城口县稻曲病的发生与防治

水稻稻曲病又名青粉病 ,俗名“丰收果” ,是水稻上发生较为普遍的一种病害。近年来 ,随着杂交水稻的推广 ,栽培制度的变革 ,水稻稻曲病在城口县逐年由次要病害上升为主要病害 ,危害程度也逐年加重 ,已严重影响着城口县水稻的产理和质量。据１９９５至２０００年调查 ,田间病穗率一般达０%～４７% ,平均达２５．８% ,单穗病粒率达０%～６８% ,平均４．１% ,最高单穗病粒数达６８粒 ,产量损失严重。为了掌握稻曲病在城口县的发生危害情况 ,控制稻曲病的危害 ,提高水稻品质 ,减少产量损失。受县政府委托于１９９５年开始对稻曲病的致病因素及防…     

2013-2016年河南省小麦茎基腐病的发生危害情况及特点

2013-2016年连续4年对河南省不同类型麦田小麦茎基腐病发生和危害情况等进行了调查。结果表明,小麦茎基腐病在河南省已经广泛分布,每年均都有不同程度发生,其中2013年病田率为45.8%,病田白穗率为0.4%~11%;2014年病田率为12.6%,病田白穗率为0.1%~3.7%;2015年病田率为32.5%,病田白穗率为0.1%~16.1%;2016年发生最重,病田率为65.1%,病田白穗率为0.1%~31.5%。调查还发现,河南省小麦茎基腐病发生的特点是北部和西部发生较重;小麦-玉米连作田发生较重,而小麦-水稻连作田块发生较轻;干旱的田块发生危害重。病害产量损失的初步测定结果表明,感病最严重的分蘖病茎高度减少55.8%,且不能结实;能结实病茎较健茎高度减少14.0%~18.0%,穗粒数减少22.7%~54.5%,穗粒重减少33.3%~90.5%,千粒重减少3.2%~73.2%;当病田白穗率为22%时,有效穗数减少33.3%,产量损失达51.6%。本文还针对目前国内对小麦茎基腐病研究薄弱的问题,提出了今后需要加强的研究工作。     

玉米弯孢菌叶斑病危害损失及防治指标研究

对河南玉米弯孢菌叶斑病危害损失测定结果表明,产量损失与病级、病情指数之间均存在着极显著的直线相关。病级每提高１级,产量损失平均增加８.２５％。病情指数每增加１０％,产量损失平均增加４.１４％。在产量损失构成中,千粒重下降处主导地位,约占６６.６％;穗粒数减少次之,约占３３.４％。根据病情指数与产量损失率的数学模型,分高、中、低产田对经济允许危害水平进行了估算,并确定了防治指标。经田间验证,可以用此指导该病的防治。     

稻曲病与水稻产量损失的关系

稻曲病与水稻产量损失的关系八十年代以来，随着高产耐肥品种的推广和施肥水平的提高，百色地区稻曲病的发生危害逐年加重，并上升为水稻穗期的主要病害。为了解稻曲病发病对产量损失的影响，我们在田阳县晚稻田进行稻曲病危害损失率测定。通过田间调查取样、室内考种、统...     

玉米纹枯病产量损失测定和发生规律

不同地区玉米纹枯病产量损失测定结果表明,产量损失与病情严重度级别之间存在着显著的直线相关,严重度每提高一级,产量损失增加约10％左右,在产量损失的构成中,千粒重下降处于主导地位,粒数的减少其次;始病愈早,发病愈重,相应的产量损失也愈大。不同地区,播期不同,发病期亦不同。从生育期来看,却是基本一致的,玉米抽雄期为发病始盛期,乳熟期为发病高峰期。品种间发病差异明显,但未发现高抗品种,目前生产上广泛应用的掖单系统杂交组合,中抗至中感,其丰产性较好。增施钾肥112.5～262.5kg能显著地减轻病害和增加产量,可作为防病措施推广应用。另外,大田调查还发现,轮作、间作和控制种植密度能减轻病害发生。     

恩施自治州玉米灰斑病对产量损失的初步测定

恩施自治州地处湖北省山区,玉米种植面积很大,是主要粮食作物之一。在玉米的常年种植中,玉米灰斑病一直是我州玉米上的一种常见病害。由于许多玉米品种对灰斑病的抗性逐年丧失,以及在生产中高氮肥栽培和后期管理不足等各方面原因,玉米灰斑病已经逐渐成为我州玉米上的主要病害之一,玉米灰斑病的危害程度也呈逐年上升趋势,尤其是在中高海拔山区,玉米灰斑病危害严重,对玉米的产量造成较大损失。     

水稻稻曲病发生规律及防治技术

水稻稻曲病发生规律及防治技术８０年代以来，稻曲病危害日趋严重，发生面积不断扩大，随着病粒增加，产量损失加重．已成为我市水稻上第二大病害。为此我们对该病发生规律及防治进行了初步试验和观察，现将其结果报道于后。１发生危害特点１．１发生面积大；危害损失重。...     

