THE PLANT WORLD 93 



The Home Garden and Greenhouse. 



Conducted by F. H. Knowlton. 



[The editor of this department will be glad to answer questions of a rele- 

 vant nature, and also to receive short articles on any phase of this subject.] 



Necessity for Tillage. — An important point has been made in recent 

 years regarding the necessity of keeping the soil light and loose about 

 growing crops, but the reasons why this is so do not seem to be widely 

 understood. The following succinct statement is taken from Farmers' 

 Btilletin 161 on Practical Suggestions for Fruit Growers, by H. P. Gould, 

 and while primarily applying to care of orchards, is of much wider ap- 

 plication. He says : 



"The offices of tillage are several. Among the most important are: 



1. The setting free of plant food by increasing the activities in the 

 soil. 



2. The soil is made finer and hence presents greater surfaces to the 

 roots, thus increasing the area from which the roots can absorb nutri- 

 ment . 



3. The surface of the soil is kept in such condition that it immedi- 

 ately absorbs all the rain that falls during the summer, when it is apt 

 to be dry. Little is lost by surface drainage. 



4. Moisture is conserved thereby. When the surface is undisturbed 

 for weeks the soil becomes packed, so that the moisture from below 

 readily passes to the surface and is evaporated, thus being lost to the 

 growing crop. If the surface is kept light and loose by tillage, so that 

 the capillarity is broken, but little of the soil moisture comes to the 

 surface and evaporation is not so great. In this way nearly all the 

 moisture remains in the soil, where it can be used by the plants. 



5. Thorough tillage has a tendency to cause deeper rooting by the 

 plants. The surface of the soil is made dryer by tillage during the 

 early part of the season than it would otherwise be ; hence the roots go 

 where the soil is moist. The advantage of deep rooting during drought 

 is obvious." 



Insect Pests. — The insects that are most likely to make trouble for 

 house plants and plants grown in greenhouses are the aphis or green fly 

 and the so-called red spider, either of which will speedily destroy the 

 plants unless checked. The green fly can easily be kept down with a 

 tobacco preparation, either by burning the leaves or by using a fine powder 

 made of the ground-up leaves and stems. One of the most satisfactory- 

 preparations on the market is that known as aphis punk, which comes 

 in the form of rolls of paper impregnated with tobacco. A single piece 

 will kill all the green flies in a house 10 by 20 feet except possibly a few 

 that may be hidden deep in half -opened flowers. The punk should be 

 dampened before use and should not be permitted to blaze, but simply 



