LITERATURE OVERVIEW
CONTENTS
1. WEED MANAGEMENT (11)
2. CONSERVATION TILLAGE (12)
3. CYPERUS ESCULENTUS (13)
3.1 C. ESCULENTUS INTERFERENCE WITH CROP PRODUCTION (14)
3.2 CONTROL MEASURES FOR C. ESCULENTUS (16)
4. COVER CROPS (18)
4.1 WEED SUPPRESSION DUE TO ENVIRONMENTAL INTERFERENCE (18)
4.2 WEED SUPPRESSION DUE TO CHEMICAL INTERFERENCE (20)
4.2.1 Allelopathy research (20)
4.2.2 Allelochemicals (21)
4.3 COVER CROPS USED (24)
4.3.1 Cereals: stooling rye and oats (24)
4.3.2 Annual ryegrass (28)
5. REFERENCES (29)
CHAPTER 1
LITERATURE OVERVIEW
“Other seed fell among thorns and the thorns grew up and choked them”
Matthew 13:7
KwaZulu-Natal (KZN) is one of the nine provinces of the Republic of South Africa, characterized by the Great Drakensberg Escarpment to the west and the Indian Ocean to the east. Most of the mean annual rainfall of 845 mm is received during the summer months (October-March) with the mean maximum and minimum temperatures reaching 25.2?30.4°C and -1.4?10.7°C, respectively. An average of 6.1?7.2 hours of sunshine is received in summer (Kars et al., 1999). Growing conditions are more favourable for crop production compared to most of the other provinces. Smaller areas of maize (Z ea mays), soyabeans (Glycine max), dry beans (Phaseolus vulgaris) and potatoes (Solanum tuberosum) are planted in KZN, yet higher yields per hectare are produced compared to provinces with bigger production areas. On average 4.4 tons ha-1 of maize are produced in KZN (4.6% of the total maize production) compared to the 3.0 tons ha-1 in the Free State Province which has 38% more land planted to maize (Anonymous 2005).
However, not only is maize the second most important field crop besides sugarcane (Saccharum officinarum) in KZN, it also forms part of the agricultural activities that provide 60% of the rural population in the province with food security and a sole or complementary income. Some of the factors that affect agriculture and rural development include poverty, high input costs, uneconomical farm sizes and the quality and quantity of produce (Kars et al., 1999). For instance, for a conservation tillage maize farmer in KZN to make a profit in 2010, more than nine tons of yellow maize per hectare, valued at R1255 ha-1 (US$1=R7), had to be produced (Whitehead & Archer 2008). Because weeds are one of the major pests in most cropping systems, it contributes not only to the higher input costs, but to the overall quantity and quality of produce. If weed
interference could be minimized not only could it lead to obtaining higher yields but also contribute to food security.
1. WEED MANAGEMENT
There is a close association between weed growth and crop production. Moss (2008) stated that the primary objective of weed management should be to better understand this association in order to improve current weed management and control programmes. Weed control is generally directed at controlling weed seedlings, not only because they are more manageable but weeds become less competitive later in the season. Amaranthus palmeri (Palmer amaranth) reduced maize yields between 11 and 91% as amaranth densities increased from 0.5?8 plants m-1 row (Massinga et al., 2001), while with Echinochloa crus-galli (barnyard grass) interference, maize yield loss ranged between 26 and 35% when barnyard grass emerged early. Yield loss due to the latter weed was only 6% when it emerged later in the maize growth season (Bosnic & Swanton 1997).
The development of herbicides during the late 1940s and onwards, provided a simple solution to weed control, resulting in higher crop yields. Currently however, this reliance on chemical control has been critically scrutinized due to the development of herbicide resistance, the negative impact on food and environmental safety, the growth in the organic food production sector (Bastiaans et al., 2008) and shifts in weed populations (Buhler 2002). In addition, the availability and less complicated management of weeds with herbicides in comparison to other methods, gives the impression that weeds can easily be controlled after crop establishment and therefore cultural and tillage methods are in many instances not considered.
Arguments against this simplification of weed management and the reliance on one weed control method have recently been published (Liebman & Davis 2000; Buhler 2002; Bastiaans et al., 2008). More emphasis should be placed on reducing weed densities, preventing weed reproduction minimizing weed competition and manipulating the crop competitiveness with the weeds. Weed emergence and
density can be reduced through crop rotations, restricting light from reaching the soil surface, the formation of a physical barrier and preventing seed dispersal. Crop competitiveness can be enhanced through modification of the planting date to ensure crop emergence before the weeds, improved cultivars for rapid germination and root development, quicker canopy closure, increased planting populations (Bastiaans et al., 2008) and using allelopathic crop cultivars (Belz 2004; Khanh et al., 2005). Conservation tillage, together with the use of cover crops, are two important factors in adjusting existing weed management systems aimed at reducing weed fitness and improving crop yields.
2. CONSERVATION TILLAGE
Although the primary objective of tillage operations is to prepare a crop seedbed and not weed control, tillage influences weed seed germination by reducing the soil surface cover, it changes the soil temperature and moisture patterns, and it alters weed seed distribution in the soil profile (Locke et al., 2002). Land users in South Africa are obliged by law to adhere to the Conservation of Agricultural Resources Act of 1983 to conserve natural resources by, among other things, combating and preventing soil erosion and maintaining the production potential of the soil. Methods such as conservation tillage, suitable conservation works and avoidance of cultivation during periods of high erosion hazard are advised (Russell 1998). Conservation tillage makes use of crop residue left on the soil surface to reduce the impact of raindrops on the soil surface and to reduce the velocity of surface runoff. In KZN, conservation tillage is practised as direct drilling when a blade cuts through the crop residue, opening a furrow into which seed and fertilizer are deposited. It has several advantages over conventional tillage systems as it reduces soil erosion, soil compaction, energy requirements, evaporation and runoff (Russell 1998; Giller et al., 2009).
These advantages came at a cost to weed management as the increased complexity thereof requires a higher level of management. According to Locke et al. (2002) careful management with herbicides is required as more post-emergence herbicides could be needed if the weeds were allowed to establish after
crop planting. The introduction of herbicide-resistant genetically modified (GM) crops improved weed control options for conservation agriculture and it could be economically viable if only post-emergence herbicides were used (Reddy 2001). There is, however, a possibility that with the continued use of these GM crops and the limited seed migration into the field, traits such as herbicide resistance could evolve faster than under conventional tillage (Martínez-Ghersa et al., 2000).
