12 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE 



Three similar lots, each of 12 plants, were dug after the first heavy 

 frost and immersed for periods of 6, 9, and 12 hours, respectively, 

 in a dip containing 1 cubic centimeter of ascaridole to 6 liters of 

 water. The roots had not previously been trimmed, but, after dip- 

 ping, the roots were cut on and divided into l^-inch pieces and 

 planted in a coldframe. They developed normally in the spring, but 

 were somewhat slow in beginning growth. The roots of the plants 

 of three other similar lots, each of 12 plants, were trimmed and cut 

 into pieces, after which both plants and root cuttings were immersed 

 in a dip like that for the other three lots and for the same periods, 

 respectively. These root cuttings were planted in the same manner 

 as those of the other three lots and made the same growth in the 

 spring, The mature plants of all six lots were placed in cold storage 

 until February 1, when they were potted and placed in the green- 

 house, where their growth was equal to that of the controls and in 

 many cases superior. 



Still other plants were removed from cold storage February 1 and 

 three lots, each of 12 plants, immersed for 6, 9, and 15 hours, respec- 

 tively, in a dip containing, as before, 1 cubic centimeter of ascaridole 

 to 6 liters of water. Twenty-four hours after removal from the dip 

 these plants were potted and placed in the greenhouse. Their 

 growth there was superior to that of the controls. 



TREATMENT OF SEDUM SPECTABILE 



The showy sedum, Sedum spectabile, has a coarse, matted root 

 system and is frequently infested with the larvae of the Japanese 

 beetle. To test the efficacy of wormseed oil as a protective dip, four 

 lots, each of six plants of this species, were dug in the early spring, 

 the surplus soil adhering to the roots removed by shaking, and the 

 four lots immersed for 12, 15, 18, and 24 hours, respectively, in a dip 

 of wormseed-oil emulsion containing 1 cubic centimeter of ascaridole 

 to 6 liters of water and at a temperature of 70° F. All came through 

 the treatment without injury to the roots. At the time of dipping, 

 the plants had made about 3 inches of top growth. This was injured 

 by the dip and sloughed off, but on potting the plants and placing 

 them in the greenhouse, the treated plants soon threw out new top 

 growth and prospered, soon catching up with the controls. 



VALUE OF WORMSEED OIL AS AN INSECTICIDE 



The results of the experimental work which has been described in 

 the preceding pages indicate that a dip the insecticidal basis of which 

 is wormseed-oil emulsion is, under certain conditions, a reliable 

 destroyer of the larvae of the Japanese beetle, though not rapid in its 

 action. Of all the compounds tested for this purpose it is the least 

 toxic to plants. The cost of treatment with this insecticide is not 

 prohibitive ; 1 pound of wormseed oil, assaying 75 per cent ascaridole, 

 will make 500 gallons of dip. It seems probable that this treatment 

 could be utilized in many similar cases of needed control of insects. 



TREATMENT OF PEONY ROOTS 



Figure 2 represents a typical peony root, the root cavity being split 

 open to show its characteristics as a hiding place for the larvae of the 

 Japanese beetle. In the majority of peony roots the cavities contain 

 more or less soil, usually compact and in one solid mass ; whereas in 

 iris the soil is interspersed in very small individual amounts through 



