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1.
Between 1980 and 1986, commercial winter wheat fields at the milky-ripe stage were surveyed for insect pests. Leaf injuring insects were common. On average 42% and 95% of the surveyed fields were injured by leaf miners and the cereal leaf beetle, respectively. On average 14% of the leaves was skeletonised by the cereal leaf beetle and leaf injury tended to be high in seasons after winters with low temperatures. Blossom midges were the most important midges. In the period 1980–1984, the orange and lemon blossom midge infested 71 and 21% of the surveyed fields, respectively, Insecticides were mainly used to control aphids. Despite control, on average 80% of the fields and 22% of the tillers were infested by aphids.  相似文献   

2.
Studies of cereal aphids and barley yellow dwarf virus (BYDV) from 1989 to 1992 revealed that Poa annua is an abundant weed of commercial winter barley crops during the summer months. P. annua was frequently infected with BYDV, and there were usually similarities with the BYDV infection of the surrounding barley crop. These P. annua weeds were often infested by cereal aphids both in July (pre-harvest) and in September (in cereal stubble fields). Poa -infested cereal stubbles may be major local sources of viruliferous aphids, increasing the risk of BYDV in nearby winter cereals. P. annua plays an important role in the epidemiology of S. avenae -transmitted BYDV.  相似文献   

3.
The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.  相似文献   

4.
对室内筛选出来的2种三唑类杀菌剂与吡虫啉的复配剂及其组分单剂的田间防治效果进行了比较,结果显示:复配剂A对小麦叶锈病、白粉病和小麦蚜虫的防治效果分别为90.18%、91.21%和99.06%;复配剂B对上述小麦病虫的防治效果分别为89.58%、92.47%和98.71%。复配剂的防治效果优于三唑酮和戊唑醇田间推荐浓度下对小麦叶锈病(84.89%、88.68%)和小麦白粉病(90.24%、90.54%)的防治效果,低于烯唑醇田间推荐浓度下对小麦两病的防治效果90.59%、92.31%;复配剂与吡虫啉在田间推荐浓度下对小麦蚜虫的防治效果97.55%持平。试验结果表明复配剂A与复配剂B在田间具有良好的防治效果,可以作进一步的试验,以期得到大面积推广。  相似文献   

5.
The models in the Danish decision support system (DSS) PC-Plant Protection (PC-P) have been developed during the past 15 years of research on cereal pests in Denmark. Recently, the system was reintroduced as a web-based DSS and is now called Crop Protection Online (CPO). CPO includes models for powdery mildew, rusts, septoria, rhynchosporium, net blotch, eyespot, aphids and leaf beetle larvae and is based on empirical data on: (i) the specific effect of each plant protection product; (ii) control thresholds; (iii) importance of pests according to growth stage; (iv) variation in susceptibility to pathogens among cultivars; and (v) influence of weather on the development of pests. The system has been validated in numerous trials and has proved to give good control of pathogens at low product inputs. The margin of product use has been similar or better compared with standard treatments included in the field trials. In trials where CPO was compared with other DSS, CPO resulted in the lowest input of fungicides, measured as TFI (TFI expresses the ratio applied doses/standard doses throughout a growing season) and the highest margin over product use. Differences in the prices of fungicides and in the grain price may change that. The system is under development in Poland and the Baltic countries, and is also ready for export to other countries.  相似文献   

6.
Data from surveys of winter wheat fields in the period 1974–1986 and of seed lots in the period 1962–1986 and identifications of diseases on plant samples were compiled to describe the occurrence of snow mould (Monographella nivalis) andFusarium spp. On average,M. nivalis dominated overFusarium spp. The complex ofFusarium spp. constituted mainly ofF. culmorum, followed byF. avenaceum andF. graminearum. M. nivalis was dominant in May on stem-bases and in July on leaves and leaf sheaths. On seedsM. nivalis predominated only in years with low temperatures in July and August.Average brown footrot infection in the field was 4% tillers in May and 5% culms in July. Brown footrot intensity in July was high in cropping seasons with high precipitation in October and with low temperatures in October, November and December. In July during the early eighties, an average of 8% of leaves and 6% of flag leaf sheaths were infected byM. nivalis. Average ear blight incidence was 1.2% glumes infected. Seed contamination by these pathogens averaged 16% in the years 1962–1986. The contamination was high in years with high precipitation in June, July and August. Aspects of cv. resistance and yield loss are illustrated.  相似文献   