Also, weed populations and seed bank dynamics can be altered by conservation tillage. Most of the weed seeds occur in the upper 10 mm of soil and very few below 100 mm (Buhler 1995; Peachy et al., 2004). Small-seeded annual broadleaf and most grass species have the ability to increase prolifically because they germinate and become established when the seeds are at or near the soil surface. Summer annual species that do not require burial for establishment are also well adapted to proliferate (Buhler 1995). Conventional tillage appears to favour Digitaria sanguinalis (crab finger-grass), Sorghum halepense (Johnson grass) and Tagetes minuta (khaki weed), whereas conservation tillage promotes E. crus-galli (De La Fuente et al., 1999), Amaranthus retroflexus (redroot pigweed), Setaria viridis (green foxtail) (Buhler 1992), Chenopodium album (common lambsquarters) and Solanum nigrum (black nightshade) (Barberi & Mazzoncini 2001). Perennial weed populations tend to increase (Giller et al., 2009) and be more diverse (Locke et al., 2002) under conservation tillage. In KZN, Cyperus esculentus (yellow nutsedge), among others, can become a dominant and difficult weed to control in conservation tillage if insufficient weed control is practiced (Fowler 2000).
3. CYPERUS ESCULENTUS
Cyperus esculentus is an herbaceous perennial weed which can be identified by an above-ground triangular stem-like fascicle of leaves which later develops into a solid triangular rachis. Thin rhizomes and roots develop from bulbs situated at the base of the fascicle. Rhizomes consist of elongated internodes and nodal cladophylls which differentiate into tubers and shoots (Wills et al., 1980; Stoller
& Sweet 1987). C. esculentus spreads mainly through germinating tubers, and not as effectively by sexually produced seeds, which are viable and have longevity, but seedlings lack the vigour for survival in field situations (Stoller & Sweet 1987; Lapham & Drennan 1990).
In most soils, the rhizomes of C. esculentus are concentrated in the upper 15 cm of soil, resulting in 80% and more of the tubers occurring in this zone. Very few tubers are found below 20 cm (Friesen & Hamill 1977; Stoller & Sweet 1987). Day length determines the vegetative and reproductive growth of C. esculentus periods of 8?12 hours promote tuber formation, and 12?16 hours are conducive for vegetative growth (Friesen & Hamill 1977; Williams 1982). Tubers are formed four to six weeks after seedling emergence (Stoller & Sweet 1987).
During dormancy, storage conditions influence tuber sprouting, as cool moist conditions are more favourable than dry conditions (Friesen & Hamill 1977). Differences in tuber germination and multiple sprouting are not correlated with tuber weights but tuber size does influence seedling vigour (Stoller et al., 1972; Thullen & Keeley 1975). During tuber sprouting, one or more of the buds on the tuber begin to grow. A tuber can have more than one sprout forming, while others stay dormant. The number of sprouts decreases after each germination. More than 60% of the dry weight and nutrients in the tuber are used for the initial sprouting, 6?18% during the second and 2?10% during the third sprouting (Stoller et al., 1972; Thullen & Keeley 1975). Removing sprouts at regular intervals reduces the shoot numbers and tuber longevity, especially when done at four-week intervals (Thullen & Keeley 1975; Stoller & Sweet 1987).
3.1 C. esculentus interference with crop production
Cyperus esculentus interference with crop production has been demonstrated by various authors. Cotton (Gossypium hirsutum) yields decreased linearly with an increase in C. esculentus densities. Regression equations revealed an average yield loss of 19 kg ha-1 for each additional initial tuber m-1 of crop row (Moffett & McCloskey 1998), and approximately 18 kg ha-1 for each additional nutsedge
plant m-2 (Patterson et al., 1980). C. esculentus competition with cotton for the entire growth season reduced yields more than if the weed was present for shorter periods of time.
Stoller et al. (1979) reported that, although variability was seen from year to year, average maize yield losses were 8% for every 100 shoots m-2.Yield reductions were more prominent in years when lower than normal rainfall was received during the growing season. Jooste and van Biljon (1980) found that the second sprouting of C. esculentus on the Mphumalanga Highveld in South Africa competed more with maize during the 8?16 week period than in the 0?8 week period. Maize yields were reduced by 11.4% on a Hutton soil (dry soils) and by 23.9% on an Avalon soil form (relatively wet soils). They concluded that it was possible that the first flush of nutsedge may reduce maize yields more than what they reported. Reinhardt and Bezuidenhout (2001) found that maize emergence was retarded in soil where C. esculentus grew for 28 days and then removed on the day the maize was sown. Maize was not affected if tubers and maize seeds were planted at the same time.
Cucumber (Cucumis sativus) yields were reduced when 15 or more C. esculentus plants m-2 grew with the crop. However, the cucumber plants were able to compete successfully with C. esculentus if the crop was seeded at optimum densities, producing an optimum stand (Johnson III & Mullinix Jr 1999). The shoot dry weight of tomatoes (Lycopersicum esculentum) were reduced by 34% due to C. esculentus competition, with no differences in the interference from below- and above-ground competition (Morales-Payan et al., 2003).
Little and van Staden (2003) reported that C. esculentus was the main competitor for water and nutrients with an Eucalyptus hybrid clone, Eucalyptus grandis x E. camaldulensis in Zululand, South Africa, directly after planting, with a subsequent reduction in tree growth. Aqueous extracts of tubers and foliage of immature and mature C. esculentus plants inhibited the growth of the essential ectomycorrhiza, Boletus maxaria on agar medium isolated from patula pine
(Pinus patula) roots (Reinhardt & Bezuidenhout 2001). Their findings proposed that the interference of C. esculentus with seedling development of patula pine was indirect, through the primary inhibition of the ectomicorrhizal symbiont B. maxaria by allelochemicals released from the weed.
Although Jangaard et al. (1971) did not investigate the allelopathic effects of C. esculentus, they identified certain phenolic compounds in the tubers that are known for their allelopathic potential. Compounds identified included p-coumaric, ferulic, p-hydroxybenzoic, syringic, vanillic, salicylic, protocatechuic and caffeic acids, with p-coumaric and ferulic acids in higher concentrations. Allelopathic effects were suggested when extracts and dried material of C. esculentus and C. rotundus (purple nutsedge) reduced the growth of cereals, vegetables and soyabeans (Tames et al., 1973; Meissner et al., 1979; Drost & Doll 1980).
