NURSERY PRACTICE ON THE NATIONAL FORESTS. 73 



safeguards are necessary to prevent losses resulting from unusual 

 conditions. 



In cases where the slope of the ground permits and where a supply 

 of water is available, heavy flooding of the beds will prevent frost 

 damage. The temperature of the water is usually above that of the 

 air and it does not cool so' rapidly. A considerable quantity of Wild 

 meadow hay spread over the beds will prevent frost injury as well 

 as rapid thawing in case freezing has already taken place. The 

 method followed in orchards of building a smudge may be used. 

 Either wood or hay will serve the purpose, and small piles will have 

 to be distributed in the paths throughout the nursery. Emphasis 

 must be laid upon the need of anticipating the danger, of preparing 

 for it, and taking action when the danger is most imminent. Heavy 

 frosts can generally be foreseen the evening before and the local 

 Weather Bureau can doubtless notify the man in charge when there 

 is any real danger. Thermostat alarms may also be provided. If 

 proper precautions are taken, wholesale losses can be prevented even 

 though the plants are tender and the frost heavy. Losses from frost 

 have not in general been heavy at Forest Service nurseries. At the 

 Savenac Nursery 1-0 western yellow pine, Douglas fir, and Engel- 

 mann spruce ; at the Monument, Douglas fir and Engelmann spruce ; 

 at the Pocatello, 1-0 western yellow pine not under shade frames; 

 at the Wasatch, 2-0 Douglas fir ; and at the Boulder, 1-0 Douglas fir 

 have been injured to some extent; while at the Wind River spring- 

 sown seedlings of noble fir were badly injured by a late frost. At the 

 Beaver Creek Nursery mulching with ripe timothy hay effectually 

 prevented frost damage, but resulted in the production of a heavy 

 crop of hay, which vastly increased the amount of weeding neces- 

 sary in the nursery. 



INSECTS. 



The principal insect damage which has been noted in the nurseries 

 of the National Forests thus far has been due to cutworms, white 

 grubs, grasshoppers, aphids, and pine-tip moths. The following 

 information regarding life histories and habits of these insects and 

 the general methods of combating them has been furnished by the 

 Bureau of Entomology, which investigates insects affecting forest 

 and shade trees and hardy shrubs, including forest nurseries. 



CUTWORMS. 1 



Cutworms are the larvae or caterpillars of night-flying moths and 

 sometimes are destructive to young seedlings, cutting them off at or 



1 For further information on cutworms and their control, see U. S. Dept. Agr. Farmers' 

 Bulletin 739. 



