120 research outputs found
Phytophthora Diseases of Citrus in Taiwan
No full text自1976年7月至1980年5月，自本省15縣229柑橘園內採集土壤及罹病之果實、葉片及莖部組織。利用葉片誘釣法及配合選擇性培養基分離，疫病菌可自14縣108果園中分得。依疫病菌之分離頻率及重要性，依次如下；A1及A2型的phthora parasitica及P. palmivora分佈於中南部柑橘園中，P. parasitica引起根腐病及鋸腐病，而P. palmivora引起根腐病及褐腐病；A1型的P. citrophthora及P. cinnamomi與同絲性之P. citricola存在於中部以北地區，主要為害根系。以上5種疫病菌均對甜橙有病原性。而P. heave, P. insolita及P. humicola僅自土壤中分得，對甜橙無病原性。在檢定之79種柑橘品種系中，甜橙類對P. parasitica及P. palmivor抵抗力最弱；椪柑、桶柑、檸檬及葡萄柚次之；酸橘、枳橙及廣東檸檬中感；部份柚類中等；酸橙、根殼及紅柚為中抗；金柑類及烏柑刺則具強烈之抗性。
From July 1976 to May 1980 soils and diseased fruit, leaves and stems were collected from 229 citrus orchards in all 15 counties on the island of Taiwan, and assayed for the presence of Phytophthora by baiting with discs of citrus leaves and plating on selective medium. Phytophthora species were isolated from 108 citrus orchard in 14 counties. Based on the frequency of isolation and pathogenicity to citrus, both of A1 and A2 mating types of P. parasitica and P. palmivora were isolated from the central and southern area. P. parasitica was the main pathogen causing foot rot, and root rot, while P. palmivora causing fruit brown rot and root rot. A1 but not A2 types of P. citrophthora and P. cinnamorni, and P. citricola (Homothallism) were mainly distributed on the central and northern regions, causing citrus root rot. All of the 5 species were pathogenic to sweet orange. P. heave, P. insolita and P. humicola infrequently isolated from soils were non-pathogenic to sweet orange.
One to two months old citrus seedling were planted in artifical inoculated-diseased soils for testing of resistance to P. parasitica and P. palmivora. Of 79 citrus and related tested varieties, sweet orange (9 varieties) were most susceptible; ponkan, tankan, lemons and grape fruit were next; sunki, troyer and rangpur lime were susceptible; some of pummelo were morderate; sour orange, trifoliate orange and red pummelo were morderately resistant; while Severinia and Kumquat were high resistant
Oospore germination of Peronophythora litchii
No full textThis germination in the fungus, causing fruit rot of Litchi chinensis, was 30-35% in distilled water but most of the oospores produced short germ tubes which did not develop further. C. 2% produced 1 or 2 sporangia on each germ tube. Sometimes germ tubes penetrated the oogonium wall but more frequently they emerged through the oogonium stalk and antheridium. Occasionally up to 10 germ tubes emerged from a single oospore, but in most cases only 1 produced sporangia, some of which released differentiated zoospores after chilling. Attempts to establish colonies from the germinating oospores were not successful. These results supported previous reports [RPP 58, 99] that the fungus is a transitional sp. between Phytophthora and Peronospora
Soil-Borne Fungal Diseases of Citrus in Taiwan
No full text本省柑橘之重要土壤傳播性真菌病害包括疫病、幼苗猝倒病與細根腐敗病、流膠病、及木材腐敗病等，其中以疫病最具破壞性。危害本省柑橘之主要疫病菌共有五種，依次為Phytophthorn porositicQ , P. polmivoro , P. citrophthoro , P. citricolo 及P. cinnomomi。病菌主要危害柑橘之幼苗、根系、樹幹基部、及果實。初次感染源主要來自污染之栽培介質與灌溉用水，連續降雨與土壤濕度過高為誘發病害猖獗之重要因子。目前可行之防治策略為使用抗病或耐病品種之健康種子育苗以供為砧木，使用無病原菌栽培介質與灌溉水，苗期宜有防雨設施，注意田間排水，及藥劑防治。幼苗猝倒病與細根腐敗病由Pythium spp., Rhizoctonio Solon¡（或R. soloni like), Phytophthoro spp. 及Fusarium spp.所引起，注意育苗用栽培介質之衛生與種子消毒即可預防本病害。引起樹幹流膠之病原菌除疫病菌外，大部分為弱病原菌，分離到的有Rhizoctonio sp., Fusorium sp., Diplodio sp ., 及Phomopsis sp.等，一般在樹勢衰弱時，才會由樹皮傷口侵入感染，引起之流膠病徵與疫病菌引起者不盡相同，注意施肥、施藥、水患、及保持樹勢健旺，可預防本病害。木材腐敗病大部分由靈芝或樹舌引起，危害較少。
