4 G. L. McNew 



activities of the cell. It has become increasingly self-evident that any- 

 one who understands the chemical processes of the living cell has the 

 potential power of regulating that cell's activities and its ultimate 

 incorporation into a tissue and thence into a functional organ. The 

 person who can control the activities of the living cell without de- 

 stroying its life can determine the ultimate fate of the individual 

 plant. 



This breath-taking concept has long since dropped from the realm 

 of human fancy and daydreaming into the reality of agricultural 

 practice. There is no really valid reason why the physiologists and 

 chemists should not eventually design molecules that will duplicate, 

 circumvent, block, or accelerate any and all the activities of the gene. 

 The great problem is to design such a molecule so it will operate 

 gently but specifically in the desired manner without disrupting 

 major vital processes. 



Probably the greatest handicap to achieving this Utopia of chemi- 

 cal control has been the simple difficulty of properly administering 

 the material so its effects will be felt over a prolonged period of time. 

 Exogenous chemicals have not yet duplicated the effect of genes be- 

 cause they are applied crudely in massive doses that are dissipated or 

 detoxified in very short order. What is needed is a relatively inert 

 chemical that will generate the proper regulant over a long period 

 of time as it is required in cell functions. 



The idea of a chemical that would generate a plant growth regu- 

 lant over a sustained period is not an impossibility. Those people 

 working with the dithiocarbamate fungicides, for example, have done 

 this very thing. Relatively inert dithiocarbamates that can be piled 

 on foliage in heavy doses without injury to the crop but which gener- 

 ate highly fungitoxic isothiocyanates as they are needed are now being 

 used to control fungous diseases of plants by the tens of millions 

 of pounds each year. The protectants are so ephemeral they cannot 

 readily accumulate in sufficient amount to injure plants as may occur 

 with a more stable material such as a copper fungicide. There is sub- 

 stantial evidence that several other organic sulfur molecules generate 

 toxicants for fungi and nematodes in situ. There is good reason to 

 believe that the entomologists have comparable tools in the organic 

 phosphate insecticides and miticides that serve as systemic eradicants. 



THE NATURE OF PLANT REGULANTS 

 NOW IN EXISTENCE 



Great achievements in plant growth regulation have come into 

 being by the use of relatively simple chemicals that have been dis- 



