The response to saprol (systemic fungicide) in lettuce species and cultivars and its inheritance

Summary The response of Lactuca sativa, L. serriola and L. saligna to saprol was studied. Spraying the whole plant or part of a leaf caused wilting of susceptible plants. A similar effect was observed when leaves were soaked in a solution containing saprol.Inheritance studies with L. sativa and L. serriola showed that resistance to the wilting reaction caused by saprol is controlled by a single recessive gene.Contribution no. 198-E, 1978 series.     

Development of potato late blight (Phytophthora infestans) in differently developed potato crops and the potential to graduate the fungicide dose according to crop biomass

Phytophthora infestans is a serious disease in potato production and control of the disease often requires 10 or more fungicide applications during the growing season. Control is typically carried out using a constant fungicide dose in the entire field although there may be large differences in crop development and biomass across the field. The objective of the study reported in this paper was to test whether the fungicide dose response curve controlling P. infestans was dependent on the crop development and biomass level. If such a biomass-dependent dose response was found it was further the purpose to evaluate the potential to optimize fungicide inputs in potato crops applying a site-specific crop density-dependent fungicide dose. The study was carried out investigating the fungicide dose response controlling P. infestans in potatoes at three biomass densities obtained growing the potato crop at three nitrogen levels. Furthermore, the field experiments included four levels of fungicide dose rate at each nitrogen rate, an untreated control, the recommended fungicide dose rate and two reduced dose rates and the experiments were replicated for three years. Nitrogen level and thus crop density had a limited although significant influence on attack of P. infestans whereas fungicide dose rate by far was the most influential variable. In contrast the interaction of nitrogen rate and fungicide dose rate that would indicate a biomass-dependent dose response was insignificant. If the variation in crop density and biomass level obtained in the study is representative for the variation found cultivating potatoes in heterogeneous fields there seem to be limited potential for fungicide optimization applying fungicides against P. infestans site-specific according to crop density or biomass.     

Leslie矩阵模型在油松毛虫种群动态分析中的应用研究

油松毛虫(Dendrolimus tabulaeformis)是我国华北地区油松林的重要害虫之一。其分布面积广、发生频繁、危害严重。有人曾对油松毛虫种群的生物学特性、防治以及种群动态的研究作过有关的报道,本文则通过对油松毛虫的数量变动进行跟踪调查,并用Leslie矩阵模型对其种群动态进行了模拟,这对害虫的测报具有重要的实践意义。一、材料与方法 (一)标准地概况 1984—1986年与1988—1989年我们分别在密云县五座楼场和石墙沟村选择了5块油松纯林作为标准地,概况列在表1中:     

6种杀菌剂对桑树轮纹病菌的室内毒力测定

在室内培养条件下,采用菌丝生长速率法测定了6种杀菌剂对桑膝节霉的抑制效果。结果显示,6种杀菌剂对桑树轮纹病病原菌桑膝节霉的菌丝生长均有不同程度的抑制作用,其中50％多菌灵、75％百菌清、10％苯醚甲环唑、250 g／L丙环唑、450 g／L咪酰胺和70％甲基硫菌灵的EC50分别为2.45 mg／L、2.51 mg／L、1.68 mg／L、1.31 mg／L、0.46 mg／L和7.99 mg／L。测试药剂中,供试桑树轮纹病菌对450 g／L咪酰胺最为敏感,250 g／L丙环唑次之。450 g／L咪酰胺和250 g／L丙环唑皆可作为防治桑树轮纹病的最佳药剂,用于田间试验。     

高节竹梢枯病发生规律及防治试验

在掌握高节竹梢枯病Arenrinium phaeospermurn发生规律的基础上,对10种杀菌剂进行室内药效测定,选出的70％甲基托布津、50％多菌灵、80％402乳剂、40％异稻瘟净、20％粉锈宁等5种杀菌剂对暗孢节菱孢菌有较强的抑菌作用。野外防治试验表明,采用综合治理措施,防治效果可达88．2％。     

Seasonal and interannual ecophysiological responses of beech (Fagus sylvatica) at its south-eastern distribution limit in Europe

Due to its wide European distribution and its drought-susceptibility, beech (Fagus sylvatica L.) received intensive attention recently in the light of global warming. Contrary to central European beech ecosystems, little is known about the ecophysiology of beech at its south-eastern European distribution limit. Here we tested whether climatic fluctuations during a three-year period affected the ecophysiology of a beech site in Greece. Attention was paid at comparing our findings to the intense effects the 2003 extreme drought had on beech forests in central Europe.     

THE ESTIMATE OF THE EFFECTIVE FUEL COMBUSTION VALUE OF FOREST COMMUNITY IN THE DAXINGAN MOUNTAIN

FoRESTFUELCoMBUSTIoNVALUECombustionvalueisanimportantparameterofmaterialburningcharacteri-stics.Itmeansthattheheatreleasesfromtheunitofmaterialcompleteburningtocooldownthestartingtemperatureofreactionmaterals(l).Undertheconditionofthesamepressureandenoughoxygeninthecombustor,materialscombustionva1ueisrelatedtotheinnerenergyofthematerialstatefromthebeginningtotheendduringreaction.Thecombustionvaluesuchasmeta1,carbon,hydrogencanbemeasuredaccurate1y.Toforestfuels,theirenergycan'tbethesam…     

通辽地区美国白蛾发生规律及防治对策初探

通过对通辽地区2016-2019年气温的调查统计得知:超过10℃的天数主要集中在3-11月,分别为174天、176天、182天、175天;超过10℃的有效积温分别为1 728.1日度、1 743.9日度、1 761.4日度、1 731.1日度;根据美国白蛾完成1个世代所需要的有效积温可知,发生代数分别为1.95代、1.97代、1.99代、1.96代;故通辽地区属于2代区。     

Pragmatic population viability targets in a rapidly changing world

To ensure both long-term persistence and evolutionary potential, the required number of individuals in a population often greatly exceeds the targets proposed by conservation management. We critically review minimum population size requirements for species based on empirical and theoretical estimates made over the past few decades. This literature collectively shows that thousands (not hundreds) of individuals are required for a population to have an acceptable probability of riding-out environmental fluctuation and catastrophic events, and ensuring the continuation of evolutionary processes. The evidence is clear, yet conservation policy does not appear to reflect these findings, with pragmatic concerns on feasibility over-riding biological risk assessment. As such, we argue that conservation biology faces a dilemma akin to those working on the physical basis of climate change, where scientific recommendations on carbon emission reductions are compromised by policy makers. There is no obvious resolution other than a more explicit acceptance of the trade-offs implied when population viability requirements are ignored. We recommend that conservation planners include demographic and genetic thresholds in their assessments, and recognise implicit triage where these are not met.     

美洲斑潜蝇发育历期和有效积温的研究

研究结果表明，美洲斑潜蝇的卵、幼虫、蛹、成虫的发育起点温度分别为１６．８２，１６．５６，１２．８２，１８．１６℃；有效积温分别为３３．４３，３２．４７，１１５．９５，３９．５０日度。并得出各虫态的发育历期与温度的４个关系式。本资料可用于美洲斑潜蝇的发生期及世代的预测。