Effect of planting date,fungicide timing and cultivar susceptibility on severity of narrow brown leaf spot and yield of rice

Narrow brown leaf spot (NBLS) of rice (Oryza sativa L.) is caused by Cercospora janseana (Racib). O. Const. (Synonyms: Cercospora oryzae Miyake, Passalora janseana Racib. U.). Experimental studies were conducted at Rice Research Station, Louisiana State University, and Agricultural Center, Crowley, to manage NBLS by fungicide application of propiconazole at different growth stages of rice cultivars having different susceptibility levels to NBLS in different planting dates. Results of these studies revealed that April (early) had less NBLS severity as compared to May (late) planting. Very susceptible cultivars, CL131 and Cheniere, had the highest and resistant cultivars, Della and Presidio, had the lowest NBLS severity at both the planting dates. Propiconazole application significantly reduced the NBLS severity in comparison to untreated. Fungicide application at panicle initiation was the most effective time to manage NBLS on the very susceptible and susceptible cultivars at both planting dates. NBLS on moderately susceptible cultivars was best managed by applying fungicide either at panicle initiation or early boot stage in early planting but panicle initiation was the best time to apply fungicide in late planting. Resistant cultivars did not need fungicide in April planting but did need in May planting. Rice yield was determined to be higher in April than May planting. Fungicide application at early boot stage protected the yield by 9.4% in April planting and 34.2% when applied at panicle initiation in May. Susceptible cultivar, Cheniere, exhibited the greatest yield and resistant cultivars had lowest yield in both the planting dates regardless of its susceptibility level to NBLS. Yield of very susceptible to susceptible cultivars was reduced in late planting but no effect was observed on yield of moderately susceptible and resistant cultivars.     

水稻抗纹枯病育种成效的初步评价

以广东省和江苏省里下河农科所新近育成的部分籼稻品种（系）、扬州大学农学院的研究组以不同抗源杂交后代向抗感两个极端选育的9份籼稻品系以及另一组合向抗病方向选育的5份籼稻品系为材料,设置抗感病对照,进行田间纹枯病菌接种试验。结果表明品种间对纹枯病的抗性存在极显著差异;聚类分析将参试材料按抗性水平高低聚为6类：高度感病、感病、中等感病、中等抗病、抗病和更高水平抗病。广东品种在6种类型中均有分布,但属于抗和更抗类型的品种只有3个。扬州大学农学院对抗×抗杂交向抗感两个极端选育的品系在病级的中间类型中几乎没有分布;而向抗病方向选育的品系则仅分布于中抗至抗病的范围内,且属于抗的品种数占此类品种的60%。江苏省里下河农科所近些年育成的几个品种则只分布于后4类之中,且最高水平抗性的3个品种中,其品种占2/3。表明水稻对纹枯病的抗性是可遗传的性状,对抗性的选择有效。     

Integrating a host-resistance factor into the FAST system to forecast early blight of potato

A host resistance factor was integrated into the FAST (Forecaster ofAlternariasolani onTomatoes) system to initiate and to schedule fungicide applications for three levels of potato cultivar susceptibility while maintaining disease control and yield. Four cultivars ranging from susceptible to moderately resistant were each treated with the fungicide chlorothalonil during two field seasons. The five fungicide treatments were a 7-day schedule initiated after 50% flowering; a non-sprayed control; and three FAST application schedules based on combinations of critical levels of cumulative severity (CS, the disease severity values as a function of leaf wetness and temperature) and cumulative rating (CR, the disease rating values as a function of average temperature and hours of relative humidity greater than 90%) values. The FAST system predicted the onset of early blight and subsequent periods conducive for disease development in 1993 and 1994. There were cultivar-by-spray-schedule interactions for both disease severity and yield, suggesting that differences in early blight sus-ceptibility exist between cultivars. Use of the recommended schedules for the cultivar’s targeted level of susceptibility reduced early blight severity and minimized fungicide use while maintaining yield. These results indicate that a host-resistance factor can be incorporated into the FAST system.     