3.2 Control measures for C. esculentus
Shading reduces the total number of shoots and tubers, dry weight, plant height and leaf area of C. esculentus due to its C4 photosynthesis pathway. C. esculentus growth was significantly increased when plants were removed from the shade into full sunlight (Patterson 1982). Both Keeley and Thullen (1978) and Santos et al. (1997) found that 20?30% shade was detrimental to growth. In contrast, Jordan-Molero and Stoller (1978) reported that 30% shade did not influence the weed’s growth. Various crops planted at different plant populations reduced the above-ground growth of C. esculentus due to the low intensity of light reaching the weed. Ghafar and Watson (1983) showed that increasing the maize population from 33 300 to 133 300 plants ha-1 significantly reduced the C. esculentus above-ground biomass, tuber number, weight and height at the end of the growing season, with a concomitant significant increase in maize yield. Maize, barley (Hordeum vulgare), hemp (Cannabis sativa) and stooling rye (Secale cereale) reduced the above-ground biomass and density of C. esculentus secondary shoots in comparison with when a crop was absent (Lotz et al., 1991).
Crops that create a regime of low light intensity during a long C. esculentus growth period suppressed tuber formation more strongly than crops that shadow the weed for a relatively short period of time (Lotz et al., 1991). Various other authors confirmed that shading suppresses tuber formation (Jordan-Molero & Stoller 1978; Keeley & Thullen 1978; Patterson 1982; Li et al., 2001). However, according to Stoller et al. (1979), maize planted in 75-cm rows did not provide enough shade to prevent C. esculentus from producing tubers. This is supported by Santos et al. (1997). Reductions in total leaf area were primarily the result of less leaves produced, as well as them being thinner compared to those in full sunlight (Patterson 1982). Thomas (1969) found that temperature had the greatest effect on C. esculentus tuber survival, while the duration of desiccation did not significantly influence tuber survival. A combination of temperature and humidity was more effective in killing tubers than either treatment alone.
Although Stoller and Woolley (1983) and Stoller and Sweet (1987) stated that mulching would not be effective for growth suppression because the leaves of C. esculentus have sharp tips that could penetrate hard surfaces, Webster (2005) found that pots covered with 32 μm black-opaque and colourless-clear polyethylene mulches restricted nutsedge growth, as very few shoots emerged through the mulch. The biomass of C. esculentus shoots under the mulch was lower compared to the non-mulched treatment, with shoots under the black having a greater biomass than those under the clear mulch. Both mulches reduced tuber production to nearly half of the non-mulched control. Orme?o-Nú?ez et al. (2008) concluded that a dense stooling rye mulch between rows in a vineyard reduced C. esculentus growth by 81%.
The limitation of herbicide options for C. esculentus control in conservation agriculture and the variability of chemical control (Jooste & van Biljon 1980), creates the opportunity to incorporate the use of cover crops in a weed management system to reduce the weeds’ fitness in order to increase crop competitiveness
4. COVER CROPS
If the reliance on herbicides for weed management is reduced or eliminated, weed suppression must be approached from a crop cultivation perspective. Interest in the use of cover crops has been motivated primarily to produce crops in a more environmentally sustainable manner. Some of the benefits of cover crops include improving water infiltration, soil structure, reducing soil erosion, releasing nutrients upon decomposition, increasing the soil organic matter and preventing the leaching of N from the previous season (Liebman & Davis 2000). Cover crops can be grown in rotations after the main crop has been harvested or could grow simultaneously during part or all of the main crop season. For the purpose of reducing C. esculentus growth in a maize conservation tillage system in KZN, the term cover crop refers to crops planted in autumn after the main crop has been harvested and then killed during the following spring before planting the next main crop into the residues. The cover crop residues remaining on the soil surface could suppress weed growth through environmental and chemical interference.
4.1 Weed suppression due to environmental interference
Seed germination is dependent on adequate, but not excessive, supply of water, suitable oxygen:carbon dioxide ratio, and optimum temperatures and light (Monaco et al., 2002). Cover crop residues remaining on the soil surface can physically modify the germination environment by intercepting light and rain and interfering with the heat and water transfer between the soil and atmosphere (Teasdale et al., 2007).
Exposure to light is one of the basic requirements of many weed seeds to germinate. Residues on the soil surface would intercept the incoming radiation promoting dormancy of species with a light requirement. According to Teasdale and Daughtry (1993) light transmission was more obstructed by live hairy vetch (Vicia villosa) plants than desiccated hairy vetch material, influencing the suppression of weed growth. Changes in the light spectrum reaching the seed under plant residue could affect the light quality, thereby suppressing germination and growth of photo-dormant species (Teasdale & Mohler 1993). Red
light converts phytochrome to an active form, promoting germination, while far-red light inactivates phytochrome, thus inhibiting germination. Most weed seeds germinate when exposed to the red light portion of sunlight and not in darkness. However, desiccated cover crops have limited influence on the red:far red light ratio due to the absence of chlorophyll (Teasdale & Mohler 1993).
Plant residues on the soil surface lower the soil surface temperature by acting as insulation from the air temperature and intercepting solar radiation thus delaying cooling of the soil surface more than heating (Teasdale & Mohler 2000). Not only could germination be delayed at lower maximum soil temperatures due to the residues but the temperature of the residues itself could suppress germination. Teasdale and Mohler (1993) recoded residue temperatures of 41°C when the air temperature was 37°C. Changes in the soil temperature may enhance mineralization rates, thereby influencing nutrient availability (Facelli & Pickett 1991).
Plant litter on the soil surface may retain some rain water, depending on the litter characteristics (Facelli & Pickett 1991), thereby limiting the amount of water available for germination. During dry periods soil moisture under the residues could be higher creating favourable conditions for germination. However, saturated conditions could reduce germination. C. album and S. viridis establishment was reduced by soil moistures above field capacity under hairy vetch residues (Teasdale 1993).
The residues on the soil surface may obstruct seedling roots reaching the soil thereby reducing the growht of seeds and sprouts. Seedlings emerging from beneath the residues need to devote more energy penetrating it, leading to higher seedling mortalities. Small seeded species are more sensitive to covering, especially at the cotyledon stage. Once the stored resources of the seed are depleted no energy is available for growth (Baerveldt & Ascard 1999; Liebman & Davis 2000). The degree of weed control provided by the residues is likely to be
influenced by the weed species and growth stage, the thickness of soil cover and the soil type.
