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Bacterial Rhizome Rot of Colored Calla Lily
Lin, Tru Sheng
|關鍵字:||Bacterial soft rot|
carotovora subsp. carotovora。測 試彩色海芋種球傷口對細菌性軟腐
種薯表皮之帶菌量，具軟腐癒合組織之種薯表皮帶菌量 可介於104 ~
106 cfu/g dry material間。於溫室試驗中，栽種具軟腐癒合組織之種薯
仍為104 ~ 105 cfu/g dry periderm；而當種薯Erwinia屬軟腐細菌浸菌
泡煉石、南海蛭石、 珍珠石、深層火山岩、TKS-1 Instant及水苔等介
A total of 37 strains of soft-rot Erwinia were isolated from the diseased plant tissues collected from colored calla lily grown fields. Based on the physiological and biochemical tests, they were all identified as Erwinia carotovora subsp. carotovora. The incidence of rhizome rot of colored calla lily caused by E. corotovora subsp. carotovora was greater in the rhizomes artificially wounded than those not artificially wounded. The soft rot incidenceof colored calla lily cultivar Best Gold inoculated with E. carotovora subsp. carotovora through the wounds just after flowers being plucked was 100 %, while the incidence of rotting decreased to 16.7 % when the inoculation was made 36 hours later. Rhizomes of colored calla lily obtained from various sources were detected for the soft-rot Erwinia, the results showed that 23.3 % ~ 84 % of rhizomes were contaminated with soft-rot Erwinia. The number of soft-rot Erwinia on rhizomes of colored calla lily after storage was detected on modofiedCVP selective medium. The results showed that soft-rot Erwinia on rhizomes with cured rotted lesions could reach to 104 ~ 106 cfu/g dry periderm. In green housetest, the soft rot incidence of colored calla lily grown from rhizomes with cured rotted lesions, rhizomes which rotted lesions were excised and symptomlessrhizomes was 86.7 %, 33.3 % and 6.7 %, respectively. Sensitivity of the 37 strains of E. carotovora subsp. carotovora. to commercial formulated agroche- micals was tested on nutrient agar plates. It was found that all the Erwinia carotovora subsp. carotovora strains tested were sensitive to basic copper sulfate + cufram Z (500X), copper oxychloride + manzeb + zinzeb (500X), cuprous oxide (500X), kasugamycin + copper oxychloride (1000X), oxine-copper + copper hydroxide (500X) and tribasic copper sulfate (500X). And with the exception of 1 ~ 3 strains, most strains tested were also sensitive to streptomycin + tetracycline (1000X), streptomycin sulfate (100 and 200 ppm) and thiophanate-methyl + streptomycin (1000X), while all the strains tested were resistant to mancozeb (400X), nonyphenol copper sulfonate (500X) and tecloftalam (1000X). Treatment of rhizomes with agrochemicals was able to reduce the population of E. carotovora subsp. carotovora on the rhzomes artificially infested. Chemical treatment of rhizomes at 45℃ were much better than that at 26℃ to reduce the population of E. carotovora subsp. carotovora onthe rhizomes. However, the effectiveness of chemical treatment varied among the rhizomes treated. Copper oxychloride + manzeb + zinzeb (500X) appeared to be the most effective among 11 agrochemicals tested to reduce the population of E. carotovora subsp. carotovora on the infested rhizomes. When the infested concentration of E. carotovora subsp. carotovora was at 108 cfu/ml, the number of E. carotovora subsp. carotovora on the infested rhizomes after treated with copper oxychloride + manzeb + zinzeb (500X) at 45℃ for 40 minutes could reduce to an undetected level. When the infested concentration of E. carotovora subsp. carotovora was at 106 cfu/ ml, the number of E. carotovora subsp. carotovora on most of the infested rhizomes after treated with both copper oxychloride + manzeb + zinzeb (500X) and thiophanate-methyl + streptomycin (1000X) could also reduce to an undetected level. In addition, soft rot incidence of both copper oxychloride + manzeb + zinzeb (500X) and thiophanate-methyl + streptomycin (1000X) treated rhizomes was much lower than that of untreated rhizomes. Among 11 commercial growing media examined, no soft-rot Erwinia was detected after enrichment in these media. Survival of E. carotovora subsp. carotovora in these growing media was studied, it was found that E. carotovora subsp. carotovora could survive much better in these media at low temperature (12℃) than at high temperature (30℃). E. carotovora subsp. carotovora was able to survive for over 180 days in vermiculite, perlite, Hydrocorn, TKS-1 Instant, volcano rock and sphagnum moss at 12℃, whereas they could only survive less than 50 days at 30℃. High humidity (RH 100 %) was favorable for E. carotovora subsp. carotovora to survive on the leaves of colored calla lily. In addition, application of 1 % of calcium nitrate solution to colored calla lily during the growing season could increase the calcium content of various parts of plants.
|Appears in Collections:||植物病理學系|
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