ANNUAL RErORT, 1930 24..') 



Eradication of Nematodes in Greenhouse Soils. (L. H. Jones). A mix- 

 ture of equal parts by weight of calcium cyanide (Cyanogas) with paradi- 

 chlorobenzene, incorporated in the soil of a ground bed in two applications 

 with an interval of seven days, successfully eradicated nematodes. Each 

 application was at the rate of 2400 pounds per acre. Twenty-nine days 

 after the second application, tomatoes were planted in the bed. The first 

 crop was adversely aifected by the paradichlorobenzene. The second crop 

 was excellent, both in foliage growth and production. The bed has re- 

 mained free from nematodes for more than a year while beds on either 

 side have been severely infested. Though this treatment is not practical, 

 the results seem to promise some measure of success for the effort to 

 apply the principle of dry chemical applications to the eradication of nema- 

 todes in the soil. 



Ridding Soil of the Narcissus Nematode. (L. H. Jones). The narcissus 

 nematode {Tt/Ienchus dipsaci) is quite distinct from the parasitic species 

 found in greenhouse soils. The former has been eradicated by treatments 

 that failed entirely when used against the greenhouse nematode. Soil 

 infested with the narcissus nematode was freed of this organism by each 

 of the following treatments: steam in one application, chloropicrin (tear 

 gas) in one treatment, Cyanogas in two treatments, and a combination of 

 Cyanogas and paradichlorobenzene in one treatment. Narcissus was grown 

 on the treated soils and the bulbs stored until autumn. Efficacy of the 

 treatments was determied by examination of the bulbs. 



Carnation Blight. (E. F. Guba, Waltham). The causal fungus (Alter- 

 naria dianthi S. & H.) does not survive the second winter in the field, in- 

 dicating the importance of a two-year rotation. Commercial varieties show 

 different degrees of susceptibility to bliglit, and the reaction of all types to 

 the disease has been carefully studied. In general, the Matchless and re- 

 lated broad-leaved types are very susceptible. 



The early occurrence of the disease is often noted in the propagating 

 house and in the flats, but the value of Bordeaux treatments could not be 

 shown in the absence of disease as a factor where the experiments were 

 conducted in 1930, Injuries to the leaf tissue by red spider, artificially with 

 the needle, and by the knife were shown to favor infection of the leaves. 

 Pruning the cuttings, therefore, increased the danger of infection. 



Laboratory experiments with fungicides have demonstrated the super- 

 iority of Bordeaux mixture and calcium arsenate sprays in preventing 

 germination of the spores and infection of potted plants. A variety of 

 dust mixtures containing combinations of naphthalene, copper sulfate and 

 Cxlcium arsenate in combination with lime or sulfur as fillers prevented 

 spore germination, but on potted plants the most effective protection 

 against infection was obtained with dust mixtures containing calcium 

 arsenate. Of the dusting mixtures used in the field, calcium arsenate, 

 monohydrated copper sulfate and lime gave the best results; but better 

 control was obtained with copper sprays; e.g., Hammond's copper solu- 

 tion, sal soda Bordeaux and caustic soda Bordeaux. Sal soda Bordeaux 

 proved superior to the other sprays used, but none of the sprays or dusts 

 used in 1930 gave satisfactory control of the disease. 



Experiments in progress show that loss from disease after the plants are 

 housed is influenced by the prevalence of disease on the plants in the field, 



