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1.
The mode of action of soluble silicon against strawberry powdery mildew (Sphaerotheca aphanis var. aphanis) was investigated in four experiments. First, silicon-treated leaves from plants grown with silicate (Si+) and control leaves
were excised, inoculated with conidia, and subsequent germination and formation of appressoria in a petri dish was assessed
after 24 h. The germination rate was 49.7% on Si+ leaves, and was 67.2% on control leaves (t-test, P < 0.01). Second, we soaked cellulose membranes in various solvents and then placed the membranes on 4% water agar, dusted
the membranes with conidia, and examined after 12 h. No difference was apparent between any treatment and the control (distilled
water). Third, strawberries growing hydroponically with additional silicon in the medium were inoculated with conidia, and
leaves were observed with a scanning electron microscope 1–2 days after inoculation. Germ tubes and secondary hyphae were
shorter and had fewer branches on Si+ leaves than on the control. Moreover, penetration appeared to be inhibited. Fourth,
the cuticle was separated from leaves from plants grown as in the third experiment, placed on water agar, and dusted with
conidia. Germination of conidia, observed with a light microscope, on Si+ leaves was suppressed markedly to 40%–60% of that
of the control. These results suggested that soluble silicon induced physiological changes in the cuticle layer after absorption
by the plant. In addition, soluble silicate reduced germination of conidia, formation of appressoria, and possibly the penetration
of powdery mildew. 相似文献
2.
L. J. Dallagnol F. A. Rodrigues F. A. O. Tanaka L. Amorim L. E. A. Camargo 《Plant pathology》2012,61(2):323-330
The effects of silicon (Si) supplied in the form of potassium silicate (PS) were evaluated on epidemic components of powdery mildew of melon under greenhouse conditions. The PS was applied to the roots or to leaves. In the first experiment, epidemic components were evaluated after inoculation with Podosphaera xanthii. In the second experiment, the disease progress rate was evaluated on plants subjected to natural infection. The area under the disease progress curve was reduced by 65% and 73% in the foliar and root treatments, respectively, compared to control plants, as a consequence of reductions in infection efficiency, colony expansion rate, colony area, conidial production and disease progress rate. However, root application of PS was more effective than foliar application in reducing most of the epidemic components, except for infection efficiency. This can be explained by the high Si concentration in leaf tissues with root application, in contrast to the foliar treatment where Si was only deposited on the external leaf surfaces. The effects of PS reported in this study demonstrated that powdery mildew of melon can be controlled, and that the best results can be achieved when PS is supplied to the roots. 相似文献
3.
Comparison of root and foliar applications of potassium silicate in potentiating post‐infection defences of melon against powdery mildew 
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下载免费PDF全文 L. J. Dallagnol F. A. Rodrigues S. F. Pascholati A. A. Fortunato L. E. A. Camargo 《Plant pathology》2015,64(5):1085-1093
The application of silicon to the roots or leaves reduces the severity of powdery mildew (Podosphaera xanthii) in melon but the latter treatment is less effective. This study compared key biochemical defence responses of melon triggered by P. xanthii after root or foliar treatment with potassium silicate (PS). Treatments consisted of pathogen‐inoculated or mock‐inoculated plants supplied with PS via roots or foliarly, as well as a non‐treated control. The activity of defence enzymes and the concentration of phenolic compounds, lignin and malondialdehyde were determined from leaf samples at different time points after inoculation. Pathogen‐inoculated plants irrigated with PS showed both an accumulation of silicon and primed defence responses in leaves that were not observed in pathogen‐inoculated plants either sprayed with PS or not treated. These responses included the anticipated activity of peroxidase and accumulation of soluble phenols, the activation of chitinase and repression of catalase, and the stronger activation of superoxide dismutase, peroxidase and β‐1,3‐glucanase. Moreover, the lignin concentration increased in response to inoculation, whereas the malondialdehyde concentration decreased. For the foliar treatment, however, only an increase in lignin deposition was observed compared with the control plants. The results show that silicon strongly plays an active role in modulating the defence responses of melon against P. xanthii when supplied to the roots as opposed to the foliage. 相似文献
4.
野生茄叶片土壤添加物和浸提物调控茄子黄萎病抗性的机制初探 总被引：2，自引：1，他引：1
1. College of Agricultural Resources and Environment, Heilongjiang University, Harbin150080, China;2. College of Horticulture, Shenyang Agricultural University, Shenyang110161, China;3. Shenyang Agricultural Institute, Shenyang110034, China 相似文献
5.
