不同杀菌剂对苹果炭疽叶枯病的防治效果

为了筛选出防治苹果炭疽叶枯病的有效杀菌剂, 采用室外先接种后施药和先施药后接种的方法, 测试了6种药剂的内吸治疗效果和8种药剂的保护效果。在病菌侵染后的72 h内使用吡唑醚菌酯, 或在病菌侵染后的24 h内使用咪鲜胺对病斑的显症有一定的治疗效果。波尔多液在喷施后18 d, 对炭疽叶枯病菌侵染的抑制效果仍达50%, 肟菌?戊唑醇、烯酰?吡唑酯和唑醚?代森联3种药剂在施药后的第11天, 其保护效果与对照仍有显著差异, 持效期达11 d, 代森锰锌、甲基硫菌灵、氢氧化铜和咪鲜胺4种保护剂的持效期只能维持6 d。炭疽叶枯病的防治应以波尔多液为主, 并与吡唑醚菌酯等有机杀菌剂交替使用, 有机铜制剂不能替代波尔多液。     

A Serious Disease of Annato Caused by Glomerella cingulata

Abstract

The occurrence of a disease of annato apparently restricted to the pods is reported, and is caused by a Colletotrichum state of Glomerella cingulata.     

Infections of Glomerella cingulata on olive in Italy1

Olive anthracnose, caused by strains or populations of Glomerella cingulata (anamorph Colletotrichum gloeosporioides) pathogenic for olive, was introduced into southern Italy before or during the 2nd World War presumably from Albania or Greece. In the following 20 years, severe outbreaks of fruit rot and dieback of twigs and branches were recorded in several areas of Puglia, Calabria, Sicilia and Sardegna. After the 1970s, the epidemics gradually regressed. At present, the disease is restricted to certain humid areas of southern Italy. Factors associated with this regression are discussed, including a supposed change in virulence of the fungus, possibly as a consequence of mixing of the introduced strains infecting olive trees with local, less pathogenic populations of G. cingulata. The first results of a comparison of olive isolates with isolates of the pathogen from citrus and Annona muricata in Calabria suggest that the population from olive is relatively homogeneous and can be distinguished from the population infecting other hosts by a number of morphological, pathogenic and biochemical characteristics.     

解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌的抗生作用

为明确解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌的抗生作用, 采用平板对峙法和菌丝生长速率法以及孢子萌发法测定了解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌菌落生长和孢子萌发的抑制作用?结果表明:菌株TS-1203对苹果炭疽叶枯病菌具有显著的抑制作用, 其菌液对病菌的抑制率高达70.4%; 其发酵液对苹果炭疽叶枯病菌的抑制率随着发酵液浓度的增加而升高, 尤其当发酵液浓度为15%时, 其抑菌率为 59.0%; 发酵液处理苹果炭疽叶枯病菌孢子24 h后, 其萌发抑制率与芽管生长抑制率分别为78.2%与64.3%, 且芽管出现畸形; 利用TS-1203发酵液处理苹果离体叶片后接种炭疽叶枯病菌, 其防效为70.1%?综合分析表明, 解淀粉芽胞杆菌TS-1203对苹果炭疽叶枯病菌具有良好的抑制作用?     

Resistance to acylalanine fungicides in Phytophthora megasperma f.sp. medicaginis

