1897.] PUBLIC DOCUMENT — No. 33. 79 



any disease of his chrysanthemums to carry on a series of 

 experiments with various fungicides, in order to get at some 

 idea of the best method of treatment. Without such co- 

 operation on the part of the grower we can do but little 

 toward remedying such a disease as this, which does not 

 occur everywhere, and consequently can only be experi- 

 mented upon wherever it may happen to break out. The 

 same is true with many other diseases, especially those 

 alfecting various hot-house plants. If we could plant chrys- 

 anthemums and 1)e sure of getting rust, mildew and leaf spot, 

 and similarly with other plants, if we could be sure of getting 

 all their diseases, then our opportunities for experiment w^ould 

 be unlimited ; but such, of course, is not the case. While 

 some diseases are very general, many others appear only 

 here and there, and the opportunities for experiment are 

 limited to those places. We will gladly aid any one as 

 much as possible in carrying on such experiments, and will 

 give them our personal attention so for as we may be able. 



" Drop " of Lettuce. 



This disease has been for the last few years the most diffi- 

 cult one with which the lettuce growers about Boston have 

 had to contend. Some growers always have a large number 

 of })lants attacked, while others have it so l)adly that they fre- 

 quently lose half the crop. The annual loss to the lettuce 

 growers about Boston from this disease alone amounts to 

 several thousand dollars. The effect of the disease shows 

 itself in a single night, and it is not very difficult to detect, 

 inasmuch as the whole plant simply collapses. It not only 

 makes its appearance on the young plant a few weeks old, 

 but on the mature ones as well. Lifting the diseased plant 

 out of the soil, it shows at once that the troul)le is localized 

 in the soft, rotten stem, which is not unusually covered with 

 fungous growths sufficiently thick to be seen with the naked 

 eye. Examination made with the microscope reveals the 

 presence of numerous fungous filaments ramifying through- 

 out the stem and root. The oro-anism causing- the disease is 

 a species of damping fungus (Botrytis), which has previously 

 been described in the ninth annual repoi"t of this station. 



