Vol. 16—1962 - NorthEastern Weed Science Society

Vol. 16—1962 - NorthEastern Weed Science Society Vol. 16—1962 - NorthEastern Weed Science Society

08.06.2015 Views

26 some damage to .test: crops. Granuw Or directeOgt..emergence .tna~.,a~ lay-~ may :hold prOlllise. ;: . •. . '. :' . . .. }. . ,:. ~,.: . . '" ." ."f :', : The thiolcarbamates continue to be promising as exce~lent. her~ici~[~n. a number of weed-crop situations. The high activity of several' of these compounds as pre-eme1"!Wncetreat.nts .'1Ul.dthel.owllc.t~·tY'as post.,.eJI)erpnce ,treatments add to the versatilftj 'of' possible l18eii~" Soil-incQriJoration and fol'llh,tlation.stlldies arecontilll.liq -rapidly_ R-1607 (propyl di-,e-proPYlth10lcarbamate) .an4a-1870 (eth1l-di-~~J..:" thiolcarbamate) appear particularly promising in a aeries of vegetable, leaf', .salad, 'and cole .cropeas ,pre-pluting soll-inc~t;l.pnor pr.-emer~ treatments" R-l6o?ia report~.J":I'1 promiains'~-l!I01beans ,as a pr........ ~e treatment; with the granular f'OI'lIIUlation superior,to~eemulsif'iablec0DPJ8n'" trate spray formulation. ':' The 6>1b/A'rate of R-2061(p:I'OPyl eth1l-,e~~lthioloarballla~) l.ooks go:od as. a :.pOtJlt...tanaplant tr •• ~t in "tomatot,.. ,peppers •. and str~berr~.a . at 6lb/A; . ~ep.riOdof

27 CELLSTRUCTUREANDPLANTGROWTHCRMONEACTION ArthlW W. Galston l The Chemical control of pJ.Qil groWth is largeJg.~ empirical art which has only occasionally approached the level of a pre~table science. This empiricism is largely a consequence of our imperfeot unqerstanding of the nature of· the action of growth reg~ator,y chemical~ .such as the auxins.and gibberellins. It is a constant source of embarrassment to plant physiologists and biochemists that roughly 35",~s after the disoove1'!Y of auxins we are . still completely unable to. describe their mode of. &lotion in plant cells. Lest we become too humble and emba;rrasaed about this sta!te of affairs, it 1s well to recall that nowhere in biochemistr,y or phys1010gf :l,.sthere complete understanding of the mode of action of any honnone} even such well known systems as insulin have not been definitely pin-pointed biochemically. This has caused some people to wonder whether if, in invelitigating the mechanism of hormone action, we have not been barking up the wrong tree. All of us have been looking for chemical effects, and in order to lilXPlain the ver,y great efficacy of very few molecules of the honnone,we have tended to assume that the hormone either becomes part of an enzyme systelll; or controls the action of an enzyme system. Only in this way, it has been believed, can we . get the proper amplification to pe:nnit relatively large biological effects to be produced by a small number of molecules. Nonetheless, this line of. reasoning has been most unrewarding in the past and In fact we still know of no honnone whose action can be oompletely explained with reference to ~ partioular enzyme system. Perhaps a part of the reason for our ignorancElof the mode of action . of honnones lies in the fact that we are only now beg!nntng to understand the structure of the ver,y complexl1llichine which we call the living cell. Just as one could not hope to understand the funotioning of an automobile engine without knowing in detail the structure of its component parts, M the student of any aspect of cell physiology cannot hope to be able to supply definitive answers without an intimate knciwledge .of the structure of the cell and of its component parts, In recent years a revolution in our understanding of cell structure has resulted from. 1;tle systematic applicat+on of electron miorosoopy and ultra-thin sectioning to tJ1e ,study of various cell types. BeeauseI believe that this new info~t:l,.on is basic to any discussion of oell physiology and of auxin action, ! shall preface IIl;y remarks with a brief description of our modern view of tpe plantoell. In so doing, I would like to remind you that while the o~nar,y light mioroscope is able to give us magnifioations in the range. of 1,000 diameters with a resolution dOlm to '.2 mierons, the eleotron lIIicrosoope has already given us olear pictures at 150,000 diameters magnif1~ation with a resolutipn of 0.003 microns. In faot the theoretical limit of resolution, being based on the wave length of the radiation employe~ can be imprpved still further by two orders of magnitude , This clearly brings us liown to the range of molecular dimensions. We should therefore expeot ~t ~thin the next several decades, the ~stematic improvement of elec~onMicroscopy and related. techniques will permit us to have a fairly qetailed view of the

26<br />

some damage to .test: crops. Granuw Or directeOgt..emergence .tna~.,a~<br />

lay-~ may :hold prOlllise. ;:<br />

. •. . '. :' . . .. }. . ,:. ~,.: . . '" ." ."f :', :<br />

The thiolcarbamates continue to be promising as exce~lent. her~ici~[~n.<br />

a number of weed-crop situations. The high activity of several' of these compounds<br />

as pre-eme1"!Wncetreat.nts .'1Ul.dthel.owllc.t~·tY'as post.,.eJI)erpnce<br />

,treatments add to the versatilftj 'of' possible l18eii~" Soil-incQriJoration and<br />

fol'llh,tlation.stlldies arecontilll.liq -rapidly_<br />

R-1607 (propyl di-,e-proPYlth10lcarbamate) .an4a-1870 (eth1l-di-~~J..:"<br />

thiolcarbamate) appear particularly promising in a aeries of vegetable, leaf',<br />

.salad, 'and cole .cropeas ,pre-pluting soll-inc~t;l.pnor pr.-emer~<br />

treatments" R-l6o?ia report~.J":I'1 promiains'~-l!I01beans ,as a pr........ ~e<br />

treatment; with the granular f'OI'lIIUlation superior,to~eemulsif'iablec0DPJ8n'"<br />

trate spray formulation.<br />

':' The 6>1b/A'rate of R-2061(p:I'OPyl eth1l-,e~~lthioloarballla~) l.ooks<br />

go:od as. a :.pOtJlt...tanaplant tr •• ~t in "tomatot,.. ,peppers •. and str~berr~.a .<br />

at 6lb/A; . ~ep.riOdof

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