SAP-STAIN, MOLD, AND DECAY IE" GREEN WOOD. 



29 



THE EXPERIMENTAL STEAMING OF EED-OAK AND WHITE-OAK BLOCKS AT THE LABORATORY OF 

 FOREST PATHOLOGY, MADISON, WIS. 



During the spring of 1919 tlie writer performed several series of 

 experiments at the Madison laboratory to determine the efficiency of 

 steam at atmospheric pressure in destroying mold and sap-stain fungi 

 in artificially infected red or white oak blocks 2^ by 2^ by 10 inches. 

 Incidentally the rate of drying and the amount of checking were 

 noted in connection 

 with the steaming. 



The blocks were 

 sawed from the sap- 

 wood of summer-cut 

 logs, weighed, and 

 then sprayed with a 

 water suspension of 

 spores taken from 

 cultures of mold 

 fungi originally de- 

 rived from infected 

 material sent in by 

 the writer. A list 

 of the fungi used in 

 these experiments 

 follows : 



Aspergillus flaviis. 

 Aspergillus niger. 

 Cephalotliecium roseum. 

 Ceratostomella sp. 

 Citromyces sp. 

 GrapMum sp. 

 Monilia sitophila. 

 Mucor sp. 



Penicillium asperuluni. 

 Penicillium divaricatum. 

 Penicillinm liiteum. 

 Penicillium pinopliilinn. 

 Penicillium rugulosum. 

 Syncephalastrum sp. 

 Trichoderma sp. 



Fig. 10. — Square billets close piled in a box car. This type 

 of raw stock suffers considei'ably when piled in the 

 manner shown here. Stripping or cross piling while in 

 transit or storage is essential if losses from fungi are 

 to be avoided. 



The sprayed blocks were then placed in a tile chamber, which 

 served as an incubator. After several weeks in this chamber, where 

 an average relative humidity of 95 per cent and an average tempera- 

 ture of 70° F. prevailed, the blocks became well infected and de- 

 veloped countless numbers of the fruiting bodies peculiar to the fungi 

 mentioned above (PI. II, fig. 1). 



