Arizona republican., 1919-03-16

This later turns brown or black and | involves the entire thickness of the | leaf killing all the invaded tissue. | The other form is more conspicuous | end confines it's attacks to the larger ] veins or midribs of the leaves and the adjacent tissue. A water soaked i appearance is first noted. followed by a darkcning of the area infected and later the death of the tissue. This stage has been enormously termed rust by some of the growers. Squares are affected in the same man. ner as the leaves and frequently shrivel and dry up.
 The black arm type of infection is the more serious form of this dis ease. Conspicuous reddish brown areas are noticeable first which turn to dark brown or black color as the disease advances. Infection occurs at any time during the season and usually the stems branches, petioles of the leaves and the peduncles of the flowers are involved The bacterial eXudate is especially common when these parts are attacked. The effect is to cause a casting or shedding of the bolls or to so weaken the plant that the crop does not mature normally. Bolls are also attacked in the same manner as the other parts of the plant. The or ganism has been found penetrating the lint and even extending 10 the interior of the seed coat. It is by this means that the disease is carried over to the following season.
 Control Measures
 The control of this disease may be considered to be in the experimental stage as yet. In experiments conducted in Georgia and South Carolina during the past two or three years it has been shown that the most practical method of control is through the treatment of
 the seed. Several Egyptian cotton growers in Maricopa, Pinal and Pima counties are planning to treat their seed this season for a portion of the total acreage in each case in cO-opera
 ton with the writer in experiments he
 is conducting in the capacity of con-
 sulting plant pathologist of the Ari- Zona Agricultural Experiment station. | The object of the treatment is to kill all dormant forms of the organism that might be on or within the seed coa'. i Two methods used most successfully l so far are the hot water and bichlor- I ide Of mercury or corrosive sublimate | treatments.
 Hot Water Treatment
 1 This consists of immersing the seed | in a tub or vat of hot water for a | given period of time. The seed should
 be treated in lots of about a peck in
 order to quickly and uniformly reach
 the desired temperature. A perfor-
 ated tin pail, sack or a basket is
 used. The treatment will be greatly
 facilitated if two vessels are used
 The first should be used to bring the seed to the desired temperature ir order to not lessen the temperature
 when transferred to the second. Gal vanized tubs or boilers heated over { 1 kerosene or gasoline stove arc mos
 convenient. The temperature of botl
 vessels should be kept as near constan
 as possible, 150 degrees Fahrenheit
 being the standard. A reliable ther
 momcter Standard dairy thermomete
 recommended is therefore absolutely
 necessary. Should the temperatur,
 fall below 149 degrees F. or rise abov
 15S degrees F. the time of immersion
 should be increased or decreased ac
 cordingly. Dip the seed in the frs
 vessel and thoroughly agitate for on minute,N then transfer to the secon, vessel and leave fifteen minutes, Whel the time of immersion has elapse, drain quickly and spread the seed ou to dry CT plant within twelve hours Seed treated in hot water germinate readily and under some circumstance might be planted while still wet. l. case this is done the grower shoul allow for the increased weight of tll seed due to the absorption of water One pound of seed will absorb one fourth its weight of water.
 BichIoride of Mercury or Corrosiv Sublimate Treatment
 This consists of treating the see for one hour with a solution made C one part of bichloride of mercury { 1000 parts of water. One ounce c the material dissolved in seven an one-half gallons of water makes tn required strength. It is necessary use wooden, granite or earthen vessel I as the solution corrodes metal. Whe making the solution dissolve amour | necessary to use in a small amour of hot water then dilute to the re quired strength. Any quantity desire may be made at one time and use later as the solution does not deter ! iorate with age. Not more than thre
 lots of seed should be dipped into u
 same solution as the seed removes il bichloride of mercury thus weakenir the strength. It is advisable. to hay