7.
The survey was carried out over an area representing about 47% of the cereal acreage of the United Kingdom. Estimates of the acreage of fields containing wild oat (Avena fatua L. and A. ludoviciana Dur) ranged from 15% (Northern Ireland) to 74% (England, South West Region). The degree of infestation over the total acreage was 58%‘light’, 34%‘medium’, and 8%‘heavy’. Blackgrass (Alopecurus myosurodies Huds.) was found only in the central and southern regions, estimates of the infested cereal field acreage ranging from 2% (Wales) to 23% (South East England). Nine per cent of the fields were rogued for wild oat. On average, only 10% of the infested acreage received herbicide treatment for wild oat and blackgrass though, in some regions, up to 23 % was treated. The timing of treatment and the herbicide used were recorded. Information on the extent and type of herbicide used for broad-leaved weeds was also recorded. Data on sowing dates of the crops, the previous cropping, previous infestations, the soil type and the state of field drainage were obtained and were correlated with the incidence of wild oat and blackgrass where relevant.  相似文献   

8.
Field trials were conducted in spring wheat to observe effects of jasmonic acid (JA) on aphids, thrips and wheat blossom midge (WBM). Two spring wheat varieties (Triso and Kadrilj) were sprayed twice, with two concentrations of JA plus control. Wheat pests and associated natural enemies (Coccinellidae, Empididae and Aphelinidae) were surveyed by direct count and sweep net methods. Thrips larvae and adults and WBM larvae were estimated by dissecting wheat ears. Wheat midge larvae were monitored using white traps in treated and untreated plots. At the end of season, wheat yield was assessed in treated and control plots. There was a significant difference in the number of insect pests and their natural enemies between treatments in both varieties. Plants in control plots had higher numbers of aphids, thrips and midges than in treated plots. There were more aphids, thrips and midges on the variety ??Triso?? than on ??Kadrilj??. JA application enhanced wheat yield in treated plots compared to control plots. The results indicated that JA mediated induction of plant defense in wheat plants can improve resistance against insect herbivores. JA could be used to develop environmentally sound crop management with reduced insecticide applications.  相似文献   

9.
为明确蚜虫内共生细菌Buchnera能否协助蚜虫抑制植物的防御反应,采用混合抗生素除去瓜蚜Aphis gossypii体内的Buchnera,采用刺吸电位技术和生命表方法比较除菌瓜蚜和正常瓜蚜在黄瓜上的适合度,并测定被除菌瓜蚜和正常瓜蚜预侵染黄瓜叶片中H2O2、茉莉酸和水杨酸的含量变化以及抗蚜特性变化。结果表明,除菌瓜蚜体重较正常瓜蚜极显著下降了71.15%,净增殖率极显著下降了95.60%,但寿命延长了2.34倍;刺吸电位图谱显示除菌瓜蚜几乎不产生代表唾液分泌的E1波和韧皮部被动吸食的E2波。在黄瓜叶片中,除菌瓜蚜比正常瓜蚜能激发产生更高水平的H2O2;在为期14 d的侵染中,除菌瓜蚜侵染诱发总茉莉酸含量持续升高、总水杨酸含量持续下降,而正常瓜蚜侵染诱发总茉莉酸含量先升高后降低、总水杨酸含量先降低后升高。在被除菌瓜蚜预侵染黄瓜上,瓜蚜进入稳定取食的时间显著滞后于正常瓜蚜预侵染处理,且前3 d的产蚜量显著低于正常瓜蚜预侵染处理。表明Buchnera除了可为蚜虫提供必需的营养外,还有调控和抑制寄主植物防御反应的功能。  相似文献   

10.
J. C. FORBES 《Weed Research》1984,24(6):431-438
A roadside survey of 4749 fields in eight areas of NE Scotland was conducted annually from 1979 to 1982. The proportion of grass fields infested with ragwort remained steady at 18–19% from 1979 to 1981 but fell to 13·5% in 1982. This fall resulted from fewer fields becoming newly infested and from more fields that had remained in grass ceasing to be infested. The proportion of infested fields remaining in grass that showed a reduction of two or more points on a 0–5 logarithmic scale of ragwort density (a possible indication of the frequency of control measures) was 24·0% in 1979–1980, 21·7% in 1980–1981 and 36·3% in 1981–1982. The incidence of ragwort infestation was consistently higher in some areas than in others and was not related to the proportion of arable crops. The change in incidence of infestation varied greatly between different areas, as did the proportion of infested fields whose score on the 0–5 scale fell by two or more points. In 1979–1980 and 1980–1981 this proportion had to exceed 22% to effect a net decrease in the incidence of infestation in an area, but in 1981–1982 no relationship was evident between these two measures of change. The incidence of infestation in all areas increased with increasing sward age but one area (Moray and Nairn) had a much higher proportion of young grass infested than any of the others. Over 99% of ragwort infestations consisted of Senecio jacobaea, infestations of S. aquatints Huds. being rare.  相似文献   

