48 EXPEEIMENT STATION RECOED. 



most common causes of spray injur}-, by admitting the spray material to the 

 interior tissues of tlie leaf. 



Varietal susceptibility seems important, at least with pears, as Duchess was 

 more susceptible to foliage injury than any of the other varieties. A com- 

 mercial brand of arsenate of lead used alone caused foliage injui'y to appear 

 sooner on peaches than when used in combination with lime sulphur 1 : 150. 

 The russeting of apples from lime-sulphur sprays is very rare and of minor 

 importance. 



The injurious action of lime sulphur is claimed to be fundamentally different 

 from that of Bordeaux mixture. The Bordeaux mixture injury usually does 

 not occur at once, but appears under certain atmospheric conditions, while 

 the lime-sulphur injury is initiated before the solution dries on the trees. 



Lime sulphur as a summer spray, E. Wallace (Ncio York Cornell Sta. Bui. 

 289, pp. lJtl-162, figs. 9). — The general results are given of investigations of 

 lime sulphur as a summer spray, conducted during 1909-10 by the author as 

 a fellow on the Niagara Sprayer Company Fellowship in the Department of 

 Plant Pathology of Cornell University (E. S. R., 22, pp. 650, 652). 



It is claimed as a result of these experiments, which extended throughout 

 both a dry and a wet season, that lime-sulphur solution properly used in combi- 

 nation with lead arsenate is as effective in controlling apple scab as Bordeaux 

 mixture. Home-boiled and commercial preparations of lime sulphur diluted 

 1 : 30 and 1 : 40 combined with lead arsenate, and Bordeaux mixture 3 : 3 : 50 with 

 lead arsenate, were found about equally effective in controlling the scab. It is 

 claimed that the addition of lead arsenate to the lime-sulphur sprays increased 

 the fungicidal value of the lime-sulphur mixture about 50 per cent. 



According to the laboratory tests, sediment from heavy grade Niagara lime 

 sulphur with a 2 : 30 dilution proved to have about half as much fungicidal 

 value as the solution volume for volume, but varied with the magnesium content 

 of the lime used in the spray. Magnesium, oxid, according to laboratory tests, 

 was found to have considerable fungicidal value. 



On apple trees the scab was reduced from 79.4 per cent to 29.5 per cent by 

 a 1 : 30 lime-sulphur spray, and to 10.9 per cent when arsenate of lead was 

 added to the spray. On pear trees 3 applications of a 1 : 40 solution of lime 

 sulphur reduced the early pedicel infection of 73 per cent to 13 per cent, while 

 the same concentration of lime sulphur with lead arsenate reduced it to 6 per 

 cent with only one application. 



Comparisons of properly prepared home-boiled concentrated and commercial 

 lime-sulphur sprays showed that the control w'as practically equal in each 

 case. It is claimed that the precipitation of the sulphur present in the lime- 

 sulphur solutions by means of carbon-dioxid gas did not affect the fungicidal 

 properties of the spray, at least when used for brown rot on Atlanta peaches, 

 where it reduced the rot from 45 per cent to 1.5 per cent with 2 applications 

 of a 1 : 30 lime-sulphur solution alone, and to 6.5 per cent by one application. 

 When the lime-sulphur and lead-arsenate spray was applied with the gas 

 sprayer, serious injury to the foliage of the peach trees resulted, apparently 

 due to the action of the gas on the arsenical present ; on apples this caused 

 only slight injury in the case tested. 



The first spraying before the blossoms open is chiefly instrumental in giving 

 a better set of fruit when the early season favors scab infection, and in pre- 

 venting foliage injury from later applications by keeping the fungus off the 

 leaves. The second application after the blossoms fall is usually the most im- 

 portant one in keeping the fruit free from scab. The third application two 

 weeks later seemed from the experiments to be of little importance during 1909 

 and 1910. 



