52 



i'LANT 1'KO1'A(.:AT10i\ 



Tliiekivia basicoht ;iii(l L'liuiiiu bclicola. J'.y c.Npcriniciitiiii; with soil 

 infested with Pytliium ilcbtirytiiiiiiii. licating to 130 to 212 dej^rees 

 and treating with 20 to oO i)cr cent solutions of formaUn and various 

 quantities of carhon liisulpliidc, he found that Canielina, a plant 

 very susceptible to attacks of this fungus made good growths, the 

 action of this fungus being reduced even to nothing. 



79- Damping-off seedlings in plant beds, according to the Minne- 

 sota station, is commonly caused by Pythium debaryanum or Rhizoc- 

 tonia. These attack a large variety of plants as well as live upon 

 dead organic matter in the soil. Very little can be done to check- 

 the disease when such conditions prevail. Therefore methods which 

 kill fungi are needed to prevent the disease. The preventive 

 methods must be applied before sowing the seed, otherwise the seed 

 will be killed also. 



FIG. 43— WORK IN THE CUTTING BENCH 



1. Opening a furrow with a wooden label. 2. FIrmino the cuttings 

 sand, side view. ?>. End view. 4. Removing rooted cuttings for potting. 



Chemical agents have been tested as fungicides against damping- 

 off, but of these formalin alone has proved of value. Treatment of 

 the soil with formalin (one part fonnalin to 100 of water and lesser 

 strengths), as frequently recommended, does not kill the fungus. 

 Although it may check the disease for some time it will allow damp- 

 ing-oflf to develop later if weather conditions permit. The value of 

 formalin at these strengths, therefore, depends largely on the time 

 weather conditions favorable to damping-off appear. 