Isolates ofPhytophthora megasperma f. sp.medicaginis resistant to the systemic fungicide metalaxyl were obtained by mycelial adaptation and by mass selection from zoospores either untreated or treated with UV irradiation or with the chemical mutagenN-methyl-N-nitro-N-nitrosoguanidine. In an assay with one-week-old lucerne seedlings all of 19 spontaneously obtained isolates showed a relatively low degree of resistance and were less virulent than the original isolate. Only one of these isolates showed resistance in vivo in this test. From 176 highly resistant isolates obtained after mutagenic treatment, 81 were as virulent as the orginal isolate and 33 of the latter displayed a considerable degree of resistance in vivo.Metalaxyl at a concentration of a.i. in soil of 20 mg.l^–1 failed to control root rot of 7–8 week old lucerne plants inoculated with mycelial fragments of virulent resistant isolates. Under similar conditions root rot caused by the original isolate was completely prevented even at a concentration of a.i. of 2.5 mg.l^–1.The resistance to metalaxyl appeared to be highly stable since virulent and resistant strains did not loose their resistance after 12 infection cycles in a seedling assay in the absence of the fungicide, neither did mixed populations of a resistant and a sensitive isolate under similar conditions.The likelihood of development of resistance to acylalanine fungicides under practical conditions is discussed.Samenvatting VanPhytophthora megasperma f. sp.medicagninis, een wortelpathogeen van luzerne, konden tegen metalaxyl resistente isolaten worden verkregen na adaptatie van mycelium en selectie uit, zoösporen die al dan niet behandeld waren met het chemisch mutagensN-methyl-N-nitro-N-nitrosoguanidine. Alle 19 spontaan verkregen isolaten vertoonden een lage graad van resistentie en hun virulentie in een zaailingentest was lager dan van het oorspronkelijke isolaat. Slechts één van deze isolaten vertoonde resistentie in vivo. Bij toetsing van 176 isolaten met een hoge graad van resistentie die na een mutagene behandeling waren verkregen bleek dat 81 isolaten even virulent waren als het oorspronkelijke isolaat en dat er 33 een aanzienlijke graad van resistentie in vivo te zien gaven.Metalaxyl in een a.i. concentratie van 20 mg.l^–1 grond kon het optreden van wortelrot bij 7–8 weken oude luzerne planten niet verhinderen, wanneer deze werden geinoculeerd met gefragmenteerd mycelium van resistente isolaten. Onder dezelfde omstandigheden kon het oorspronkelijke isolaat reeds volledig worden bestreden bij een a.i.-dosering van 2.5 mg.l^–1.Resistentie tegen metalaxyl bleek een zeer stabiele eigenschap te zijn omdat bij een viertal getoetste stammen de resistentie niet verdween na 12 infectiecycli in een zaalingentest bij afwezigheid van het fungicide.Onder deze omstandigheden bleek ook dat de resistente stammen niet verdwenen uit mengpopulaties van een gevoelige en een resistente stam hetgeen erop wijst dat de virulentie van de resistente isolaten van hetzelfde niveau is als dat van het oorspronkelijke isolaat.Op grond van de gevonden resultaten mag de mogelijkhei tot resistentieontwikkeling tegen acylalanine fungiciden in de praktijk aanwezig worden geacht.     

Analysis of a Secreted Aspartic Peptidase Disruption Mutant of Glomerella cingulata

Peptidases have been implicated in the pathogenicity of fungi that cause disease in plants. Expression of the secreted aspartic peptidase gene (gcsap), of a Glomerella cingulata isolate pathogenic on apples, is induced during appressorium formation. To determine whether the secreted aspartic peptidase (GcSAP) is essential to pathogenicity, gcsap was disrupted using a vector containing a 637 bp fragment of genomic DNA that encodes the sequence spanning the two active site aspartic acid (Asp) residues. To ensure that the truncated gcsap gene products could not have residual peptidase activity the codons for the active site residues Asp¹¹² and Asp²⁹⁷ were both mutated to histidine residues. Both PCR and Southern analysis confirmed disruption of gcsap. Neither gcsap mRNA nor GcSAP activity was detected in the disruption mutant. Pathogenicity tests on fruit from three apple cultivars showed that GcSAP was not required for pathogenicity. The disruption mutant grew on medium containing protein as the sole source of nitrogen because G. cingulata secretes a previously undetected peptidase(s). A serine peptidase that had a pH optimum between pH 7.0 and 8.0 and a K _m of 0.25 mM for the synthetic substrate succinyl-Ala–Ala–Pro–Phe-p-nitroanilide was identified.     

