| dc.description.abstract | Erwinia carotovora subsp. carotovora, the causative agent of hollow stalk
disease, is one of important disease on tobacco. Until now, there is no effective
pesticide to control this disease. One among the control agents, which is well
recognized, is by fluorescent pseudomonads because is easily isolated and has an
antagonistic ability to some pathogens. Although a lot of researches are to isolate
fluorescent pseudomonads and have been commercialized, however the
fluorescent pseudomonads generally was specific antagonist to some pathogens.
The aim of this research is to isolate fluorescent pseudomonads from Sukorambi
(SA), Gebang (GB), Sukowono (SC), Mumbulsari (MD) areas. The isolates were
test in vitro by hypersensitive reaction (HR), Gram, and fluorescence. In vivo
experiment was done with randomized complete design (RCD) and symptoms on
leave and stalk were observed to obtain disease severity and incubation period.
Forty-five fluorescent pseudomonads were isolated from Sukorambi (SA),
Gebang (GB), Sukowono (SC), Mumbulsari (MD), and twelve isolates were
selected based on the strong of fluorescence. All the isolates were negatively
hypersensitive reaction on tobacco leave and had Gram negative. These isolates
were able to inhibit E. carotovora subsp. carotovora growth with vary in diameter
of inhibition. Isolates from MD, especially MD2 had the longest diameter of
inhibition with range of 12,3 mm - 13,2 mm. In vitro experiment, all the
fluorescent pseudomonads isolates have inhibition mechanism of bacteriostatic as
showed turbidity on the 1% water peptone after incubation for 48 hours. Based on
the screening result on diameter of inhibition, three isolates were chosen from the
in vivo experiment. Tobacco plant inoculated with three isolates of fluorescent
pseudomonads (GB3, SC2, and MD2) and E. carotovora subsp. carotovora were
started to show the wilting leave from 9 days post inoculation (dpi). Isolates GB3
and SC2 showed earlier symptom (9 dpi) than isolates MD2 (15 dpi). Moreover,
isolate MD2 was also delayed the incubation period for six days compare with
isolates GB3 and SC2. The isolate MD2 also reduced the disease severity to
41,7% compere to isolates GB3 (58,3%) and SC2 (58,4%). In summary,
fluorescent pseudomonads isolates from Mumbulsari, especially isolate MD2, was
more effective to control E. carotovora subsp. carotovora than isolates GB3 and
SC2. | en_US |
