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121.
Powdery scab caused by Spongospora subterranea f. sp. subterranea (Sss) causes extensive losses in potato production systems globally. Two pot experiments were established in the greenhouse in summer 2013 and winter 2014 to evaluate the effectiveness of different soil chemicals, fumigant, amendments and biological control agents (BCAs) against Sss in the rhizospheric soil, potato roots and tubers. The study used visual assessment methods to assess the effect of treatments on root galling and zoosporangia production, and qPCR to measure Sss concentration in the soil and in the potato roots and tubers. All six soil treatments, namely metam sodium, fluazinam, ZincMax, calcium cyanamide, Biocult and a combination of Bacillus subtilis and Trichoderma asperellum recorded significantly (P < 0.05) lower numbers of zoosporangia in the roots compared to the untreated control. The same effect was observed on the concentration of Sss DNA in the roots at tuber initiation. A more diverse picture was obtained when root gall scores at tuber initiation and Sss DNA in the rhizospheric soil at tuber initiation and harvesting were compared. Significant differences (P < 0.05) were also noted in disease severity, disease incidence, and tuber yield between metam sodium, fluazinam, ZincMax, calcium cyanamide and the untreated control. Calcium cyanamide gave the highest tuber yield. The study demonstrated the potential of soil treatments such as metam sodium, fluazinam, ZincMax and calcium cyanamide in managing Sss in potatoes by reducing the pathogen both in the rhizospheric soil and the roots of the potato plant.  相似文献   
122.
Three species of wireworms (Coleoptera: Elateridae) known to cause severe damage to potatoes in Europe and Asia have been introduced to Canada and are now well established as pests in the westernmost province of British Columbia (BC) (Agriotes obscurus and A. lineatus) and the eastern provinces of Nova Scotia and Prince Edward Island (A. obscurus, A. lineatus and A. sputator). Conventional insecticide-based efforts to control these invasive pests have had serious environmental impacts, or are failing to prevent severe economic damage from occurring to potatoes in some key potato production areas. Research toward developing an IPM programme for these exotic species has been completed or is underway in Canada, including the following: biological and ecological studies, development of monitoring and risk assessment programmes, and development of insecticidal and alternative control strategies. This research is summarized and implications for wireworm management in Europe are discussed. In addition to wireworms, one of the primary economic insect pests of potatoes in BC is the tuber flea beetle, Epitrix tuberis (Coleoptera: Chrysomelidae). The larvae of this beetle feed on developing or mature daughter tubers, producing surface channels or tracks and holes directly into the tuber. In the past, growers would apply 7–10 foliar sprays of broad-spectrum insecticides per growing season, which was not always successful in controlling this pest. In the EU, a newly identified flea beetle, Epitrix papa sp. n., as well as the North American species, E. cucumeris, have been identified as attacking potatoes initially in Portugal (2004) and later also in Spain. The potential spread of these emergent pests to various EU and non-EU countries is of concern, and if established would require the development of management strategies. The former development of a highly effective IPM programme developed in BC for E. tuberis is discussed, as is its potential for E. papa and E. cucumeris management in Europe.  相似文献   
123.
Precision agriculture is a farming management concept based on observing, measuring and responding to inter- and intra-field variability in crops. In this paper, we focus on responding to intra-field variability in potato crops and analyse variable rate applications (VRAs). We made an overview of potential VRAs in potato crop management in The Netherlands. We identified 13 potential VRAs in potato, ranging from soil tillage to planting to crop care to selective harvest. We ranked them on availability of ‘proof of concept’ and on-farm test results. For five VRAs, we found test results allowing to make a cost-benefit assessment. These five VRAs were as follows: planting, soil herbicide weed control, N side dress, late blight control and haulm killing. They use one of two types of spatial data: soil maps or biomass index maps. Data on costs and savings of the VRAs showed that the investments in VRAs will pay off under practical conditions in The Netherlands. Savings on pesticide use and N-fertilizer use with the VRAs were on average about 25%, which benefits the environment too. We foresee a slow but gradual adoption of VRAs in potato production. More VRAs will become available given ongoing R&D. The perspectives of VRAs in potatoes are discussed.  相似文献   
124.