棉花品种抗黄萎病性与体内生化成分相关分析 总被引：12，自引：0，他引：12
对棉花不同抗感黄萎病性品种生化成分分析结果表明:棉花品种在无菌土中体内可溶性还原糖含量相应地高于接菌土中的含量。蕾期抗耐品种平均含量为2.276％,高于感性品种的1.417％,而铃期趋势相反。叶片单宁含量高于根部。在无菌土中,抗耐品种叶片单宁含量平均为3.58％,高于感病品种的3.28％;而在接菌条件下趋势相反。根部棉酚含量显著高于叶部,但两者极显著相关。在无菌土和接菌土中,抗性品种棉酚含量均高于耐性品种,而耐性品种又高于感性品种。棉株体内棉酚含量与棉花品种抗黄萎病性显著正相关。同工酶谱测定显示,过氧化物酶在抗感品种的无病症叶片中,酶带特征基本一致,叶片显症后表现主酶带区加宽,主酶带数增多,变化趋势与症状严重度正相关。在显症条件下,抗性品种酯酶同工酶活性略强于感性品种;与无症叶相比,显症叶的SOD酶带数由原来的4—6条减少至3—4条,抗性品种的酶带数少于感性品种1—2条。 相似文献
6.
不同剂型吡虫啉在烟叶和土壤中的残留及消解动态 总被引：3，自引：2，他引：1
采用高效液相色谱检测技术,于2010—2011年开展了吡虫啉可溶液剂、可湿性粉剂、微乳剂和颗粒剂4种常见剂型的不同施药剂量、不同施药次数和采收间隔期的田间试验,研究了不同剂型吡虫啉在烟叶和土壤中的残留降解规律与最终残留量。结果表明,在3个添加水平（0.01~5 mg/kg）、5次重复下,鲜烟叶、干烟叶和土壤中吡虫啉的平均回收率和相对标准偏差（RSD）分别为85.6% ~89.3%,5.0% ~5.7%;85.0% ~88.3%,3.5% ~5.0%;84.1% ~91.5%,3.4% ~8.0%;符合农药残留检测要求。吡虫啉最小检出量（LOD）为0.3 ng（S/N=3）,最低检测浓度（LOQ）分别为:鲜烟叶0.01 mg/kg,干烟叶0.03 mg/kg,土壤0.01 mg/kg。由于推荐剂量不同,不同剂型农药在烟叶上的原始沉积量有较大差别,可溶液剂、可湿性粉剂、微乳剂和颗粒剂4种剂型的吡虫啉降解速率均较快,半衰期分别为5.7~6.6、3.1~3.7、5.0~5.1和10.5~11.4 d。在不同处理的干烟叶中,吡虫啉残留量有明显差异,根据国际烟草科学合作研究中心（CORESTA）的指导性残留限量为5 mg/kg,建议大田喷雾施药的3种剂型（可溶液剂、可湿性粉剂和微乳剂）安全间隔期为14 d,移栽期穴施的颗粒剂安全间隔期为70 d。 相似文献
7.
Suppressive effect of potassium silicate on powdery mildew of strawberry in hydroponics 总被引：1，自引：0，他引：1
From 1996 to 1997, potassium silicate (SiO2) was tested at 0, 25, 50, and 100mgl–1 in hydroponics to control powdery mildew. Other elements were added in the usual amounts, and the strawberries were cultivated hydroponically in a greenhouse for 4 months (from October to January). The powdery mildew spread in the control plot, but little mildew developed in the plot with 25mgl–1 silicate, and none in plots with more than 50mgl–1 silicate. The suppressive effect lasted for about 4 months on fruits and even longer on leaves. On analysis of mineral content in the leaves, only the silicate content differed markedly between the control and treated plants. Nitrogen, phosphate, potassium, and calcium contents did not differ greatly. The maximum silicate content was about 24 times that of the control, and disease severity decreased significantly when the content was more than 1.5% in the leaves. The hardness of the strawberry leaves, measured by a creep meter, was increased by the silicate treatment. 相似文献
8.
