28 BULLETIN 453, U. S. DEPARTMENT OF AGRICULTURE. 



will be found satisfactory. The securing of final results along these 

 lines will of necessity require several years' experimenting, because 

 of the differences between different soils and the number of species 

 of parasites and of conifers which have to be considered. Meantime, 

 the foregoing results are published to enable nurserymen to make use 

 of the experience already gained. Under the following heading are 

 outlined a number of treatments, at least one of which should be 

 found successful and profitable at any coniferous nursery where 

 damping-off is prevalent. 



SOIL TREATMENTS RECOMMENDED. 



No treatments can be guaranteed as either safe or effective on all 

 soils. However, it is nearly certain that for any nursery at least one 

 of the following will be found successful. It is therefore recom- 

 mended that any nurseryman who has serious losses from damping- 

 off test some of these treatments on a small scale until he finds which 

 one is best suited to his conditions. At least two successful tests 

 should be made before a treatment is judged safe for large-scale use. 



Treatments for heavy soils. 



1. Sulphuric acid, three-sixteenths fluid ounce per square foot of bed, dissolved in 

 from 1 to 2 pints of water per square foot of bed and applied immediately after the 

 seed is sown and covered. 



2. Same as treatment 1, but use one-fourth ounce acid per square foot. 



3. Copper sulphate, one-eighth avoirdupois ounce per square foot, dissolved in water 

 and applied immediately after the seed is sown and covered. 



4. Same as treatment 3, but use three-sixteenths ounce per square foot. 



5. Zinc chlorid, one-half ounce per square foot, dissolved in water and applied 

 immediately after the seed is sown and covered. 



6. Formaldehyde, one-half fluid ounce per square foot, dissolved in water and 

 applied 10 days before the seed is sown. Keep the bed covered with paper, tarpaulin, 

 or tight shade frames during these 10 days. Do not spade up formaldehyde beds after 

 treatment. If necessary to cover the seed with soil from outside of the plat, which 

 has not been treated, use subsoil just dug up from at least 1 foot below the surface. 



7. Same as treatment 6, but apply the treatment only three days before sowing and 

 do not cover with paper. 



8. Air-slaked lime, one-half avoirdupois ounce per square foot, applied dry and 

 raked into upper 3 inches of soil just before sowing. (If hydrated lime is used, three- 

 eighths ounce per square foot will be sufficient.) Immediately after seed is sown and 

 covered apply three-tenths ounce of sulphuric acid per square foot, dissolved in water. 



9. Same as treatment 3, but use one-fourth ounce per square foot. 



In dissolving disinfectants, use sufficient water to make from 1 to 2 

 pints of solution per square foot. Two pints should be used if the 

 soil is dry; 1 pint is sufficient when the soil is wet. 



Treatments for sandy soils. 



1. Sulphuric acid, one-eighth fluid ounce per square foot, dissolved in water and 

 applied immediately after the seed is sown and covered. 



2. Same as treatment 1, but three-sixteenths ounce per square foot. 



