30 



BULLETIN 479, U. S. DEPARTMENT OF AGRICULTURE. 



Wire mesh for covering the frames can be purchased in rolls 150 

 feet in length ami in widths of 4 feet for the top screen and 1 foot 

 for the sides and ends of the frames. The 1-foot strip is cut in 

 6-inch widths. Experience at Forest Service nurseries has demon- 

 strated that screen as fine as three meshes to the inch is necessary to 

 keep mice out of the seed beds. 



The cost of these frames complete, including a shade frame of 

 lath, is from $3 to $7 each, depending upon the lumber used and the 

 skill and wages of the men who construct them. Money can be saved 

 by purchasing material which is surfaced on four sides, since it can 



SIDE VIEW OF FRAM E 







TOP VIEW 











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4 



1 









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TOP VIEW OF COVER 



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SIDE VI EW 



Fig. 4. — Pettis seed-bed frame. 



be painted much more rapidly and requires less paint. Such frames 

 ordinarily last only from 3 to 5 years or will need repairing by the 

 end of that time. The bottom sill in particular is very liable to rot. 

 At the old Garden City Nursery protective frames were used whose 

 sides and ends were of 1 by 8 inch boards, the top only being cov- 

 ered with wire screen. These were more satisfactory at this nursery 

 because they afforded a better protection against wind, and were con- 

 siderably cheaper than the wire frames. 





