ABSTRACT


Robert Ehrenfeld K.1
 
Studies were made of effects of chloro tetracycline (Aureomycin) on the causal agent of the disease of sugarbeet called "marchitez virosa" (yellow wilt). In these tests, diseased plants of sugarbeetand spinach were treated with a solution of chlorotetracycline hydrochloride in powdered form939 MCGM per mg., in a concentration of 100 ppm. The following methods of treatment were used.
1. Roots of diseased sugarbeet plants were immersed in a solution of Aureomycin for periods of24, 12, 9 and 6 hours.
2. Foliage of diseased sugarbeet and spinach plants was sprayed with a solution of Aureomycinat 24-hour intervals over a period of 2 months.
3. The soil around the roots of diseased sugarbeet and spinach plants was drenched with a solutionof Aureomycin at 4-day intervals for a period of 2 months.
4. Roots of diseased sugarbeet plants 6 months of age were immersed in a solution of Aureomycinfor 6, 12 and 24 hours.
In these tets, it was found that Aureomycin had a marked effect in suppression of symptons in diseasedsugarbeet plants.
No effects of Aureomycin were observed on diseased spinach plants, possibly because the diseasedplants bolted and died before effects could be produced.
In general, the therapeutic effects of the antibiotic appeared to be greater in plants treated byroot immersion than in those treated by spraying the foliage. However, a high degree of recoverywas obtained in plants with each treatment and recovery was almost complete in a number of thetreated plants. No results were obtained from soil drenching.
The results indicate that the disease is induced by an agent whose multiplication is inhibited, butnot eliminated, by chlorotetracycline. The progress of the disease was arrested for periods of a fewdays or weeks, after which there was a relapse and typical symptoms appeared in the foliage thathad been produced by recovered plants.
From the results of these tests it seems possible that the causal agent of yellow wilt of sugarbeet isnot a virus, but a mycoplasmalike entitly. In any case, these results are considered preliminary to futureinvestigations which may lead to a better understanding of the causal agent and its relationship toits vector and host plants.
Key words:
1Ing. Agr., Proyecto Virus, Iansa, Casilla 13-D Linares.