Arizona republican., 1921-10-22
Five Diseases Cause Damage
 In Cotton Fields of Arizona

grown a cotton crop in 1920 In the latter, black arm is bad in untreated rows and fairly abundant in adjacent rows. but shows Up only to a slight extent in isolated rows planted with treated seed. This experimental plot was planted on land strewn with bolls from the previous crop which may account for the slight develop ment of the diseases caused by Bac- terium maivacearum, in rows planted with treated seed.
 Root rot caused by Ozonium omni- vorum presents a more difficult prob , lem. For years this disease has ray aged many of the cotton districts of the South and it is very prevalent in ! Arizona, not only in cotton fields. | but alsorin alfalfa fields and in or | chards. Its symptoms are too we'll known to require detailed description. | Most growers are familiar with the sudden wilting of cotton plants and with the appearance of the routed roots with their coating of dirty white or brownish strands of fungal filaments. Since the fungus lives in the soil, ordinary sterilizing agents are not to be thought of. It is prob able that the soil is not worked enough in many farms in Arizona. Thorough working of the soil. thus increasing aeration, together with crop rotation using such immune plants as corn, millet wheat and sor- ghums, appears to be the only treat ment that is at all likely to be sue
 cessful.
 Scofield's recent work appears to
 show that the common belief among agricultralists that spots infected
 with the root rot fungus re-appear from one year to another in exactly the same location is not always true.
 The suggestion of Sheer and Miles
 that infection of farm lands may
 follow the removal of soil from an
 infected field and its transferral to
 other fields for the purpose of bac-
 terial inocculation is worth consider ation. The rapidity with which Tex as root rot is spreading in Arizona is alarming. Some idea regarding
 the extent of it's raVages on a ! given area of soil may be gath cred from the results of actual counts l of cotton plants killed on the Sahua- 1 rita plot near Tucson where one i hndred and eleven large plants were l killed within twentytwo days on a l space of approximately one half acre.
 Sore shin is essentially a disease | of the young cotton plants charac- l ANA A<-Nb ny rusty lGSAoAlS lAa0l bGAO VI the surface of the soil on the stalk.
 Like the Texas root rot, that disease 1 is caused by a soil-dwelling fungus 4 and the course to be followed in l combating it is a similar one. No l figures appear to be available as to 1 the extent of losses in Arizona due | to this fungus, but reports from T farmers indicate a rather heavy loss
 when conditions are favorable for the ' disease. It should be remembered
 that conditions favorable for any !, disease usually are conditions un- favorable for the crop concerned
 Plants like animals ere usually much 5 more susceptible to attacks of para sites when they become weakened , by unsuitable conditions of nourish
 ment ventilation, and temperature
 When farmers realize this fact, losses l from plant diseases will show a de ! crease and agricultural bank ac- ' counts will correspondingly profit.