 or less, while the other was injured more severely. Table V also 

 shows that on July 24, 1917, when they were again examined, all in- 

 jured slightly had recovered and made a normal growth. For each 

 dose, therefore, up to and including 5 ounces, one tree entirely re- 

 covered and made a normal growth the season following fumigation. 

 Apparently for the period over which the experiment was allowed 

 to run, the smaller doses were sufficient to furnish a vaj^or of maxi- 

 mum toxicity. Had the experiment been allowed to run longer, it 

 is probable that a greater graduation in the toxicity of the various 

 doses would have been observed, as the larger doses had by no means 

 completely volatilized at the time the examination was made. As in 