Phytophthora diseases, seedling damping off and fibrous root rot, gummosis, and wood rot are the important soil-borne diseases of citrus in Taiwan. Based on the frequency of isolation and pathogenicity to citrus, Phytophthora species were the most destructive fungal pathogens, and a total of 5 species including P. parasitica, P. palmivora, P. citrophthora, P. citricola, and P. cinnamomi were detected to be distributed wildly in citrus orchards. These fungi could attack seedlings, root systems, wound bark of stems, and fruit of citrus. The contaminated cultural media and irrigation water were the main sources carrying the primary inoculum, and heavy rainfall and moist soil environment were the two key factors inducing serious Phytophthora diseases. Integrated use of 1. healthy seeds, 2. resistant or tolerant root stocks, 3. disinfected cultural media or vergin soil, and pathogen free water for irrigation, 4. greenhouse or plastic sheet covering to protect young seedlings from rainfall, and 5. protective chemicals, could provide a satisfactory effect for decreasing citrus diseases caused by Phytophthora. Seedling damping off was mainly caused by Pythium spp., Rhizoctonia solani (or R. solani like), Phytophthora spp., and Fusarium spp. Sterilized or disinfected cultural mixtures and using healthy seeds cound improve seedling problems caused by these fungi. Rhizoctonia sp., Fusarium sp., Diplodia sp. and Phomopsis sp. have been isolated from the diseased barks of citrus stems with gummosis. All of the four fungi were weak pathogens which attacked weak citrus trees, and caused gummosis symptoms different from those induced by Phytophthora. Control of gummosis could be achived by enhanceing citrus trees growing stronger by avoding flooding fields and application of inadiquate ferterlizers and chemicals. Wood decay and root rot of citrus, which were occassionaly found in citrus orchard, were mainly caused by Ganoderma and Phellinus spp
(65(3):278-285)Occurrence and Control of Stunting Disease of Water Bamboo
No full text2001 年在埔里發生一種茭白矮化的病害，發病面積約500 ha，罹病株葉片變窄而短、葉片與葉鞘的角度常大於45 度而葉領間距縮短，以致於外觀呈現矮化的病徵。有些發病植株於幼苗期即結筍，但所結之筍細小而無商品價值，這病害稱之「矮化症」。經由生長箱栽培試驗結果顯示，茭白正常植株經過長暗期 (16 h d-1)或長暗期 (16 h d-1) + 暗期中斷 (1 h d-1) 的處理，則呈現與田間相同的矮化病徵，矮化的病株經過長光期 (16 h d-1) 或長光期 (16 h d-1) + 光期中斷 (1 h d-1)，則恢復正常生長。田間夜間照光試驗區分為照光0、4、8 及12 h 的處理，60 d 後矮化症發病率分別為45.3、3.5、0 與0%，株高分別為127.0、158.5、171.2 與186.4 cm，鮮重分別為2.5、3.2、3.8 與4.3 kg plant-1。茭白於正常期 (1 月) 種植與提早種植20 d 或40 d 之處理，發病率分別為5.4、14.9 與55.3%，三者皆有顯著差異 (P < 0.05)，而這三時期種植予以夜間照光8 h，則發病率皆低於1.1%。由上述結果，顯示矮化症是茭白植株於長夜季節的生理反應，提早於冬季中期前種植會使病害嚴重，夜間照光可防治矮化症並能促進植株生長。
In spring 2001, a kind of stunting disease of water bamboo (Zizania latifolia) occurred in about 500 hectares of farmland in Puli Township, central Taiwan. The leaf blades of the diseased plants were short and narrow, the distances between leaf collars were shortened, and the angles of the blades and sheaths were greater than 45 degrees. These symptoms caused the appearance of the plants looked dwarfing. Some of the diseased seedlings produced small smut galls, but the edible galls were small and valueless. Results from cultivation test in growth chamber showed that the normal plants were stunted with the same stunting symptoms in the fields after the treatments of long dark period (16 h d-1) or long dark period with dark interruption (1 h d-1); whereas, the stunted plants were back to normal growth