18 MASS. EXPERIMENT STATION BULLETIN 441 



Tetramethyl thiuram disulfide (Tuads), zinc trichlorophenate (Dow Seed 

 Protectant No. 9) and Guantal were apparently injurious to the leaf-bud cuttings 

 of Rhododendron, and Dow Seed Protectant No. 9 had a similar unfavorable 

 effect on cuttings of red cedar and Japan quince. 



The effects of solution-immersion treatment applied in the usual manner with 

 only the bases of the cuttings being immersed, were compared with the effects 

 of immersion of the entire cuttings in solutions of a root-inducing substance. 

 Rooting of fall cuttings of two yews was more hastened or improved by complete 

 immersion in indolebutyric acid 150 mg./l. or naphthaleneacetic acid 25 mg./l., 

 18 hr. than by basal treatment only and this was true also of fall cuttings of 

 Hinoki cypress in indolebutyric acid 50 mg./l., 18 hr. But the rooting of fall 

 cuttings of arbor-vitae and two species of Juniper was as much improved by one 

 method as by the other, and the rooting of cuttings of five hemlocks taken be- 

 tween October and January was more improved by immersing only the bases of 

 the cuttings than by immersing the cuttings entirely. 



Some work was done with potassiuni nitrate in solution, used with or without a 

 root-inducing substance. Rooting of December cuttings of Norway spruce was 

 improved by potassium nitrate 100 mg./l., 23 hr., used alone. Rooting of fall 

 cuttings of red cedar, oriental bitter-sweet, and inkberry was more improved by 

 potassium nitrate 50 mg./l. used with indolebutyric acid than by the latter used 

 alone. 



Powder-dip treatment of December cuttings of Norway spruce with 2, 4, 5- 

 trichlorophenoxyacetic acid 0.5 mg./gm. resulted in improved rooting if the 

 carrier was activated charcoal but not if it was talc. 



Arasan (tetramethyl thiuram disulfide), used as a seed treatment, protected 

 seedlings of Finns Mugo var. Miighus against damping-ofif better than did either 

 Phjgon or Spergon (tetrachloro-parabenzoquinone) similarly used. 



Applied as a soil treatment immediately before seeding, Arasan 0.5 gm. per 

 square foot improved the stands of Carolina Rhododendron and a Rhododendron 

 catawbiense hybrid. 



Diseases of Plants Caused by Soil-infesting Organisms, with Particular Atten- 

 tion to Control Measures. (W. L. Doran.) The application of soil fungicides in 

 fertilizer used as a carrier was found to be a simple and effective method for the 

 control of certain soil-borne fungus diseases of plants. It is especially useful in 

 the case of such light applications (per acre) that the fungicide could hardly be 

 distributed except in some carrier. A liquid carrier would mean more labor and, 

 as is stated below, the results with water may be inferior to those with fertilizer. 



Especial attention was given to the control of clubroot of cabbage, smut of 

 onion, and damping-off of certain vegetables by some organic fungicides applied 

 to the soil in a 5-8-7 fertilizer (15.6 gm. per square foot) immediately before 

 seeding. The effectiveness and safety of some of the fungicides thus applied 

 were compared with their effectiveness and safety when applied in water to soil 

 immediately after seeding. Observations were meanwhile made as to which soil 

 fungicide applied in fertilizer is better and safer with one species of plant, which 

 with another. 



Dithane D14 (disodium ethylene bisdithiocarbamate), Dow Seed Protectant 

 No. 9 (zinc salt of 2, 4-trichlorophenol), Fermate (ferric dimethyldithiocarba- 

 mate), Arasan or Tuads (tetramethyl thiuram disulfide) gave better and safer 

 control of damping-off of all vegetables when applied in fertilizer to soil before 

 seeding rather than in water after seeding. 



Phygon (2, 3-dichloro-l, 4 naphthoquinone), Tuads, and Dithane applied in 

 fertilizer gave better control of damping-off in limed soils than in the same soils 

 not limed. But there were also good results with these and other fungicides 

 applied in fertilizer to unlimed soils. 



