8 BULLETIN 52, U. S. DEPAETMENT OF AGEICULTUKE. 



An experiment was conducted on the spring bloom about 3 miles 

 northwest of Miami, on a place managed by Mr. C. O. Hickok. It 

 included a block of 25 seedling trees which bloomed profusely between 

 March 8 and 28. Spraying was begun when the panicles on most of 

 them were about half grown, March 14. The flowers on six trees 

 were beginning to open when the first spray was applied. No trace 

 of disease was apparent on the inflorescence at that time. Seven 

 trees were left ^^dthout spray, as controls. The spraying dates were 

 as follows: March 14, 20, 25; April 2. 



Sprayed and unsprayed trees alike blighted. An occasional fruit 

 was set, but the total number was negligible and the unsprayed trees 

 had quite as much proportionately as the sprayed. 



DISCUSSION OF THE SPRAYING EXPERIMENTS. 



Mangos come into bloom very irregularly. On March 8, 1912, on 

 the Flanders place most of the buds were just beginning to swell, 

 but a number had reached a length of 4 or 5 inches. This habit of 

 irregular blooming makes it difficult to select a proper time to begin 

 spraying. Spraying before the buds begin to grow is of no value so 

 far as protecting the inflorescence, and later the j^oung fruit, is con- 

 cerned. These must be kept covered with the fungicide while grow- 

 ing d fungus invasion is to be prevented. The difficulty of so pro- 

 tecting the inflorescence is at once apparent. Elongations of the pan- 

 icles continue for a period ranging from 10 to 15 days. Those which 

 were sprayed every third day were practically all disease free when 

 the flowers began to open. This, however, requii-ed four sprayings 

 in one case and six in the other. Those sprayed every fourth day 

 showed but little more disease than those sprayed every third day, 

 but those on which the spray was applied at 5 and 6 day intervals 

 had traces of disease, showing that they were less perfectly protected. 



The spraying of the inflorescence at least three times, beginning 

 when the buds are just swelling and repeating every fourth day until 

 the flowers open, will help to prevent the dropping of fruit caused 

 by the disease on the peduncles and pedicels. 



The blighting of the blossoms is by far the most serious form of 

 this disease, as it does not lend itself to control by spraying. The 

 inflorescence may be kept in a clean condition up to the time of bloom- 

 ing; but, when this takes place, immediately there are hundreds of 

 points which are not covered by the fungicide and are open to infec- 

 tion. . Observation has shown that infection takes place in this man- 

 ner. A Totafari tree in the Subtropical Garden bloomed heavily in 

 March, 1912. It was sprayed three times with Bordeaux mixture 

 between the times when the buds began to swell and the flowers opened. 

 The peduncles and pedicels showed no trace of disease when the 

 flowers began to open. On March 26 the tree was in full bloom and 

 there was every indication that a good crop of fruit would be set. 