15%壬菌铜水乳剂防治柑桔炭疽病药效试验

试验表明15％壬菌铜水乳剂对柑桔炭疽病防效好，且耐雨水冲刷，持效期长，使用浓度600～800倍液时，1次药后防效达90％以上，2次药后防效达85％以上，与25％咪鲜胺乳油800倍液防效相当，且壬菌铜水乳剂价格低廉，值得推广使用。     

Chemical control of the olive rot caused by Glomerella cingulata1

The effect of various fungicides on Glomerella cingulata, the causal agent of a serious rot of olive fruits, was evaluated both in vitro and in the field. The following fungicides were tested: copper oxychloride, Bordeaux mixture, ziram, myclobutanil, hexaconazole, metiram, bitertanol and benomyl. Field trials were carried out in Calabria (southern Italy) for 2 years on two olive cultivars, Ottobratica (susceptible) and Sinopolese (resistant). The minimum effective concentrations of bitertanol, hexaconazole, myclobutanil, benomyl, metiram, ziram, and copper oxychloride on mycelial growth in vitro were < 5, < 50, < 50, < 1000, < 1000, < 1000, < 1000 μg ml^?1, respectively. The ED90 values for conidial germination were 0.01, 0.02, 50, 50, 1000, 1000, and 1000 μg ml^?1 of benomyl, ziram, myclobutanil, copper oxychloride, bitertanol, hexaconazole and metiram, respectively. In field trials, Bordeaux mixture and copper oxychloride proved to be the most effective products; however ziram, myclobutanil, bitertanol, metiram, and hexaconazole reduced the incidence of fruit rot significantly.     

小麦白粉病菌对甲氧基丙烯酸酯类杀菌剂敏感性及其交互抗性

 20世纪70年代后期以来,小麦白粉病在我国小麦产区上升为主要病害,严重制约小麦生产。沿海北部及淮北地区,小麦白粉病常年发生4级左右。目前麦类白粉病的防治药剂主要有三唑类、嘧啶类、苯并咪唑类、甲氧基丙烯酸酯类及硫代氨基甲酸盐类等。但小麦白粉病菌变异快,繁殖迅速,以及药剂长期单一使用,造成小麦白粉病菌易产生抗药性。1995年我国小麦白粉菌对三唑酮的平均抗性水平在16.8倍以上。因而,急需寻找和开发替代三唑酮防治小麦白粉病的新型药剂。甲氧基丙烯酸酯类杀菌剂继三唑类杀菌剂后出现, 是一类内吸保护型杀菌剂,主要作用于真菌的线粒体呼吸链中细胞色素bc1复合物,阻止电子传递,抑制真菌生长。此类药剂于1996年投入德国市场,尚未在我国小麦白粉病防治上大量使用。     

Genetics of responses to morpholine-type fungicides and of avirulences inErysiphe graminis f. sp.hordei

The genetics of the responses of the barley powdery mildew pathogen,Erysiphe graminis f.sp.hordei, to three morpholine-type fungicides were studied. Resistances to a phenylpropylamine fungicide, fenpropidin, and to a morpholine, fenpropimorph, co-segregated in crosses of a sensitive isolate, DH14, with each of two resistant ones, CC151 and CC152. In the cross CC151×DH14, the results were consistent with resistance to both fungicides being controlled by a single gene, at a locus namedFenl. In the other cross, CC152×DH14, the genetics of resistance were more complicated; the data were consistent with the segregation of two complementary, unlinked genes which each conferred resistance to both fungicides. Fenpropidin-resistant progeny of CC151×DH14 were significantly more resistant to fenpropimorph than were fenpropidin-resistant progeny of CCI 52×DH14, although the resistant progeny of the two crosses did not differ significantly in their level of fenpropidin resistance. Fenpropidin-resistant progeny of CC151×DH14 were significantly more resistant to another morpholine, tridemorph, than were fenpropidin-sensitive progeny, but this was not the case for CC152×DH14. Resistance to triadimenol, a C14 demethylation-inhibitor (DMI) fungicide, segregated in both crosses. Triadimenol resistance appeared to be controlled by one gene in each cross and was not associated with morpholine resistance. CC151×DH14 also segregated for eight avirulence genes. Two of these matched theMla6 resistance, while one gene matched a previously unknown resistance in a Pallas near-isogenic line, P17, which also carries a known resistance gene,Mlk. Fenl was not significantly linked to the triadimenol resistance gene,Tdl(a), or to any of the eight avirulence genes.Avr _a6 1, Avr _a12 ,Avr _La ,Avr _p17 andTdl(a) were linked, as wereAvr _a 10 andAvr _k .Abbreviations ED₅₀ median effective dose - Fpd fenpropidin - Fpm fenpropimorph - PCA principal components analysis - Tdm tridemorph     

