CONTRIBUTIONS FROM THE WISLEY LABORATORY. 113 



Both ordinary Burgundy and Wisley Lacto-Burgundy were used, 

 the mixtures having the following compositions : — 



Burgundy mixture 



Copper sulphate 9 

 Sodium carbonate 11 



oz. 

 oz. 



Water 



gallons. 



Wisley Lacto-Burgundy 



Copper sulphate 9% oz. 

 Sodium carbonate 11 oz. 

 Milk § pint. 



Water 3 gallons. 



Prior to the spraying, special attention was given to diseased twigs 

 in pruning with a view to reducing the amount of disease. The 

 prunings from ten trees included 220 weak and useless growths, 223 

 dead ends, and 48 diseased shoots ; thus over 250 shoots removed were 

 probably affected with Exoascus. 



The trees, which included both nectarines and peaches, were sprayed 

 on February 20, before the bursting of the buds. Four trees only 

 (' Pineapple,' ' Hale's Early,' ' Humboldt ' and ' Darwin ' ) were sprayed 

 a second time (March 5) to ensure that some trees were thoroughly 

 covered. One half of a tree of each of the varieties ' Elruge ' and 

 ' Pineapple ' was left unsprayed as a control. 



The first signs of leaf curl were detected on April 23. By May 4 

 the symptoms had become pronounced, but only on the unsprayed 

 halves of the varieties ' Elruge ' and 1 Pineapple! On May 7 the effect 

 was remarkable ; on eight of the ten sprayed trees and the sprayed 

 halves of the other two it was difficult to find curled leaves, whilst 

 on the unsprayed halves, especially in the case of ' Elruge,' there 

 were nearly as many curled as uncurled leaves. On May 11 the 

 average number of leaves on each tree was estimated to be about 

 1500. On this date the number of curled leaves counted in situ was 

 as follows : — 





>«_i No. of curled 



Variety. 



iviixLuie. 



leaves. 



Variety unknown 



' Elruge ' (sprayed half) 



(unsprayed half) 

 ' Barrington ' 

 ' Royal George ' . 

 ' Lord Napier ' . 

 ' Pineapple ' (spra}^ed half) . 



(unsprayed half) 

 ' Hale's Early ' . 

 ' Humboldt ' 

 ' Bellegarde ' 

 ' Darwin ' . 



Burgundy 



none 

 Burgundy 



Wisley Lacto-Burgundy 

 none 



Wisley Lacto-Burgundy 



Burgundy 

 Wisley Lacto-Burgundy 



16 

 O 



230 

 6 

 0 



7 

 0 



44 

 0 

 0 

 2 



18 



On ' Darwin ' the 18 leaves occurred on four diseased twigs. 



The accompanying sketch (fig. 44) was made in May direct from 

 the tree 1 Elruge ' at the boundary between the sprayed and un- 

 sprayed halves, and shows, on the right, two sprayed twigs with no 

 curled leaves ; on the left, two unsprayed twigs, with a number of 



VOL. XLI. 1 



