70 Tke Bulletin*. 



we find that it kills out the young grass and weeds so effectively and stirs the 

 ground (lightly) so close up to the young plants that it is a very great benefit 

 to tliem. At the same time let lis remember that such rapid early cultication is 

 very annoying to cut-worms, cotton root-louse and other underground insects, so 

 that by this practice we not only encourage the crop but we discourage its insect 

 enemies. 



8. KoTATTOX. — A wisely planned, carefully carried out system of crop rotation 

 is always advisable. It helps the land by resting it from the exhausting eirects 

 of a single crop, it results in much larger yields per acre, and it makes the growth 

 90 strong and vigorous that slight injury by insects is quickly outgrown and 

 consequently scarcely noticeable. Rotation is discouraging to insects that live 

 underground or to insects which do not move freely from jjlace to i)lace. Further- 

 more, "when a rotation is followed tlie acreage in each crop is apt to be reduced 

 and the value per acre is increased at the same time, so that we can more easily 

 and with greater profit use more expensive and more effective measures of control. 

 For instance, with cotton boll-worm, if one has 100 acres in cotton only making 

 one-third of a bale per acre, he could not afford to go to very great expense to 

 combat boll-worm. But if he has only thirty-three acres, making a bale per acre, 

 he could well aiVord to go to the expense of dusting over all the plants with 

 poison or use other expensive measures, for his crop would justify it. Further- 

 more, if one man makes only one-third bale per acre, and boll-worms were to 

 destroy one-fourth of that, he would have only a very unprofitable crop left. But 

 if by practicing rotation he has worked his land up to a bale per acre, even if the 

 boll-worm destroyed one-fourth of his crop he would still have a profitable crop 

 left. 



Summary. — These considerations show us plainly that even though we may not 

 consider it worth our while to give special attention to every pest which may 

 attack our crops, yet it is abundantly worth while to put in practice such methods 

 as will actually make larger crops anyway, and which will at the same time 

 reduce the damage from insects. Injuries from insects usually seem worst on 

 crops that are not doing well. All that we can do to grow big crops will make 

 our losses from insects relatively less. The man whose land is held steadily 

 at a standard of a bale or more of cotton per acre, or sixty bushels or more of 

 corn per acre, is not usually the one who complains most of insect damage to 

 cotton and corn. 



DISEASES OF PLANTS.* 



F. L. STEVENS. 



The loss incurred from plant diseases is often underestimated by the farmer; 

 passes unrecognized, or is regarded as natural and inevitable. As a matter of 

 fact plant diseases are exceedingly destructive, and the difference between profit 

 and loss on a given crop is often traceable to the way in which the plant diseases 

 are handled. In general, plant diseases may be described as including all rots, 

 molds, blights, mildews, rusts, smuts and spots of various kinds. Many of these 

 depreciate the value of the yield or cause its loss during storage. Leaf spots, 

 blights, etc., reduce the amount of green matter of the leaf, and thereby reduce 

 the starch-making power of the leaf. Tlie purpose of the loaf is to produce 

 starch, to nourisii the wood, twigs and fruit of following months and years. If 

 the green portion of the leaf and its starcli-producing power be destroyed future 

 yields must suffer accordingly. The number of diseases of the nature under dis- 

 cussion is very large. There are several hundred serious and injurious plant 

 diseases. Of "these niany can be prevented by proper treatment, although, of 

 course, there are many others for which no satisfactory treatment is known. 

 The treatment is based upon our knowledge of the nature of these diseases, most 

 of which are caused by parasitic bacteria or fungi. Bacteria and fungi are very 

 small living organisms which grow upon or in the crop plant, draw nourishment 



•The Illustrations are loaned by MacmiUan Co.. from Stevens & Hall's book, Disease of Plants 