几种化学物质诱导彩色马蹄莲对软腐病抗性的研究 总被引：1，自引：0，他引：1
本试验测定了纳米硅、草酸、硅酸钠和硫酸亚铁4种化学物质在不同浓度下对彩色马蹄莲软腐病菌的室内抑菌活性和诱导抗病效果。结果表明,硫酸亚铁3种浓度对彩色马蹄莲软腐病菌均表现较强的抑制作用;1 g/L纳米硅、0.15 g/L草酸和0.2 g/L硅酸钠3种化学物质对软腐病菌无明显抑制作用且诱导抗病效果较好,分别达到62.28%、77.56%、88.46%;经3种化学物质诱导处理后再进行接种,诱导处理和接种期间彩色马蹄莲叶片组织内过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)酶活性均高于对照,其中硅酸钠处理后彩色马蹄莲叶片组织内POD、PAL活性高于纳米硅和草酸处理,草酸处理后叶片组织内PPO活性高于纳米硅和硅酸钠处理。 相似文献
9.
运用旱作雨养土壤水库储水模式的田间试验方法,研究了其对烤烟农艺性状、物理性状、化学成分以及产量和产值的影响。结果表明,旱作雨养土壤储水模式(T)处理下的烤烟农艺性状综合表现优于一般大田种植模式(CK),烤烟田间长势均匀,茎杆粗壮;烟叶单叶重和叶质重在两处理间达到显著差异,T处理烤烟各部位烟叶单叶重和叶质重均高于CK,中部叶的单叶重和叶质重分别达22.90 g和76.67 g·m~(-2);T处理上部烟叶的填充值和含梗率为3.64 cm~3·g~(-1)和26.29%,显著低于CK处理,而中上部烟叶平衡含水率表现为TCK,且差异显著;T处理能够改善烟叶化学成分,其中能够显著提高不同部位烟叶钾含量和钾氯比,其均值达2.74%、6.89,同时较CK显著降低了总氮、烟碱和氯含量;同时旱作雨养土壤储水模式能够提高烟叶的产量产值,烟叶的产量为2 156.7 kg·hm~(-2),显著高于CK。 相似文献
10.
Effects of foliar- and root-applied silicon on the enhancement of induced resistance to powdery mildew in Cucumis sativus 总被引：3，自引：0，他引：3
Two cucumber ( Cucumis sativus ) cultivars differing in their resistance to powdery mildew, Ningfeng No. 3 (susceptible) and Jinchun No. 4 (resistant), were used to study the effects of foliar- and root-applied silicon on resistance to infection by Podosphaera xanthii (syn. Sphaerotheca fuliginea ) and the production of pathogenesis-related proteins (PRs). The results indicated that inoculation with P. xanthii significantly suppressed subsequent infection by powdery mildew compared with noninoculation, regardless of Si application. Root-applied Si significantly suppressed powdery mildew, the disease index being lower in Si-supplied than in Si-deprived plants, regardless of inoculation treatment. The resistant cultivar had a more constant lower disease index than the susceptible cultivar, irrespective of inoculation or Si treatment. Moreover, with root-applied Si, activities of PRs (for example peroxidase, polyphenoloxidase and chitinase) were significantly enhanced in inoculated lower leaves or noninoculated upper leaves in inoculated plants of both cultivars. Root-applied Si significantly decreased the activity of phenylalanine ammonia-lyase in inoculated leaves, but increased it in noninoculated upper leaves. However, Si treatment failed to change significantly the activity of PRs in plants without fungal attack. Compared to the control (no Si), foliar-applied Si had no effects either on the suppression of subsequent infection by P. xanthii or on the activity of PRs, irrespective of inoculation. Based on the findings in this study and previous reports, it was concluded that foliar-applied Si can effectively control infections by P. xanthii only via the physical barrier of Si deposited on leaf surfaces, and/or osmotic effect of the silicate applied, but cannot enhance systemic acquired resistance induced by inoculation, while continuously root-applied Si can enhance defence resistance in response to infection by P. xanthii in cucumber. 相似文献
11.
为明确公主岭霉素在草莓生产中的防病诱抗效应,于大田采用五点取样法调查公主岭霉素对草莓白粉病的防控效果及对植株生长性状的影响,并于室内采用生测法测定其对草莓叶片防御酶活性和根际土壤酶活性的影响。结果显示,以公主岭霉素水浸提液100倍稀释液进行灌根并协同叶面喷雾对草莓白粉病的预防效果为71.90%;单独叶面喷雾对草莓白粉病的治疗效果为69.90%;灌根协同叶面喷雾预防与叶面喷雾治疗的综合防控处理对草莓白粉病的防治效果可达85.37%。公主岭霉素水浸提液100倍稀释液灌根后草莓幼苗的株高、叶柄长、叶长、叶宽、叶数、径冠等方面均优于清水对照;叶面喷施可提升叶片中多酚氧化酶和超氧化物歧化酶的活性,喷雾后1 d内即较清水对照显著提高;5 d后过氧化氢酶活性显著高于清水对照。灌根后根际土壤中蔗糖酶的活性在用药后15 d内均显著高于清水对照。表明合理施用公主岭霉素可实现对草莓白粉病的有效防控,并诱导提升草莓植株的抗病性,改善草莓生长环境,促进其生长。 相似文献
12.
