130 



THE REPORT OF THE 



]^o. 36 



years afterwards. Another point that should be brought out here is that the four 

 trees treated with carbolineuni in my experimental plot in 1913 (Dec. 1, 1913), 

 were not attacked during the summers of 1914 and 1915 and] only a single larva 

 was found in them during 1916. This would indicate that carbolineum treated 

 trees are not readily selected by the females for oviposition, provided untreated 

 trees are available. This point will be further investigated by the writer. 



The results of the treatment of the second block of about an equal number of 

 trees are shown in the following table. 



TABLE IV. CRYPTORHyNCHUs LAPATHi, Linn. 



Treatment 



When 

 Applied 



No. 

 Trees 



Examined 



No. 

 Fnfested 



Larvae 

 per Tree 



Not 

 Infested 



Per cent. 

 Infested 



Carbolineum . . . . 



Check 



Check 



Apl. 12 & 13, 

 1916 



1,540 



1,540 



76 



76 



536 



536 



1.28 



1.28 



9.5 



9.5 



3.42 



3.42 



In this block we have extremely interesting results showing most conclusively 

 the effectiveness of the carbolineuni treatment. The author visited this nursery 

 and showed the owner the method of treatment, but did not further supervise the 

 work. In treating the trees the following day the workman failed in many cases to 

 cover the base of the trees with the material, and also failed to apply it safficiently 

 high on the trunk. As a result all of the infestations, amounting to nearly 1.3 per 

 cent., occurred either at the base or above the highest point of treatment. Another 

 interesting point is in regard to the check row. This row running through the 

 centre of the block contained 639 trees. When the owner saw the excellent results 

 in the treated trees he thought why should he not save most of the check row. So 

 on June 3, 4 or 5, he did not know the exact date, ho treated 555 of the trees, leaving 

 some at either end as a true check. The treatment, even at this late date, had a 

 marked effect as shown by the percentage of infestation as found on June 23, 

 During the first week in June all of the larvse were still at work in the cambium 

 layer and wherever sufficient material was applied most of the larvse were killed. 

 The trees then readily outgrew the injury. The carbolineum had no apparent effect 

 in the retardation of growth. 



Method of Application-. 



After many trials it was found that the simplest method of application was by 

 the use of cotton waste. The carbolineum is non-injurious to the hands so each 

 workman carried a small amount of the tnaterial in a dipper or tin can. The 

 cotton waste was dipped into the material and then rubbed carefully up and down 

 the trunk. It is not necessary usually to go higher than four or five feet, but great 

 care should be exercised to see that the base of the tree is well treated and all parts 

 of the trunk well covered. At the same time the material should not be allowed 

 to run down to the roots. After the trees are pruned workmen can apply the 

 material at a very rapid rate. It is preferable to make the application on a warm 

 day as the carbolineum is then thinner and more easily put on the trees. 



*Only 1,560 trees were examined, but these W:re selected rows and the percentage 

 of infestation is fairly accurate. 



