8 Bacterial Disease of the Mango 



The orchard in which the spraying experiments were carried out is 

 situated on a slope to the east of the town, and contains 28 trees arranged 

 in four rows of seven trees each. The trees are ten or twelve years old 

 and comparatively small — about 12 feet high and 35 feet in circum- 

 ference — so that the spraying could be thoroughly done. 



There is a range of hills to the south of the orchard and the pre- 

 vailing winds are from the south-east. The disease had started in the 

 south-east corner of the orchard, and from there had spread right 

 through. Before the experiments were commenced the trees were all 

 diseased: row (1) being bad right through while in the other rows trees 

 (6) and (7) were the worst. 



Plan of Winter Bros. Orchard, Barberton. 

 East 200 ft. / 



Four Rows of Mango Trees, 18 feet apart. 



The arrow indicates the direction of the prevailing winds. 



* These trees were the first to contract the disease. 



Rows 1 and 3 were sprayed with an iron sulphide solution, using 

 the following formula: 



Quicklime . . . . 4 lbs. 



Flowers of sulphur . . 4 „ 



Iron sulphate . . . . \\ „ 



Water . . . . . . 25 gallons 



and following the directions given in the circular published by this 

 Division. 



Rows 2 and 4 were sprayed with Bordeaux mixture, using a 2-2-50 

 formula for the first spraying and a 4-4-50 in subsequent applications. 



In each row tree No. (3) was left unsprayed as a control. 



The experiment was carried out by Mr P. A. van der Bijl, M.A., of 

 this Division, and he was assisted in the earlier part of the work by 

 Mr H. F. Benger. During the seasons 1912—1913 and 1913—1914, the 

 spraying was also done by Mr van der Bijl, and it is from his reports 

 that this account of the spraying experiments is compiled. 



The following table gives the result of the experiment in connection 

 with weather conditions, etc. The slight discrepancy between this and 



