14 The Bulletin. 



the whole plant — root, stem and leaves — and even the soil, will be 

 found covered with a mass of fine cottony fibres. In a week or ten 

 days after the plant wilts the sclerotia or reprpductive bodies of the 

 fungus will have formed in the dead plant and soil. These lie in the 

 ground and carry over the trouble for the next crop. Each affected 

 plant should be removed, therefore, before it forms its sclerotia and 

 infects the soil. As a protection to succeeding crops, it pays to go 

 over the bed regularly and remove all diseased plants as soon as the 

 wilting is noticeable. It is found that the sclerotia spread the dis- 

 ease by throwing their spores on to the under side of the leaves. In 

 future experimental work it is intended to try the effect of mulches 

 in protecting the plants from infection. 



VARIETIES OF LETTUCE. 



There are more than one hundred distinct varieties of lettuce listed 

 in America ; of these, only the heading varieties are at present much 

 in demand. Loose lettuce, though of fine quality, does not ship well 

 and is little grown except in a local way. For winter lettuce-growing 

 the Big Boston variety seems to so well fill all requirements that it 

 is at present the leading commercial lettuce. 



FRAMES. 



Frames for winter lettuce-growing may be of any desired width 

 and length to suit the land to be used, but convenience seems to have 

 fixed their width into two standard sizes, viz., 16 feet for wide or 

 double frames and 9 feet for narrow or single ones. Three feet is 

 found to be a suitable width for passageways between the frames. 

 From this it can be seen that with the narrow frames one-fourth 

 of the. area is used in walks, and with the wide ones a little less than 

 one-sixth. For convenience in heating and irrigating lettuce and in 

 removing covers, frames are usually made about one hundred feet 

 long. Wide frames are best adapted to warm locations and are 

 often used with canvas covers, but without heating-pipes. The nar- 

 row bed& are specially adapted to steam-heating and forcing. On 

 our Truck Test Farm the frames are made 17 feet 4% inches by 

 104 feet 3-% inches, so as to include one twenty-fourth of an acre. 

 This makes them convenient in estimating yields and profits. The 

 ends of the frames are removable and are taken out when the beds 

 are being prepared for setting, so that horse cultivation can be given. 

 The rafters which support the cotton covers are 4 feet apart in wide 

 frames and 6 feet in narrow ones, and are also removable. Un- 

 dressed inch lumber 12 inches wide is used for construction of the 

 frames. (See Plans 1 and 2.) 



