378 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



Fungi are particularly common disease agents in plants where they 

 are responsible for such ailments as white pine blister-rust, corn smut, 

 potato scab, wilt of fruit trees, blights of vegetables and ornamentals, 

 and root rots of many crops. 



One scientific approach against plant diseases is to exploit the nat- 

 ural disease resistance of individual plants by producing disease- 

 resistant strains. Apart from the time such a program obviously 

 entails, often special difficulties are encountered in attempting to com- 

 bine disease-resistant factors (genes) with those for high-yield or 

 favorable appearance. Always lurking under cover is the adaptable 

 parasite, able to evolve and grow on the new "resistant" plants. 



The use of sprays to kill fungi has become a widespread practice. 

 However, on a large scale this may be prohibitively expensive, as 

 nearly all fungicides are ineffective except at high concentrations. 

 Unfortunately, many are detrimental to the plants and poison birds 

 and even man, if proper precautions are not taken. 



Since antibiotics operate at extremely low concentrations and may 

 be absorbed by plant cells, it was logical to try them as sprays against 

 bacterial infection. This was first done successfully in the United 

 States by W. J. Smith, of the Wyoming Experiment Station, in 1949. 

 He used a streptomycin preparation against the bacteria that cause 

 halo blight of beans. Subsequently, antibiotic preparations came into 

 rather wide use against bacterial infections, including bacterial spot 

 of tomatoes and peppers, blast of stone fruits, wildfire of tobacco, seed- 

 piece decay and blackleg of potatoes, and bacterial wilt of chrysanthe- 

 mums. Special preparations of streptomycin and the tetracyclines 

 have been developed by commercial companies for agricultural use. 



The Upjohn Company of Kalamazoo, Michigan, has pioneered in the 

 development of the antibiotics effective against fungus infections of 

 plants. Their Actidione is derived from Streptomyces griseus, the 

 same organism that produces streptomycin. Actidione controls such 

 fungus infections as melting out of golf turf, onion mildew, and mint 

 rust. As little as one-third of an ounce of Actidione is sufficient for the 

 treatment of 50,000 square feet of turf. Antibiotics, unlike ordinary 

 fungicides, become a part of the cell sap of each individual cell of 

 the plant, "grow" with the plant, and are proof against rain. 



It has been found by R. L. Wain, of the University of London, for 

 example, that griseofulvin can be transported freely within plant 

 tissues and confers a systemic fungicidal effect. As pointed out above, 

 griseofulvin was the first compound found to be effective in the sys- 

 tematic treatment of ringworm in man. 



Professor Wain has indicated that : 



Natural resistance to infection may also be associated with the presence of 

 protective chemicals within the plant cells. Whilst animal cells are completely- 

 filled with protoplasm, adult plant cells contain only a thin layer of this material 