4.2 Weed suppression due to chemical interference
The allelopathic effects of cover crops on weed growth is the primary means of chemical interference and have been documented (Weston & Duke 2003). Plants interfere directly and indirectly with their neighbours, with a subsequent reduction in growth in any one or both of them as a consequence. Direct effects are attributed to competition and allelopathy, while indirect effects are attributed to changes in the growth environment due to physical effects and the presence of pests and diseases (Hoffman et al., 1996). With competition, growth factors are diminished, while with allelopathy, chemical compounds that are released into the environment affect plant growth (Khanh et al., 2005).
4.2.1 Allelopathy research
The root exudation and leaching of allelochemicals from a range of crops employed as cover-, smother-, companion- or intercrops form the basis of a weed management strategy involving allelopathy (Belz 2004; Khanh et al., 2005). However, the discipline of allelopathy has had its share of controversy, in part due to the following limitations: (a) complex research methodology is required for distinguishing between allelopathy and competition (Belz 2004), (b) the widely held assumption that all chemicals extracted from plants would exhibit allelopathic characteristics, and (c) the assumption that the mere presence of allelochemicals in plant tissue presents strong evidence for allelopathy (Inderjit & Callaway 2003).
In the past, to prove that allelopathy was the cause of plant growth inhibition, unrealistic bioassays using leachates or extracts of plant parts in artificial conditions have been used (Foy & Inderjit 2001; Olofsdotter et al., 2002). Bioassays are important in the study and demonstration of allelopathy. Therefore, in order that experiments produce more convincing evidence for the existence and function of allelochemicals they should meet the following criteria: (a) showing allelochemicals being released from the donor plant and arrives in
functional concentrations under natural conditions at the receiver plant, (b) determination of the fate and persistence of allelochemicals in soil, (c) elucidation of the uptake mechanism of the receiver plant and its subsequent response (Blum 1999; Inderjit & Callaway 2003). To discover whether or not these subunits work together, a field study is necessary (Inderjit & Weston 2000; Khanh et al., 2005), but the evaluation of the contribution of each phenomenon to the overall effect in a field situation is difficult and therefore selection of allelopathic cover crop plants under field conditions is not an option (Foy & Inderjit 2001; Olofsdotter et al., 2002). In evaluating the ability of rice to control weed growth, research was focused on bioassays and field work that led to a correlation between growth inhibition and allelochemical release, which formed the basis of a subsequent international breeding programme for developing competitive rice cultivars (Olofsdotter 2001).
4.2.2 Allelochemicals
All plants synthesize secondary metabolites which are generally considered not important for primary metabolic processes essential for a plant’s survival. These metabolites represent a vast number of biologically active compounds, of which some are allelopathic and are referred to as allelochemicals. The allelopathic effect on plants is often the result of a combination of these chemicals released together, as individual compounds are often present in concentrations below their inhibition thresholds (An et al., 1998; Inderjit & Nayyar 2002).
Allelopathic plants do not develop in isolation and environmental conditions influencing plant growth will directly affect allelochemical production and expression. The extent of their phytotoxicity depends on soil characteristics, abiotic and biotic factors, the donor and target plant species and cultivars used (Inderjit & Nayyar 2002).
Adsorption, desorption and degradation of allelochemicals in soil are just as common a phenomena as with herbicides, and therefore, soil texture, organic and
inorganic matter, moisture and micro-organisms as well as allelochemical solubility in water will affect their phytotoxic activity in the soil (Inderjit et al., 2001; Kobayashi 2004). A recent example of this is the abiotic and biotic variables that degraded the allelochemical parthenin released from the alien invader plant Parthenium hysterophorus (Parthenium), causing it to have short but variable half-lives in soil, depending on temperature, moisture and microbial activity (Belz et al., 2009). Soil micro-organisms can use allelochemicals as a food source and if allelochemicals are released, the micro-organism population can increase in response. Plant growth inhibition can be the result not only of the allelochemicals present but also because the micro-organisms can transform these compounds to new chemicals of lower or higher bioactivity. In addition, microbes can immobilize nutrients, with subsequent reduction in plant growth (Schmidt & Ley 1999).
The abiotic factors water and nutrient content, temperature and applied herbicides have a significant influence on the availability of allelochemicals. In a review by Tang et al. (1995) various examples were given in which stress factors caused an elevation in allelochemicals. Gershenzon (1984) came to the conclusion that the accumulation of secondary metabolites under stress conditions must be an adaptive response to conditions under which the function of these compounds becomes important. Einhellig (1987) showed how certain herbicides synergize or supplement the activity of allelochemicals, which can have implications for conservation tillage as it is dependent on herbicide use. The fate of allelochemicals under stress cannot be generalized. The availability of growth resources for donor and target plants can be influenced by the presence of allelochemicals. Donor plants may be less influenced due to their adaptation to the stress, while target plants could lack this ability. Damage is therefore caused by abiotic stress or allelochemicals, or by both (Inderjit & Nayyar 2002).
Choosing the cover crop species and cultivar would also have an impact on the allelopathic effect produced on weed species (Weston & Duke 2003). Differences in their ability to suppress weed growth were reported for, among others, stooling
rye and its different cultivars (Pérez & Orme?o-Nú?ez 1993; Burgos et al., 1999), wheat (Triticum aestivum) (Tollenaar et al., 1993) and clover (Triflolium sp) (Creamer et al., 1996).
Reports on the influence of allelochemicals on plants most frequently identified effects which are readily observed in the field or under controlled conditions. Delayed or inhibited germination and the stimulation or inhibition of root and shoot growth are often reported (Rizvi et al., 1992). The major difficulty is to separate secondary effects from primary causes. An important question that always remains is whether or not the inhibitor reaches the active site in the plant in sufficient concentration to specifically influence that reaction, and if other processes may also be affected.
The mode of action of a chemical can broadly be divided into a direct and an indirect action (Rizvi et al., 1992). Effects through the alteration of soil properties, nutritional status and an altered population or activity of micro-organisms and nematodes represent the indirect action. Direct action involves the biochemical/physiological effects of allelochemicals on various important processes of plant growth and metabolism. Some of the processes influenced by allelochemicals are:
? reduction in mineral uptake;
?inhibition of cytology and ultrastructure;
?inactivation of phytohormones and upsetting their balance, and
? inhibition of photosynthesis, respiration and protein synthesis (Rice 1984;
Putnam 1985).
Under natural conditions the action of allelochemicals seems to revolve around a fine-tuned regulatory process in which many such compounds may act together on one or more of the above processes (Rizvi et al., 1992).
