28 



the development of fungi. The depth of the soil which would have 

 to be treated, the considerably large volume of air-space* which 

 would have to be subjected to fungicides, and the difficulty of reach- 

 ing this space, together with the extremely delicate relationship exist- 

 ing between the soil and plant-growth, make the problem of the 

 application of a fungicide to the soil a difficult one. Certain deli- 

 cate organisms such as that which gives rise to Club-foot appear to 

 be affected by the application of lime to the soil, and sulphur is 

 used in the same way as a remedy for Potato-scab, but unfortunately 

 all fungous and insect pests are not so susceptible to treatment. 

 From the beginning of our experiments upon the treatment of soil 

 fungi we had little faith in the treatment of the soil by means of 

 chemicals, but the reported beneficial results obtained by some gar- 

 deners by the use of certain substances, induced us to give them a 

 trial. There are always certain substances recommended for every 

 disease, which constitute panaceas as it were for all troubles. The 

 number of diseases for example which lime and sulphur are believed 

 to cure would fill a volume, but the number that they actually exert 

 an influence upon would require only a small space for enumer- 

 ation. One writer in a gardener's journal stated a few years ago in 

 the most positive language that the Rot Disease of lettuce can be 

 entirely controlled by simply sprinkling a little lime upon the sur- 

 face of the soil. It may be very gratifying to gardeners to learn 

 from one of their brethren that a troublesome disease can be dis- 

 posed of so readily ; nevertheless should they give the remedy a 

 trial and find it to their sorrow a failure, they are likely to feel quite 

 differently. The practice of advocating remedies which have never 

 been thoroughly tried, and which nine times out of ten fail, consti- 

 tutes a menace to the introduction of efficient ones. We have 

 already briefly alluded to experiments in which lime, sulphur and 

 charcoal were tried separately on different beds (see experiment 2) 

 and the negative results obtained from their use. These substances 

 were sprinkled on the surface of the soil quite liberally, in fact, so as 

 to entirely cover the surface with a thin coating. In every instance 

 the mycelium of the Drop fungus was observed growing over the 

 surface of the soil coated with this substance without apparently the 

 slightest ill effect to the fungus. Another experiment was also tried 



*The volume of space in tlie average lettuce soil is about 40^ or 50?*. 



