【発明の詳細な説明】[Detailed description of the invention]
本発明はタバコ植物の毛茸分沁物に含まれる
４，８，13―duvatriene―１，３―diol（以下
DVTと略記する。）を有効成分として含有するタ
バコうどんこ病防除に関する。
従来からタバコうどんこ病防除剤として、チオ
フアネートメチル剤、DBEDC剤、TPN剤などが
使用されているが、これらはいずれも葉たばこの
香喫味に悪影響をもたらすことから、たばこ用農
薬の使用基準によつて散布回数は２回以内、しか
も葉たばこ収穫の10〜20日以前に散布しなければ
ならないとされている。ところがタバコうどんこ
病は収穫期に多発するため、有効な防除が期し難
い場合が少くなかつた。
これに対し、本願発明の防除剤はタバコうどん
こ病に高い防除効果を有するだけでなく、従来の
農薬にみられる葉たばこ香喫味への悪影響が全く
なく、逆に香喫味の向上をもたらすものであり、
散布回数や時期に制限を設ける必要が全くない優
れた特徴を有する。
タバコ植物の毛茸は茎，葉，腋芽，花などの表
面に密生する茸状の腺毛であり、その先端から樹
脂が分沁され、その樹脂の中にDVTが含まれて
いる。DVTは今のところ他植物には存在が確認
されていないいタバコ植物に特異的に含まれる物
質である。
本発明者らは、このDVTがタバコうどんこ病
に対し高い抗菌作用を有することを初めて見い出
した。
DVTは、次の構造式で表現される。
DVTはクロロホルム，エタノール等の有機溶
剤に可溶であり、タバコ植物の茎，葉，腋芽，花
および乾葉（原料葉たばこ）など、毛茸から分沁
された樹脂が存在する部分をこれら有機溶剤に浸
せきし、DVTを含む葉面脂質溶解液を得る。本
発明防除剤として使用する場合には、エタノール
により稀釈調整α―DVTが2500〜50000ppmの濃
度で含まれるようにすることが望ましい。本防除
剤を病害の発生前にタバコに散布すれば発病を予
防することができ、また病害の発生したときに散
布すれば病斑の進展、拡大を抑制することができ
る。
以下、実験例，防除試験例をあげて本発明の内
容をさらに詳細に説明する。
実験例
だるま種タバコの心止３週間後に天葉から下葉
までの腋芽2500ｇを採取し、クロロホルム2000ml
に30秒間浸せきする操作を２回繰返し、全量をろ
過する。ろ液は45℃以下でエバポレーターにて
100mlに濃縮する。これが葉面脂質溶解液であ
る。
この葉面脂質溶解液からDVTを分離する工程
は次のとおりである。葉面脂質溶解液を分液ロー
トを用いて極性によりヘキサン―80％メタノー
ル・水で分離され、ヘキサン層にはアルカンを主
成分とする非極性脂質、80％メタノール・水層に
はDVTを主成分とする極性脂質が含まれる。極
性脂質はシリカゲルによるカラムクロマト法を用
いて50％エーテル・ヘキサンでDVTがほゞ完全
に溶出されてくる。これを粗DVTとする。粗
DVTはアルミナによるカラムクロマト法を用い
て、さらにα，βの異性体を分離することができ
る。すなわち、２％メタノール・エーテルにより
α―DVT、５％メタノール・エーテルによりβ
―DVTが溶出されてくる。α―DVT，β―DVT
の定性は薄層クロマトグラフイーを用いて、定量
はガスクロマトグラフイーを用いて行なつた。
前記葉面脂質溶解液のDVT濃度を測定した結
果100000ppmであり、これを80％エタノールで
稀釈して25000ppmに調整して以下の試験をおこ
なつた。また、葉面脂質溶解液より分離された粗
DVT，α―DVTおよびβ―DVTについてもそれ
ぞれ80％エタノールで稀釈して25000ppmになる
ように調整し試験をおこなつた。
供試苗は温室でポツト栽培された品種MC―１
の16―17枚苗で中位葉の半葉に小型噴霧器を用い
て前記の稀釈調整した葉面脂質溶解液粗DVT，
α―DVT，β―DVT各溶解液および80％エタノ
ール（対照として）を散布し、他半葉を無処理対
照とした。これら各液を散布して６日後、３日後
および当日（散布後５時間目）にタバコうどんこ
病の分生胞子を接種して、20℃±１℃の温室にお
き、所定時間後に胞子の発芽抑制率、菌糸の伸長
量、分生子梗の形成状態および防除率を調査し
た。その結果を表―１から表―３に示す。
The present invention relates to 4,8,13-duvatriene-1,3-diol (hereinafter referred to as
Abbreviated as DVT. ) as an active ingredient for controlling tobacco powdery mildew. Thiophanate methyl agents, DBEDC agents, TPN agents, etc. have traditionally been used as tobacco powdery mildew control agents, but since all of these agents have a negative effect on the aroma and taste of leaf tobacco, the standards for the use of tobacco pesticides have been established. According to the law, the number of sprayings must be no more than two times, and it must be sprayed 10 to 20 days before leaf tobacco is harvested. However, since tobacco powdery mildew frequently occurs during the harvest season, it is often difficult to achieve effective control. In contrast, the pest control agent of the present invention not only has a high control effect on tobacco powdery mildew, but also has no negative effect on the flavor and aroma of leaf tobacco, which is seen with conventional pesticides, and on the contrary, it improves the flavor and aroma of leaf tobacco. can be,