近年我国水稻五大产区主要病害发生情况分析

为系统全面地掌握我国水稻病害的发生形势,为我国水稻病害分区域治理提供科学依据,本文以2010—2020年《全国植保专业统计资料》为主要依据,重点分析了我国水稻纹枯病、稻瘟病、病毒病、稻曲病、白叶枯病和恶苗病的发生及防控情况,并对水稻五大产区间病害发生情况进行了比较研究。结果表明,水稻纹枯病、稻瘟病和稻曲病是我国水稻的三大病害,广泛发生于我国水稻主产区。我国水稻五大产区病害发生为害情况不同,华中稻区和华南稻区以水稻纹枯病为害最重,造成产量损失占病害造成总损失的比例高达73.13%和69.26%,西南稻区水稻纹枯病和稻瘟病造成的产量损失接近,东北稻区稻瘟病造成的产量损失高于水稻纹枯病,华北稻区稻瘟病造成的产量损失低于水稻纹枯病。我国水稻三大病害不同年份间的防控产量损失挽回率维持在较高水平,且相对稳定,而水稻病毒病、白叶枯病和恶苗病的产量损失挽回率在不同年份间展现出一定波动。其中,水稻白叶枯病是挽回损失率最低的病害。     

水稻细条病发病程度与损失率关系的调查

水稻细条病是国内水稻检疫性病害。近年来已成为我处水稻生产的主要病害,且发病时间逐年提早,发病面积不断扩大,发病程度逐年加重。为了估测病害造成损失情况,我们连续两年进行了病害发病程度与损失关系的调查研究,现将结果初报如下:一、调查内容和方法:以汕优63为调查品种,分别在成熟期对未受害叶、倒一叶、倒二叶、倒三叶受害分级进行调查,其方法在同类型田按不同病级测产损失,按级各取样稻穗1000株室内考种,分别记载各级实粒数、空秕率、结实率、千粒重,并进行比较测定产量损失。     

水稻云形病及防治

水稻云形病是我省水稻生长中、后期的一种病害。近年来随着施肥水平的提高,氮素化肥用量的增加,云形病有逐年加重趋势,一般产量损失在8．9％－45．5％。该病主要危害叶片,先在叶尖或叶绿产生水淡状小班,后向下,向叶内呈灰褐色波浪状扩大。天气干燥时,病班停止发展,病健     

水稻纹枯病流行动态、药剂防治时期及指标的研究

 病害系统观察,药剂试验及产量损失测定表明,水稻拨节期病情开始激增,病害朝横纵二方向扩展,此时施药防治效果最佳。腊熟期病情指数与拔节期病丛率或病株率、产量损失率均呈极显著直线相关。
根据上述关系,便可由早期(拔节期)病情预测最终(腊熟期)病害严重度及产量损失率,进而依据经济阈值定义,组建了杂交稻和常规稻的四个经济阈值的动态模型,提出了在该地目前生产条件下,杂交稻和常规稻不同产量水平的经济阈值,即拔节期防治的指标,为大面积药剂防治提供了依据。     

Estimation of rice yield losses due to the African rice gall midge,Orseolia oryzivora Harris and Gagne

Abstract

The African rice gall midge, Orseolia oryzivora Harris and Gagne (Diptera: Cecidomyiidae), is an important pest of rice, Oryza sativa, in Burkina Faso as well as other countries in West and East Africa. In spite of its importance, little is known regarding the relationship between gall midge populations and grain yield losses. To determine yield losses the gall midge was reared in cages and adult midges were placed on caged plants of the rice variety ITA 123 at different population levels. The seven treatments consisted of different numbers of insects infested on the plants; 0 insect pairs (non‐infested check), and 1, 5, 10, 15, 20 or 25 midge pairs/cage. The loss in yield in relation to the non‐infested control was highly positively correlated (R² = 0.81) with the percentage of gall midge damaged tillers. The infestation by the insect on the plants resulted in the compensatory production of tillers which developed in response to the gall midge damage but the compensation was not sufficient to make up for the loss of yield due to the damaged tillers. Yield loss ranged from 0% in the control to 65.3% in the treatment with 25 pairs of adults. One per cent of tillers damaged resulted in 2% grain yield loss.     

