ANNUAL REPORT, 1931 205 



cent active Cu). These diluted sprays are neutral to litmus. On adding calcium 

 hydroxide, injury followed gas and increased proportionately with the alkali 

 present. Acid copper fungicides, i.e., normal and basic copper acetate, Bordeaux 

 1-0.20 and 1-0.22, Burgundy mixture 1:0.3 and caustic soda Bordeaux 1:0.2 

 followed by gas caused severe injury. Copper sulfate solutions .05 per cent and 

 .07 per cent with gas were not injurious. 



When gas followed spraying of cucumber plants with copper fungicides con- 

 taining calcium hydroxide, sodium hydroxide, or sodium carbonate, injury 

 always resulted. Even when the alkali component was reduced to make a mix- 

 ture neutral to litmus, injury resulted after gas. 



Injury occurred regardless of whether hydrocyanic acid gas was evolved from 

 calcium cyanide or from sodium cyanide and sulfuric acid, and of whether 

 chemical hydrated lime or milk of lime was used in the preparation of Bordeaux 

 mixtures. The injured leaves always gave soluble copper, and the amount of 

 copper and the degree of injury increased approximately with the alkali present 

 in the fungicide. 



Carbon bisulfide emulsion treatment for nematode-infested soil. Excellent re- 

 sults were obtained with both commercially prepared and homemade carbon 

 bisulfide emulsions applied to nematode-infested soil. In bushel boxes, soil 

 treated with the commercial product produced tomatoes with gall-free roots. 

 In pots, a homemade emulsion gave clean roots in all but one instance. In both 

 series of tests, the control plants were heavily infested. Repeated tests with home- 

 made emulsion in badly infested commercial greenhouses gave satisfactory 

 results. 



Carnation Blight. (E. F. Cuba, Waltham). A more complete list of 

 varieties of carnations showing their reaction to the causal organism {Alternaria 

 dianthi S. & Hall) has been prepared as a result of further study. 



The optimum temperature for growth of the organism in pure culture is 

 approximately 80° F. ; the minimum and maximum limits are approximately 

 39° and 97° F., respectively. 



Salt 5 per cent and nicotine sulfate 0.2 per cent, combined in solution and 

 used for combating red spider, were not toxic to the conidia of Alternaria and 

 did not in artificial inoculation experiments provide satisfactory protection 

 against infection of potted plants. Salt solution possessed some fungicidal value, 

 but nicotine sulfate none. 



Potassium permanganate 1-1000 strength proved a valuable disinfectant for 

 carnation cuttings. A 5-minute dip greatly improved rooting and provided rather 

 good disinfection of Alternaria inoculum accompanying the cuttings. 



Further experiments confirm the superiority of naphthalene fumigation in 

 controlling Alternaria blight and Fusarium stem-rot as compared to water 

 syringe. A difference of 35.1 per cent in yield of No. 1 blooms in favor of naph- 

 thalene fumigation was obtained. 



Bordeaux 4-4-50 to which was added 1 pound of calcium arsenate, the same 

 with the addition of }4 pint of fish oil, and Bordeaux 4-4-50 plus 14 pint of 

 fish oil, were the most efficient treatments in the field, their relative efficiency 

 being in the order given. A proprietary copper mixture, sulfur fungicides, and 

 dusting materials containing sulfur, calcium arsenate, monohydrated copper 

 sulfate, naphthalene, and lime gave no control of the disease. 



Experiments show that outdoor planting, propagation before January, 

 benching after July 10, and drip from leaks in the greenhouse greatly increase 

 the hazard from Alternaria blight. 



