. Chestnut blight. Chestnut blight; Chestnut. 520 Journal of Agricultural Research Vol. lU, No. 6 METHOD OP MAKING A TEST At the end of an exposure period the contents of each dish were emptied into sterile flasks provided for the purpose and transported to the labo- ratory at the University of Pennsylvania, where the work of making an analysis was completed. They were then replaced with other sterile dishes and sterile water introduced as before. For each water spore trap 15 to 20 plate cultures were employed, and these were made by introducing to c. c. of the water by means of a grad
. Chestnut blight. Chestnut blight; Chestnut. 520 Journal of Agricultural Research Vol. lU, No. 6 METHOD OP MAKING A TEST At the end of an exposure period the contents of each dish were emptied into sterile flasks provided for the purpose and transported to the labo- ratory at the University of Pennsylvania, where the work of making an analysis was completed. They were then replaced with other sterile dishes and sterile water introduced as before. For each water spore trap 15 to 20 plate cultures were employed, and these were made by introducing to c. c. of the water by means of a graduated i c. c. pipette into each Petri dish. In this way only 4 to 5 c. c. of the total water returned to the laboratory were used in each. ^"i 3f-Map showing the location of water spore-trap stations Nos. I to VI. Stations I and II are in the „„ J°££'^' ""* d«ta'''d.«>'nposition of which is shown in figure i; Stations III to V are at various distances from the same coppice; Station VI is to the north of a mixed chestnut and oak woodland. test, but special pains were taken to secure a uniform suspension before the removal of the quantities used. Chestnut-bark agar was used for all of these analyses (see p. 496 for formula) since experience had proved that it was a poor medium for the growth of bacteria, which were always present m some quantity. In fact, the medium is so unfavorable for the development of ordinary bacteria that in most cases the colonies remained as minute specks during the period the plates were under observation and with proper dilution offered no hindrance to the development of colomes of Endothia parasitica and other fungi. All cultures were incu- bated as nearly as possible at 25° C, and the colonies of fungi suspected of being the chestnut-blight fungus were marked at the end of three days. The count was completed on the fifth day, and any uncertain colonies. Please note that these images are extracted from scanned page ima
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