NURSERY PRACTICE ON THE NATIONAL FORESTS. 43 



has the advantage of being easy to put on and remove, and it does 

 not bring weed or grass seed to the beds. The last consideration is a 

 very important one, since weed or grass seed brought in with a 

 mulch is likely to impede nursery operations very seriously and add 

 to their cost. A mulch should not be put on thickly enough to heat 

 and should lie as loosely as possible. If winterkilling is probable, 

 the tops should be covered; if only heaving threatens, just the soil 

 around the roots need be covered. The mulch should be distributed 

 after the ground is well frozen in the fall and removed in the spring 

 before growth starts and as soon as there is little danger of serious 

 freezing at night. It can be prevented from blowing away by cover- 

 ing the seed beds with the protective frames. 



When snow comes early in the fall and lies until well into the 



spring it serves as a cover and usually makes artificial mulching 



unnecessary. In fact, where there is such a snow cover an artificial 



mulch in addition is very likely to cause heating and molding of the 



plants. Where the winters are cold and windy and the snowfall light 



mulching is generally considered advisable, but its absolute necessity 



can be determined only by trial. As the operation is expensive it 



should not be practiced unless essential. In Forest Service work it 



is practiced with all species only at the Monument, Converse Flats, 



and Gallinas Nurseries. To prevent winterkilling it is necessary 



to mulch 1-0 Arizona cypress at the Fort Bayard Nursery and 



white and Douglas firs and incense cedar at the Pilgrim Creek 



Nursery. At the Pocatello and Trapper Creek Nurseries mulch- 



mg is not practiced; but at the former some loss in Douglas 



ir is experienced from winterkilling, and at the latter a similar 



loss in western yellow pine has occurred where the snow blew 



)ff the beds in midwinter. At the Cottonwood Nursery mulch- 



ng is attended by a loss from heating and by molding due to the 



leavy snowfall, but some loss from spring heaving occurs there in 



hinly broadcasted beds of 1-0 Douglas fir, Engelmann spruce, and 



Norway spruce, and in drill-sown beds of the last two species. At 



he W T ind River and Boulder Nurseries mulching has been found 



o be unnecessary, and at the former even harmful. At the Monu- 



nent Nursery a straw covering damages Austrian pine ; and at the 



>ld Garden City Nursery it was found that heating and molding was 



nuch more likely to occur under straw than under a mulch of leaves. 



CARE OF SEEDLINGS IN SUCCEEDING YEARS. 



WATERING, WEEDING, AND SHADING. 



When plants are left in the seed beds longer than one year, the 

 ultural operations are very similar to those of the first year. Water- 

 ng and weeding are carried on as often as appear necessary. Shad- 

 ng is unnecessary with most species, but not with all. Engelmann 



