Only limited information on the metabolism of therapeutants in roots is available. 
For example, all of an actidione derivative applied to tomato roots were altered, but the 
therapeutic part of the molecule apparently remained intact and moved upward (16, 28). 
An interesting similarity in the metabolism of a group of therapeutants by animals and 
the roots of plants has been demonstrated by Jones and Wignall (26). In animals the 
detoxification of sulphonamides has been attributed to acetylation of the free amino group 
(19). This same chemical change occurred in roots of broad bean when these compounds 
were used as plant therapeutants (26). 
Application to Fruits 
At present there is only a very limited amount of published information on the fate 
of therapeutants applied to fruits. Rapid inactivation of actidione occurred when very 
low but therapeutically effective amounts were sprayed on cherry fruits. In cool weather 
this therapeutant was changed much more slowly but, even so, half of it disappeared in 
about 24 hours (54). The rapid breakdown in the fruits contrasts sharply with the 3 weeks 
required when the chemical was in leaves (18). 
Placed directly on isolated spores of the Penicillium that causes citrus fruit rot, 
the compound GS-1 killed spores ata 1 p.p.m. concentration. In contrast, even 500 times 
this amount of chemical failedto control the disease when the spores were on the fruit (8). 
This great loss in fungitoxicity is thought to be due to an enzymatic process that occurs 
in the fruit rind and changes in the chemical to an inactive form. 
In summary, when considered as two groups of compounds, growth-regulating 
chemicals and therapeutants differ widely with respect tothe amount required, the ability 
of the plant to transport these substances, and in the final distribution of the compounds 
in the plant. Regulating chemicals and therapeutants are alike, however, in the fact that 
most plants can readily absorb and metabolize both types of compounds. To use these 
substances most effectively, much more research is needed to understand not only the 
primary reactions between these compounds and plants, but also to characterize reaction 
products that result from their metabolism. 
LITERATURE CITED 
(1) Anderson, H. W., and Nienow, I. Phytopath. 37:1. 1947. 
(2) Audus, L. J. Nature 166:356. 1950. 
(3) Blanchard, F. A., and Diller, V. M. Am. J. Bot. 38:111. 1951. 
(4) Crowdy. S.H. Ann. Appl. Biol. 45:208. 1957. 
(5) Crowdy, S.H., Gardner, D., Grove, J. F.,andPramer, D. J. Exptl. Bot. 6:371. 1955. 
(6) Crowdy, S. H., and Jones, D. Rudd. J. Exptl. Bot. 7:335. 1956. 
(7) Crowdy, S. H., and Jones, D. Rudd. Nature 178:1165. 1956. 
(8) Dekker, J., and Ark, P. A. Proc. IX International Botanical Congress, Montreal, 
Canada:88. 1957. 
(9) Dekker, J., and Ark, P. A. Antibiotics & Chemotherapy 9:327. 1959. 
(10) DeRose, H. R. and Newman, A. S. Proc. Soil Sci. Am. 12:222. 1947. 
(11) Dimond, A. E., and Horsfall, J. G. Ann. Rev. Plant Physiol. 10:257. 1959. 
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