Systemic application of sodium silicate can significantly enhance the levels of leaf silica in winter wheat (Triticum aestivum L. cv. Mercia), suggesting that this material could reduce the palatability of plants to vertebrate herbivores (e.g. rabbits, Oryctolagus cuniculus L.). A bioassay was developed using hydroponically grown wheat plants. Plants treated with sodium silicate were significantly more resistant to grazing by wild rabbits than untreated plants, with severe, potentially lethal feeding damage being reduced by over 50%. Further studies were carried out to develop more practical techniques for boosting silica levels in plants using silicon-rich 'fertilisers' including calcium silicate and calcium silicate slag (CSS). Silica levels were elevated in the plant 1.9-2.8 times over the control through the application of various silicon materials, in line with those of the hydroponic treatment. Encouragingly, levels of silica were elevated even in young wheat plants, which are most vulnerable to rabbit damage, and in a range of wheat varieties. The use of CSS is particularly promising because of its lower cost in comparison with calcium silicate, and it has a proven track record in slag fertilisation of rice and sugar cane crops. At the optimum CSS application rate of 3 g silicon L(-1) soil, wheat silica levels were approximately doubled, with no detrimental impacts on long-term growth or yield. 相似文献
13.
为烟叶生产中二氯喹啉酸对烟草药害的微生物修复提供科学参考依据。以“云烟87”为供试材料,采用盆栽试验,模拟二氯喹啉酸残留浓度0.02 mg/kg,研究富必来微生物酶制剂、格芙微生物菌剂、仙丰168和腊状芽胞杆菌Bacillus cereus LY05对二氯喹啉酸致害烟株生长情况、生理生化指标、烟叶化学成分和烟叶及其土壤二氯喹啉酸残留降解的影响。结果表明,4种微生物菌剂对烟草二氯喹啉酸药害症状均有一定修复效果,其中以富必来微生物酶制剂（1：500倍液灌根,500 mL菌液量）对药害烟株修复效果最佳,烟苗移栽30和60 d后,对致害烟株叶长、叶宽、株高和茎围有显著促进作用（P<0.05）,显著增加了致害烟株地上和地下部鲜、干重,烟株主根长度最长且显著高出药剂对照41.65%;与药剂对照相比,增加了致害烟叶SOD、CAT、GSH酶活性和可溶性蛋白含量,增幅分别为56.51%、42.42%、24.47%和0.50%;显著降低了致害烟叶MDA含量,并改善了烟叶的化学成分,其两糖比、糖碱比和氮碱比分别为3.39、6.99和1.06,基本恢复至优质烟叶的品质范围;同时烟叶旺长期致害烟叶及其土壤二氯喹啉酸残留最低,分别为0.0356和0.0135 mg/kg,比药剂对照分别下降了63.31%和71.56%。腊状芽胞杆菌LY05对致害烟株有较好的修复作用,加快了二氯喹啉酸降解速率,对致害烟叶叶宽修复效果显著,有效舒缓了烟叶皱缩状,为二氯喹啉酸污染土壤及其致害烟株修复和复合微生物菌剂研制提供了新的方法和菌种资源。 相似文献
14.
为探明覆草条件下施氮水平对旱地梨树（Pyrus bretschnei deri Rehd.）生长发育和果实品质的影响,设置在全园覆草条件下株施纯氮1 kg（T1）、0.5 kg（T2）、0.25 kg（T3）和不施氮（T4,CK）四种处理,2011年至2012年测定了土壤和叶片养分、树体营养生长和果实产量品质等指标。结果表明,麦草覆盖条件下施氮能显著降低土壤pH值,提高土壤钙、锌含量,明显促进了梨叶片组织结构生长。随着施氮量的增加,梨树新梢生长量、叶面积和百叶重量、叶绿素含量显著提高。不同施氮处理均能提高梨果品产量,T1、T2、T3处理分别比对照提高25.4%、17.0%、11.6%。施氮后梨果实可溶性糖、有机酸含量明显降低,而果实硬度、可溶性固形物、水分含量等品质指标
处理间差异不显著。 相似文献
15.