after the treatments of long light period (16 h d-1) or long light period with light interruption (1 h d-1). Field trials were conducted with different night-lighting time including 4 treatments, lighting for 0, 4, 8, and 12 h, respectively. The disease incidences were 45.3, 3.5, 0, and 0%, respectively, the plant heights were 127.0, 158.5, 171.2, and 186.4 cm, respectively, and the shoots fresh weights were 2.5, 3.2, 3.8, and 4.3 kg plant-1, respectively. In the field test of beginning planting on the normal date (January 10th) or earlier by 20 or 40 days, the disease incidences were 5.4, 14.9, and 55.3%, respectively, with significant difference. By night-lighting for 8 h d-1 on these three treatments for 60 days, the disease incidences were all lower than 1.1%. The above results indicated that this stunting disease was a normal plant physiological response of water bamboo during the long-night season. Early planting before the mid-winter will enhance the disease, and nighttime illumination could prevent this disease and promote plant growth
Interaction between Likubin Bacterium and Phytophthora parasitica in Citrus Hosts
No full textInfection with Likubin bacterium (LB) followed by Phytophthora parasitica increased the mortality of sour orange and pummelo seedlings, and enhanced the P. parasitica-induced root rot in all the four types of citrus tested. The LB-induced enhancement of root infection by P. parasitica was apparent within 1h of exposure to zoospore suspension. The enhancement of P. parasitica-induced root rot was affected by the infection sequence. Inoculation of sour orange seedlings with LB before P. parasitica was more effective in increasing P. parasitica-induced root rot than LB and P. parasitica concomitantly or LB after P. parasitica. Grafting P. parasitica susceptible scions of ponkan (Citrus reticulata) onto P. parasitica-tolerant rootstocks of sour orange greatly increased the susceptibility of rootstocks to P. parasitica. Results also demonstrate the enhancement of LB-induced symptoms by P. parasitica in citrus plants
Pythiogeton zizaniae, a new species causing basal stalk rot of water bamboo in Taiwan
No full textA new species, Pythiogeton zizaniae, was isolated from diseased water bamboo (Zizania latifolia) in central Taiwan. The organism formed a colony with scanty mycelia and mycelial aggregates on rye-water bamboo medium. Special treatments were required for production of sporangia which were terminal, noncaducous and mostly ovoid. Chlamydospores were absent. The fungus was homothallic. Oogonia produced on V-8 water bamboo medium in water were mostly globose to subglobose and each was attached with a club-shaped, monoclinous antheridium by the base of the oogonium stalk. Oospores were plerotic and globose to subglobose. Py. zizaniae caused death of water bamboo suckers but did not infect seedlings of corn, rice, wheat, sorghum, cucumber, tomato, soybean or water spinach. It also did not affect cucumber and tomato fruit, carrot roots or potato tubers
(60(2):149-156)利用亞磷酸中和水溶液防治果樹苗木疫病