玉米三种叶斑病混发时的流行过程及产量损失研究

 通过2年的田间小区人工接种试验,观察比较了玉米大斑病、弯孢叶斑病和灰斑病单独及混合发生时的流行过程及对玉米产量损失的影响。结果表明,在病害混发初期,病害间无明显的负相关性,随着病情的发展,病害间的负相关性逐渐增大并达到显著水平,说明病害间有明显的抑制作用。病害混发时造成产量损失并不完全等于各病害单独造成损失之和,其中大斑病和弯孢叶斑病、弯孢叶斑病和灰斑病混合发生所造成的损失约为各病害单独造成损失之和的76%～88%,大斑病和灰斑病混合发生所造成的损失可近似看作两种病害各自引起产量损失之和,3种病害同时发生时最终损失率约为各自造成损失之和的67%～72%。     

Effect of foliar diseases of wheat on the physiological processes affecting yield under semi-arid conditions

The effects of Septoria leaf blotch (caused by Mycosphaerella graminicola) and leaf rust (caused by Puccinia recondita ) on the physiological processes affecting yield were studied under semi-arid conditions in Israel. In the absence of water stress, photosynthetic activity decreased as the rate of disease development increased. Transpirational activity was reduced in leaves infected by Septoria leaf blotch, but intensified in leaves with slight leaf rust infections (0.5-5% severity). When leaf rust seventy exceeded 5%, the transpirational water loss declined. Both diseases were associated with a decrease in the maximum rate of grain-weight accumulation, but did not affect the duration of weight accumulation. An inverse linear relationship between disease and final grain weight was observed. Under conditions of water stress, photosynthetic activity of leaves slightly infected by Septoria leaf blotch (1-5"., severity) was greater than that of uninfected leaves. Severely infected leaves (" 25% severity) photosynthesized the least. Both diseases were associated with a decrease in the maximum rate of grain weight accumulation, but the duration of accumulation was longer in tillers with a slow rate of disease development than in uninfected tillers. The relationship between disease and final grain weight in these cases was parabolic; yield was increased at low levels of infection. Theoretical explanations and practical implications of these phenomena are presented and discussed.     

Effect of varietal resistance on the yield loss function of wheat to nodorum blotch

Cultivar disease resistance ratings to nodorum blotch (caused by Parastagonospora nodorum) provide critical information to growers to assist with disease management. However, less has been done in terms of yield losses from diseases under different cultivar resistance scenarios. The purpose of this study was to characterize yield and quality loss responses to wheat nodorum blotch as influenced by variety partial resistance, epidemic intensity, and environment. The trial series includes four site/years in Western Australia. Five varieties, Magenta, Calingiri, Trojan, Janz, and Scout were used for all four trials. These varieties represented resistant/susceptible categories MRMS, MS, MSS, S, and SVS, respectively, and were selected on the basis that they were adapted to the western region, had similar maturities, and were resistant to diseases that were potential contaminants. Trials were sown in a strip-plot design with three replicates and five disease levels, with intersecting main-plots of varieties and disease levels, which facilitated comparisons across disease levels within varieties. Current categories of resistance were well reflected in yield and quality responses. A negative exponential relationship was observed between yield and disease, with a nonlinear yield loss function for both flag leaf and glume infection. This indicates that yield is most affected during early stages of disease on flag leaves and glumes. The functional form of yield loss response over four site years was similar among varieties, but varieties differed in their extent of disease expression. Partial resistance in commercial wheat varieties reduced yield loss by 40%–60% of losses observed in susceptible varieties.     

