470 EXPERIMENT STATION RECORD. 



planta. A 10 to 15 per cent mixture of kerosene and water may be applied on sunny 

 days, or whale-oil soap at the rate of 1 lb. to 4 gal. water. An examination of a 40- 

 acre peach orchard about 12 years of age indicated that although San Jose scale had 

 been present for 6 or 7 years, Spharostilbe coecophila had held the scale in check with- 

 out the assistance of any insecticide treatment. It is believed that at least during the 

 warm rainy weather the fungus is capable of controlling the scale. Spraying with 

 kerosene, crude oil, whale-oil soap, or resin wash destroys the fungus, while fumiga- 

 tion with hydrocyanic-acid gas does not affect it. 



White peach scale {Diaspis pavtagona) was tirst observed in Florida in 1889. The 

 infestation appears to have come from California. A list of the food plants of this 

 sjiecies is given, together with notes on its appearance and life history. This scale 

 may be controlled l)y the winter treatment recommended for San Jose scale or by 

 fumigation under tents. The chief natural enemies are Chilocorus hindnenis, and the 

 parasitic fungus mentioned as an enemy to San Jose scale. 



Treatment for San Jose scale in orcliards. II, Spraying with kerosene 

 and crude petroleum, F. A. Sirrine {New York State Sta. Bui. 213^ pp. 25-51, 

 ph. 4). — The experiments in controlling the San Jose scale reported in this bulletin 

 were made on Long Island and in Westchester County, N. Y. The applications of oil 

 were made by means of pumps for producing a mechanical mixture with water. It 

 was found that the mixture produced by such pumps always varied to the extent of 

 5 per cent on either side of the percentage which was desired. During the experi- 

 ments in the use of kerosene it was found to be unsafe to use low-grade kerosene in 

 a 15 per cent mixture in water on peach trees in a dormant condition. The same 

 mixture appeared to injure apple trees, even in a dormant condition. It is believed, 

 therefore, that low-grade kerosenes are unsafe at all seasons of the year and for all 

 kinds of trees. Moreover, it proved to be unsafe to use 150° flash-test kerosene in a 

 15 per cent mixture of water on dormant jjeach, or to spray apple trees with pure 

 kerosene or a 50 per cent mixture as late as March 13. It was found during these 

 experiments that mechanical mixtures of kerosene varying from 15 to 25 \)ev cent 

 may be used on apple and pear while the trees are in full leaf, but that similar mix- 

 tures varying from 10 to 15 per cent are liable to cause damage to stone fruits in the 

 same condition. In the author's experiments it was found safe to apply a good grade 

 of kerosene to pear and apple trees in a dormant condition, but that these trees were 

 injured if sprayed after the beginning of growth in the spring. With stone fruits the 

 reverse condition held true. The use of dilute mechanical mixtures of kerosene on 

 dormant peach invariably killed the tree, while pure kerosene was applied when the 

 buds were swelling with but little injury. The tests with crude petroleum were made 

 on plum, peach, pear, and apple. It was found that pure crude petroleum, or even 

 a 50 per cent mechanical mixture, could not be safely used on apple, peach, or pear. 

 Crude petroleum of a specific gravity of 0.795 in a mechanical mixture of 15 per cent 

 injured pear buds to some extent, while a mixture of 50 to 60 per cent killed all the 

 buds. The trees apparently recovered from the treatment, however, and jiut forth 

 other buds from which a good crop of fruit was developed. A 15 per cent mechanical 

 mixture of crude petroleum killed all the fruit buds on peaches and a 25 per cent 

 mixture killed the trees outright. A 15 to 25 per cent mechanical mixture of crude 

 petroleum had no bad effect on peaches and plums when applied after the buds had 

 begun to swell. During these experiments it was shown that 1 application of a 15 

 per cent mechanical mixture of crude petroleum did not kill all the scales, but that 

 2 applications of this strength, or 1 of 25 per cent mixture, killed all the scales whieii 

 were touched with the spray. The cost of spraying pear trees 12 ft. in height with 

 crude petroleum was 12 cts. per tree, while the cost of spraying standard apple trees 

 with crude petroleum was 40 cts. per tree. While spraying under favorable condi- 

 tions costs only about one-third as much as fumigation, it is urged that spraying is a 

 disagreeable method of controlling San Jose scale, and that the narrow margin 