Resistance Evaluation to Sheath Blight in Transgenic Rice Lines

Resistance of forty-one homozygous rice lines transformed with chitinase gene (RC24) and β-1,3 -glucanse gene β-1,3-Glu) to sheath blight was analyzed by inoculation. Among different lines, the resistance had significant differences according to the result by cluster analysis. The lines could be categorized into resistant, moderately resistant, moderately susceptible and susceptible types, while 92.1% of which belonging to moderately resistant or moderately susceptible type. For different resistant or susceptible lines, the resistance to rice sheath blight was remarkable correlated with the chitinase activity of transgenic lines except resistant type lines, in which enzyme activity coded by target gene was lower than moderately resistant type. The chitinase activity of transgenic lines tested at different time after inoculation or different organs of the same plant was uniform, which suggested that the expression of chitinase gene was constitutive in nature. Check varieties chitinase activity would change at different time after inoculation and reach a peak at sometime, but it had no difference at various pans of the same plant.     

Development of a formulation of Pseudomonas fluorescens PfALR2 for management of rice sheath blight

Pseudomonas fluorescens isolates that inhibited growth of Rhizoctonia solani, the rice sheath blight pathogen, were isolated from the rhizosphere of different crops. One of the most effective strains, PfALR2, was developed as an antibiotic resistant strain and a peat-based formulation was developed for this bacterium. The effective dose of a peat formulation was assessed for seed treatment, root treatment, soil application and foliar spraying. All individual treatments controlled the disease effectively. However, a combination of all four treatments resulted in the best sheath blight control in the greenhouse. In field trials, application of the peat-based formulation of PfALR2 effectively controlled the disease, increased yield, and efficacy was comparable to that of the commercially available fungicide, carbendazim.     

水稻苗期纹枯病抗性鉴定微室接种技术的改良

水稻对纹枯病的抗性属于典型的数量性状,多数栽培品种的抗病水平较低,并且抗性差异较小。水稻纹枯病接种和抗性评价体系是培育抗病品种的重要基础。利用植物生长箱的控温、控光和控湿条件以及生长势相对一致的水稻秧苗,对苗期纹枯病微室接种技术进行了改进。试验品种苗期的纹枯病抗性从高到低依次为YSBR1、特青、泰粳394、日本晴和Lemont,并且与大田成株期接种鉴定的结果一致。RT-PCR分析显示,苗期和成株期接种纹枯病菌均诱导4个水稻抗病相关基因的表达。通过"叶枕高"和"苗挺高"计算的各品种苗期病级变幅分别为2.82~8.54级和1.20~3.39级。前者与大田成株期的病级变幅一致,因而"叶枕高"病级计算方法更适用于微室接种鉴定体系。     

Effects of combined application of potassium phosphite and fungicide on stem and sheath disease control,yield, and quality of rice

Phosphite has been shown to suppress some diseases in different plant species but disease control in rice has not been investigated. In 2012/13 and 2013/14 potassium phosphite was sprayed at 1775 g ha⁻¹ and 3550 g ha⁻¹ in field plots of rice in Uruguay to determine if phosphite alone or in combination with label rates of a mixed strobilurin and triazole fungicide could be used to effectively control stem rot and aggregate sheath spot in irrigated rice. Six treatments consisting of different combinations of potassium phosphite alone or with a fungicide and an unsprayed control were assayed in one application at late-boot to early-heading. Phosphite alone in single and double rate slightly reduced severity and incidence of stem rot and produced a small yield increase over the unsprayed control. Fungicide at a 50% label rate with phosphite reduced stem rot severity and incidence to a similar level as the fungicide alone applied at the label rate. Disease severity was reduced by approximately 25% and incidence by 17–20% when compared with untreated control. Yield increase was 5% for both treatments over the unsprayed control. Fungicide combined with phosphite at single and double rates reduced stem rot severity by 40–45% and incidence by 34–38% when compared with untreated control, with yield increased by 10% over the unsprayed control and 5% over plots treated with a fungicide. These results indicate that a single application of potassium phosphite combined with fungicide can be used efficiently to manage of rice stem diseases.     

转基因水稻株系的纹枯病抗性分析

对通过基因枪转化获得的41个转水稻碱性几丁质酶和苜蓿β-1,3-葡聚糖酶基因（RC24和β-1,3-Glu）的高世代纯合株系进行纹枯病抗性接菌鉴定,结果表明不同转基因系间抗性存在极显著差异,聚类分析可分为抗、中抗、中感、感病四种类型,但其中92.1%的株系属中抗或中感类型;选择不同抗感类型的代表性株系,测定其几丁质酶活力,结果显示中抗、中感、感病类型转基因株系表达的几丁质酶活力与其纹枯病抗性表现呈现一致性,而抗病类型表达目标基因编码的酶活力低于中抗类型;接菌诱导后,在不同时间或同一植株的不同部位检测,转基因系的几丁质酶活力因其组成性表达而无明显差异,而未转基因的对照品种在诱导后不同时间其几丁质酶活力表达呈“峰”式曲线分布,同一植株不同空间位置的酶活力却无明显差异。     

