20 



BULLETIN 571, U. S. DEPARTMENT OP AGRICULTURE. 



Table XVI. — Spraying experiments against the larvse of the pecan leaf case-bearer at 



Monticello, Fla., in 1913. 



Plat 

 No. 



Number 



of 



trees. 



Treatment. 



Date of applica- 

 tion. 



Results. 



I 

 II 



113 

 12 



One application of 

 paste lead arsenate 

 at 3 pounds to 50 

 gallons of water. 



Aug. 14 and 15, 

 1913. 



Very satisfactory control. Nearly all 

 larvae were killed and only a very 

 few remained to construct hiberna- 

 cula in the autumn. Was exceed- 

 ingly difficult to detect any hibern- 

 acula. No appreciable amount 

 of damage was done by the few 

 overwintering larvae to the buds 

 during the spring. 



As many as 12 hibernacula were 

 found around a single bud; the 

 average was about 3 hibernacula to 

 the bud. During the spring the 

 larvae appeared in numbers and 

 seriously damaged the buds and 

 foliage. Some trees were nearly 

 defoliated. 









The results obtained on Plat I, as shown in Table XVI, were highly 

 satisfactory, since most of the larvae were killed by the arsenical appli- 

 cation. By destroying the larvse during the late summer or early 

 autumn, the trees were protected from attacks during the subse- 

 quent spring, at which time very serious injuries occur to the buds 

 and tender foliage through the peculiar manner of the feeding of 

 overwintering larvae. During the following spring (1914) , the trees on 

 Plat I put forth their foliage in perfect condition, but on account of 

 the ravages of the case-bearer larvae the unsprayed trees (Plat II) 

 were kept in a state of partial or total defoliation for several weeks, 

 and this condition interfered seriously with the setting of nuts. A 

 slight arsenical injury was done to the foliage, but in no case was the 

 damage so severe as to cause the leaves to drop. 



More extensive spraying experiments were carried out with lead 

 arsenate in 1914 than in 1913. Table XVII shows the series of 

 experiments conducted in the Abe Simon orchard. 



Table XVII. — Spraying experiments against the larvae of the pecan leaf case-bearer at 



Monticello, Fla., in 1914- 



Plat 

 No. 



Number 



of 



trees. 



Treatment. 



Date of appli- 

 cation. 



Result. 



I 

 II 



22 

 4 



18 



Powdered lead arsenate at 

 2 pounds to 50 gallons of 

 water. 



1914 

 Aug. 13 



Practically perfect control. Scarcely 

 any larvae succeeded in escaping 

 the poison to construct hibernacula. 

 Foliage rather seriously injured by 

 the heavy application of arsenical. 



III 



Paste lead arsenate at 3 

 pounds to 50 gallons of 

 water. 



Aug. 14 



determined by the great abundance 

 of hibernacula and the prevalence 

 of larvae in the buds during the 

 following spring. 

 Practically perfect control. Scarcely 

 any larvae succeeded in escaping the 

 poison to construct hibernacula. 

 Foliage rather seriously injured by 

 the heavy application of arsenical. 