11.
Results of annual surveys of winter wheat fields from 1974 to 1986 were compiled to describe epidemics of powdery mildew and rusts in relation to weather and cultivar resistance.An average of 29 and 70% of fields were infected by powdery mildew in May and July, respectively. Mildew prevalence in May was positively correlated with average temperature in October and with average temperature over the months December, January, February and March. In addition, it was correlated negatively with the average grade of mildew resistance of the cultivars sown each year. Prevalence of mildew in July did not show consistent correlations with weather characteristics nor with mildew prevalence in May.Yellow rust was usually not detected in May and on average 18% of the fields was infected in July. The occurrence of yellow rust decreased after 1977, when the farmers adopted cultivars resistant or moderately resistant to yellow rust.Brown rust was usually not detected in May, while in July on average 48% of the fields was infected. Brown rust intensity in July was high in years with a high March temperature and high precipitation during April and May.Black rust was rare in the Netherlands, with 3 and 1% of the fields infected in July 1977 and 1981, respectively.  相似文献   

12.
The infestations of two biotypes of Panicum miliaceum L. were monitored over a 5-year period (1981–1985) as they occurred in two townships in southwestern Ontario, Canada. On average, 16·5% of the cultivated fields in Hullett township were infested with the black-seeded biotype while 12·9% of the fields in North Norwich township were infested with the golden-seeded biotype. Neither population showed clear signs of increasing. The two biotypes were similar in their ability to persist as adult infestations. The black-seeded biotype showed a greater potential for colonizing uninfested fields. The crops grown in this region showed different susceptibilities to infestation by P. miliaceum. Corn (maize) fields were susceptible while most grain fields were resistant to infestation. White beans were susceptible to infestation by the black-seeded biotype. Wheat and oat crops were more resistant to infestation by the golden-seeded biotype than to those of the black-seeded biotype.  相似文献   

13.
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14.
Infestations of aphids(Macrosiphum rosae L.) and of twospotted spider mites(Tetranychus urticae Koch) were examined in relation to growth and sporulation ofClonostachys rosea andBotrytis cinerea, and to suppression of the pathogen by the agent, in green rose leaves. Leaves were infested artificially with 10 aphids/leaflet for 3 h, or naturally with 15-30 aphids/leaflet for 7-12 days or with undetermined numbers of mites for 10-12 days. Leaves that had or had not been infested were inoculated withC. rosea, withB. cinerea, or withC. rosea plusB. cinerea. Germination incidence and germ tube growth ofC. rosea andB. cinerea on the phylloplane in most instances were much greater in leaves previously infested with aphids or mites compared with noninfested leaves. After combined inoculation,C. rosea suppressed germination ofB. cinerea from 47% to 19% in noninfested leaves, but in leaves that had been infested the agent was ineffective and germination incidence of the pathogen increased to 75-93%. Previous infestation with naturally introduced aphids or mites, but not brief infestations of artificially introduced aphids, markedly increased sporulation ofC. rosea after the leaves died during an initial 7-15 days of incubation on a paraquat agar medium, regardless of whether or notB. cinerea was present. Sporulation ofB. cinerea was similarly increased when inoculated alone. After 15-20 days, however, conidiophores of the agent or pathogen covered most of the leaf surface in these treatments. In leaves inoculated withC. rosea plusB. cinerea, the agent suppressed sporulation of the pathogen almost completely in both previously infested and noninfested leaves. Thus, aphid and mite infestations did not compromise the ability ofC. rosea to suppress inoculum production byB. cinerea in the leaves. Increased nutrient availability on the phylloplane through exudation or as honeydew or frass is proposed as a basis to explain effects of the pest infestations onC. rosea andB. cinerea.  相似文献   

15.
The incidence of Alopecurus myosuroides seedheads was monitored annually for 10 years in the cereal fields of a 173-ha arable and dairy farm. A. myosuroides persisted at low population densities, despite the use of herbicides and grass breaks in the rotation. The distribution of the weed was irregular, with none occurring on at least 60% of the positions surveyed in the cereal fields. Spatial distributions were compared between years, and some significant correlations were found from year to year in continuous cereals, and in cereal crops separated by a 3-year grass ley.  相似文献   

