192 Perspectives in Microbiology 



biotics, undergoes fairly rapid destruction in soil (30). 

 Although this evidence does not exclude the possibility of 

 some control of the soil population by antibiotics, particu- 

 larly root disease microorganisms, it limits very much the 

 conditions under which the population can be controlled. 



Provided that antibiotics are available, they can be ab- 

 sorbed and translocated through the plants. Here is one 

 more evidence of absorption of organic materials by plants. 

 Pramer (28, 29) and Crowdy and Pramer (7) observed that 

 basic materials move less rapidly than neutral or acidic 

 ones and that uptake is more rapid by cuttings than by 

 rooted plants. Furthermore, absorption and translocation 

 vary with the plant species and the environmental condi- 

 tions. Once absorbed, streptomycin and griseofulvin, and 

 doubtless others, persist in plants. Active material, which 

 was presumably the streptomycin with which the plants 

 were treated, has been detected in plant tissue ten weeks 

 or more after treatment (36). 



Nickell (25, 26) reported that the addition of certain 

 antibiotics to soil resulted in increased growth of plants 

 during early stages of development and that antibiotics 

 increased germination of some seeds. 



This type of response awaits confirmation,^ but there is 

 ample evidence that many plant diseases can be controlled 

 by use of antibiotics (21, 43). In our laboratories, Robison 

 has successfully controlled a bacterial wilt of chrysanthe- 

 mum with streptomycin (36). Many of the antibiotics are 

 effective systemically. Treatment for control of plant dis- 

 eases may consist of adding the antibiotic to the seed or to 

 the cut shoot, to the soil or sand substrate, or as a spray or 

 dust to the aerial parts of the plants. Downward movement 

 through the plants is slow, and this limits treatment of the 

 top parts of plants for control of root infections. The po- 

 tentialities of antibiotics for control of plant diseases appear 



2 In a recent report Barton and MacNab (Effect of antibiotics on plant 

 growth. Contrib. Boyce Thompson Inst., 17:419-434, 1954) observed little 

 or no favorable effect of antibiotics on germination of seeds, growth of 

 seedlings, or development of plants in soils. 



