亞麻立枯病之種子傳播和種子處理試驗

Abstract

亞麻立枯病病原菌雖係土壤傳播真菌，但也可經由種子而萬播。採收自罹病亞麻田之種子質輕、不飽滿而略扁平、表面有皺紋、無光澤、千粒重為2.3~3.0g，依發病程度而異；反之健全田之種子較重、飽滿、黑褐色、表面平滑、有光澤、千粒重為3.6g。種子攜帶病原菌之比率為0.42~6.00%，與田間亞麻罹病率成正相關。病原菌亦可侵入種皮內，其比率為0.02~0.1%。以發病亞麻田（發病率26~50%）採收之種子播種會引起萌前腐敗，亦可導致發生幼苗立枯病，前者達15.7%，後者為7.6%。 亞麻種子以50% Benlate W. P., Benlate T-20, 50%Vitavax-Thi-ram W. P., 50% Bavistin W. P.等0.5~0.1%（依重量計算）行拌種處理，可有效防止病原菌之蔓延，但因亞麻種子表面有膠質，遇水黏結成團，處理工作不易進行。故採用Dowfumo MC-2 1.5 lbs/22.32m3行燻蒸處理，為既有效又經濟之方法。 Although flax wilt pathogen, Fusarium oxysporum f. sp. lini, is a well known soil-borne fungus, it can also be transmitted by seeds. Seeds harvested from diseased flax fields are lighter, yellowish to dark brown, rough and dull, weight per thousand seeds varied from 2.3 to 3.0 g depending upon the percentage of wilt flax in the field. On the other hand, seeds from healthy flax fields are heavier, dark brown, smooth and shining, weight per thousand seeds is 3.6 g. Seeds from diseased fields carried F. oxysporum f. sp. lini with the rates varied from 0.42 to 6.00%, proportioned with the severity of flax wilt. However, wilt pathogen was detected not only on the seed but also in the seed. There were 0.02-0.10% of seeds found to carry the pathogen inside the seedcoat. Sowing of seeds from moderately diseased field (26-50% of flax wilt) resulted 15.7% of preemergence rot and 7.6% of seedling wilt. Slurry-overcoating of flax seeds with Benlate, Benlate T-20, Vitavax-Thiram, or Bavistin at the rate of 0.5-1.0% by weight was effective in controlling seedling wilt and increasing stands. However, because of flax seeds are covered with a layer of gelatinous substance and are adhering in mass when wet, slurry-overcoating is not a good method for flax seed treatment. Fumigation with Dowfume MC-2 at the rate of 1.5 lbs/22.32 cu m for 14 hr during the storage period in a compact warehouse is recommended.