70 BULLETIN 479, U. S. DEPARTMENT OF AGRICULTURE. 
sown and covered at the rate of three-sixteenths of a fluid ounce in 
solution with 1 quart of water to the square foot of seed-bed sur- 
face. This acid applied at the rate designated has been found very 
efficient. TThen acid is used seed beds must be kept well moistened 
during the germination period. Xegleet of this results in concen- 
tration of the acid in the surface soil through capillary rise of the 
solution, and the growing apex of the radicles of the germinating 
seed are killed, which may result in the death of the plants. For 
some other nurseries different amounts of acid were found success- 
ful: at a good many places it was found mmecessary to take 
any special precautions in the way of extra watering in the acid- 
treated beds. The results obtained from this treatment are in 
accord with what has been found true elsewhere, that damping-off 
is much less prevalent in soils of an acid than in those of a weakly 
alkaline reaction. Experiments at the Vermont Agricultural Ex- 
periment Station 1 indicate that damping-off is likely to be less 
serious in beds to which there has been applied a well-rotted compost 
of horse manure and muck. Such an application will undoubtedly 
tend to make the soil more acidic in its nature and thus antagonistic 
to the development of the fungus. 
In addition to checking damping-off effectively, acid treatment at 
the Bessey Nursery has resulted in the production of stock that aver- 
ages fully an inch higher than nonacid-treated stock. At this nursery 
another feature of the acid treatment is that it seems to kill the weed 
seed and very greatly reduces the cost of weeding thereby. During 
1912 the cost of weeding acid beds was 80.0014, while the cost of non- 
treated beds was $0.0125 per square foot. 2 The extra cost of acid 
treatment was $0,005 per square foot. The total cost of acid and 
weeding was therefore $0.0091 per square foot, as compared to 
$0.0125 for weeding only of nontreated beds. Thus the saving in 
the cost of weeding at least fully offsets the increase in cost due to 
acid treatment. 
A 1 per cent formaldehyde solution applied at the rate of three- 
fourths of a gallon per square foot about a week before the seed 
is sown has been shown x to be very effective in preventing damping- 
off, but it is known that formaldehyde may kill seed which is still 
dormant. On the whole, the experience with formaldehyde at most 
Forest Service nurseries has not been as satisfactory as with acid. 
The formaldehyde, especially with sandy soils, must be applied two 
or three weeks before seed are sown in order to avoid killing them. 
1 Gifford. C. M. " The Damping-off of Coniferous Seedlings." Vt. Agr. Exp. Sta. 
Bui. 157. 
- Cost of acid treatment will be temporarily higher during the European war on ac- 
count of increased price of acid. 
