Effect of Penicillin or Tetracycline Injections of Citrus Trees Affected by Greening Disease Under Field Conditions in Reunion Island

In a companion paper (BovC et al., 1980) we explained why the prokaryote associated with citrus greening disease is not a mycoplasma, and showed that greening-affected citrus seedlings, which had absorbed penicillin through their roots, developed an abundant root system and produced new, vigorous, symptomless shoots. On the basis of these results, as well as previous ultrastructural studies (Garnier and BovC, 1977) we concluded that the greening organism probably possesses a peptidoglycan-containing cell wall typical of gram negative organisms and is a member of the division Gracilicutes (BovC et al., 1980). In this paper, we add further evidence to this conclusion by showing that, under orchard conditions, penicillin injections into trunks of greening-affected sweet orange trees result in remarkable tree recoveries similar to those achieved with tetracycline injections.