4.3 Cover crops used
4.3.1 Cereals: stooling rye and oats
Stooling rye is an annual cereal crop with a fibrous root system and hollow stems that can reach heights of 80?180 cm, depending on the cultivar. As a green plant it is utilized as a green manure and animal fodder, especially during the winter, while the grain is used for flour and alcohol production. In the cooler regions of KZN it is planted as animal fodder in autumn and used from May to September. Oats is a tufted winter-growing annual and in South Africa, oats are mainly produced as a winter grazing or green feed and produce the highest amount of forage per unit area. Planting commence in March and April with the main growth from March to October (Dickinson et al., 1990).
Stooling rye is preferred as a cover crop due to its potential to produce abundant biomass that suppress weed emergence and growth (Koger et al., 2002). In the absence of herbicides, grass control by a stooling rye cover crop increased by 46?61% above the no-cover or conservation tillage system (Yenish et al., 1996), while the biomass of C. album, Polygonum aviculare (prostrate knotweed) and Fallopia convolvulus (climbing knotweed) were reduced by the stooling rye cultivar ‘Forrajero-Baer’ (Pérez & Orme?o-Nú?ez 1993).
Oats reduced the number of individuals of Picris echioides (bristly ox-tongue) by 94% (de Bertoldi et al., 2009). Weed density was reduced by oats and grazing vetch (Vicia dasycarpa) with 90 and 80% respectively while reduction by lupins (Lupinus angustiflolius) were less successful at only 23% compared to the control plots (Murungu et al., 2010). In trials done by Seavers and Wright (1999) oats were more suppressive than barley and wheat. They concluded that the suppressive effect was not only due to the canopy that was formed as the oats had the slowest canopy development of the test species but retained their weed growth reduction throughout the growing season. This was confirmed by Fourie et al. (2006) who reported effective long-term control of summer weeds with oats, rye and black oats (Avena strigosa).
The influence of residues on crop growth and weed suppression varies with the time of cover desiccation, resulting in partial suppression of specific weed species. In tomatoes, stooling rye provided 4?8 weeks control after planting, depending on the season and time of desiccation (Smeda & Weller 1996). Soyabean yields were significantly higher when planted into stooling rye residues that were killed two weeks before planting compared to treatments that were planted a day after the stooling rye was killed (Liebl et al., 1992). This was confirmed by Raimbault et al. (1990) who found that crop growth was retarded if planted into stooling rye immediately after the stooling rye was killed. The effect was increased when used in a no-till system compared to a conventional tillage system. According to Yenish et al. (1995), the residual effect of killed stooling rye does not persist beyond 170 days.
The reduction in weed growth is further influenced by cultivar choice although differences of opinion exist about the attributes of different cultivars. Walters et al. (2005) found that the cultivars ‘Elbon’ and ‘Matice’ provided better weed suppression due to their higher yields and soil coverage, while Tollenaar et al. (1993) found that ‘Kodiak’ and ‘Gordon’ reduced maize yields the most, despite their low yields and therefore low biomass. They attributed it to the higher below-ground biomass. In addition, higher benzoxazolinone content were found in ‘Bonel’ and ‘Aroostok’, although they did not have the highest yields (Burgos et al., 1999). The cultivar ‘Wheeler’ reduced maize heights and yields when the maize was planted immediately after the stooling rye was killed (Raimbault et al., 1990) The benzoxazolinone content of ‘Bates’ increased between 30 and 60 days after planting and decreased thereafter (Burgos et al., 1999). The differences in weed suppression could be attributed to the decomposition products of stooling rye tissue of different ages. According to Wójcik-Wojtkowiak et al. (1990), tillering plants gave the highest level of inhibition, but crop residues did not exhibit toxicity. The level of toxicity was found to be dependent on decomposition time and increase as tissue degraded, reaching a maximum after 3-4 weeks of degradation before decreasing.
Favonoids and saponins have been identified in oats (de Bertoldi et al., 2009), while one of the allelochemical groups responsible for the allelopathic expression of stooling rye is collectively called benzoxazolinones or benzoxazinones (Belz 2004). The production of BOA (benzoxazolin-2(3H)-one) involves two precursors, a benzoxazinoid acetal glucoside and its aglucone (Figure 1). The acetal glucosides DIBOA-Glc are transformed to aglucone DIBOA (2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one which, in turn, forms BOA (Sicker et al., 2004). Weed control in the field could be attributed to the formation of AZOB (azoperoxide) which would increase the phytotoxicity.
FIGURE 1 Chemical formation of BOA from DIBOA (Sicker et al., 2004)
Glucosides are regarded as non-toxic in juvenile plants and are stored in the vacuole until needed. Aglucones are released when plants are attacked by insects or fungi, when residues are being decomposed, and through root exudation (Yenish et al., 1995; Burgos et al., 1999). DIBOA is chemically unstable in solutions and during decomposition and is therefore converted to BOA. According to Burgos and Talbert (2000), BOA is not solely responsible for the phytotoxic reactions in plants.
Low concentrations of allelochemicals are rapidly broken down by microbes in the soil and are adsorbed onto the soil colloids (Kobayashi 2004). The continuous release of allelochemicals from the donor plants into the rhizosphere will compensate for these loss factors. It must be borne in mind that an effect on the receptor plant would only be noticed if the plant is susceptible to the allelochemicals in such a way that it would cause damage or result in the death of the plant. Chiapusio et al. (2004) and Belz et al. (2007) confirmed that the effect of allelochemicals is dependent on the concentration. Typically, at the higher concentrations the growth inhibiting effects are most severe, whereas growth stimulation is possible at the lowest concentrations of a particular compound.BOA is also more concentrated in certain plant parts than in others. Rice et al. (2005) confirmed work done by Tang et al. (1975) that more BOA occurs in stooling rye shoots than in the roots.
According to Chase and Nair (1991), it is very difficult to determine the concentrations of compounds at a specific point in time in nature. These compounds can function on their own or in combination with others. Benzoxazolinones should be resistant to microbial transformation to have any allelopathic effect (Yenish et al., 1995). The allelopathic activity in the field should be high due to exudation by roots and decomposition of material. Microbes convert BOA into AZOB (2,2’-oxo-1,1’-azobenzene), which has a higher toxicity than DIBOA and BOA (Nair et al., 1990; Chase & Nair 1991). Rice et al. (2005) identified DIBOA and BOA in shoot tissue of stooling rye while DIMBOA glucose ((2R)-2-beta-D-glucopyranosyloxy-4-hydroxy-7-methoxy-(2H)-1,4-benzoxazin-
3(4H)-one) and MBOA (2,4-hydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one) were more prevalent in root tissue. Lettuce (Lactuca sativa) was more affected by crude extracts of the shoot tissue than the root tissue.