Effect of split applications of fenpropimorph-containing fungicides on sensitivity of Erysiphe graminis f.sp. tritici

A field trial was conducted in the south of the Netherlands over a period of 3 years (1992–94) in order to test the effect of fenpropimorph-containing fungicides on the sensitivity of Erysiphe graminis f.sp. tritici to fenpropimorph. In general, use of split applications resulted in a better protection against wheat powdery mildew than use of normal applications. This is ascribed to a better timing of the split applications. The sensitivity to fenpropimorph of the mildew population in plots treated with normal applications of both fungicides did not change during the growing seasons of the years investigated. In contrast, the sensitivity of the mildew population from plots treated with split applications of Corbel became significantly lower. A significantly lower sensitivity was also found in the mildew population from plots treated with split applications of Tilt Top in 1993 and 1994. These results indicate that split applications can increase the rate at which E. graminis f.sp. tritici can become less sensitive to fenpropimorph. Because maintenance of sensitivity of the pathogen population is valued highly, the split application strategy of fenpropimorph-containing fungicides is not recommended for wheat powdery mildew control.     

Genetic control of the resistance of Erysiphe graminis f.sp. hordei to five triazole fungicides

The genetics of resistance to ergosterol demethylation inhibitor (DMI) fungicides of the triazole (conazole) group was examined in a cross between two isolates of the barley powdery mildew fungus, Erysiphe graminis (=  Blumeria graminis ) f.sp. hordei . One isolate, E1, was previously identified as being resistant to the triazole fungicide triadimenol, while the other, HL3/5, was sensitive. The 56 progeny tested were classified into two distinct groups, either being resistant to triadimenol, like E1, or sensitive, like HL3/5. The segregation ratio was not significantly different from 1:1, consistent with responses to triadimenol being controlled by a single gene. In further tests with cyproconazole, epoxiconazole, propiconazole and tebuconazole, all the progeny classified as resistant to triadimenol were also more resistant to each of these other triazole fungicides than were any of the triadimenol-sensitive progeny. This is consistent with the triadimenol resistance allele also conferring cross-resistance to the other triazoles. The ratio between the responses of the resistant and sensitive progeny (the resistance factor, RF) was greatest for triadimenol, followed by tebuconazole, propiconazole, epoxiconazole and cyproconazole, in that order. The RF for triadimenol was much greater when the fungicide was applied as a seed treatment than when it was sprayed. Five isolates, covering the five levels of responses to triadimenol identified previously in the UK population of E. graminis f.sp. hordei , were used as standards; a triadimenol-sensitive isolate and one with the lowest level of resistance were sensitive to all four of the other fungicides, while three isolates with higher levels of triadimenol-resistance were also more resistant to the other chemicals.     

Abscission Layer Formation as a Resistance Response of Peruvian Apple Cactus Against Glomerella cingulata

ABSTRACT Stem disks from 2-year-old cacti Cereus tetragonus (susceptible) and C. peruvianus (resistant) were inoculated in the center (pith) with Glomerella cingulata isolated from Colletotrichum stem rot in three-angled cacti. The susceptible cactus became extensively colonized, whereas colonization was limited to a small area in the resistant cactus. The resistant cactus formed prominent abscission layers (ALs) in parenchyma internal to the inoculation site. Ethanol extracts of the fungal culture also stimulated AL formation in the resistant cactus. Initial cell division followed at 2 to 4 days after treatment, and layering of multiple cells at 7 days after treatment. After 10 days, the outer layers were sometimes sloughed from the inner layers. No AL formation was induced in susceptible C. tetragonus treated with ethanol extract or in untreated control cacti. Light and electron microscopy revealed that initial cell division occurred by cell wall formation, and that an additional cell wall was layered in pre-existing parenchyma cells without ordinary cell division. Later, separation layers formed in ALs where inner cell walls appeared to be thickened secondarily, and the cell walls and middle lamella within the layer dissolved. These results suggest that AL formation in the resistant cactus is induced by fungal metabolites, and that it serves as a histological barrier against anthracnose pathogens.     