125.
本文详细阐述了中国和越南4个村蔬菜生产中的肥料施用情况,概述了施用肥料的种类、施用时间和施用数量。评价了影响肥料施用的因素,比较了施肥量和蔬菜从土壤中带出的养分量。在研究区域,农户施用了50多种肥料,施氮量间于0~700kg/hm^2。肥料施用时间因蔬菜种类和地区不同而不同。氮的施用量主要受作物种类影响。大部分中国蔬菜的氮、磷施用量过大,而钾肥施用量不足;相对而言,越南蔬菜的局部养分平衡比中国的情况好一些。因此,局部的养分平衡显示了不同蔬菜种类、不同季节和不周村社的养分投入量和养分输出量有很大区别。  相似文献   
126.
Rabies is a zoonotic disease that remains endemic in large parts of southern Africa because of its persistence in wildlife and domestic dog vectors. The black-backed jackals (Canis mesomelas) is primarily the wildlife vector responsible for rabies outbreaks in northern parts of South Africa. Two trials were carried out to investigate antibody responses to the oral rabies vaccine Raboral V-RG® in black-backed jackals under captive and free-ranging conditions. In captive jackals 10/12 (83%; 95% confidence interval [CI]: 52% – 98%), seroconverted after single oral vaccination. Nine captive jackals had protective antibody titres (> 0.5 IU/mL) at 4 weeks (median: 2.1 IU/mL; inter quartile range [IQR]: 0.6–5.7) and 10 jackals had at 12 weeks (median: 3.5 IU/mL; IQR: 1.5–8.3) and three maintained antibody titres for up to 48 weeks (median: 3.4 IU/mL; IQR: 2.0–6.3). Four sites were baited with Raboral V-RG® vaccine for wild jackals, using fishmeal polymer and chicken heads. Baits were distributed by hand or from vehicle at three sites in north-eastern South Africa, with an average baiting density of 4.4 baits/km2 and at one site in central South Africa, at 0.12 baits/km2. This resulted in protective antibody titres in 3/11 jackals (27%; 95% Cl: 6–61) trapped between 3 and 12 months after baiting in north-eastern South Africa, compared with 4/7 jackals (57%; 95% Cl: 18–90) trapped after 3–18 months in central South Africa. This study shows the potential utility of oral rabies vaccination for the control of wildlife-associated rabies in north-eastern and central South Africa, but extensive studies with wider distribution of bait are needed to assess its potential impact on rabies control in wild jackals.  相似文献   
127.
Feline chronic gingivitis/stomatitis (FCGS) is a painful inflammatory disease in cats. Extraction of teeth, including all premolars and molars, has been shown to be the therapy of choice in cats not responding sufficiently to home care (e.g. tooth brushing) and/or medical treatment (corticosteroids and/or antibiotics). In this study, we hypothesize that a cat food with an omega‐6 polyunsaturated fatty acid (ω6 PUFA) to ω3 PUFA ratio of 10:1 reduces inflammation of the FCGS and accelerates soft tissue wound healing of the gingiva after dental extractions, compared to a cat food with a ω6:ω3 PUFA ratio of 40:1. The cats were fed diets with chicken fat and fish oil as sources of fatty acids. In one diet, part of the fish oil was replaced by safflower oil, resulting in two diets with ω6:ω3 PUFA ratios of 10:1 and 40:1. This double‐blinded study in two groups of seven cats revealed that dietary fatty acids influence the composition of plasma cholesteryl esters and plasma levels of inflammatory cytokines. The diet with the 10:1 ratio lowered PGD2, PGE2 and LTB4 plasma levels significantly, compared to the diet with the 40:1 ratio (p = 0.05, p = 0.04, and p = 0.02 respectively). However, feeding diets with dietary ω6:ω3 PUFA ratios of 10:1 and 40:1, given to cats with FCGS for 4 weeks after extraction of all premolars and molars, did not alter the degree of inflammation or wound healing.  相似文献   
128.
