34 MASS. EXPERIMENT STATION BULLETIN 441 



On September 16, attention was called to a serious outbreak of black scale on 

 Gardenias in a commercial greenhouse. The infestation occurred in both sec- 

 tions of one range, comprising a total of 60,000 square feet. The plants were in 

 their second year of growth and were coming into their first season of full pro- 

 duction. Scale was present throughout both houses but the heaviest attack was 

 centered in the three south benches of the east house. On many plants both 

 buds and leaves were heavily infested and much of the foliage was coated with 

 sooty fungus. Examination of sample leaves from the house showed an average 

 of 56.5 crawling young and 54.8 older stage scales per leaf, or a total of 111.3 

 scales per leaf. 



On this same date a 25-foot section of one bench in the area of heaviest infesta- 

 tion was given a spray of a 25 percent DDT emulsion at 1 :250 dilution. The rest 

 of the eastern half of the house was sprayed with nicotine sulfate 1:500 + fish 

 oil soap 4 pounds per 100 gallons, on September 17, 24, and at 7 to 10 day inter- 

 vals thereafter. 



One application of the DDT emulsion reduced the number of scales from an 

 average of 111 per leaf to 2, within two dajs, and held it at approximately the 

 same figure for three months. In the meantime weekly applications of nicotine 

 sulfate failed to prevent an increase in the number of scales so that by late 

 October it was necessary to make an application of DDT emulsion to the whole 

 house to prevent serious damage to the plants. By this time, in this area, leaves 

 and buds had become heavily infested (average 150 scales per leaf). The small 

 number of scales in the section sprayed with DDT (average 1.6 scales per leaf) 

 indicated how completely the pest had been controlled in that section. Both 

 leaves and buds were practically clear of scales. The new, terminal growth was 

 noticeably greater and the plants were in much more vigorous condition. More- 

 over, the DDT emulsion left no white deposit on the foliage, an objectionable 

 feature of the use of DDT in the form of wettable powder. 



The Value of Control Measures to Supplement the Standard Spray Program 

 for Apple Pests in Massachusetts. (A. I. Bourne, in cooperation with the De- 

 partments of Pomology and Plant Pathology.) Injury from frost so reduced the 

 set of fruit that it was necessary to rearrange the location of the spray tests. 



In the orchard where the lead arsenate tests were made, the set of fruit was 

 very light on the unsprayed check trees. They were in an exposed section of the 

 orchard and suffered greatly from frost damage. There was also a heavy drop 

 from disease and insect attack. All of the apples on these trees were blemished 

 by scab; 50 percent were scarred by curculio; 67 percent were damaged by codling 

 moth (blossom end and side worm "stings"); and about 33 percent showed scar- 

 ring by minor pests and were infested by apple maggot. 



The regular schedule, with lead arsenate the insecticide, held codling moth to 

 16 percent injury and curculio to 6}4 percent, and reduced scab to 19 percent 

 damage. When the emergency codling moth spray was interposed between the 

 2d and 3d cover spray, codling moth and minor insect pest damage was cut down 

 to a mere trace, and this extra application reduced scab to 11 percent blemished 

 fruit In a season of unusually heavy attack. The application of a mid-August 

 spray did not give any measurable additional reduction of codling moth. 



Results would indicate that if the emergency spray is carefully timed on codling 

 moth development, no other additional spray is required, and that the increased 

 protection from scab afforded by this spray would also justify its use. 



In the orchard to which the tests with DDT were transferred, the test blocks 

 received the regular schedule up through the calyx and first cover spray. In the 