Effect of low volume copper sprays with polyisobutene sticker on mango blossom blight (Glomerella cingulata) in Dominica

Abstract

Two spraying strategies to control mango blossom blight caused by Glomerella cingulata were tested in Dominica In one trial, a single dose of 4% copper oxychloride (18 g per tree) was applied to foliage before flowering had started, while the other trial compared fortnightly applications of concentrations up to 2%, starting after flowering. The early single dose gave a significant increase in fruit set, whereas the repeated doses gave no significant effects. Early application, followed by a low volume spraying of protectant fungicides, may reduce the cost of disease control. The addition of 0.5% polyisobutene sticker, tested in the single dose trial, gave a consistently improved fruit set compared to the non‐sticker treatment, significant at one recording date; the overall evidence was encouraging. In vitro tests showed that the fungus was less sensitive to copper than to chlorothalonil and some systemic fungicides.     

First report of Pestalotiopsis guepini and Glomerella cingulata on blueberry in Buenos Aires (Argentina)

Blueberry is a relatively new crop cultivated in the provinces of Buenos Aires, Córdoba, Río Negro and Santa Fe (AR). In 1996, an unknown disease was observed. Plants ready to be planted near Buenos Aires and plants growing in a glasshouse in Buenos Aires, both imported from USA, had their stems blighted. Pestalotiopsis guepini and Glomerella cingulata were determined as causal agents of the symptoms.     

Baseline sensitivity to proquinazid in Blumeria graminis f. sp. tritici and Erysiphe necator and cross‐resistance with other fungicides

BACKGROUND: Proquinazid is a new quinazolinone fungicide from DuPont registered in most European countries for powdery mildew control in cereals and vines. The aim of this paper is to present baseline sensitivity data in populations of Blumeria graminis f. sp. tritici EM Marchal and Erysiphe necator (Schw) Burr as well as results from cross‐resistance studies with other fungicides. RESULTS: Proquinazid exhibited a high intrinsic activity on B. graminis f. sp. tritici isolates at rates ranging from 0.000078 to 0.02 mg L^?1. Erysiphe necator isolates were comparatively less sensitive to proquinazid, with EC₅₀ values ranging from 0.001 to 0.3 mg L^?1. Proquinazid controlled equally well B. graminis f. sp. tritici isolates sensitive and resistant or less sensitive to tebuconazole, fenpropimorph, fenpropidin, cyprodinil and kresoxim‐methyl. A positive correlation (r = 0.617) between quinoxyfen and proquinazid sensitivities was found among 51 B. graminis f. sp. tritici isolates. Quinoxyfen‐resistant B. graminis f. sp. tritici isolates were slightly less sensitive to proquinazid than the quinoxyfen‐sensitive isolates; however, proquinazid remained much more active than quinoxyfen on these isolates. A stronger sensitivity relationship (r = 0.874) between proquinazid and quinoxyfen was found among 65 E. necator isolates tested in a leaf disc assay. The sensitivity values for proquinazid were significantly lower than those for quinoxyfen, confirming the higher intrinsic activity of proquinazid on both pathogens. CONCLUSION: Given the history of resistance development in powdery mildew and the observed sensitivity relationship with quinoxyfen, specifically in E. necator, we conclude that the risk of resistance developing to proquinazid might be influenced by the use of quinoxyfen. Based on these results, the authors recommend that proquinazid and quinoxyfen be managed together for resistance management. Copyright © 2009 Society of Chemical Industry