Arizona republican., 1921-04-18
Treatment Of Cotton Seed For
 Black Arm Outlined By EIpert

Tinted, for then small air-bubbles protect the organism Even when the lint stubs are so short that they are invisible to the naked eye. seeds treated with formalin or mercuric chloride often carry over the organ ism unharmed.
 Infection of the plants in the field appears to be through the stomata or breathing pores" of the green parts and also through wounds made by insects that attack the plant. Just how it is spread is not certainly known. Insects probably help. Cot ton plants often show numerous in- sect visitors such ants, bees, and grasshoppers. In all probability man is also an agent of dispersal. Imple- ments used in cultivating the cotton crop undoubtedly spread the disease to a certain extent A cultivator dragging an infected plant against a
 moist healthy one probably would ! frequently communicate the disease | to the latter. Whether irrigation
 water may act as a carrier is not
 known. It is known, however. that | the seed is a very important means of spreading the disease from field
 to field and from farm to farm. Every culture that the writer has
 made this year, using seed from last
 years crop, shows abundant infec-
 tion, and fields that were planted
 near Tucson last year on ground that
 had never before borne a crop of
 cultivated plants were badly infected
 with black-arm orsanizm.
 Since the seed appears to be the most important agent of dispersal, seed treatment is the most effective
 means of combating black arm. The only method of treatment that has proved successful is the sulphuric acid treatment. This treatment is
 best carried on in the following man. ner: A large stone crock holding 1o to 90 gallons, according to the
 amount of seed to be treated, is partly filled with sulphuric acid. Con-
 centrated acid must be used to obtain the best results. A second crock that has been drilled with numerous
 openings about an eighth inch ir
 diameter through the bottom and
 sides is then filled with seed and
 immersed in the sulphuric acid for
 from Is to 20 minutes. Twenty min utes is the longest time that the seed can be left in the acid with safety In the meantime the seed is con-
 stantly stirred with a wooden ladle The acid entirely removes the iin'
 and at the same time kills the bac-
 terium that is responsible Tor DlacA'
 arm. At the end of Is or 20 min utes the perforated crock is hfte- from the acid, and after the acid ha! , drained off the seed, the contents art
 rinsed with water. The rinslug mus be done carefully with q large amour of water, otherwise heat sufficien- t' iniure the seed will develop. A bar : rel standing at hand filled With xate may be used by plunging the perfo : rated crock containing the seed int ] it, or a large hose with good wate } pressure may be utilized. The see' is then spread out to dry on can . vas and covered in order to preven re-infection by flying particles
 lint and dust.
 S The sulphuric acid method f treating cotton seed appears to be heroic one. both as concerns tn : operator and the seed. That 1t in ; wolves danger to the operator IS cer ', ltainly true. However, many farm i ling operations are dangerous Tn a writer remembers the many accident
 that happened on the farm even l
 the commonplace operation Of WOO Q chopping. Some farmers, a few who's . names finger in memory, evldentl = solved the problem to their own sat
 tisfaction at least, by leaving the DO e to their wives. This plan probabi a should not be followed in treatin t cotton seed with sulphuric acid, al 't though it is likely that many house a wives who are used to such opera - tions as the handling of scalding- hC O fruits during the canning seaso 'I would prove perfectly capable (
 sterilizing cotton seed without injur . either to themselves or the seeo K So far as the seed is cDncerne e percentages of germination as hig = as 97. 5 per cent of treated seed ha' " been obtained in the plant patholoG ' laboratory of the Arizona Experimel ,s Station. "a Several precautions then must l observed in the sulphuric acid trea ., ment of cotton seed. In the fir - place the acid eats into both lies .d and clothing very quickly. Care mu .e be taken never to touch the acid 70 the acid-coated seed and vessel ,t and drops of acid must not l. splashed up in stirring. Childre 2 should never be allowed around u ,e place where the process is under va De Vessels used must be glass or croci at cry. for the acid destroys meta ly very easily. When the process 1s finished. acid and vessels should re locked up until they can be attend' ,h to later. the former safely sealed mt glass bottles and the latter tho
 
 a. oughly washed with water.
 st A second precaution is necessa
 in order not to undo the work of al nt injecting the seed. After seed ne treated it must never be handl
 with the same vessels that are us re for the untreated seed. If one us rs his hands in scooping up the Il iie, treated seed and later handles | lu treated seed with them, he m . partly undo the work that has ju of been completed. A scoop should I'- used for the untreated seed and i3 clean piece of board for leveiling { .s bile of treated seed. Both kinds sb seed should never be handled wi ce the same vessels, tools, or implemer
 without sterlizing the latter. Ste
 ilization of vessels may be accom-
 lished by dipping them for a f'