Studies on Fungicides — III 



67 



Figure 4. sphere of influence of spore excretions 



a, A slide with a dried drop Oi bordeaux mixture and five drops of 

 spore suspension, b, The same, with the drops connected by a film or 

 bridge of water 



To increase the distance and the number of spores, petri dishes were 

 employed. A drop of bordeaux mixture was placed near the edge of a 

 dish. On an arc of a circle 2 centimeters distant, three drops of spore 

 suspension were pipetted, each drop as far away from the others as 

 possible. In addition, three drops were placed on three other arcs, 

 which were respectively 4, 6, and 8 centimeters distant from the bor- 

 deaux area. The spores were given time to adhere to the glass. This 

 series also was carried in quadruplicate. 



The drops on 1 he slides were connected by a film of water, as was done 

 in the preliminary experiment. With the petri dishes, the whole was 

 flooded with a thin film of water. Germination tests were made in the 

 usual maimer, and the average results for each series are recorded respec- 

 tively in tahles 10 and 17. A control similar to that in the preliminary 



TABLE Hi. Percentage Germination of Sclerotinia amkkicana Conidia at Varying 

 Distances prom an Area of Dbied Bordeaux Mixture (Kfokf-Scspension Drops 

 and Bordeaux Drop Placed on Slides and Connected by a Bridge of Water) 



