224 



VEGETABLE FORCING 



Fig. 77. Pot grown plant ready for market. 



the crop as well as in marketing it, and can be used only 

 for local markets. 



Insect enemies. The green fly is recognized as the 

 most serious insect enemy of lettuce. It is controlled 

 almost exclusively by fumigating with tobacco or nico- 

 tine preparations, instructions for the use of which are 

 given on page 105. Fumigations should be made at regu- 

 lar intervals so there will be no possibility of the insects 

 becoming sufficiently numerous to damage the crop or to 

 impair its selling quality. 



The nematode sometimes attacks the roots of green- 

 house lettuce, though it is not regarded as a serious 

 enemy of this crop. 



White grubs may be troublesome in soils which have 

 not been steam sterilized. This is the larval stage of the 

 June bug or May beetle. Old compost heaps and manure 

 piles are favorite breeding places. The eggs or young 

 larvae may be introduced into the houses by infested soil 

 and manure, and the grubs may cause considerable injury 



