10 BULLETIN 44, U. S. DEPAETMENT 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 crude 

 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. 



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 1 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 Bales, ('. c, and Pierce, B. G. Forestatlon of the sand liills of Nebraska and Kansas. 

 U. S. Department of Agriculture, Fdresl Service, Bulletin 121, p. 32, 1913. 