It has an excellent feature that there is no need to set any restrictions on the number of times or timing of spraying. Hair mushrooms of tobacco plants are mushroom-shaped glandular hairs that grow densely on the surfaces of stems, leaves, axillary buds, flowers, etc., and resin is excreted from their tips, and DVT is contained in the resin. DVT is a substance unique to tobacco plants that has not been confirmed to exist in other plants. The present inventors discovered for the first time that this DVT has a high antibacterial effect against tobacco powdery mildew. DVT is expressed by the following structural formula. DVT is soluble in organic solvents such as chloroform and ethanol, and parts of the tobacco plant stems, leaves, axillary buds, flowers, and dried leaves (raw tobacco leaves) where resin is separated from hair mushrooms are soluble in organic solvents such as chloroform and ethanol. to obtain a leaf lipid solution containing DVT. When used as a pesticidal agent of the present invention, it is desirable that the α-DVT diluted with ethanol be contained at a concentration of 2,500 to 50,000 ppm. If this control agent is applied to tobacco plants before the onset of disease, it is possible to prevent the onset of the disease, and if it is applied when the disease has occurred, it is possible to suppress the development and spread of lesions. Hereinafter, the content of the present invention will be explained in more detail with reference to experimental examples and pest control test examples. Experimental example 2500g of axillary buds from top leaves to lower leaves were collected 3 weeks after heart arrest of Daruma tobacco, and 2000ml of chloroform was collected.
Repeat the soaking process for 30 seconds twice and filter the entire amount. Filter the filtrate in an evaporator at 45℃ or below.
Concentrate to 100ml. This is the leaf lipid solution. The steps for separating DVT from this leaf lipid solution are as follows. The leaf lipid solution was separated by polarity using a separating funnel between hexane and 80% methanol/water, with the hexane layer containing non-polar lipids mainly consisting of alkanes, and the 80% methanol/water layer containing mainly DVT. Contains polar lipids. For polar lipids, DVT is almost completely eluted with 50% ether/hexane using column chromatography using silica gel. This is called the rough DVT. Coarse
DVT can further separate α and β isomers using column chromatography using alumina. i.e., 2% methanol/ether for α-DVT, 5% methanol/ether for β-DVT.
- DVT is eluted. α-DVT, β-DVT
Qualitative determination was performed using thin layer chromatography, and quantitative determination was performed using gas chromatography. The DVT concentration of the leaf lipid solution was measured and found to be 100,000 ppm, which was diluted with 80% ethanol to adjust to 25,000 ppm, and the following test was conducted. In addition, crude oil separated from the leaf lipid solution was
DVT, α-DVT, and β-DVT were also diluted with 80% ethanol to a concentration of 25,000 ppm and tested. The test seedlings were cultivar MC-1 grown in pots in a greenhouse.
