DISEASES OF PLANTS. 1093 



Experiments have been carried on to test the effects of dusting with quicklime and 

 slaked lime for preventing winter rot. Of the two kinds of lime used, finely pow- 

 dered quicklime was preferable. The lime in either form does not prevent the rotting 

 of tubers already affected, but will protect sound ones against the spread of the dis- 

 ease. Both forms of lime seem to hasten the sprouting of the tubers in the spring, 

 those treated with quicklime sprouting a fortnight earlier than the untreated ones; 

 while those treated with slaked lime sprouted 3 weeks in advance of the others. 



Potato experiments in 1904, C. D. Woods (Maine Sta. Bid. 112, pp. 1-12). — An 

 account is given of experiments conducted to test the effect of storage on the rotting 

 of potatoes and experiments with dry Bordeaux mixture and soluble Bordeaux mix- 

 ture as a preventive of potato blight. 



From the experiments on the keeping of potatoes it is concluded that the infection 

 with the fungus takes place chiefly if not entirely in the field before digging, and is 

 usually the result of diseased vines. In the majority of cases the infection is indi- 

 rectly through the soil, and not directly through the vine. Spores produced from 

 rotten potatoes left in the land in the preceding year or introduced in manure will 

 affect a subsequent crop. There appears to be much less liability of loss from rotting 

 in the cellar in the case of late-dug potatoes. 



in the experiments with fungicides for the prevention of potato rot, dry Bordeaux, 

 which was formerly marketed under the nameof Fungiroid, was tested. The plants 

 were treated with the dry powder, and comparisons made with similar treatments 

 with regular Bordeaux showed that the dry Bordeaux mixture applied to dry vines 

 is not effective in preventing blight and rot. It will be tested for another season on 

 damp vines to see if it is of value as a fungicide in garden culture of potatoes. 



The soluble Bordeaux mixture tested was made from a formula furnished by the 

 Wisconsin Experiment Station, and consists of a copper sulphate solution, in which 



1 lb. of copper sulphate is dissolved in 2 gal. of cold water, and a solution of sucrate 

 of lime, which is formed by slaking* 10 lbs. of fresh lime in 30 lbs. of water, strain- 

 ing, and adding to the solution 25 lbs. of granulated sugar to 50 lbs. of water. These 



2 solutions are mixed in equal parts and 3 parts of water added. Prepared in this 

 manner the solution contains about the same amount of copper hydrate as the ordi- 

 nary Bordeaux mixture. 



The soluble Bordeaux mixture was used in spraying potatoes in comparison with 

 ordinary Bordeaux mixture of equal strength, and it was found to cost more, both in 

 material and labor, and the yields were smaller and the quality inferior from the 

 plats sprayed with soluble Bordeaux mixture than ordinary Bordeaux mixture. On 

 this account it is not to be further recommended. 



A bacterial disease of lettuce, P. Voglino (Ann. R. Acad. Agr. Torino, 46 (1903); 

 abs. in Ztschr. Pflanzenkrank., 14 (1904), No. 2, p. 96). — The occurrence of a bacterial 

 disease of lettuce due to Bacillus lactucse. is reported. Considerable loss is said to 

 have been caused by the disease, which was very conspicuous throughout the year 

 except during May, when it was somewhat less abundant. 



Rich soils and moist situations seem to favor the occurrence of the disease. It is 

 characterized by a marked softening of the leaves and stems, and in severe cases by 

 the browning and decay of the tissues involved. An examination of the stems 

 showed the fibrovascular bundles and laticilerous tissues filled with bacteria, which 

 were isolated and described. Pure cultures of the organisms on gelatin and lettuce 

 juice formed round, ivory-white colonies which gradually changed to rose colored. 

 Inoculations from the pure cultures of the organisms produced the disease with all 

 its usual characteristics in about 14 days. Plants grown in soils unusually rich in 

 nitrogen were said to suffer more from the disease than those not so situated. 



A new apple disease, W. Paddock (Colorado Sta. Rpt. 1904, p. 99). — The author 

 reports the occurrence of an apple disease, which is believed to be new to science, 

 that has been observed in several parts of the State. The fungus (Alternaria sp.) 



