THE PECAN LEAP CASE-BEAKER. 



23 



cates that the pecan is practically as susceptible to burning as is the 

 peach and that the same precautions must be used in order to prevent 

 serious injury to its foliage. 



fumigation experiments against hibernating larvae. 



Experiments Against Larv^ on Pecan Nursery Trees. 



As the pecan leaf case-bearer may be freely distributed through 

 the medium of nursery stock as larvae in hibernacula about the buds, 

 it was considered advisable to obtain some data in regard to fumiga- 

 tion. A specially constructed box, measuring 10 feet long, 3 J feet 

 high, and 3 feet wide, was used for this work. The box was so made 

 as to be practically air-tight. In order to test the effect of fumigation 

 on the larvae as well as on the plant itself, a number of infested, 

 grafted, or budded pecan trees, ranging from 3 to 5 feet in height, 

 were used. In order to have the trees in the best possible condition, 

 they were dug from the nursery during the afternoon of the day before 

 fumigation, and immediately after the fumigation experiments were 

 completed the trees were set out in the laboratory yard at Monticello, 

 Fla. The method and results of these experiments are shown in 

 Table XX. 



Table XX. — Fumigation experiments on pecan nursery trees for destruction of over- 

 wintering larvse of the pecan leaf case-bearer at Monticello, Fla., in 1916. 



Experi- 

 ment 

 No. 



I 



II 

 III 



Number 

 of trees. 



Treatment. 



Fumigated for 1 hour with 1 ounce 

 of sodium cyanid 1 per 100 cubic 

 feet, using formula 1-2-3. 2 



Fumigated for 1 hour with li ounces 

 of sodium cyanid per 100 cubic 

 feet, using formula 1-2-3. 



Check; untreated 



Date of 

 fumiga- 

 tion. 



1916. 

 Feb. 25 



Results. 



Larvae were not killed, and these 

 larvsedestroyedthebuds. Trees 

 were not injured by fumigation. 



All larvae were killed. No ap- 

 parent injury to trees by fumi- 

 gation. 



Larvae emerged in numbers and 

 buds on the trees were badly 

 damaged. 



1 Sodium cyanid used was equivalent to 129 per cent potassium cyanid. 



2 Formula: 1 ounce (avoirdupois) sodium cyanid, 2 fluid ounces of sulphuric acid, 3 fluid ounces of water 

 to 100 cubic feet of space- 

 It will be noted in Table XX that in experiment I, where 1 ounce 



of sodium cyanid per 100 cubic feet was used, the case-bearer 

 larvse were not killed, while in experiment II, where 1£ ounces of 

 cyanid was used, the results were very satisfactory, as no larvae 

 emerged from the hibernacula. On May 1, 1916, it was found that 

 the buds on trees in experiments I and III were badly damaged by 

 the larvae and that the buds and foliage on trees in experiment II 

 were not injured. So far as could be determined, the fumigation had 

 no effect whatever on the trees, as both the check and fumigated 



