Bulletin 228] pear thrips and pp:acii trkk borkr. 369 



two rows, making in all one huiulrcd tliirt}' trees. This was six trees 

 more than one sixth of the orchard, and the adjacent unsprayed trees 

 made an excellent check. The application was made witli a hand pump, 

 without constant agitation, with the result tluit the last wiiitt'wash 

 sprayed from the tank was much thicker than the first. The last trees 

 sprayed, especially the last six, which were in unsprayed rows, were 

 covered with a very thick, heavy whitewash. This application was made 

 when very few blossom buds were open sufficiently to admit tlie llirips. 

 At the time of full blossom it was very apparent that the nund)er of 

 blossoms was in direct proportion to the amount of whitewash. The 

 trees which had a thin coating of whitewash had very few blossoms; 

 those which had a ver}' thick coating of whitewash had abuiulanc(! 

 of blossoms. Fig. 1 shows thickly whitewashed trees in full I)lo()m. 

 Fig. 2 shows adjacent unsprayed trees with very few blossoms, the 

 blossom buds having been destroyed by the thrips. The amount of 

 fruit corresponded to the amount of blossom. 



The season of 1911 the experiment was repeated on a larger scale. 

 Between one and two weeks before the time for the buds to open. 

 Mr. Bogen sprayed a large number of trees verj- thoroughly with thick 

 whitewash. Time is a great factor in the control of thrips, and we 

 had hoped to show from this experiment that the whitewash A\()uld 

 have the same beneficial effect when applied a week or more before the 

 buds open as when applied at the time of opening An exceedingly 

 heavy downpour of rain washed the lime from the buds and defeated 

 our plans. By the time the orchard was again dry enough for spray- 

 ing, the buds Mere just beginning to open and conditions were ripe for 

 duplicating the experiment of the previous season. 



About one half of the orchard was used for the experiment. It con- 

 sisted, including checks and sprayed trees, of seven rows, thirty-six 

 trees to the row. The same material was used as in the previous experi- 

 ment. Two rows were sprayed, one row unsprayed, two sprayed, two 

 unsprayed, with this exception, that in the one unsprayed row of trees 

 seven trees were spraj-ed bj^ mistake. 



The results were the same as the previous year. All the sprayed 

 trees, including the seven in the unsprayed row, came into full blossom. 

 The unsprayed trees blossomed very feebly. The fruit corresponded 

 very closely to the blossoming. The spraj^ed trees averaged eight times 

 as much fruit as the unsprayed trees. Fig. 3 shows sprayed and 

 unsprayed trees at picking time. Fig. 4 shows the fruit from a sprayed 

 and an unsprayed tree. 



We used eighty (80) pounds of quicklime for one hundred (100) gal- 

 lons of spraying material. The whitewash was strained through one 

 fourteenth (1/14) inch mesh wire screen and the same sized screen u.sed 

 on the suction hose of the pump. The ordinary Bordeaux no/zles 