In a study conducted by Burgos and Talbert (2000) results showed that small-seeded seeds are more sensitive to benzoxazolinones than large-seeded species. However, there was variation between the reactions of small seeds. Therefore, seed size alone apparently does not account for the variability in allelopathic
expression. The root and stem elongation of cucumber was more effected by DIBOA than BOA in a petri dish bioassay (Burgos et al., 2004).
4.3.2 Annual ryegrass
Annual ryegrass (Lolium multiflorum) is an annual pasture species which provides additional fodder to animals. Cultivars are divided into two categories, Italian and Westerworld cultivars. Italian ryegrass cultivars need vernalisation in order to become reproductive and can be sown in autumn or spring. If planting occurs in spring a longer grazing period is obtained. Westerworld types are sown in autumn and will become reproductive as soon as the day length increases and they then flower in spring. The two types of cultivars are further divided into diploids and tetraploids, with diploids having narrow, shorter leaves, but being more hardy and with greater density than the tetraploids (Dickinson et al., 1990).
Decomposition of annual ryegrass residues is slow and residues remain on the soil surface for longer (Reddy 2001). Despite this, weed growth suppression is variable, as Brachiaria ramose (browntop millet) suppression declined over time, but C. esculentus growth remained constant. In comparison with other cover crops tested, annual ryegrass suppressed weed growth the most (Burgos & Talbert 1996; Reddy 2001).
Interference from annual ryegrass is ascribed to the finer root system of annual ryegrass enlarging the root area, allowing more nutrients and water to be extracted (Liebl & Worsham 1987; Stone et al., 1998). In addition, nitrogen mineralization can be exploited better because of a more effective root system (Kramberger et al., 2008). Data are lacking regarding the allelopathic potential and identity of putative allelochemicals in annual ryegrass even though circumstantial evidence exists that the species is allelopathic (Smith & Martin 1994). Various allelochemicals have been identified in other Poaceae species (Sánchez-Moreiras et al., 2004).
非洲猪瘟的防控 公司标准化编码 [QQX96QT-XQQB89Q8-NQQJ6Q8-MQM9N]
非洲猪瘟：世界范围内无疫苗，应如何防控？ 根据农业农村部通报，8月1日，我国辽宁省沈阳市发现疑似猪瘟病例，发病47头，死亡47头；8月3日，经中国动物卫生与流行病学中心（国家外来动物疫情研究中心）确诊为非洲猪瘟，对疫点内913头生猪进行扑杀。这是国内首例非洲猪瘟。 非洲猪瘟（ASF）是什么 非洲猪瘟是由非洲猪瘟病毒引起的猪的一种急性、热性、高度接触性动物传染病，国内将其列为一类动物疫病，主要通过接触病毒或污染物以及被感染的蜱叮咬后感染。病毒潜伏期15天，强毒力毒株致死率达100%。但不是人畜共患病，不感染人。 非洲猪瘟的传播方式 1、患病动物循环，包括非洲软蜱、非洲野猪、疣猪和薮猪等。 2、蜱和家猪循环，非洲软蜱叮咬并吸入感染了ASFV的猪的血液，同时也将病毒吸入体内，并携带和传播ASFV，在体内存活可长达 8 年之久，更长的能终生带毒。此外，吸血昆虫，例如蚊、虻等，可以通过叮咬将 ASFV 从感染猪向未感染猪传播。 3、家猪之间传播循环。此传播途径没有生物传媒参与，病死猪和感染带毒的猪群，尤其是地方流行的家猪携带病毒成为该病的主要传染源。患慢性病的带毒猪可终身带毒，并通过其排泄物而散播病毒。 非洲猪瘟的临床症状
非洲猪瘟是一种高度传染性疾病，可感染所有日龄猪只，无性别差异。没有能够用来确诊ASF的特异性症状，但通常如果所有日龄组的猪只都表现出极高的死亡率的话，那么就很可能是ASF，尽管其表现会和CSF（古典猪瘟）类似。 该病有四种发病形式：特急性、急性、亚急性和慢性。特急性和急性形式可能有下列症状： 动物猝死，几乎没有征兆； 发病初期体温升高，临死前2天体温下降，外表症状开始表现明显； 皮肤偏紫色（仅浅色皮肤的猪可观察到），耳尖、尾尖、肢体末梢、胸腹部； 死前24-48小时食欲减退，精神不振，发酣以及运动失协； 呕吐、腹泻（有时带血），眼部流出分泌物； 6至13天内死亡，最长20天； 母猪流产； 家猪死亡率常接近100％。 如何防控非洲猪瘟？ 目前全球尚无针对预防非洲猪瘟的疫苗，只能通过扑杀的方式防疫。但高温、消毒剂可以有效杀灭病毒，所以做好养殖场生物安全自查、严格执行猪场日常消毒程序、提高机体免疫力是防控非洲猪瘟的关键。 1、慎重引种，选择规模适度、信誉度高、种猪健康状况好的猪场引种； 2、加强生物安全，做好隔离消毒.
