Tests with the seventh antibiotic, F-17, have been run to determine 

 its effectiveness against rust in beans and wheat. 



A brief description of these new antibiotics and a statement of their 

 performance in the ARS tests follows. 



Oligomycin 



Oligonnycin was isolated by University of Wisconsin scientists. In 

 laboratory tests at the Wisconsin Agricultural Experiment Station, 19 

 plant-disease organisnns proved sensitive to it. In greenhouse tests there, 

 it was first added to soil in which alfalfa seed was planted and later ap- 

 plied to seedlings in water. The antibiotic afforded complete protection 

 against a species of Pythium , a type of fungus which causes damping-off 

 in plants of several commercial crops . This genus of fungi constitutes one 

 of the nnost destructive groups of plant pathogens that are generally un- 

 controlled by the best methods known today. 



Results of ARS Bean Tests 



Oligomycin was the most effective of the six antibiotics included in the 

 comparative tests against 4 diseases of beans. It was toxic to all four 

 disease organisms when applied to the plants at a concentration of 100 

 p. p.m. 



Griseofulvin 



Griseofulvin was isolated in England and is produced by a species of 

 Penicillium which is related to the organism frona which penicillin is ob- 

 tained. The discoverers of this antibiotic report that a large number of 

 fungi on artificial media proved sensitive to it, and that it protected foliage 

 against powdery mildew of barley, gray mold of lettuce, and Alternaria or 

 early blight of tomatoes. It has also been reported that it is translocated 

 within plajits, that it may be more effective through root than leaf absorp- 

 tion, and that it persists in the tissue of tomato leaves. 



Results of ARS Bean Tests 



Griseofulvin protected beans from rust but was ineffective against the 

 other 3 diseases. It is believed, however, that use of a different solvent to 

 obtain a water suspension of this antibiotic would have resulted in greatly 

 increased effectiveness. 



Filipin 



University of Illinois scientists, who isolated Filipin, report that it 

 has dennonstrated protection against some seed-rotting fungi, and that 

 dust-seed treatments completely protected cucumber and spinach seedlings 

 against pre-emergence damping-off caused by Rhizoctonia , another de- 

 structive species of plant-disease organism. Spraying young tomato and 

 bean plants at a concentration of 1,000 p. p.m. of this antibiotic was re- 

 ported to have caused no damage. 



Results of ARS Bean Tests 



Filipin protected lima beans from downy mildew, and partially pro- 

 tected beans against anthracnose, but the concentrations used were excep- 

 tionally high. 



- 8 - 



