New York Agricultural Experiment Station. 329 



plants produced in a higher temperature have a tendency to a 

 spindling growth, and to lack the crispness and compactness of 

 lettuce grown in a cooler temperature. Plant lice become more 

 troublesome in a higher tetnperature than in a moderately cool tem- 

 perature. Extremes of heat or cold should be avoided, as also 

 should rapid fluctuations from one extreme to the other. 



2. As much ventilation should be given as possible and still 

 keep the temperature within the range just given. The crop suc- 

 ceeds best when it is given plenty of fresh aii". 



3. So far as possible water only on bright, sunny days, prefer- 

 ably early in the day, when the houses may be ventilated freely 

 so that the leaves, and especially the tender hearts, will soon dry. 

 Water standing on the leaves a long time offers favorable condi- 

 tions for the development of blight. Of course this caution does 

 not apply where sub-irrigation is practiced. 



4. The aphis (green fly) should not be allowed to get estab- 

 lished on the plants. .Just before the pot is plunged into the soil it 

 is turned upside down and the under side of tlie leaves, as well as 

 the upper surface, is dusted thoroughly with tobacco dust. The 

 plants are not watered over head for three or four days afterward to 

 avoid washing oS. the tobacco. About a week later the}' are dusted 

 with tobacco again, taking especial care to cover thoroughly the ten- 

 der foliage in the center of the plant. By free ventilation and keep- 

 ing the temperature cool, and by watchful care of the plants, not 

 waiting for the aphis to get established before fighting them, a let- 

 tuce house has been run at this Station all winter without fumi- 

 gating once. Fumigation should be used only as a last resort. 

 Keglecting the ventilation, neglecting the heating and neglecting 

 the cleanliness of the house and plants in general may be expected 

 to lead rapidly to conditions where the only remedy is fumigation. 



Summary. 



The growing of lettuce in pots is believed to have several advantages over 

 growing it in benches, namely : 



1. Plants may be marketed M'ithout disturbing their roots, and so 

 may be kept perfectly fresh for a long time, an advantage that is 

 much appreciated by retail dealers. 



2. As soon as a plant is removed from the bench its place may be 

 immediately filled with another potted plant, so that the entire 

 bench room may be kept constantly occupied. 



