Control of San Jose Scale With Lubricating Oil. 3 



intentional carelessness in spray methods on the part of many 

 nfrowers. In the past one thorough dormant spray with liquid lime- 

 sulphur solution has ahvays controlled the scale satisfactorily, and 

 practically all growers made the dormant application. When the 

 scale first began to increase, some growers failed to apply the dor- 

 mant spray and others were careless in their work. The tips of 

 branches, especially in the tops of trees, were often missed, and scale 

 infestations began at those points. There was carelessness, also, as 

 to the amount of spray material used in the tank. Often mistakes 

 were made in the size of measuring buckets or even in the size of 

 spray tanks, so that the dilute spray solution was not strong enough. 

 Many growers hurried their spraj'ing operations to such an extent 

 that the covering of spra}^ material was insufficient to insure a 

 thorough coating of all parts of the tree, which is very essential. 



The first marked increase of the San Jose scale followed soon after 

 the advent of the spray-gun. Many orchards in which spray-gTins 

 were used di(^not receive a thorough application. The coarse adjust- 

 ment of the gun was used in trying to reach the tops of trees, with 

 the result that the tips were not thoroughly coated with spray mate- 

 rial. Several gun-sprayed orchards showed scale infestations which 

 began in the tops of the trees. 



. Perhaps one of the most important factors in the scale increase 

 has been unfavorable weather. At the time of the spring dormant 

 spray, rainy weather and high winds often interfere with an appli- 

 cation. This was especially true in the spring of 1920, when unfa- 

 vorable weather delayed the spring application and warm weather 

 opened the fruit buds before opportunity was afforded to apply the 

 spray. With the buds opening as quickly as they did in 1920, some 

 growers caused burning by spraying late and others were not able to 

 go over their entire orchards. Thus, in trying to take advantage of 

 the warm spring days when lime-sulphur solution is most effective 

 against the scale, growers often did not find time enough to complete 

 the spray application. The prevailing winds at this time of 3^ear 

 blow strongly from the south, which makes it difficult to cover the 

 north side of a tree thoroughly. It has often been noted that the 

 young scale '' crawlers " of the first generation are first observed in 

 the spring on the north side of trees. 



The lack of a sufficient number of parasites and the scarcity of 

 predacious enemies of the San Jose scale has been another important 

 reason for the rapid increase of the insect. This, together with a 

 long, favorable breeding season, has tended to cause an imusually 

 rapid increase in the scale infestation. AMiere a few scales escaped 

 the dormant treatment, they increased to such numbers by late fall 

 as to be scattered all over an orchard. The scale spread so quickly 

 in 1921 that some orchards, which growers considered free from the 

 scale in the spring, were either partially or almost entirely killed by 

 late fall. 



DISTRIBUTION OF INJURIOUS INFESTATIONS. 



Speaking generally, the San Jose scale has become destructive 

 during the past year throughout the southern limits of the apple belt 

 in the Central Western States. Besides northwestern Arkansas, 



