DISEASES OF CULTIVATED PLANTS 679 



ease. The wild cherry trees, as well as the knots in the orchard, 

 should be removed if one wants to develop an orchard of plum or 

 cherry. 



The knots are due to a presence of a fungus in the growing 

 cells of the wood, causing an unusual development of those cells. 

 After the knot is formed the fungus produces spores of two kinds 

 one developing in the early part of summer (June), the other 

 towards fall. Both kinds cause new knots when they germinate 

 and have a chance to grow. The remedy is to cut out all knots in 

 the fall or winter, spraying in addition 'before buds start in the 

 spring, to kill any spores that may have lodged on the tree. 



General Directions. The fruit grower should look after his 

 own business and the interest of his investment in fruit trees suf- 

 ficiently to cut out and destroy such trees as may be affected with- 

 out waiting to be notified of their presence. It is impossible that 

 the State Horticultural Inspectors should visit all places in a year's 

 time. The owner or his tenant is on the place daily, and can keep 

 closer watch on the conditions than is possible on an occasional 

 visit on the part of an inspector. The owner should, as all good 

 orchardists do, know his orchard before and after the inspector 

 calls, and attend on his own account to the aids to the health of 

 his orchard which he knows are necessary in this region fungi- 

 cides, insecticides, cultivation and other improved methods of man- 

 agement. 



Judicious pruning of fruit trees is very essential the removal 

 of dead or drying, especially of diseased branches, should be at- 

 tended to as surely as the shoeing of the horses. The annual spray- 

 ing against fungi and insects should be as much a part of the year's 

 work as plowing. 



Piles of trash should not be left in or near the orchard or 

 other fruit fields. They harbor many insects and diseases, besides 

 being unsightly and useless. The brush fire is an excellent preven- 

 tive measure. A fall fire for summer's trash and a spring fire 

 for the prunings and trimmings from the orchard should be part 

 of every farmer's calendar. Burn all trash not of value for fuel or 

 stable use. Burn also the remains of rotten or dried up apples, 

 pears, plums and peaches left on the trees, or under them, by the 

 action of the rot fungi. It has been found that much of the rapid 

 spread of these diseases in the early spring and summer is due to 

 the spores holding over from the previous season on the partially 

 decayed fruits, or to the development of especially active spores 

 from fungi remaining dormant in these fallen mummies. Much can 

 be done to check this loss by destroying them before spring. 



In the case of field crops if any have had serious diseases 

 this season do not use the same crop on the affected fields next 

 year. Cabbage, cauliflower and turnips should not follow one 

 another in a field where club root, black rot or soft heart (heart 

 rot} has occurred, as each is affected by the same diseases that at- 

 tack the others. Potatoes and beets should not follow each other 

 for the same reasons on fields in which the scab is seriou,--. (Md. 

 E. S. Cir. 61.) 



