282 Journal of Agricultural Research vol. VI.NO.S 



expelled spores to drought and direct light; still, the fact that dry her- 

 barium material a year old was found to furnish viable spores shows that 

 spores may exhibit considerable resistance to dry air when free from the 

 apothecium. 



PARASITISM OF HYPODERMA DEFORM ANS 



An attempt to grow the fungus on culture media failed. The spores 

 in every case germinated and in some cases produced an abundant white 

 mycelium, but in the course of six months, after frequent transfers, the 

 mycelium turned a light yellow and died. A somewhat better result was 

 obtained by adding to the culture medium a strong extract made from 

 yellow-pine needles in water, but at the end of eight months the mycelium 

 died. 



A quantity of needles bearing apothecia with mature spores were col- 

 lected in the spring of 1914 near Missoula, Mont., and taken to the field 

 station in the Priest River Valley, Idaho, for experiments on parasitism. 

 The fungus has not been found in this region. The needles were thor- 

 oughly washed in distilled water and the apothecia allowed to expel 

 their spores in small sterilized flasks. Needles and spores were shaken 

 up in water to which a i per cent sugar solution was added. The mix- 

 ture was allowed to stand one day and then thoroughly sprayed over 

 four 3-year-old yellow-pine seedlings having young tender shoots with 

 needles. The inoculated seedlings were immediately inclosed in tough, 

 transparent oiled paper bags and protected from injury. A second ex- 

 periment was initiated by binding infected needles on healthy 3 -year-old 

 seedlings. In the part of the Priest River Valley where these experi- 

 ments were performed the yellow pine is not common, being only spar- 

 ingly represented in a mixture of white pine, grand fir, spruce, hemlock, 

 and Douglas fir. The experiments were made on May 20. In Septem- 

 ber the last-formed needles of the inoculated seedlings were turning 

 reddish brown in spots, mostly at the tips. In the following spring, May 

 to June, the needles which showed infection in the fall and which had 

 become wholly brown developed the characteristic long, shiny black 

 apothecia with mature spores (PI. XXXII, fig. i). Only the needles 

 formed during the previous year were infected. Four control plants, 

 also covered with bags, were entirely free from the disease. The needles 

 of the seedlings on which infected needles were bound showed a much 

 more general infection of the last-formed needles than those by the former 

 described method. In these experiments every needle produced in 1914 

 was infected. Those of previous years remained healthy. This indi- 

 cates that old needles are riot attacked and that the young needles may 

 remain attacked indefinitely after infection. All the infected needles did 

 not produce mature apothecia. Those merely turning brown were filled 

 with the mycelium of the fungus. The experiment at this point was 

 discontinued. In all probability, given time enough, the brown-infected 

 needles would have produced apothecia. 