专业文档 批次张桂红表示如果猪场能够做到分区饲养管理、建议严格的生物安全体系对于新建猪场，化生产同时还建立隔离栏舍的话，将对非洲猪瘟的防控有很大的帮助。那么这些猪场又该如何在现有要在这些方面做优化可能较 为伤筋动有些猪场建立已久， 骨，的基础上来防控非洲猪瘟呢?在猪的方面，养猪人在引种时一定要注意隔离和检测，且平时要做好相关的排查工作，如果发现猪只出现体表发绀、耳朵或体表出现紫斑、毛孔出血、厌食、腹泻等症状时，要提高警惕，最好是采样送到相关的非洲猪瘟检测实验室进行检测。对于当前的非洲猪瘟疫情猪场主要措施就是预防；非瘟清，主要用于防治猪的病毒性传染病 （瘟疫病，如非洲猪瘟、蓝耳、圆环、流感等）用于非洲猪瘟、蓝耳、圆环、链球菌、流感、附红体、弓形体及混感等引起的猪发热性（瘟热性）疾病的治疗与预防。症见：高热神昏、精神萎顿、结膜潮红、充血；皮肤发红，体表出血、瘀血，四肢、下腹、会阴、臀部等部位 便秘或排脓性粪便干硬、呼吸困难；呕吐，食欲减退或废绝，尤其严重；咳嗽、喘气、血便；母猪伴有不孕、流产、死胎。剖检病死猪可见脾脏、肝脏、肺脏等脏器和淋巴结严重肿大，并广泛性出血瘀血。本病急性发病时死亡
率很高，尤其是母猪、大猪死亡更快。预防拌料 吨料），连公斤非瘟清/ 2-3 预防量（公斤非瘟清/ 吨料），每月使用7-14 天；治疗量（4-5 7 天；用 常规投药，猪只免疫力、抵抗力强，可有效抵御野毒侵袭；抗应激能力强，消化功能好，生长速度快；疫苗免疫后抗体产生迅速而整齐；重大疫情时，不发病或发病少，病情轻，易于治疗。 用本多家猪场与公司的试验结果表明，本产品已经有很好反馈。对于当前的猪场流行疫病，减轻病体现出显著的“三减一降”效果，即：减缓发病、产品进行预防性、保护性投药， “三减”给猪场留下了宝贵的时间，为实质性控制疾病与降低损失情、减少死亡；降低损失。 创造了条件。“猪场要慎重剖检疑似猪只! ”张桂红特别强调，剖检有可能会成为传染源，风险极大，所以她建议猪场不要轻易剖检疑似病猪。规范人员进场的流程，要注重员工和外来人员的隔离，同时要做好相关的科至于人员方面，普宣传工作和加强对员工的培训。猪源产品、相关文献显示，原粮存在一定携带非洲猪瘟病毒的风险，所以猪场做好饲料的运输安全管理非常重要，如果能在场内建设中转料塔可大大降低病毒进入生产区的风险。
非洲猪瘟疫情应急实施方案 （2020年版） 为有效预防、控制和扑灭非洲猪瘟疫情，切实维护养猪业稳定健康发展，保障猪肉产品供给，根据《中华人民共和国动物防疫法》《中华人民共和国进出境动植物检疫法》《重大动物疫情应急条例》《国家突发重大动物疫情应急预案》等有关规定，制定本实施方案。 一、疫情报告与确认 任何单位和个人，一旦发现生猪、野猪异常死亡等情况，应立即向当地畜牧兽医主管部门、动物卫生监督机构或动物疫病预防控制机构报告。 县级以上动物疫病预防控制机构接到报告后，根据非洲猪瘟诊断规范（附件1）判断，符合可疑病例标准的，应判定为可疑疫情，并及时采样组织开展检测。检测结果为阳性的，应判定为疑似疫情；省级动物疫病预防控制机构实验室检测为阳性的，应判定为确诊疫情。相关单位在开展疫情报告、调查以及样品采集、送检、检测等工作时，要及时做好记录备查。 省级动物疫病预防控制机构确诊后，应将疫情信息按快报要求报中国动物疫病预防控制中心，将病料样品和流行病学调查等背景信息送中国动物卫生与流行病学中心备份。中
国动物疫病预防控制中心按程序将有关信息报农业农村部。 在生猪运输过程中发现的非洲猪瘟疫情，对没有合法或有效检疫证明等违法违规运输的，按照《中华人民共和国动物防疫法》有关规定处理；对有合法检疫证明且在有效期之内的，疫情处置、扑杀补助费用分别由疫情发生地、输出地所在地方按规定承担。疫情由发生地负责报告、处置，计入输出地。 各地海关、交通、林业和草原等部门发现可疑病例的，要及时通报所在地省级畜牧兽医主管部门。所在地省级畜牧兽医主管部门按照有关规定及时组织开展流行病学调查、样品采集、检测、诊断、信息上报等工作，按职责分工，与海关、交通、林业和草原部门共同做好疫情处置工作。 农业农村部根据确诊结果和流行病学调查信息，认定并公布疫情。必要时，可授权相关省级畜牧兽医主管部门认定并公布疫情。 二、疫情响应 （一）疫情响应分级 根据疫情流行特点、危害程度和涉及范围，将非洲猪瘟疫情响应分为四级：特别重大（Ⅰ级）、重大（Ⅱ级）、较大（Ⅲ级）和一般（Ⅳ级）。 1.特别重大（I级） 全国新发疫情持续增加、快速扩散，21天内多数省份发
非洲猪瘟防控方案 This manuscript was revised on November 28, 2020
非洲猪瘟防控工作方案 为切实做好全省非洲猪瘟防控工作，严防疫源输入我县，根据《省畜牧兽医局办公室关于做好非洲猪瘟防控工作的紧急通知》等文件精神要求，结合我县实际，特制定本方案。 一、指导思想与工作目标 （一）、指导思想 根据省委省政府部署要求，统一思想，确保认识到位、责任到位、措施到位。按照“广排查、早发现、快反应、严处置、全根除”要求，强化全面排查巡查、强化疫情应急处置、强化生物安全措施、强化生猪及其产品移动监管、强化检疫监督执法、强化联防联控、强化宣传引导。切实推进养殖业健康发展，维护市场稳定。 （二）、工作目标 1、监测排查覆盖率达到100%； 2、运载工具消毒率达到100%； 3、严禁从疫区及疑似疫区调运生猪及其产品； 4、应急处置率达到100%。 二、防控重点及工作措施 （一）、防控重点 对辖区内生猪养殖场、屠宰场、交易市场（仔猪行）、无害化处理收集中心等重点场所开展全面排查，发现临床类似猪瘟症状，且治