Effect of host plant resistance and insecticide on brown planthopper Nilaparvata lugens (Stål) and predator population development in the Mekong Delta, Vietnam

Crop yield and populations of brown planthopper Nilaparvata lugens (Stål), whitebacked planthopper Sogatella furcifera (Horvath) (Homoptera: Delphacidae), green leafhopper Nephotettix spp. (Homoptera: Cicadellidae), and hemipteran and spider predators were monitored on rice varieties susceptible, moderately resistant, and highly resistant to N. lugens, under insecticide-treated and insecticide-free conditions. Nilaparvata lugens outbreaks and hopperburned plants were observed only in plots of the insecticide-treated susceptible varieties. In insecticide-free plots, the yield of the susceptible variety was lower than those of resistant varieties in only one of four seasons. In plots of a moderately resistant and a highly resistant variety, populations of N. lugens, S. furcifera, Nephotettix spp., and predators were generally similar, and yields did not differ, under both insecticide-treated and insecticide-free conditions. In insecticide-free plots, predator-N. lugens ratios were generally higher on resistant varieties than susceptible varieties. Two conclusions can'be drawn from our results relevant to the question of what levels of N. lugens host plant resistance are appropriate for farmers who do not overuse insecticides. First, susceptible varieties will not necessarily be damaged by N. lugens, even when N. lugens outbreaks occur in adjacent plots. Second, moderate and high levels of N. lugens resistance do not appear to be incompatible with biological control of N. lugens or other homopteran pests.     

武运粳系列水稻品种对纹枯病的敏感性差异研究

通过分品种分小区种植、系统调查了水稻纹枯病的发生情况。结果表明,不同武运粳系列品种对纹枯病的敏感度有差异,武运粳21号、武运粳24号、武运粳27号在高温高湿条件下纹枯病发展蔓延较快,属感病品种;武运粳29号、武运粳30号、武运粳31号纹枯病发生较轻,属抗病品种;其余品种为中感品种。     

Application of fungicides to reduce yield loss in anthracnose-infected lupins

A range of fungicides were evaluated for control of anthracnose (Colletotrichum lupini) in lupin. Glasshouse investigation identified fungicides that reduced disease severity with varying degrees of efficacy. When applied 1 d prior to infection, azoxystrobin, chlorothalonil, mancozeb and copper oxychloride fungicides were highly effective. Systemic fungicides such as tebuconazole, benomyl and carbendazim were less effective. Application timing was important; fungicides such as chlorothalonil and mancozeb were less effective when applied 5 d prior to infection compared with 1 d prior. Application after infection was ineffective for all fungicides. In field experiments application of azoxystrobin, mancozeb or chlorothalonil during flowering and podding reduced incidence of anthracnose infection on pods. Yield responses occurred in moderately susceptible, moderately resistant or resistant cultivars. Seed infection was reduced but not eradicated. Application of foliar fungicides for anthracnose control is potentially a viable management option for lupin production in high anthracnose risk areas of Western Australia.     

2020年我国审定的水稻品种基本特性分析

归纳分析了2020年我国通过省级以上审定水稻品种的基本特性。2020年我国通过省级以上审定的水稻品种共有1 936个次（574个品种通过国家审定）,籼型常规稻、籼型三系杂交稻、籼型两系杂交稻、粳型常规稻、籼粳交杂交稻和不育系分别为144、670、582、424、45和71个,其中,国审品种数比2019年增加54.30%,非国审品种数比2019年增加43.07%。2020年通过审定的籼型常规稻、籼型两系杂交稻、籼型三系杂产稻、粳型常规稻和粳型杂交稻区试产量分别为519.59、609.99、589.82、610.00和685.30 kg/667 m²,除粳型常规稻外,其他类型品种的区试产量相比2015—2019年均有一定程度提升。2020年国审品种优质达标率为78.57%,非国审水稻品种优质达标率为60.61%,均比2019年有提高,表现好。2020年通过审定的品种综合抗性表现总体仍不够好,国审品种中仅13.59%的品种对稻瘟病表现为中抗以上水平,仅5.11%的品种对白叶枯病表现为中抗,非国审品种中仅34.08%的品种对稻瘟病表现为中抗以上水平,仅20.09%的品种对白叶枯病表现为中抗以上水平,但有部分品种对稻瘟病和白叶枯病表现出高抗。     

