IIM)-).] PUBLIC DOCUMENT — No. 83. 13 



crops grown in sterilized soil were prone to mildew. This 

 may result to some extent Avlien the crop is not properly 

 handled ; but mildew is confined to the houses of only a 

 very few commercial growers, and its existence in a house 

 at all can be accounted for otherwise. We introduced the 

 mildew into our house several times, but it always died out, 

 and was never known to live through the summer. On the 

 whole, far better lettuce crops are turned out to-day than 

 five years ago, and there is a decided decrease in the amount 

 of infection, due to the application of improved methods of 

 treatment and culture. 



As regards the effects of sterilized soil on the growth of 

 cucumbers, our experiments and those of others have shown 

 favorable results, since cucumbers will stand a considera))le 

 amount of forcing without any detriment ; and we have 

 none of the drawbacks due to excessive stimulation of the 

 crop, such as we find in lettuce. When cucumbers are grown 

 under single lights of glass, or under favorable conditions as 

 regards light, the stimulating eflects due to sterilization act 

 most advantageously ; while, on the other hand, where the 

 crop is grown under exceedingly abnormal conditions as 

 regards heat, light and moisture, as it sometimes is, no 

 appreciable results are noticeable, except in so far as the 

 treatment eliminates undesirable pests from the soil. In- 

 deed, no form of stimulation is of any practical value to 

 plants when their conditions of growth are extremely ab- 

 normal. Sterilization is especially efficacious in destroying 

 eel Avorms and preventing timber rot, and also destroys some 

 insect pests ^vhich trouble the cucumber. One of the special 

 advantages in grooving cucumbers in sterilized soil is con- 

 nected with the seed and seedling, since germination of the 

 seeds is hastened, the plants are accelerated, and damping- 

 off is prevented. A considerable amount of acceleration is 

 given to the growth of the seedling ; and in our ex})eriments, 

 where seeds were sown in sterilized and unsterilized soil, 

 we olitaincd an increase in the actual germination of the 

 seed ccjual to 33 per cent, in favor of sterilized soil. The 

 expense of sowing seeds and starting seedlings in sterilized 

 soil would be slight, and the results obtained render this 

 process especially desirable. 