北京地区花生病毒病及流行规律研究

1985—1987年研究表明北京地区花生上流行的病害主要有黄瓜花叶病毒CA株系(CMV-CA)引起的黄花叶病害和花生轻斑驳病毒(PMMV)引起的轻斑驳病害。血清鉴定451份花生病害样品,黄花叶病害样品受CMV-CA侵染占95.7％,轻斑驳病害样品受PMMV侵染占91.3％,中后期病害样品受CMV-CA和PMMV复合感染较普遍。CMV种传率2％左右,种传病苗在花生出苗后开始出现,6月病害进入高峰。三年CMV-CA流行程度明显不同,主要取决于苗期蚜虫发生早晚、发生量及苗期降雨量。PMMV种传率低于1％,病苗出现稍晚,但病害扩散快,6月上旬进入高峰,7月上、中旬发病率达100％。三年流行程度差异不明显。     

Coupling Disease-Progress-Curve and Time-of-Infection Functions for Predicting Yield Loss of Crops

ABSTRACT A general approach was developed to predict the yield loss of crops in relation to infection by systemic diseases. The approach was based on two premises: (i) disease incidence in a population of plants over time can be described by a nonlinear disease progress model, such as the logistic or monomolecular; and (ii) yield of a plant is a function of time of infection (t) that can be represented by the (negative) exponential or similar model (zeta(t)). Yield loss of a population of plants on a proportional scale (L) can be written as the product of the proportion of the plant population newly infected during a very short time interval (X'(t)dt) and zeta(t), integrated over the time duration of the epidemic. L in the model can be expressed in relation to directly interpretable parameters: maximum per-plant yield loss (alpha, typically occurring at t = 0); the decline in per-plant loss as time of infection is delayed (gamma; units of time(-1)); and the parameters that characterize disease progress over time, namely, initial disease incidence (X(0)), rate of disease increase (r; units of time(-1)), and maximum (or asymptotic) value of disease incidence (K). Based on the model formulation, L ranges from alphaX(0) to alphaK and increases with increasing X(0), r, K, alpha, and gamma(-1). The exact effects of these parameters on L were determined with numerical solutions of the model. The model was expanded to predict L when there was spatial heterogeneity in disease incidence among sites within a field and when maximum per-plant yield loss occurred at a time other than the beginning of the epidemic (t > 0). However, the latter two situations had a major impact on L only at high values of r. The modeling approach was demonstrated by analyzing data on soybean yield loss in relation to infection by Soybean mosaic virus, a member of the genus Potyvirus. Based on model solutions, strategies to reduce or minimize yield losses from a given disease can be evaluated.     

Effect and underlying mechanisms of pea-cereal intercropping on the epidemic development of ascochyta blight

Field experiments were conducted in western France for two consecutive years to investigate the effect of pea-cereal intercropping on ascochyta blight, a major constraint of field pea production world-wide. Disease pressure was variable in the experiments. Intercropping had almost no effect on disease development on stipules regardless of disease pressure. In contrast, disease severity on pods and stems was substantially reduced in the pea-cereal intercrop compared to the pea monocrop when the epidemic was moderate to severe. Therefore, a pea-cereal intercrop could potentially limit direct yield loss and reduce the quantity of primary inoculum available for subsequent pea crops. Disease reduction was partially explained by a modification of the microclimate within the intercrop canopy, in particular, a reduction in leaf wetness duration during and after flowering. The effect of intercropping on splash dispersal of conidia was investigated under controlled conditions using a rainfall simulator. Total dispersal was reduced by 39 to 78% in pea-wheat canopies compared to pea canopies. These reductions were explained by a reduction in host plant density and a barrier or relay effect of the non-host plants.     

Volunteer winter wheat: its effects and control in ryegrass seed production

The effects of different populations of volunteer winter wheal and their control with ethofumesate and TCA on growth, seed yield and yield components of S.24 perennial ryegrass were investigated in lield experiments in 1978 and 1979. Reductions in ryegrass seed yield due to the presence of wheat depended on the density of wheat and the number and dry weight of ryegrass tillers. The greatest percentage reduction in ryegrass seed yield occurred at high densities of wheat (300 plants m^?2) when the number of ear-bearing tillers and 1000 seed weight of ryegrass were reduced. When Ihe density of wheat was low (80 plants m^?2) a smaller reduction in ryegrass seed yield occurred and the number of live wheat plants remaining gradually decreased. Within the range of wheat densities in these experiments (0–300 plants m ^?2) a 1% loss in ryegrass seed yield occurred for every 10 wheal plants m^?2 present in the crop post winter. Both herbicides caused a reduction in number of ryegrass tillers during growth but, except where TCA was applied at 12 kg ha^?1 in November, ryegrass seed yields were not significantly reduced (in comparison with a wheat-free control) and were always greater than those obtained in the presence of wheat where no herbicides had been applied. Levels of volunteer infestation of 300 wheat plants m^?2 were controlled with minimum risk of crop damage by applications of 6 kg ha^?1 TCA in either October or November, or by application of 1–9 kg ha^?1 ethofumesate in November.