ANNUAL REPORT, 1939 23 



Soil in metal flats with double bottoms, the upper one perforated, was watered 

 from below, with solutions introduced between the bottoms and thus beneath 

 the soil, after seeding. Damping-off was satisfactorily controlled by as little 

 as 2, or even 1 teaspoonful formaldehyde per gallon of water, with some chemical 

 injury in a too dry soil from 4 or even 3 teaspoonfuls. 



As little as one teaspoonful formaldehyde per quart of water per square foot, 

 applied from above and worked into soil before seeding, controlled damping -off. 



In applications up to those heavy enough to cause chemical injury, damping-off 

 was not controlled by urea, thiourea, diacetone and sulfamic acid. Results were 

 more encouraging with oxyquinoline sulfate and salicylanilide and their use is 

 being further investigated. 



Damping-off and Growth of Seedlings and Cuttings of Woody Plants as Affected 

 by Soil Treatments and Modifications of Environment. (\V. L. Doran.) Sand, 

 sand-peat, and sandy soil were compared as rooting media for cuttings of sixteen 

 species. Nine rooted best in soil, six in sand-peat, and only one in sand. 



Cuttings of Cornus florida L., Syringa vulgaris L., Viburnum Carlesii Hemsl., 

 Primus maritima Marsh., and P. subhirtella Miq. all rooted better if taken in 

 June than if taken later in the summer. 



Indolebutyric acid was more effective than indoleacetic acid in improving 

 rooting of cuttings of the seven species with which both were used. All treat- 

 ments referred to below were with solutions of indolebutyric acid and were for 

 18 to 24 hours at 18° to 20° C. 



Rooting of cuttings of five species was, however, more improved by solutions 

 at initial temperatures of 30° to 35° C. (soon falling to 20° C.) than at an initial 

 and approximately constant temperature of 20° C. Treatment at initial tempera- 

 tures of 40° C. or higher was injurious. 



Dilutions of indolebutyric acid (mg. per liter) which most improved rooting of 

 summer cuttings of the following deciduous species (and of holly and hemlock) 

 and late-fall cuttings of the conifers were: 12.5 mg. for Japanese quince and 

 flowering dogwood; 25 mg. for lilac. Wistaria, American holly, and Viburnum 

 Carlesii; 50 mg. for common hemlock, arbor-vitae, four species of Rhododendron, 

 and Cotoneaster horizontalis Decne.; 100 mg. for Irish juniper, two species of 

 Chamaecyparis, and two varieties of Norway spruce. 



A delayed treatment of cuttings of incense cedar with indolebutyric acid, which 

 was applied fifteen months after cuttings were taken, was very effective in im- 

 proving rooting. 



Treatments effective with softwood cuttings did not affect the rooting of hard- 

 wood, winter cuttings of four out of five deciduous species. 



Damping-off of seedlings of Carolina hemlock, Hovenia dulcis Thunb., and 

 Stewartia pentagyna L'Herit. was not well controlled by seed treatment with red 

 copper oxide. 



Carnation Blight Caused by Alternaria dianthi S. & H. (E. F. Cuba, Waltham.) 

 Some features of this project are awaiting further field study before publication 

 is attempted. Meanwhile, extensive breeding is in progress in an effort to obtain 

 suitable varieties resistant to Alternaria blight and especially branch rot, caused 

 by Fusarium dianthi Prill. & Delacr., a serious parallel carnation disease problem. 

 The work is being carried on in cooperation with the New England Carnation 

 Growers Association and Prof. Harold E. White. 



Chemical Soil Surface Treatments in Hotbeds for Controlling Damping-off of 

 Early Forcing Vegetables. (W. L. Doran and E. F. Guba, Waltham.) Treat- 

 ments were applied to the surface of the soil immediately before or after seeding 

 and the results were the same. 