研究建立了烟叶及土壤环境中嘧肽霉素残留的高效液相色谱(HPLC)检测方法:鲜烟叶样品采用V(乙腈):V(水)=19:1的混合溶剂提取,干烟叶及土壤样品采用V(乙腈):V(水)=17:3的混合溶剂提取,经PEP-SPE固相萃取柱净化,HPLC检测。结果表明:在0.05～2 mg/kg添加水平下,嘧肽霉素在鲜烟叶、干烟叶和土壤中的平均回收率分别为82.7%～89.6%、78.7%～81.5%和79.6%～97.8%,相对标准偏差(RSD)分别为4.9%～5.7%、2.1%～5.8%和3.2%～6.1%;烟叶和土壤中嘧肽霉素的最小检出量(LOD)均为0.05 mg/kg。采用所建立的方法测定了田间不同施药剂量、施药次数和采收时间下烟叶及土壤样品中嘧肽霉素的消解动态及最终残留。结果表明:嘧肽霉素在鲜烟叶和土壤中的半衰期分别为3.4～5.1 d和1.3～3.1 d;于烟草现蕾-成熟期,以2%嘧肽霉素水剂按有效成分28.2～42.3 g/hm2的剂量施药2～3次,距末次施药后7、14和21 d,烟叶及土壤中嘧肽霉素的残留量均低于LOD值(0.05 mg/kg)。 相似文献
16.
Epidemics of apple powdery mildew were monitored on leaves of vegetative extension shoots in a mixed-cultivar orchard in 1979. 1980 and 1981. Cultivars Cox's Orange Pippin. Golden Delicious. Ida Red and Suntan were very susceptible but little mildew developed on cv. Discovery in any year. Results with cvs Crispin and Spartan were less consistent due, in part, to differing patterns of vegetative growth. The rankings of cultivars for disease incidence (proportion of leaves with mildew), number of colonies and mildewed area were similar, and were also consistent on fungicide-sprayed and unsprayed trees in 1981. Less disease occurred on fungicide-treated Golden Delicious than on Cox's Orange Pippin. Most infections occurred on the rolled leaves at the shoot tip. Spore production was greatest on leaves at positions -1 to -4 where leaf 0 was the youngest and leaf - 1 the adjacent and older unrolled leaf. 相似文献
17.
不同硅源制剂对小麦白粉病的作用效果及对白粉病菌孢子萌发的影响 总被引：4，自引：1，他引：3
研究了不同形态硅源制剂二氧化硅纳米粒子溶胶(60nm和100nm)、正硅酸乙酯、硅酸钠对小麦白粉病的作用效果以及对白粉病菌孢子萌发的影响。结果表明,在相同浓度下几种硅源制剂处理盆栽小麦幼苗对白粉病防效分别为48.78%、43.73%、40.31%和33.29%,室内处理小麦离体叶段对白粉病抑制率分别为59.67%、53.51%、51.10%和42.22%。离体叶段接种白粉菌后1.5~2h、6~7h取样,在相差显微镜下观察白粉菌孢子萌发过程,发现这几种硅制剂对白粉菌孢子初生芽管(PGT)的形成几乎没有影响,但对附着胞(AM)的形成有较大影响,其中以二氧化硅纳米粒子溶胶对AM的影响最大。 相似文献
18.
Angelo Garibaldi Giovanna Gilardi Ettore Erik Cogliati Maria Lodovica Gullino 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(1):123-132
Downy mildew of lettuce, caused by Bremia lactucae, is difficult to control in soilless systems by using conventional methods of disease management because few chemicals are
registered, while resistant cultivars face the problem of resistance break down; therefore other methods for disease control
need to be investigated. The effect of silicon salt as well as increased electrical conductivities against downy mildew was
evaluated in four experiments carried out in hydroponically systems, using the cultivar of lettuce “Cobham Green”, known for
its susceptibility to the pathogen. Silicon, as potassium silicate, was added at 100 mg l−1 of nutrient solution at three levels of electrical conductivity: 1.5–1.6 mS cm−1 (EC1), 3.0–3.5 mScm−1 (EC2, 0.70 g l−1 NaCl) and 4.0–4.5 mS cm−1 (EC3, 0.95 g l−1 NaCl) respectively. Lettuce plants, grown for 14–20 (trials 1 and 2) and 36–45 (trials 3 and 4) days in the different nutrient
solutions tested, were inoculated with B. lactucae conidia with a maximum of two inoculations before final disease assessment carried out 14–21 days after the inoculation able
to give symptoms. EC and potassium silicate significantly influenced downy mildew incidence and severity, while their interaction
was not a significant factor. The addition to the standard nutrient solution (EC1) of potassium silicate resulted in a significant
reduction of downy mildew severity in trials 1 and 2 where plants were artificially inoculated 15 and 20 days after transplanting.