Treatments of tubers with chemical disinfectants (70 % ethanol, 1 % sodium hypochlorite, 2 % copper sulphate, 5 % peracetic acid, 10 % hydrogen peroxide, 1 % MennoClean (benzoic acid), 5 % trisodium phosphate and 0.2 % caffeine) were evaluated for control of blackleg caused by ‘D. solani’. All disinfectants effectively killed bacteria in axenic cultures within 5 min and all, except hydrogen peroxide and trisodium phosphate, were able to kill ‘D. solani’ in spiked potato extracts. Treatments with all disinfectants except trisodium phosphate, reduced the pathogen populations on the periderm of tubers previously inoculated by dipping in a suspension of ‘D. solani’, when the disinfectant was applied for at least 15 min. However, in replicated greenhouse experiments, treatments with all disinfectants except hydrogen peroxide and caffeine resulted in phytotoxicity, reducing sprouting of tubers with 10 – 100 %. Sodium hypochlorite and MennoClean were selected for further studies. Treatments of inoculated tubers with these disinfectants prevented developing of soft rot symptoms on tubers when subjected to favourable rotting conditions. In replicated greenhouse experiments, inoculated tubers treated with sodium hypochlorite and MennoClean reduced the blackleg disease incidences from 50 % to 0 % and to 5 %, respectively, and symptomless infection of potato stems from 93 % to 0 % and to 5 %, respectively. A combination of both compounds was highly phytotoxic. The potential use of sodium hypochlorite and MennoClean in an integrated management strategy for potato blackleg is discussed.  相似文献   
129.
徐同 Peer  R 《植物病理学报》1989,19(3):179-184
 本文报道萤光假单胞菌(fluorescent Pseudomas spp.) WCSX 13.WCS 417andWCS 358在水培系统中香石竹根部的定殖及其对香石竹镰刀菌枯萎病的抑制作用。细菌处理两周后,WCS 417在感病品种Lena和中抗品种Pallas根部的定殖分别为8.8×102cfu/cm和9.8×102cfu/cm,而WCS 358分别为0.9×102cfu/cm和0.13×102cfu/cm。在通气的三角瓶中水培的Pallas品种,人工接种病原菌香竹石尖镰孢Fusarium oxyspotum f.sp.dianthi (Prill.&Del.) Snyd.&Hans.(Fod)6周后,用WCSX·13和WCS 417根部处理的病指分别为0.19和0.31,未细菌处理的对照为0.58,细菌处理植株的根部及茎内组织的病原菌种群密度低于对照。营养膜技术(NFT)栽培的Lena品种,WCS 417细菌处理的发病率比对照减少13%。  相似文献   
130.
In the Taï region of the Ivory Coast, mature forest is felled and burned and a crop of rice is grown; forest is then allowed to regenerate for 20 or more years before being cropped again. The top 10 cm of soil beneath a 21-year-old forest prior to felling contained 2000 viable seeds m?2 of mainly woody species of previous successional stages no longer represented in the vegetation. Seedling emergence was greater in full sunlight than under leaf canopy, especially for herbaceous species of open habitats. Burning destroyed almost half of the seeds, but overall germination of those that survived was advanced by about 2 weeks. Germination of some common pioneer species was enhanced by the fire. Provided that burning took place and the rice was planted immediately, vegetation arising from the seed bank did not present a problem. The density never exceeded 70 seedlings m?2 and little or no weeding was required. Species present at densities greater than 1 seedling 10 m?2 were all recorded in the seed bank.  相似文献   
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