86 MANAGEMENT OK THE FORCING-HOUSE. 



Methods of controlling greenhouse pests by fumiga- 

 tion.* The insects and the fungi which seriously injure 

 greenhouse plants are comparatively few in number, but if 

 allowed to develop unchecked they are capable of entirely 

 ruining every susceptible plant in the houses. There are 

 some plants which are almost entirely free from such 

 attacks, but they form isolated exceptions to a very gen- 

 eral rule. All who have had any experience in growing 

 plants under glass know that diseases are sure to appear, 

 and that insects will originate apparently from nothing. 

 Indeed, so certain are these pests to appear that every 

 thorough gardener is at all times prepared for them, or 

 even takes steps towards their destruction before they 

 have been seen. Fortunately, he has at his command 

 abundant means of protecting his plants, and houses in 

 which insects or fungi are found in large numbers are 

 silent but convincing witnesses of bad management and 

 neglect. When a greenhouse has once become thor- 

 oughly infested, it is almost impossible to rid the plants 

 of their parasites, and it requires constant and prolonged 

 attention to bring about this result ; and even when this 

 has been done, the plants will in many cases have be- 

 come so weakened that they will scarcely repay the time 

 and labor employed in saving them. The care of plants 

 should begin before they are attacked, and this care 

 should be given uninterruptedly. By treating apparently 

 uninfested plants many invisible enemies may be de- 

 several hours, it could be sterilized, and the finer and more delicate 

 seedlings be grown then with little danger if subsequent care was 

 used to not introduce soil from the beds. In testing the virulence 

 ol the Artotrogus Debatyanus, and of the sterile fungus, several 

 experiments have been made by steaming pots of earth, growing 

 seedlings in them and then inoculating some of the seedlings with 

 the lungus while other pots were kept as checks, and all were under 

 }ke conditions with respect to moisture, temperature, etc. The seed- 

 lings which were not supplied with the fungus remained healthy, 

 while those supplied with the fungus were diseased and many were 



*Lodeman, Bulletin 96, Cornell Kxp. Sta. 