This efficacy was slight on plants grown for 36 and 45 days before inoculation in a soil drenched with EC1 amended with potassium
silicate. EC2 gave a significantly similar downy mildew reduction than EC2 added with potassium silicate in trial 3. Plants
grown for 36 and 45 days at the highest electrical conductivity (EC3) showed a significant reduction in severity of downy
mildew compared with that observed at EC2 level. The best results, in terms of disease control, were given by the addition
of potassium silicate to the EC3 solution. This combination also led to a significantly increased plant biomass. The possibility
and benefits of applying potassium silicate and increased EC amendments in practice is discussed. 相似文献
19.
Ruwanka N. K. Ratnayake W. A. Malkanthi Daundasekera Hearth M. Ariyarathne Manawadevi Y. U. Ganehenege 《Phytoparasitica》2018,46(4):541-549
Beneficial effects of Silicon (Si) on disease control have been shown in a number of plant pathosystems. The present study ascertained the effect of root application of soluble Si on postharvest quality of bitter gourd (Momordica charantia L.) with special reference to the disease development by Fusarium oxysporum. Plants were treated with Potassium silicate (Si+) by amending the soil mix (200 mgSi /kg soil). Treatments were started at the four leaf stage and continued up to 28 days at seven days intervals. Soil amendments with Si significantly reduced the postharvest weight loss and extended the shelf life by 2 days through delayed ripening and reduced fungal rot development. Si analysis in bitter gourds, harvested from Si?+?plants revealed that fruit tissues accumulated nearly1.5 times as much silicon (0.54% dry weight) as those grown in control (Si-) mix (0.36% dry weight). Extracts from Si?+?plants exhibited a stronger antifungal activity on thin layer chromatography (TLC) against Cladosporium cladosporioides. Methanolic extracts of fruit pericarp separated on TLC plates showed four antifungal zones at Rf 0.17, 0.51, 0.64 and 0.93. Compound separated at Rf 0.64 was observed in samples from Si?+?and/or challenged with F.oxysporum. Antifungal zone at Rf 0.51 was present only when Si?+?fruits were challenged with the fungus. These results suggest that by using soil application of soluble Si, postharvest quality of bitter gourd can be improved and shelf life can be enhanced by 2 days compared to the control. Enhanced fungitoxic activity may have some role in Si-induced disease resistance againstpostharvest fungal pathogens. 相似文献
20.
C. Gigot S. Saint‐Jean L. Huber C. Maumené M. Leconte B. Kerhornou C. de Vallavieille‐Pope 《Plant pathology》2013,62(5):1011-1019
The use of cultivar mixtures to control foliar fungal diseases is well documented for windborne diseases, but remains controversial for splash‐dispersed diseases. To try to improve this strategy, a cultivar mixture was designed consisting of two wheat cultivars with contrasted resistance to Mycosphaerella graminicola , responsible for the rainborne disease septoria tritici blotch (STB), in a 1:3 susceptible:resistant ratio rather than the 1:1 ratio commonly used in previous studies. The impact of natural STB epidemics in this cultivar mixture was studied in field experiments over 4 years. Weekly assessments of the number of sporulating lesions, pycnidial leaf area and green leaf area were carried out on the susceptible cultivar. In years with sufficient STB pressure, disease impacts on the susceptible cultivar in the mixture were always significantly lower than in the pure stand (e.g. 42% reduction of pycnidial leaf area for the three upper leaves in 2008 and 41% in 2009). In years with low STB pressure (2010 and 2011), a reduction of disease impacts was also shown but was not always significant. After major rainfall events, the number of sporulating lesions observed on the susceptible cultivar after one latent period was reduced on average by 45% in the mixture compared to the pure stand. All the measurements showed that a susceptible cultivar was consistently protected, at least moderately, in a mixture under low to moderate STB pressure. Therefore, the results prove that the design of an efficient cultivar mixture can include the control of STB, among other foliar diseases. 相似文献