Miscellaneous Uses 299 



thaleneacetic acid treatment to torce flowering has been found to 

 alleviate this situation. 



AUXIN THERAPEUTICS 



Inhibitory influences ol auxins are not restricted to higher plants, 

 but fungi, bacteria and virus organisms have been inhibited by aux- 

 ins in a variety of instances. In a few cases these inhibitions are 

 direct, but more generally the auxins seem to alter the constitution 

 of higher plants in such a way as to discourage the growth of para- 

 sitic microorganisms. 



An auxin inhibition ol bacteria (ontaminating mold cultures has 

 been reported by Stevenson and Mitchell (1945), and the possibility 

 of controlling bacteria in PenicilUum cultures was suggested. 



Limasset et al (1948) reported that auxin could inhibit X and 1' 

 virus in tobacco. This was repeated using mosaic virus by Kutsky and 

 Rawlins (1950). It is interesting to note that naphthaleneacetic acid 

 and indolebutyric acid were effective against the virus, but several 

 other auxins were without effect (Kutsky, 1952). 



One of the most promising therapeutic uses of auxins is against 

 fungal parasites. In studying apple canker, a disease caused by 

 Nectria galligerna, Crowdy (1948) hoped that auxins might help to 

 heal over the canker lesions. The application of indolebutyric acid 

 produced rather startling therapeutic effects. This led him to measure 

 the effects of the auxin upon growth of the organism in pure culture, 

 but he found little toxicity there. The treatment of bean plants with 

 a variety of phenoxyacetic acids led to the further discovery that the 

 chocolate spot disease, caused by Botrytis cineraea, was effectively 

 prevented by auxins and by anti-auxins, especially 2,4,6-trichloro- 

 phenoxyacetic acid and 2,4,6-trichlorophenoxyisobutyric acids (see 

 chapter VII) (Crowdy and Wain, 1950, 1951). Applied to the roots, 

 these materials move through the plant, probably in the transpiration 

 stream, and act as systemic fungicides. The use of stronger auxins is 

 complicated by excessive epinastic and distortive effects, whereas these 

 compounds have much less formative effects on the host plant. Similar 

 control of fusarium wilt (Fusariiim oxysporum var. cubense) has been 

 obtained with a variety of auxins (Davis and Dimond, 1953), even 

 though the fungus is not particularly inhibited by the auxins (Hes- 

 sayon, 1952). Davis and Dimond (1953) conclude that the metabolism 

 of the plant is altered in such a way as to resist the pathogen. 



The lack of correlation between auxin activity and systemic fungi- 

 cidal action is puzzling. Some anti-auxins are effective against the 

 chocolate spot of bean; phenyl acetic acid, which is a weak anti- 