Potassium phosphite combined with reduced doses of fungicides provides efficient protection against potato late blight in large-scale field trials

Potato late blight caused by the oomycete Phytophthora infestans is a devastating disease of potato worldwide. Most of the potato cultivars grown in conventional agriculture are susceptible, or at best moderately resistant, and require frequent applications of fungicides to avoid heavy yield losses.In field trials spanning four years, we have investigated the effect of potassium phosphite, an inorganic salt on potato late blight. Potassium phosphite is known to induce defence responses in potato and to also have direct toxic effects on oomycetes, which in turn counteract late blight and tuber blight development. However, the use of this salt is not yet implemented and approved in European potato cultivation. We compared the effect of phosphite alone with fungicides currently used in Swedish potato cultivation. We also investigated the combined use of potassium phosphite and reduced doses of fungicides. Table potato cultivars and starch potato cultivars with different levels of resistance were used.We found that potassium phosphite in combination with reduced doses of fungicides results in the same level of protection as treatments with the recommended full dose of fungicides. These combined treatments reduce the need of traditional fungicides and may also decrease the selection pressure for fungicide resistance development in the pathogen. In relatively resistant starch potato cultivars using phosphite alone gave sufficient protection against late blight. Furthermore, in starch potato a combination of phosphite and fungicides at two-week intervals provided similar protection to weekly applications of fungicide at the recommended dose. Foliar treatment with phosphite also gave protection against tuber blight at similar levels to that of the best-performing fungicide. Our data suggests that potassium phosphite could be used in potato cultivation in temperate regions such as in Sweden, at least in combinations with reduced rates of fungicides. The implementation of the use of phosphite in practical potato crop protection as part of an IPM strategy is discussed. Doses, intervals and combinations could be adjusted to the level of cultivar resistance.     

江苏省主推及新育成小麦品种抗赤霉病评价及毒素积累分析

为明确江苏省小麦主推和新育成品种对赤霉病的抗性水平,2018年至2020年采用单花滴注接种和自然发病方法,对280个江苏省小麦品种进行赤霉病抗性鉴定,并对部分自然发病鉴定品种进行了籽粒DON毒素积累分析。结果表明,85个品种对赤霉病达到中抗及以上水平,其中淮南品种60个,淮北品种25个。经连续3年重复鉴定,筛选出18个抗性水平高且稳定的小麦品种,包括16个淮南品种和2个淮北品种。自然发病条件下,病穗率在10%以上的品种中,90%以上表现为中感及感病。不同小麦品种籽粒中DON毒素积累水平差异较大,毒素水平与小麦品种的病情指数呈正相关。综上所述,淮南较淮北品种的赤霉病抗性高,籽粒DON积累量低;人工接种鉴定可以较准确地反映小麦品种的赤霉病抗性;不同小麦品种发病严重程度与DON毒素积累量呈显著正相关。     

Quantitative analysis of host resistance,fungicide and weather effects on potato early and late blight using computer simulation models

Models which simulate the development of potato early blight, potato late blight and fungicide dynamics were used to analyze the effects of host resistance, fungicide and weather on individual and combined epidemics of these diseases. Fungicide and host resistance effects were based on (and accurately reflected) products and cultivars available to commercial potato growers in northeastern USA. Moderate resistance to early blight had a 2-3 fold greater effect than did moderate resistance to late blight in suppressing early and late blight, respectively. Analysis of simulation experiments indicated that replacement of an early blight susceptible cultivar with a cultivar moderately resistant to the disease would permit a reduction in the fungicide application frequency from once every week to once every two weeks without loss of disease suppression. Fungicide effect in suppressing late blight was 2-3 fold greater than in suppressing early blight. Variation in seasonal weather (typical of northeastern USA) influenced late blight development more strongly than it affected early blight development, and it affected epidemics of individual diseases more than combined epidemics.     

