LEADING VEGETABLE CROPS I69 



of-door conditions. Plants are usually set from 6 to lo 

 inches apart in the rows and the rows from 12 to 15 

 inches apart, depending upon type and variety 

 grown. Hand cultivation with the wheel hoes is 

 depended upon almost entirely. 



It is a good plan to heavily manure with well- 

 rotted compost in the fall of the year and plow 

 under, leaving the soil roughly ridged over winter. 

 This will permit of quick drying out in the earlier 

 spring, when the soil may be readily prepared for 

 planting much earlier than otherwise would be the 

 case. Lettuce may be transplanted to the open, 

 when the plants have been properly handled, as soon 

 as it is possible to prepare the soil. The plants will 

 stand from 20 to 25 degrees below freezing without 

 serious injury. A location comparatively free from 

 weeds should be selected when possible in order to 

 lessen the expense of cultivation and hand weeding. 



Abundance of moisture should be supplied, for the 

 value of the crop depends directly upon rapid 

 growth. No crop will give better results with irri- 

 gation than lettuce. Crops should be ready for har- 

 vesting from five to seven weeks after started in 

 the open. It is cut and packed in baskets, hampers 

 and ventilated barrels. The type grown and the 

 market supplied will largely determine the type of 

 package to be used. 



The lettuce is troubled with two or three serious 

 enemies, the most common and persistent of which 

 is the green aphis. This pest is much more destruc- 

 tive under greenhouse conditions than in the field. 

 It is a sucking insect and can be destroyed most 

 readily by the use of tobacco in some of its various 

 forms. The common treatment in the greenhouse 

 is to burn quantities of tobacco stems or vaporize 



