86 MANAGEMENT OF 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 
of the Artotrogus Debaryanus, and of the sterile fungus, several 
experiments have been made by steaming potsof earth, growing 
seedlings in them and then inoculating some of the seedlings with 
the fungus while other pots were kept as checks, and all were under 
like 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 
killed outright.” ‘ 
*Lodeman, Bulletin 96, Cornell Exp. Sta. 