Using a small sprayer, apply the diluted foliar lipid solution crude DVT to half of the middle leaves of 16-17 seedlings.
α-DVT, β-DVT solutions and 80% ethanol (as a control) were sprayed, and the other half of the leaves were used as an untreated control. Six days after spraying these solutions, three days later, and on the same day (5 hours after spraying), conidia of tobacco powdery mildew were inoculated, placed in a greenhouse at 20°C ± 1°C, and spores were removed after a specified period of time. The germination inhibition rate, the amount of hyphal elongation, the state of conidiophore formation, and the control rate were investigated. The results are shown in Tables 1 to 3.
【表】【table】
【表】【table】
【表】【table】
【表】
以上の結果から明らかなとおり、無処理区およ
び80％エタノール散布区は発芽抑制率、菌糸の伸
長量、分生子梗の形成時期およびうどんこ病防除
率ともに同程度であるのに対し、DVTを含む溶
液を散布した区は（分生子梗の形成のβ―DVT
を除いて）いずれも明らかな差異を示し、DVT
がうどんこ病菌に抗菌性を有すること、さらにう
どんこ病防除効果を有することは明らかである。
防除試験例
タバコうどんこ病の発生したほ場のタバコ（品
種MC―１）にたいし防除試験をおこなつた。下
位葉と中位葉の一葉当り平均病斑数がそれぞれ
20.5個と5.4個発生した７月１日に、葉面脂質溶
解液（DVT濃度25000ppm）を噴霧器を使用し
て、葉面積100cm2当り0.3mlの割合で散布し、散布
の６日と12日後に進展した病斑数を調査し、防除
率と薬害を調べた。[Table] As is clear from the above results, the germination inhibition rate, the amount of mycelial elongation, the timing of conidiophore formation, and the powdery mildew control rate are the same in the untreated plot and the 80% ethanol spray plot. , the area sprayed with a solution containing DVT (β-DVT for conidiophore formation)
) all showed clear differences, and DVT
It is clear that it has antibacterial properties against powdery mildew fungi and also has a powdery mildew control effect. Example of control test A control test was conducted on tobacco (variety MC-1) in a field where tobacco powdery mildew had occurred. The average number of lesions per leaf on lower and middle leaves is
On July 1, when 20.5 and 5.4 individuals appeared, a foliar lipid solution (DVT concentration 25,000 ppm) was sprayed using a sprayer at a rate of 0.3 ml per 100 cm2 of leaf area, and on the 6th and 12th days after spraying. The number of lesions that developed later was investigated, and the control rate and chemical damage were investigated.
【表】
表―４にみられるとおり、葉面脂質溶解液の散
布により高い防除効果をあげることができた。
この防除試験に供試したタバコの収穫葉を常法
により乾燥し、その乾葉については官能検査をお
こなつたところ、散布区の乾葉は通常の乾葉に比
べて、タバコの喫味が増加し、刺激、辛味がやゝ
減少して丸味がで、全体的にのみごたえがあると
の評価をえた。
以上述べたとおり本願発明は、タバコうどんこ
病に対する高い防除効果を示すだけでなく、葉た
ばこの香喫味にたいする影響も好ましいものであ
つて、いままでの農薬にみられない利点を有する
ものである。[Table] As shown in Table 4, we were able to achieve a high control effect by spraying the foliar lipid solution. Harvested tobacco leaves used in this pest control test were dried in a conventional manner, and a sensory test was conducted on the dried leaves, and it was found that the dried leaves in the sprayed area had an increased tobacco flavor compared to normal dried leaves. However, the pungent and pungent taste was slightly reduced and the taste became rounder, and the overall taste was evaluated as good. As described above, the present invention not only exhibits a high control effect on tobacco powdery mildew, but also has a favorable effect on the flavor and taste of leaf tobacco, and has advantages not seen in conventional agricultural chemicals.