Rodent Injury to Trees. 449 



at the Potehefstroom Experiment Station. Most of the washes that 

 were used contained sulphur. The mixtures were tested by painting- 

 them on young- seedling peach trees, standard privets, oaks, etc., and 

 on the back of large eucalyptus trees. Air-slaked lime was used in 

 making up the washes, quicklime not being available. 



In 1917 an experiment was conducted to test the reputed virtues 

 of cactus juice as an adhesive. When sliced and soaked in water, at 

 the rate of one pound to a gallon, spineless cactus yielded a thick 

 gelatinous mixture. Washes were applied during the first week of 

 August, and were of the following composition : — 



1. Plain limewash, made with lime and water. 



2. One part lime and one part sulphur, in cactus solution. 



3. Two parts lime and one part sulphur, in cactus solution. 



4. Three parts lime and one part sulphur, in cactus solution. 



None of the washes proved to adhere satisfactorily^ Although 

 the cactus solution appeared to be very sticky, the washes prepared 

 with it washed ojB: the trees just as quickly as the plain limewash. 



The following washes were applied on 24th August, 1918 : — 



1. Plain limewash. 



2. One part lime and one part sulphur in dilute iron-sulphate 



solution. 



3. One part lime and one part superphosphate in copper- 



sulphate solution. 



Upon drying, No. 3 formed a coating that could not even be 

 rubbed off, and it appeared that a wash of a most adhesive nature 

 had been found. However, when heavy rains fell. No. 3 was the first 

 to go. Results from No. 2 were not conclusive. As No. 3 at first 

 gave much promise, the following tests were begun on 26th August : — 



1. Plain limewash. 



2. Lime, in copper-sulphate solution. 



3. Two parts lime and one part' sulphur in copper-sulphate 



solution. 



4. Superphosphate in copper-sulphate solution. 



5. Two parts superphosphate and one part sulphur in copper- 



sulphate solution. 



6. One part superphosphate and one part lime in water. 



7. Two parts superphosphate, two parts lime, and one part 



sulphur in water. 



8. Two parts superphosphate, two parts lime, and one part 



sulphur in copper-sulphate solution. 



The copper sulphate was present at the rate of 1 lb. in 8 gallons of 

 the water used in making up the mixtures. It appeared to add slightly 

 to the adhesiveness of the washes, but a heavy rain (1.68 inches) fell 

 on 1st September, and the coatings on the trees were badly injured, 

 and began to disappear. On 25th October not a coating was left. 

 In the interval between the two dat^s mentioned the rainfall was 4.11 



