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TREATMENT OF MILDEWS UPON PLANTS UNDER GLASS, 



By S. T. Maynaed. 



In Bulletin No. 4, Massachusetts Experiment Station, April, 1889, ex- 

 periments were reported upon the causes and remedies for mildews 

 upon plants under glass. Below we give a brief summary of the results. 



KOSE MILDEW.* 



Long experience in growing the rose has led many to believe that the 

 rose mildew is brought on by various conditions that weaken the vigor 

 of the leaf, such as want of an abundance of plant food in a proper 

 condition, unhealthy condition of the soil, often resulting from improper 

 drainage, irregular or overwatering, or too sudden changes of tempera- 

 ture, especially after the plants have been forced at a high temperature. 

 The successful rose grower therefore, is one who, by constant care and 

 good judgment, always provides against any or all of the above causes. 



BEMEDY, 



A sure and safe remedy, with proper precautions, was found in evapo- 

 rated sulphur. In the use of this remedy a small kerosene stove with a 

 thin iron kettle was used, and the sulphur kept boiling two or three 

 hours thrice each week when the house was closed. 



Precaution. — The only precaution needed is that the apparatus be 

 placed so that there shall be no danger of its getting upset, and that 

 only heat enough be applied to boil the sulphur, for, if by any accident 

 the sulphur should catch on fire, it would destroy all the plants in the 

 house very quickly. 



Suggestion. — It has been suggested that if the pipes are painted with 

 linseed-oil and sulphur two or three times each year, similar good results 

 would follow. It has long been the practice to paint greenhouse pipes 

 ■with a mixture of lime and sulphur, but the results have not always 

 been satisfactory, and the above suggestion may be opeu to the same 

 objection, although we know of no carefully recorded experiments in 

 the use of linseed-oil and sulphur paint. 



LETTUCE MILBEW.t 



When grown at a temperature above 40° F. at night, 55° F. in 

 cloudy, and 70° F. in sunny days, lettuce under glass is often ren- 

 dered unprofitable by the attack of this disease which causes the lower 

 leaves to decay, and often the whole plant to die quickly. Other con- 

 ditions may in a measure aid in bringing on the disease ; for instance, 



* Sph(Brotheca pannosa, (Wallr.) L^v. t Peronoapora gangliformis, Berk. 



