|Title:||Etiology, Biology and Control of a Soilborne Root Rot Complex of Green Peas||Other Titles:||豌豆根腐病（複合感染）之病因學、生物學及防治||Authors:||J.C. Tu
|Issue Date:||Jun-1991||Publisher:||農業試驗所||Start page/Pages:||17-35||Conference:||土壤病原生態與防治研討會專刊||Abstract:||
The field incidence of pea root rot in southwestern Ontario averaged 26%. The root rot complex has severely curtailed green pea yield. In order to resolve the etiology of this complex, a total of 782 fungal isolations were obtained from 465 samples collected from 33 pea fields. The isolations yielded Fusariumn solani f. sp. pisi, F. oxysporum f. sp. pisi Aphanomyces euteiches and Pythiwn spp. in 7:4:1:1 frequency. The ratio of races 1 and 2 in the F. oxysporwn isolates was 7:4. F. solani did not appear to be highly specialized and no attempt was made to determine its race profile. The disease severity caused by F. sotani (root rot), F oxysporum (wilt), Pythium and Aphanomyces averaged 3.2, 8.7, 2.6 and 4.0, respectively, on a 0-9 scale. Plants with Fusarium wilt usually died while those with Fusarium root rot showed various degrees of stunting and yellowing but rarely died. Pythiwn and Aphanomyces are considered to be minor problems in Ontario. Based on this information, a disease damage index (DDI) was developed to rank the relative importance of these four root rots. The DDI of a root rot equals the total amount of root rot (26.5%) X the frequency of occurrence of each fungus X the severity of disease caused by each fungus. The DDIs for F. solani, F. oxysporum, Pyihiwn spp. and A. euteiches, were 45, 71, 5 and 8, respectively. Therefore, Fusarium wilt is the most damaging disease followed by Fusarium root rot. While Pyrhium and Aphanomyces root rot are of minor importance. Based on the etiological and biological findings, an integrated control program has been developed. The program includes: (a) development of a new seed treatment formulation; (b) trial and selection of disease resistant cultivars; (c) formulation of suitable herbicide combinations; (d) development of a soil indexing procedure; (e) improvement of tillage practices; (f) adoption of interseason green manure crops and (g) modification of soil p11. The success of this integrated disease control program has brought pea root rot under control and increased pea yield by 150% over a three-year (1984 to 1986) period.
在渥汰華西南方豌豆根腐病之平均田間發病率為26％。複合感染引起的根腐病嚴重影響豌豆的產量。為了解此病害之病因學，總共從33個豌豆田收集465個病害標本，進行782次的分離試驗，結果獲得Fusarium solani f. sp. pis4 F. oxysporum f. sp. pisi, Aphanomyces euteiches and Pythium spp.等病原菌，其比例為7:4:1:1。F. oxysporum菌株中，race 1及race 2的比例為7:4。F. solani對寄主品種問較無選擇性，故未鑑定其生理小種。由F. solani（根腐）, F orysporum（萎凋），行Pythium 及Aphanomyces引起的平均發病度（0~9級的範圍）分別為3.2, 8.7, 2.6及4.0。通常，感染F. oxysporum之罹病株終將死亡，而罹患F. solani者僅表現不同程度之矮化與黃化病徵。另外Pythium及Aphanomyces僅少數發生。據此，發展一套病害損失指數(disease damage index, DDI)對上述四種病原菌之相對重要性加以分級。根腐病之DDI即是總發病率(26.5%) × 病原出現率 × 病原引起之發病度。結果上述四種病原，F. solani，F. oxysporum，Pythium spp.及A. euteiches之DDI依序分別為45、71、5及8。因此，F. oxysporum最重要，F.solani次之，而行Pythium及Aphanomyces較不重要。基於對豌豆根腐病之病因學及生物學之研究，發展出一套綜合防治方法，包括(a)選用種子處理藥劑之新配方，(b)種植田間抗病品種，(c)處理適當的殺草劑配方，(d)應用田間土壤指數的預測方法，(e)改善耕犁方式，(f)栽植適當的綠肥作物及(g)調節土壤pH值。本方法於1984~1986年之田間試驗表現能夠控制根腐病，並增產150％。
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