68 NATURAL CONTROL OF WHITE FLIES IN FLORIDA. 



trace of red fungus present in the experimental block of 26 orange 

 trees located in the midst of a 10-acre grove. An examination of 100 

 leaves of old growtli picked at random from the expermiental block 

 sliowed that an average of 12.6 had matured in the spring of 1909 

 or were still alive on tlie leaves as pup<ne. The new spring growth was 

 beginning to become blackened by May 21 and was generailj" moder- 

 ately blackened by June 15. The experimental block was sprayed by 

 the foreman, J\Ir. John Engle, on May 17, Jime 9, July 2, August 2, 

 September 2, and September 11, using about 2,000 pustules of red 

 fungus for the first and about 4,000 pustules of red fungus for each 

 later spra3dng. One hundred and fifty leaves picked at random on 

 June 15 had an average of 7 pustules of rod fungus per leaf; on 

 xA.ugust 21, 140 leaves had an average of 8.8 pustules, and on Sep- 

 tember 15, 50 leaves had an average of 19.6 pustules. On August 2 

 Mr. Engle WTote to the effect that the fungus seemed to be worldng as 

 well in other sections of the grove as in the experimental block. At 

 the end of the season no difference could be detected so far as sho\\'ing 

 the slightest advantage from the repeated applications. An ex- 

 amination of two lots of leaves from surrounding unsprayed trees 

 on September 15 and October 18 showed an average of 41.3 and 

 14.3 red-fungus pustules, respectiveh', on lots of 50 and 100 leaves. 

 In regard to the record of October, a misunderstanding is involved 

 which in the opinion of the junior author renders the record valueless, 

 but even if it be accepted the data show that more fungus developed 

 on the check trees immediately surrounding the experimental block 

 than on the trees to which the spore mixture was applied, 



(6) Keep Grove, Boardman, Fla. Orange trees infested with citrus 

 white Hy only; cooperative experiment with Mr. B. B. Keep. — The degree 

 of infestation in this grove was practically the same as in the Fair- 

 banks grove, but there was no fungous infection. A small block of 

 36 trees was sprayed. On May 3, a lot of 25 spring-growth leaves 

 picked at random from the experimental block showed an average 

 infestation of about 50 larvse in the first three stages. Red-fungus 

 spores were spraj-^ed as in the preceding experiments A\itliin the first 

 10 days of May, June, July, August, and September. On October 25 

 an examination of 125 leaves from the sprayed block showed an 

 average of 2.2 red-fungus pustules per leaf while from the surrounding 

 unsprayed trees an average of 0.3 pustules was found on 134 leaves. 

 On September 25 it was noted by Mr. Yothers that 72 out of 143 

 leaves examined from the experimental blo-k had considerable soot}'' 

 mold while the remainder were only slightly blackened. 