No full textA greenhouse study was conducted to determine effects of neutralized phosphorous acid solution (NPA) on control of Phytophthora diseases of kumquat (Fortunella margarita) grafted on Rangpur lemon (Citrus limon), loquat (Eriobotryajaponica cv. ‘Mogi’) and avocado (Persea americana cv. ‘Tainan’). The NPA solution was prered by dissolving phosphorous acid in water and then adding equal weight of potassium hydroxide to the solution. For kumcpat, 1-year-old seedlings were sprayed with NPA solution (1000 mg/L), 50 mL/seedling, for 2 or 3 times at weekly interval and then sprayed with zoospore suspensions of Phytophthora citrophthora, 10 mL/seedling, at 7 days afler last NPA spray. After inoculation for 14 days, each seedling was recorded for disease incidence on leaves. In another experiment, 5-year-old kumquat plants grafled on Rangpur lemon were sprayed with NPA (1000 mg/L), 500 mL/plant, for 3 times at weekly interval and incculated with the pathogen, 200 mL/plant, at 7 days after last NPA spray. For loquat, 6-month-old seedlings were treated with NPA (2000 mg/L) by soil drenching or with NPA (1000 mg/L) by spraying for 3 times at 30-thy interval. The seedlings were then incculated with Phytophthora nicotianae by placing one gram of pathogen-colonized wheat-oat grains on the wounded area of basal stems. For avocadoes, 6-month-old seedlings were inoculated with Phytophthora cinnamomi by drenching with 100 mL of chlamydospore suspension on each plant and then treated with NPA (1000 or 2000 mg/L) by soil drenching for 3 times at 3-month interval. Results showed that spraying kumquat seedlings with NPA at 1000 mg/L (a.i.) for 2-3 times significantly reduced seedling blight (44.8% infected leaves). Similarly, NPA sprayed three times on 5-year-old kumquat plants was also effective in reducing incidence of Phytophthora fruit rot leaf blight and twig blight. Application of NPA at 2000 mg/L by soil drenching or at 1000 mg/L by spraying completely controlled basal stem rot of loquat caused by P. nicotianae, whereas more than 60% of seedlings were killed in the controls. The avocado seedlings treated with NPA by soil drenching and inoculated with the pathogen were all survived during the test period, whereas 50-60% seedlings were killed in the pathogen-inoculated control. Avocado seedlings treated with NPA were taller and heavier than the pathogen-inoculated control, but they were shorter and lighter than the non-inoculated control. This study reveals that NPA is a chemical with potential for practical use in the management of Phytophthora diseases of kumquat, loquat and avocado.
本研究評估簡便調製之亞磷酸中和水溶液（neutralized phosphorous acid solution, NPA）對三種果樹幼苗疫病之防治效果。一年生的長實金柑（Fortunella margarita)／廣東檸檬（Citrus limon）嫁接苗每株噴布50 mL NPA （濃度1000mg / L ) ，每星期施用一次，2-3次後，再接種Phytophthoa citrophthora的游走子懸浮液，接種14天後疫病幾乎不會發生；而對照處理則有44.8％與50.8％的葉片染病，並且伴隨枝條流膠與枝枯。而五年生的結果金柑苗每株噴布500 mL 相同濃度的NPA 三次，可以完全保護果實、葉片及枝條不被病菌戚染；而接種病菌的對照處理的發病率分別為80%，59％及20%，發病之枝條同樣伴隨流膠與枝枯。六個月大的茂木枇杷（Eriobotrya japonica cv. ‘Mogi’）實生苗之土壤表面每株灌注50 mL NPA ( 2000 mg/L ）或噴布10 mL NPA (1000 mg / L) 三次，每次間隔30天，之後莖基部接種疫病菌P. nicotianae之麥粒菌種，90 天後均無幼苗死亡；而對照處理則有60％與65％的死亡率。六個月大的台南種酪梨（Persea Americana cv. ‘Tainan’）在接種P. cinnamomi。朋厚膜抱子懸浮液後，每盆土壤灌注100 mL NPA (1000 mg/L 或2000 mg/L）三次，每次間隔90天，NPA的處理在試驗期間均無植株死亡，而接菌對照處理有50％與60％死亡率，NPA處理組的平均株重比接菌對照處理顯著為重，但比不接菌對照處理顯著為差
Pythium sukuiense, a New Species from Undisturbed Natural Forest in Taiwan
No full textA new species, Pythium sukuiense, was isolated from an undisturbed natural forest in northern Taiwan. The fungus produces sporangia indistinguishable from hyphae and very small oogonia and oospores. Oogonia were smooth and terminal or intercalary and attached with a single antheridium. Oospores were aplerotic, with an average size of only 11 mum
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