14 HOW TO CONTROL THE PEAR THRIPS. 



The primes averaged 57 to the pound, and computations made on 

 the basis of 5 cents for prunes running 80 to the pouncL The different 

 yields and vahies were as follows: 



Plat I — Demonstration hlocJc of 1909, consisting of 580 trees. — This 

 block yielded 35 tons 212 pounds of green prunes, worth $2,109.87 

 for 580 trees, or $3.63 per tree or $392.04 an acre. 



Plat II — S2>rayed for larvse, in 1909, 80 trees. — This block yielded 

 2 tons 676 pounds of green prunes, worth $140.51 for 80 trees, or $1.99 

 per tree or $214.92 per acre. (This was part of Plat II in 1909.) 



Plat III — Remainder of orchard, consisting of 10 acres, not sprayed 

 in 1909. — This block yielded 7^ tons of green prunes worth $450.75 

 for 1,080 trees or 10 acres, making $0,417 a tree or $45,075 an acre. 



An examination of the above statement of yields and values shows 

 that great headway can be made the first year in eliminating the 

 thrips injury from an orchard by thorough spraying and that a con- 

 siderable benefit extends into the second year. 



Demonstrations for 1910. 



The 6^-acre prune orchard belonging to Mr. H. Curry was plowed 

 and cross-plowed in November, 1909, to a depth of 11 inches and har- 

 rowed after each plowing. The block was then sown to barley for 

 a cover crop which made a good growth and was at spra^-ing time 

 nearly 3 feet high. 



Examination of two samples of soil 17 by 17 inches square, taken 

 before plowing, and two of the same size taken after plowing, showed 

 that approximatel}^ 61 per cent of the thrips were killed. 



Plat A. — In addition to the fall plowing, this block of 300 trees 

 received three applications of commercial tobacco extract No. 1 com- 

 bined at the rate of 1 to 66 with 3 per cent homemade distillate-oil 

 emulsion. The first spraying was applied March 7, just as the cluster 

 buds were spreading. The second for adult thrips was made March 17, 

 as the tips of the petals were showing. The third application, which 

 was for the larvse, was made April 6, after most of the petals had 

 fallen. In all of the spraying an effort was made to direct the spray 

 into the end of each bud and to drench the trees thoroughly. 



Plat B. — This plat, consisting of 98 trees, received the cultivation, 

 but no sprajang. 



Results. — The first application was made too late to obtain best 

 results, and a large number of buds was so far advanced that it was 

 difficult to reach all of the thrips. A series of counts showed that all 

 of the exposed thrips were killed and about 30 per cent of those 

 within the buds. The second application killed practically all the 

 thrips left on the trees (over 90 per cent), as the bud clusters were 

 spreading at this time. A fair portion of the blossoms set fruit on the 



