Etiology and control of aglaonema bacterial soft rot

• Main Authors: Feng, Ching Ting, 馮靖廷
• Other Authors: Ho, Wang Ching
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/48586656278685474396

碩士 === 國立屏東科技大學 === 植物保護系 === 93 === In 2003, soft rot symptoms on Sithiporn aglaonema (Aglaonema tricolor × A. nitidium) leaves were found in a nursery at Neipu, Pingtung, in Taiwan. 7 isolates of bacteria from soft rot aglaonema tissues could cause the typical soft rot symptoms both on aglaonema plants and the detached aglaonema leaves by inoculating the bacterial suspensions of those 7 isolates with a concentration of 108 cfu/ml on the carborumdum wounded tissues. No symptoms on control plants and leaves were showed when they were inoculated with sterilized distilled water. Bacteria could be reisolated from the inoculated tissues that fulfilled the Koch’s postulated. All 7 isolates of the bacteria were proven belong to soft rot Pectobacterium, due to they were negative for gram stain. Could depredated the pectate on CVP medium and could cause soft rot symptoms on potato slices and Chinese cabbage petioles. According to Dickey & Kelman and Goto & Matsumoto, the physiological characters of these 7 isolates matched the characters of P. chrysanthemi. The primer pair 5A/5B also could further confirm that all isolates were P. chrysanthemi by polymerase chain reaction (PCR). All isolates were, therefore, named as ASR1 to ASR7. ASR3 was proven to be the most virulent isolates, after the detached leaves were dipped in a bacterial suspension, ASR3 was, therefore, chooser to run the further experiments. The disease progresses of ASR3 were parallel on wounded aglaonema plant and wounded detached aglaonema leaves. No disease would happen on unwounded plants and detached leaves. Soft rot of aglaonema could happen between 24 to 30℃ at a inoculums concentration of 104 cfu/ml and above, the higher of inoculums concentration, the faster of the disease progress, the disease progress reached optimum at 28℃ with a inoculums concentration of 107 cfu/ml. The postharvest products, the wounded detached leaves of Araceae and the cultivars of aglaonema were inoculated with ASR3 with a concentration of 108 cfu/ml and incubated at 30℃ for 5 days to evaluating the rotten ability of ASR3 on product, and for disease resistant screening of plants to soft rot. Results showed that ASR3 could macerated and rotted the storage root of carrot, radish, and sweet potato, cabbage petiole, corm of taro, leaf petiole of celery, onion slice, eggplant fruit, and leaves of green onion, but not rotted the bulb scales of garlic. Spathiphythum sp., Syngonium sp., and Epipremnum sp. of Araecae were highly susceptible and Anthurium sp., Diffenbachia cv. 'Star Bright', cv. 'Superba', cv. 'Camilla' and Zantedeschia aethiopica were immune to soft rot. Among aglaonema, cv. 'Curtisii', cv. 'White Tip' and cv. 'Snow queen' were resistant or lower susceptible to ASR3. P. chrysanthemi ASR3 could cause the soft rot of Oncidium sp. and Phalaenopsis sp., but the P. chrysanthemi from Oncidium sp.(OS2) and Phalaenopsis sp.(OS2-CHU) could not infect aglaonema. It was proven that ASR3 was more virulent then OS2 and OS2-CHU. Results of filter paper disc method used on the screening test of agrochemicals showed that all three copper could not restrain growth the bacteria of P. chrysanthemi ASR3, and the four antibiotics Streptomycin, Plantomycin, thiophanate methyl＋streptomycin, and streptomycin＋oxytetracycline showed better control of P. chrysanthemi ASR3. On detached leaves tests, the thiophanate methyl＋streptomycin 500x and 1000x showed the better protection than the other three agrochemicals Streptomycin, Plantomycin, and streptomycin＋oxytetracycline, but these agrochemicals could not restrain the soft rot development. Results of the antibiotic activity tests of Trichoderma spp. T1, T2, T4 to T17, Pseudomonas fluorescens OFP7, and Bacillus subtilis (Tai-K Bacillus) on aglaonema soft rot of isolate ASR3 using cellophane paper showed that T1, T4, T5, T6, T13, T14, T17 of Trichoderma ,and OFP7 of Pseudomonas could produced the antibiotic substances on PSA medium and restraint the growth of ASR3. The spores suspension and cultured filtrate of Trichoderma sp. T1 isolated could not protect and control the disease on detached leaves testes. The P. fluorescens OFP7 and B. subtilis (Tai-K) both showed better protection effect, but the two antagonistic bacteria both were unapparent on control effect of soft rot.