10 BULLETIN 44, U. S. DEPARTMENT OF AGRICULTURE. 
the beds are watered by large portable sprinklers fed from a moun- 
tain reservoir. Even with such excellent equipment much watering 
is expensive. Most of the commercial nurseries have very crade 
watering facilities and many of them none at all. At many nurseries 
putting in a watering system simply to prevent sun scorch would not 
pay. Indirect methods of controlling the disease are therefore of 
interest. 7 
Shade frames of 2-inch slats, half an inch thick and spaced 2 inches 
apart, have proved a cheap and quite effective method of controlling 
the trouble at Halsey, though they do not prevent all loss. This slat 
shade was tested on July 26, 1910, at noon and at 4.20 p. m., with a 
photometer using “printing-out ” paper. An average of eight deter- 
minations indicated that the shaded beds received 42 per cent of the 
amount of light received by unshaded beds at the same times of day. 
While this proportion must vary with the angle of the sun’s rays, the 
average figure obtained is considered fairly representative for the 
period of most rapid transpiration. Therefore, the term “ half shade,” 
regularly used for this type of shade, while the best available, is not 
entirely accurate. When frames are only a foot above the ground, the 
slats should be placed north and south in order that all parts of the 
bed may get a reasonably uniform amount of shade. Shade put on 
after the attack has gone far enough to become noticeable can not pre- 
vent all injury, but may decrease it. In the cases of the successful use 
of shade seen by the writer the shades had been put on several weeks 
before the attack took place. Brush supported by rough frames 6 
feet high is much used over all ages of seedlings by western commer- 
cial nurserymen and probably explains much of their relative free- 
dom from sun scorch. Shade presumably keeps the beds from get- 
ting as dry as they otherwise would and at the same time enables the 
plants to live in drier soil than they otherwise.could, by reducing the 
rate of transpiration loss from the needles. In growing stock for 
western forest planting, where it is difficult to secure survival, there 
appears the theoretical objection that shade in the nursery beds will 
make the stock more tender and harder to transplant successfully. 
Bates and Pierce? state that the half shade used at Halsey when kept 
over second-year seed beds has resulted in greater loss in the trans- 
plant beds the following year. They suggest gradually reducing the 
amount of shade on second-year seed beds. In the case of transplant 
beds it may be best to use the method tested in 1910 by Mr. C. R. 
Bechtle, formerly of the Forest Service. He erected rough temporary 
shade frames over the beds immediately after transplanting and 
removed them some weeks later when the’ trees had become partly 
1 Bates, C. G., and Pierce, R. G. Forestation of the sand hills of Nebraska and Kansas. 
U. S. Department of Agriculture, Forest Service, Bulletin 121, p. 32, 1913. 
