68 . GARDENING FOE PROFIT. 



have occasionally become affected by a species of mildew 

 or rust, which, beginning in the center of the plant, 

 quickly spreads over the whole and destroys it. I am 

 not certain of the cause and can offer no cure except to 

 advise that great care should be taken to have the plants 

 grown freely and without any sudden check by chilling 

 or by the extremes of drouth and moisture. We find in 

 the culture of plants under glass that some species are 

 particularly sensitive to such checks some varieties of 

 the Rose, for instance, if, when in a particular condition 

 of growth, the temperature for a few hours is reduced 

 from sixty-five to forty degrees at night, or if a frosty 

 southeast wind is allowed to play on the leaves for even 

 ten minutes, or if allowed to dry so that the plant wilts, 

 mildew will to a certainty be developed in twenty-four 

 hours. The Verbena, Heliotrope and Petunia, when 

 subjected to ill usage, become badly rusted. Therefore, 

 I am inclined to think that the Lettuce disease is also 

 caused by some ill usage at some period of its growth, 

 for we find that it is rarely seen when the crop is grown 

 in the open ground in spring or summer. The prevent- 

 ive suggested is that plants to be forced should be pre- 

 pared so carefully that no sudden check is given, and 

 also that the soil used on the benches be fresh, and the 

 manure used be thoroughly rotted and well mixed through 

 the soil. 



To CHECK THE APHIS OR GREENFLY. Fumigating 

 with tobacco should be done twice each week, beginning 

 the very day the plants are planted in the bench. In 

 fumigating we use refuse tobacco stems, about two pounds 

 (dry) for every 1,000 square feet of glass, damping, how- 

 ever, before using, so as to get the greatest amount of 

 smoke. For fuller particulars on this head see chapter 

 on " Wide Greenhouses for Forcing Vegetables." 



The first crop is ready about November Itt, and is 

 cut off and sold in two weeks ; the soil on the benches is 



