TOxMATO LEAF-MOLD 13 



invisible films of transpired moisture, the amount of which is increased with 

 high temperatures. Inferring from the results (Table 3, VI, VII) which are 

 outstanding, this film of moisture provides suitable conditions for toxicity. 

 The results show that protection from infection may be obtained by the 

 presence on the leaves of a covering of vaporized sulfur, and that destruc- 

 tion of exposed sources of the fungus in greenhouses may be realized by 

 vaporizing sulfur at frequent intervals. 



COMMERCIAL CONTROL 

 Spraying and Dusting Materials 



In the spring of 1925, at the Market Garden Field Station in Waltham, 

 plats of tomatoes were treated with commercial liquid lime-sulfur 2 per 

 cent, Bordeaux mixture 4-4-50, sulfur dust, copper sulfate-resin fish oil soap 

 (Va pound of copper sulfate, 5 pounds of resin fish oil soap, 50 gallons of 

 water), copper-lime dust 20-80, potassium sulfide and flour paste (5 pounds 

 flour, 4 pounds potassium sulfide, 100 gallons water), ammoniacal copper car- 

 bonate of the usual formula, and New Jersey Dry Mix. The treatments were 

 begun at the first appearance of the disease and continued at seven to ten-day 

 intervals. No control was obtained. The disease was as prevalent in the treated 

 plats as in the check. Lime-sulfur proved injurious to the foliage. 



It might be assumed from the above that lack of control was due to the 

 lateness of the initial treatments and the absence of early protection from in- 

 fection. To eliminate any doubt of the ineffectiveness of copper and sulfur 

 sprays and dusts under greenhouse conditions which the above experiment 

 might offer, a further experiment was conducted in the fall of 1925. The treat- 

 ments were started shortly after the plants were set and continued at weekly 

 intervals. The plants were grown outdoors and set in the greenhouse Septem- 

 ber 25. The following materials were applied: Bordeaux 3-4-50, copper-lime 

 dust 19-81, New Jersey Dry Mix, sulfur-lime dust 75-25, and Burgundy mix- 

 ture. A total of eleven applications was made, the first on September 28 and 

 the last on January 6. No control was obtained. 



In the fall of 1926 at the Frank Wheeler Estate, C<}ncord, Mass., individual 

 houses were dusted at weekly intervals beginning five days after the plants 

 were set, with Grape Dust, copper-lime dust 20-80, Schloesing's sulfur and 

 Trick sulfur. The dusting was done from between the rows while all the 

 ventilators were closed. Feeney Model-D two-quart dusters with up-turned 

 nozzles were used, and every effort was made to get coverings of dust on the 

 lower leaf surfaces. Five to six pounds of dust were applied each week. The 

 treatments were discontinued after five applications had been made because 

 no control was obtained. 



In the fall of 1927 a control experiment was conducted at the Market Gar- 

 den Field Station in which selected sprays were compared for their effect on 

 the disease. Individual rows were 25 feet long and 3 feet apart. The plants 

 were set July 31. Foliage on both upper and lower sides was as thoroughly 

 wetted with spray as was practically possible. The first treatments were 

 made August 10, and later treatments on August 17, 27, September 2, 9, 19, 28, 

 October 10 and 25, making a total of nine treatments. The vines were topped 

 to the wires on October 25, preceding the last treatment. All of the foliage 

 was covered with fungicide and all of it present at each application was 

 wetted with spray. After August 27 ventilation was purposely neglected to 

 provide favorable conditions for the development of the fungus. The ventila- 

 tors were closed at night and heat was not used until November 1. Foliage 



