10 EXTRACTING AND CLEANING FOREST TREE SEED. 



sufficient room for expansion, however, it is safer, in planning on 

 the number of drying sheets needed, to allow only 8 or 9 bushels to 

 each sheet. 



Time required. The time required for cones to open varies greatly 

 with climatic conditions and slightly with different species. A suc- 

 cession of clear, sunny days and frosty nights, with good winds, will 

 open cones very rapidly. In good weather mature yellow pine cones 

 will open in from 3 to 5 days. Under ordinary weather conditions 

 from 4 to 10 days are required, and in damp, stormy weather often 

 as many as 15 days. Douglas fir and Engelmann spruce usually 

 require a day or two longer under the same conditions. Lodgepole 

 pine takes so much longer that sun drying is seldom attempted. 

 Cones picked early in the season, before they are thoroughly ripe, 

 open much more slowly than those picked later. 



Number of sheets needed. An estimate of the number of drying 

 sheets needed for 1,000 bushels of western yellow pine cones may 

 be made as follows: Ten bushels of cones can be spread on each 

 sheet ; if it takes 5 days to open each batch of cones and there are 20 

 good drying days in the fall each sheet can be used four times. In 

 other words, 40 bushels can be handled on each sheet. Dividing 1 ,000 

 by this gives 25, the total number of sheets needed for the work. 

 Bad weather or the need of additional sheets for covers may make 

 this number insufficient. It is always well, therefore, to make the 

 estimate liberal, since lack of a few drying sheets at a critical time 

 may cause serious delay and even the loss of much seed. 



DRYING CONES BY ARTIFICIAL HEAT. 



With lodgepole pine, and with other species when weather condi- 

 tions are unfavorable, artificial drying must be used. This method 

 is quicker than drying by natural heat and is not dependent upon 

 the weather. It is, however, more difficult, more expensive, and 

 ordinarily does not yield as good seed; therefore it should not be 

 used except when outdoor drying is not practicable. Mast of the 

 artificial drying is done at permanent, fully ^ equipped extracting 

 plants to which cones are shipped from a large area. This circular 

 is designed for the smaller, temporary plants which must be handled 

 by less experienced men with simple appliances. 



EQUIPMENT NEEDED. 



Cabins. The first essential in drying by artificial heat is some sort 

 of shelter which will protect the cones from weather and be suffi- 

 ciently tight to make it possible to raise the temperature to at least 

 110 F. An empty room in a cabin may serve the purpose and often 

 makes as satisfactory a substitute for a regular kiln as can be ob- 

 tained. It must have tight walls and plenty of space for trays 

 around the sides and for a stove. Often one room of a cabin is used 

 for drying and another for storing and extracting. 



