GREENHOUSES FOR FORCING VEGETABLES. 77 



of November will not be fit for market until about the 

 Christmas Holidays, at which time it usually sells well. 

 For the third crop, to be planted in January, the plants 

 made by the sowing on the 20th of September should be 

 used. This crop, which has to be grown in midwinter, 

 will not be ready, if planted the first or second week in 

 January, until about the first of April. 



One of the greatest pests in growing Lettuce is the 

 Green Fly or Aphis, and the remedy must be preventive, 

 for if it once gets a foothold on the growing plant, it can- 

 not be destroyed. From its operations being mainly on 

 the under side of the leaves, nothing can reach it ; con- 

 sequently every insect must be destroyed before planting. 

 Tobacco in any form is destructive to it. So before 

 planting let the surface of the soil be sown over with 

 tobacco dust, and also let the young plants be rinsed in 

 water wherein tobacco stems have been steeped long 

 enough to give it the color of strong tea. By using these 

 precautions there is little danger that the Lettuce will 

 be attacked by the insect, although, as a further measure 

 of precaution, it will be well to strew the paths with 

 refuse tobacco stems, which will make a complete anti- 

 dote against the Aphis. There is another disease often 

 affecting Lettuce, with which, however, it is not so easy 

 to cope. It is first seen by the leaves hardening and 

 spotting brownish red, then gradually decaying towards 

 the center of the plant until it partly destroys it. The 

 cause seems to be anything that gives the plant a check 

 any too sudden change of temperature, too much dry- 

 ness or too much moisture. There is, I think, no remedy 

 after the disease has once started, so our efforts must be 

 for prevention. (See page 68). 



Mr. Hudson has used some of his greenhouses for 

 growing the Early Round Dark Red and the Small- 

 Topped Forcing Radish, which he finds better suit- 

 able for forcing than any other. These are first sown 

 about the first week in October, succession sowings being 