16.
BACKGROUND: Insect damage induces chemical changes in plants, and frequently these changes are part of a defensive response to the insect injury. Induced resistance was activated in winter wheat using a foliar application of synthetic jasmonic acid. Field trials were conducted to observe effects of jasmonic acid application on some wheat insects. Two wheat cultivars (Cubus and Tommi) were sprayed twice at growth stages (GS) 41 and 59 with two concentrations of jasmonic acid, along with control plots that were sprayed with water. RESULTS: There was a significant difference in the number of thrips and wheat blossom midges (WBM) among treatments in both cultivars. Plants in control plots had higher numbers of thrips and midges than in treated plots. There were higher numbers of thrips in the Tommi cultivar than in the Cubus cultivar, while the latter had higher numbers of WBM larvae than the Tommi cultivar. There was a positive correlation between WBM numbers and infested kernels in both cultivars. This study also indicated that jasmonic acid enhances the wheat yield in sprayed plots compared with control plots. CONCLUSIONS: The results indicate that jasmonic acid induced pest resistance in wheat plants and may act as a resistance mechanism of wheat against insect herbivores. Copyright © 2010 Society of Chemical Industry  相似文献   

17.
Methanolic extract of Artemisia annua L., a weed collected around paddy fields in north of Iran, was investigated for its toxic effects on: feeding, growth, fecundity, fertility including the biochemical characteristics of elm leaf beetle Xanthogaleruca luteola Mull. The toxicity tests indicate that insecticidal effect was 2.4-fold higher in 3rd instar larvae than in adults. The LC50 was 48% and 43.77% of a methanolic leaf extract at 24 and 48 h, respectively. The feeding deterrence was highest at 10% concentration and lowest at 0.625% for 3rd instar larvae and adults during the first 24 h and decreased thereafter. Larval duration significantly increased at higher concentrations. Larval treatment with 10% methanolic extract resulted in deformed adults (adultoids) with drastic changes in gross morphology of female reproductive system. Food digestion and assimilation significantly decreased in adults. Larval duration and adult fecundity and fertility were also significantly reduced. Twenty-four hours after treating 3rd instar larva with the extract the levels of glucose, protein, urea, uric acid, α-amylase, alkaline phosphatase, alanine amino transferase and aspartate amino transferase significantly changed. However, at 48 h the extract lost its potency. The extract did not effect the level of cholesterol in treated larva. These results indicate that Artemisia annua L. extract contains inhibitors of key metabolic pathways that may be useful in future control of the elm leaf beetle.  相似文献   

18.
1987年-2018年我国小麦主要病虫害发生危害及演变分析   总被引：3，自引：0，他引：3  
黄冲  姜玉英  李春广 《植物保护》2020,46(6):186-193
本文总结分析了1987年-2018年我国小麦病虫害发生危害及其演变情况?蚜虫?麦蜘蛛?吸浆虫?地下害虫和赤霉病?条锈病?纹枯病?白粉病是当前我国小麦上的主要病虫害?2011年-2018年这8种病虫害的发生面积为4 416.45万~6 051.42万hm2, 占小麦全部病虫发生面积的74.89%~86.07%?通过防治, 每年挽回小麦产量损失307万~2 136万t, 占全国小麦总产的3.60%~18.44%, 平均年挽回损失1 134.94万t, 占全国小麦总产的10.56%, 其中1987年-1990年?1991年-2000年?2001年-2010年和2011年-2018年经防治后平均挽回损失分别为598.13万?1 056.42万?1 272.8万和1 612.35万t; 防治后每年仍造成小麦产量损失220万~640万t, 占全国小麦总产的1.97%~6.52%; 平均年实际损失346.95万t, 占全国小麦总产的3.23%, 其中1987年-1990年?1991年-2000年?2001年-2010年和2011年-2018年分别实际损失378.11万?337.31万?355.50万和316.90万t?2000年以来, 受气候变化?耕作制度变迁和品种更替等因素影响, 我国小麦主要病虫害发生演变呈现小麦赤霉病重发频率提高?发生区域呈北抬西扩趋势, 蚜虫上升为黄淮海麦区最重要的害虫, 小麦纹枯病?白粉病?麦蜘蛛和地下害虫等小麦常发性病虫害发生相对平稳, 小麦条锈病?吸浆虫等病虫害发生趋降, 新发病虫害在局部麦区扩散危害等特点, 并针对性地提出构建小麦病虫害自动化监测预警体系?研究小麦病虫害长期灾变规律?集成和完善小麦病虫害综合防控技术等建议措施?  相似文献   

19.
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20.
The study was conducted to evaluateLiriomyza trifolii (Burgess) in the cotton fields of the Büyük Menderes Valley, Turkey, from 1999 to 2000. Leaves were sampled weekly from the middle of June to the middle of August and kept in the laboratory to observe emerging leafminers. Leafminers were initially found on cotton leaves from 35 to 66 days after sowing. The numbers of larval mines varied from one to four per leaf. The largest number of infested leaves was observed in Aydın (Center), where 18.8% and 17.7% of the sampled leaves were infested in 1999 and 2000, respectively. We conclude thatL. trifolii is a potential pest in the cotton fields of Turkey and more research is needed. http://www.phytoparasitica.org posting July 3, 2003.  相似文献   

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