60 MASS. EXPERIMENT STATION BULLETIN 37.S 



dormant condition, caused no injury on various types of deciduous orna- 

 mentals or on white spruce, arborvitae, Irish juniper, and red pine. These 

 oils at 4 percent strength applied to lilac caused no injury or retardation 

 of development and gave excellent control of oystershell scale. 



Tests of commercial DN sprays and the DNOCHP-oil emulsion on 

 estates and in orchards in Plymouth County, in cooperation with Mr. 

 R. E. Huntley, again showed control of rosy apple aphid in direct propor- 

 tion to thoroughness of coverage. Troublesome infestations of oystershell 

 scale and pear psylla were also controlled. Aphid attack was also checked 

 on various species of Viburnum, a group which suffers severe curling, 

 dwarfing, and distortion of foliage from even a light attack. The sprayed 

 shrubs were very conspicuous in midsummer because of their flat, normal 

 foliage in contrast to unsprayed checks in the vicinity. 



One significant result of the season's work in that region was the 

 condition of one orchard in which commercial DN sprays had practically 

 eliminated rosy aphid in 1939. No spray, dormant or otherwise, was 

 applied there in 1940. Inspection of the orchard in midsummer showed 

 serious injury to the foliage and distorted terminal growth, and the fruit 

 was largely "apliis apples." Subsequent examination at time of harvest 

 showed the fruit of all varieties in this orchard to be worthless. 



Summer Sprays for Apples. (A. I. Bourne in cooperation with Depart- 

 ments of Pomologi' and Botany.) Tests were made of certain variations 

 of the standard spray program to determine the value of recent tendencies 

 in spray practices and to contrast the liquid lime-sulfur with wettable 

 sulfur for scab control. Tests of the present standard program were 

 made to serve as the basis of comparison; the standard program with the 

 addition of a mid-blossom application of wettable sulfur, without arsen- 

 icals; and the standard program without the use of lime in the cover 

 sprays. Throughout the season these were contrasted with a program 

 of wettable sulfur with the addition of lime in the cover sprays and a 

 similar schedule with lime but no sulfur in the cover sprays. Lead 

 arsenate was used at a dosage of 3 pounds per 100 gallons in the pink 

 and 3d cover sprays; 4 pounds in the calyx and 1st and 2d cover sprays, 

 and 2 pounds in the 4th cover spray. In the standard program lime- 

 sulfur was used at the rate oi lYz gallons per 100. The wettable- sulfur 

 was applied at the rate of 7 pounds per 100 gallons. The pathologist 

 found scab appearing on the check trees on May 22. It increased to the 

 point where most of the leaves and much of the fruit were infested by 

 late June. A light infection of scab appeared on Mcintosh trees in the 

 sprayed plots during the first half of June following the prolonged rainy 

 period in late May. Only a slight amount of additional scab infection 

 was observed in any of the sprayed plots during the remainder of the 

 season. 



In all plots where lime-sulfur was used, its typical injury was noted, 

 especially following the pink and calyx applications. Foliage which ap- 

 peared after those sprays, however, showed no such injury, nor was any 

 injury noted on the foliage in tiie plots where only wettable sulfur was 

 applied. 



Examination of the fruit at harvest showed a considerable amount of 

 russeting in the plots sprayed with lime-sulfur. This was particularly 

 conspicuous in the plot where lime was omitted in tlie cover sjjrays. No 

 russeting was noted in tlie plots wliich received wettable sulfur. Tiie 



