Potential use of abrasive air-propelled agricultural residues for weed control

A potential new post-emergence physical weed control tactic is described. It entails plant abrasion and death upon assault from abrasive grits propelled by compressed air. Grit derived from granulated walnut shells was delivered by a sand blaster at 517 kPa at distances of 300–600 mm from seedlings of Chenopodium album in glasshouse pots. Control was influenced by size of plants at time of treatment. Seedlings at the cotyledon to 2-leaf stages of growth were mostly destroyed by a single split-second blast of grit of <1 s duration, but were unaltered by compressed air alone. Plants at the 4- to 6-leaf growth stages required up to 10 blasts of grit to be killed. These results indicate that small weed seedlings of susceptible species might be physically controlled by abrasion from air-propelled grit derived from suitable agricultural residues.     

Phelipanche aegyptiaca management in tomato

Phelipanche and Orobanche species (broomrapes) are root holoparasitic plants that cause severe damage to economically important crops. Phelipanche and Orobanche spp. are widespread in Mediterranean areas, in Asia and in Southern and Eastern Europe, attacking dicotyledonous crops and depending entirely on their hosts for all nutritional requirements. Phelipanche aegyptiaca , Phelipanche ramosa and Orobanche cernua are extremely troublesome weeds on tomatoes. These noxious parasites exert their greatest damage prior to their shoot emergence and flowering; therefore, the majority of field loss may occur before diagnosis of infection. This review summarises the four main control measures for the weedy root parasites Phelipanche and Orobanche in tomato, namely chemical and biological control, resistant varieties and sanitation. Some of these methods are commercially widely used by farmers in Israel (chemical control), some are in the final stages of development towards commercialisation (resistant varieties and sanitation), and some still require further development and improvement before commercial implementation (biological control). The review presents an up-to-date summary of the available knowledge on their use for broomrape management in processing tomatoes.     

Dynamics of soilborne Rhizoctonia solani in the presence of Trichoderma harzianum: effects on stem canker, black scurf and progeny tubers of potato

Stem canker and black scurf are diseases of potato caused by the fungus Rhizoctonia solani . Spatiotemporal experimentation and empirical modelling were applied for the first time to investigate the effect of antagonistic Trichoderma harzianum on the dynamics of soilborne R. solani on individual potato plants. Trichoderma harzianum reduced the severity of symptoms, expressed as 'rhizoctonia stem lesion index' (RSI), during the first 7 days post-inoculation when the inoculum of R. solani was placed at certain distances (30–60 mm) from the host. For example, with inoculum at 40 mm from the host, RSI was 6 and 40 with and without T. harzianum , respectively. At later observation times, the antagonistic effect was overcome. Trichoderma harzianum reduced the severity of black scurf on progeny tubers. Furthermore, the mean number of progeny tubers per potato plant was reduced by the biocontrol treatment (means of 6·5 ± 1·1 and 9·9 ± 2·7 tubers per plant with and without T. harzianum , respectively), as was the proportion of small (0·1–20·0 g) tubers (48% and 66% with and without T. harzianum , respectively). Additionally, there were fewer malformed and green-coloured tubers in pots treated with T. harzianum than in those without T. harzianum .     

Tracking fungi in soil with monoclonal antibodies

Species of the genus Trichoderma are ubiquitous soil-borne fungi that exhibit antagonism towards a number of economically important plant-pathogenic fungi and oomycetes. This review discusses recent developments in the use of monoclonal antibodies to detect these fungi in their natural soil environments and to quantify their population dynamics during antagonistic interactions with saprotrophic competitors in soil-based systems. Immunological approaches to detection and quantification are examined in relation to conventional plate enrichment techniques and to nucleic acid-based procedures. An example of recent research using a mAb-based assay to quantify the effects of saprotrophic competition on the growth of Trichoderma isolates in mixed species, soil-based, microcosms is presented. Future technological developments in immunoassays for tracking Trichoderma populations in soil are discussed and results presented showing the accurate detection and visualization of a plant growth-promoting isolate of T. hamatum in the rhizosphere of lettuce using mAb-based immunodiagnostic assays.     

A natural fungicide for the control of <Emphasis Type="Italic">Erysiphe betae</Emphasis> and <Emphasis Type="Italic">Erysiphe cichoracearum</Emphasis>

This study examines the effects of a vegetable fungicide on sugar beet powdery mildew (Erysiphe betae) and cucumber powdery mildew (Erysiphe cichoracearum). The formulations consisting of a dispersion of Brassicaceae meal in vegetable or mineral oils on infected leaves of sugar beet, reared in the greenhouse, and of musk melons cultivated under plastic tunnels, were tested in comparison to each oil taken separately. Both formulations containing Brassicaceae meals, caused 94% of conidia to be distorted while for the untreated group only 2% were distorted. Furthermore, the leaf area infected by E. betae was 56% for untreated plants and 2.7 and 9.9% respectively, for plants treated with meal containing mineral and vegetable oil. Vegetable oil considered separately or with Brassicaceae meals showed no phytotoxicity, while the formulations based on mineral oil showed a significantly lower fresh and dry weight on tomato plants. The low level or absence of phytotoxicity of plants treated with vegetable oil formulations suggests that to improve the efficacy of powdery mildew control, they could be used mixed with sulphur. The efficiency of the vegetable formulations in the powdery mildew control observed during these trials encourages further investigation on other parasitic fungi and foliar pathogens.     

农业科研单位内部控制管理探讨

根据内部控制的定义、目标、特点及原则,结合农业科研单位的实际情况,论述其内部控制在制度、管理方面存在的主要问题,提出相应的解决措施,为确保农业科研单位内部控制管理的有效实施提供参考。     

凝固型酸乳常见问题的原因分析及控制措施

分析了凝固型酸乳常见质量问题的原因,并提出了相应的控制措施。     

单片机技术在自动给料系统中的应用

文章设计了基于单片机控制的送料机自动送料机控制系统,论述了单片机AT89C51在实现其生产过程控制的自动给料系统的设计方法。     

高层建筑清水混凝土的质量控制技术措施

该工程的主体工程混凝土要求为清水混凝土,本文论述了为确保清水混凝土质量所采取的一系列施工技术措施.