101 
THE NATIONAL NURSERYMAN 
REMEDIES FOR “DAMPING OFF” 
Soil Disinfection Will Minimize Nurserymen's Loss in the 
Destruction of Young Seedlings. 
Commercial sulphuric acid has been found, by I lit 1 
United States Department of Agriculture, to be an effec¬ 
tive remedy for the loss of pine and spruce seedlings 
from “damping off.’ It is quite common for the soft tis¬ 
sues of these young seedlings to decay so rapidly soon 
after sprouting that they disappear sometimes before the 
nurseryman knows that there is anything the matter with 
them. So common indeed is loss from this source that 
many nurserymen import their seedling stock from 
Europe. This, however, is not only troublesome, but 
dangerous. The white pine blister rust has already been 
introduced into this country in this way and continued 
importations of seedlings are certain to result in the es¬ 
tablishment in the United States of other foreign pests. 
For this reason the Department attaches much impor¬ 
tance to the recent investigations of possible disinfecting 
agents which will rid the soil of the parasitic fungi which 
cause “damping off.” Of these agents the most satis¬ 
factory for commercial use in the majority of cases has 
been found to be sulphuric acid. Treatment with this 
acid not only reduces losses from “damping off” but in¬ 
creases germination. 
The number of seedlings in treated beds, may be from 
114 to 10 or even 20 times as great as in untreated beds, 
depending on how serious the disease is in the untreated 
beds. At most nurseries, moreover, the treatment also 
decreases the number of weeds and causes the pines to 
make a better growth during their first season. At one 
nursery, jack-pine seedlings have grown three times as 
high in acid-treated beds as in untreated beds. 
The treatment is not expensive, for commercial sul¬ 
phuric acid can be purchased in quantity at very low 
rates. At one nursery where careful accounts were kept 
it was found that the entire cost of the treatment, includ¬ 
ing labor, materials, and extra waterings, was less than 
-$5.00 per thousand square feet of bed. On the other 
hand the saving in the cost of weeding alone, which the 
treatment made possible, amounted to $5.30 per thousand 
square feet. 
The sulphuric acid is dissolved in water and applied to 
the beds with a paraffin-coated sprinkler just after the 
seed is sown and covered. From % to % of a fluid 
ounce of acid should be used per square foot of bed, dis¬ 
solved in enough water to make 1V 2 or 2 pints of solution. 
At some nurseries it is also necessary to water the beds 
once or twice daily during the germination period to pre¬ 
vent chemical injury to the seedlings. Individual con¬ 
ditions, however, must determine for each nursery 
whether or not this frequent watering is necessary and 
exactly how much acid should be used. 
Sulphuric acid is now in regular use on the seed beds 
at nurseries in four Western States, Nebraska, Kansas, 
Colorado, and New Mexico. Considerable quantities of 
carbonates, however, are contained in some soils in these 
States, their presence being indicated by vigorous effer¬ 
vescence or bubbling when a strong solution of acid is 
applied. Where this is the case, sulphuric acid is not 
likely to be effective. In one nursery in Kansas zinc 
chloride and copper sulphate have been found satisfac¬ 
tory substitutes when used in the same way as sulphuric 
acid. For zinc chloride V 2 ounce avoirdupois is used per 
square loot; and lor copper sulphate % of an ounce or 
less. The chloride is less apt to injure seedlings but is 
more expensive than the copper sulphate. Despite its 
greater cost, however, it is possible that the zinc chloride 
may be preferred both to sulphuric acid and to copper 
sulphate even on soils which do not contain carbonate. 
In some Northern nurseries where soil disinfection lias 
not been resorted to, fall sowing has been found to con¬ 
trol “damping off” fairly well. At all nurseries where 
the soil remains frozen during the winter, it is worth 
while to test sowing just before the soil freezes. Exces¬ 
sive moisture should be avoided in unsterilized seed beds. 
Nurserymen who wish to test these remedies should 
write to the U. S. Department of Agriculture for specific 
advice adapted to their particular localities. 
Published by the U. S. D. of A. 
Growing Peaches: Sites, Propagation, Planting, Til¬ 
lage, and Maintenance of Soil Fertility. By 11. P. Gould, 
Pomologist in Charge of Fruit-Production Investigations, 
Office ot Horticultural and Pomological Investigations. 
Pp. 24, figs. 7; Contributions from the Bureau of Plant 
Industry. January 23, 1915. (Farmers’ Bulletin 631.) 
This bulletin is intended for general distribution. 
Farmers’ Bulletins Nos. 632 and 633 continue the general 
subject of peach growing and treat of other fundamental 
orchard operations. 
Growing Peaches: Pruning, Renewal of Tops, Thin¬ 
ning, Interplanted Crops, and Special Practices. By II. 
P. Gould, Pomologist in Charge of Fruit-Production In¬ 
vestigations. Pp. 23, figs. 19. Contribution from the 
Bureau of Plant Industry. January 15, 1915. (Farm¬ 
ers’ Bulletin 632.) 
This bulletin is intended for general distribution. 
Inventory of Seeds.and Plants Imported by the Office 
of Foreign Seed and Plant Introduction during the period 
from October 1 to December 31, 1912. Pp. 60, pis. 5. 
January 23. 1915. (Bureau of Plant Industry, Inventory 
No. 33. Nos. 34340 to 34727.) . Price, 15 cents. 
Blackberry Culture. By George M. Darrow, Scientific 
Assistant, Office of Horticultural and Pomological Inves¬ 
tigations. Pp. 13, figs. 8. Contribution from the Bureau 
of Plant Industry. January 29. 1915. (Farmers’ Bulletin 
643.) 
This bulletin is of interest to blackberry growers all 
over the United States. 
Ice Houses and the Use of Ice on the Dairy Farm. By 
John T. Bowen, Technologist, and Guy M. Lambert, 
Dairyman, Dairy Division. Pp. 24, tigs. II. Contribu¬ 
tion from the Bureau of Animal Industry. January 16. 
1915. (Farmers’ Bulletin 623.) 
The use of ice on the dairy farm for the keeping of 
milk and cream in the best marketable condition is dis¬ 
cussed in this bulletin. Plans and specifications for ice 
houses are given. The bulletin is applicable to dairy 
sections where natural ice is obtainable. 