Effects of fungicides on eyespot, caused predominantly by Oculimacula acuformis, and yield of early-drilled winter wheat

The effectiveness against eyespot of nine fungicide treatments, applied at GS 31, was evaluated in early-drilled winter wheat crops. Visual assessments of stem-base diseases were made before fungicide application and at GS 39/55 and 69/70 of cultivars Consort, Savannah and Claire. Competitive PCR was used to quantify Oculimacula acuformis, O. yallundae, Microdochium nivale, Fusarium spp. and Rhizoctonia cerealis. PCR results indicated that O. acuformis was the predominant pathogen causing eyespot in all three crops. Treatments containing cyprodinil were most successful in reducing disease index and DNA of O. acuformis across cultivars. Treatments containing prochloraz were less consistent in eyespot control, significantly reducing the DNA of O. acuformis only in one instance at GS 70 of cultivar Claire. None of the fungicide treatments had any significant effect on brown foot rot or sharp eyespot, or DNA of M. nivale or R. cerealis. The potential for O. acuformis to cause yield loss was indicated by significant negative relationships between yield and eyespot incidence or DNA of O. acuformis at GS 69/70 for each wheat crop. Relationships between DNA of O. acuformis and eyespot incidence or severity at each growth stage were weak but generally improved at the later growth stages of the crops when disease symptoms were easily distinguished. Both molecular methods and visual assessment failed to predict eyespot incidence or pathogen DNA late in season using incidence or DNA of O. acuformis at GS 31. PCR assays, however, accurately identified the stem base pathogens at early growth stages of the crops when the symptoms of their respective diseases were not readily diagnosed.     

不同氮、磷、钾水平对水稻纹枯病的影响

田间试验研究了不同氮、磷、钾水平对水稻纹枯病发生程度和产量的影响。结果表明,水稻纹枯病的发病率与N、P、K关系分别为:随氮肥施入量的增加,呈先缓慢上升,再大幅度上升的趋势;随磷肥施入量的增加,呈先小幅度上升,再大幅度下降,然后再大幅度上升的趋势;随钾肥施入量的增加,呈现大幅度下降,再大幅度上升的趋势。产量结果表明:不同氮、钾处理对水稻产量影响大,不同磷处理对水稻产量影响小。适用于寒地的施氮量97kg/hm2、施磷量52kg/hm2、施钾量29kg/hm2,使纹枯病发病轻,提高水稻产量。     

水稻抗感纹枯病品种Ospgip1基因的表达特征

 从水稻基因组DNA中扩增出1 184 bp的Ospgip1基因片段。该片段包含930 bp的完整开放阅读框,终止密码子为TAA,无内含子。RT PCR结果表明,Ospgip1基因在水稻抗、感纹枯病品种中均能表达,但不同生育期、不同部位表达量有差异。实时PCR结果显示,抗病品种YSBR1和中感品种Jasmine 85中Ospgip1的表达量要明显高于感病品种Lemont;稻苗黄化处理后,无论是抗病品种还是感病品种的Ospgip1表达量均显著提高;纹枯病菌侵染使得抗病品种Ospgip1表达量大大增加,而对感病品种影响不大。     

Levels of resistance of rice cultivars and the weed Leersia hexandra L. to Nephotettix malayanus Ishihara et Kawase and N. virescens (Distant)

Studies on the mechanisms of resistance of some rice cultivars and the weed, Leersia hexandra, to Nephotettix malayanus indicated low survival and popu;ation growth of the insect on resistant cultivars. Tests on feeding behaviour indicated that more feeding punctures were made on resistant than on susceptible cultivars. The amount of honeydew excreted was not related to the levels of resistance. Honeydew excreted on resistant cultivars was acidic (pH 5·08–6·92) and on susceptible L. hexandra, basic (pH 7·56). On the basis of the quality of honeydew excreted, N. malayanus was considered to be predominantly a xylem feeder. A test on the serial transmission of the rice tungro virus (RTV) showed that N. malayanus transmitted the virus for only one day after feeding acquisition. N. virescens was a more efficient vector of RTV than N. malayanus. N. malayanus prefers to feed on L. hexandra rather than on the rice cultivars tested.     

水稻叶尖枯病接种技术及品种的抗病性

 以盆栽杂交稻汕优63为供试品种开展人工接种技术研究，并利用人工接种技术对85个品种（组合）进行了抗性鉴定。研究表明，水稻叶尖枯病菌的侵入途径主要是伤口。人工接种，以病菌分生孢子液（低倍镜视野15～30个孢子）或菌丝液，在水稻孕穗至扬花期进行剪叶蘸菌液接种为好。接种后一定时间内的病斑扩展长度可作为大田鉴定水稻品种抗性的评价标准。根据大田接种结果，不同稻型和品种对叶尖枯病的抗性差异较大。一般杂交籼稻感病，常规中籼稻次之，而粳、糯稻抗病。这一结果与水稻叶尖枯病的大田发生情况相似。抗性鉴定中发现，一般秆高、叶长且披垂的水稻品种（组合）较感病；抗病品种特别是粳糯稻品种在病健交界处表现明显的褐色过敏性反应。