疗效果不良或不明原因大量死亡的生猪，立即限制移动，及时送检，将情况按程序报省动物疫病预防控制中心。 （二）、工作措施 1、对全县所有养殖场、屠宰场、交易市场（仔猪行）、无害化处理收集中心进行告知、排查； 2、严禁从疫区或高风险区调运生猪及其产品； 3、严格环境、设备及运输车辆消毒； 4、对类似猪瘟及不明原因大量死亡的场所进行隔离、抽样送检、同时上报省防控中心。 三、实施步骤 （一）、动员部署 按照省畜牧兽医局统一部署，结合我县实际，成立以所长朱春奎为组长，副所长王能相为副组长的领导小组。制定方案，召开专题会议，确保防控工作有效有序的开展。 （二）、监测排查 按照职责分工，开展宣传告知，督促相关企业切实履行主体责任，对重点区域、重点环节进行监测排查。发现问题，及时采取应急措施。同时对监测排查过程中发现的违法违规行为进行，依法进行严厉查处。完善监测机制，强化保障措施。 四、工作要求 （一）、加强组织领导。要在当地政府的统一领导下，加强组织领导，认真履行职责，确保非洲猪瘟防控工作有力有序开展。要突出
农业部关于印发《非洲猪瘟疫情应急预案》 的通知 各省、自治区、直辖市及计划单列市畜牧兽医（农牧、农业）厅（局、委、办），新疆生产建设兵团畜牧兽医局，部机关有关司局，部属事业单位，各有关单位： 为贯彻落实《国家中长期动物疫病防治规划（2012—2020年）》，切实做好非洲猪瘟疫情应急处置工作，根据《中华人民共和国动物防疫法》等法律法规，我部组织制定了《非洲猪瘟疫情应急预案》。现印发给你们，请遵照执行。 农业部 2017年9月20日 非洲猪瘟疫情应急预案 1 总则 非洲猪瘟是由非洲猪瘟病毒引起的猪的一种急性、热性、高度接触性动物传染病。世界动物卫生组织（OIE）将其列为法定报告动物疫病，我国将其列为一类动物疫病，是我国重点防范的外来动物疫病之一。
1.1 编制目的 及时扑灭突发非洲猪瘟疫情，保障生猪养殖业健康发展。 1.2 编制依据 依据《中华人民共和国动物防疫法》《中华人民共和国进出境动植物检疫法》《重大动物疫情应急条例》《国家突发重大动物疫情应急预案》和《国家中长期动物疫病防治规划（2012—2020年）》，制定本预案。 1.3 工作原则 按照属地管理的原则，实行政府统一领导、部门分工负责，切实落实防控工作责任制，联防联控，形成防控合力。 坚持预防为主，贯彻“加强领导、密切配合、依靠科学、依法防治、群防群控、果断处置”的防控方针。按照“早、快、严、小”的要求，及早发现，快速反应，严格处理，减少损失。 1.4 适用范围 本预案适用于我国突发非洲猪瘟疫情的应急处置工作。 2 组织管理 2.1 应急指挥机构
农业部在国务院统一领导下，负责组织、协调全国非洲猪瘟疫情应急管理工作，并根据突发疫情应急处置工作的需要，向国务院提出启动国务院重大动物疫情应急指挥部应急响应建议。 地方各级人民政府兽医主管部门在本级人民政府统一领导下，负责组织、协调本行政区域内非洲猪瘟疫情应急管理工作，并根据突发疫情应急处置需要，向本级人民政府提出启动地方重大动物疫情应急指挥部应急响应建议。 各级人民政府应急指挥部应明确组成部门，各有关部门要加强协调配合，建立健全多部门共同参与的联防联控协作机制。 2.2 职责分工 农业部负责组织实施突发非洲猪瘟疫情应急管理工作，并进行检查、督导；及时发布突发非洲猪瘟疫情信息，并向有关国际组织、国家和地区通报疫情；紧急组织调拨消毒药品等应急防疫物资；提出启动、停止疫情应急控制措施建议；组织对扑杀及补偿等费用和疫情损失的评估。各地兽医部门要积极配合出入境检验检疫等有关部门，共同做好境外非洲猪瘟疫情传入风险的防范工作，及时开展突发疫情应急处置，切实落实疫情监测、流行病学调查、排查、消毒、检疫监管、扑杀等各项综合防控措施。边境地区兽医部门要着力加强边境地区防控，坚持内防外堵，配合有关部门切实落实边境巡查、消毒等防控措施。
建议严格的生物安全体系对于新建猪场，xx表示如果猪场能够做到分区饲养管理、批次化生产同时还建立隔离栏舍的话，将对非洲猪瘟的防控有很大的帮助。 有些猪场建立已久，要在这些方面做优化可能较为伤筋动骨，那么这些猪场又该如何在现有的基础上来防控非洲猪瘟呢? 在猪的方面，养猪人在引种时一定要注意隔离和检测，且平时要做好相关的排查工作，如果发现猪只出现体表发绀、耳朵或体表出现紫斑、毛孔出血、厌食、腹泻等症状时，要提高警惕，最好是采样送到相关的非洲猪瘟检测实验室进行检测。 对于当前的非洲猪瘟疫情猪场主要措施就是预防；非瘟清，主要用于防治猪的病毒性传染病（瘟疫病，如非洲猪瘟、蓝耳、圆环、流感等）用于非洲猪瘟、蓝耳、圆环、链球菌、流感、附红体、弓形体及混感等引起的猪发热性（瘟热性）疾病的治疗与预防。症见：高热神昏、精神萎顿、结膜潮红、充血；皮肤发红，体表出血、瘀血，四肢、下腹、会阴、臀部等部位尤其严重；咳嗽、喘气、呼吸困难；呕吐，食欲减退或废绝，粪便干硬、便秘或排脓性血便；母猪伴有不孕、流产、死胎。剖检病死猪可见脾脏、肝脏、肺脏等脏器和淋巴结严重肿大，并广泛性出血瘀血。本病急性发病时死亡率很高，尤其是母猪、大猪死亡更快。 预防拌料 预防量（2-3公斤非瘟清/吨料），每月使用7-14天；治疗量（4-5公斤非瘟清/吨料），连用7天； 常规投药，猪只免疫力、抵抗力强，可有效抵御野毒侵袭；抗应激能力强，消化功能好，生长速度快；疫苗免疫后抗体产生迅速而整齐；重大疫情时，不发病或发病少，病情轻，易于治疗。 对于当前的猪场流行疫病，本产品已经有很好反馈。多家猪场与公司的试验结果表明，用本产品进行预防性、保护性投药，体现出显著的“三减一降”效果，即：减缓发病、减轻病情、减少死亡；降低损失。“三减”给猪场留下了宝贵的时间，为实质性控制疾病与降低损失创造了条件。 “猪场要慎重剖检疑似猪只!”xx特别强调，剖检有可能会成为传染源，风险极大，所以她建议猪场不要轻易剖检疑似病猪。 至于人员方面，要注重员工和外来人员的隔离，规范人员进场的流程，同时要做好相关的科普宣传工作和加强对员工的培训。 相关文献显示，猪源产品、原粮存在一定携带非洲猪瘟病毒的风险，所以猪场做好饲料的运输安全管理非常重要，如果能在场内建设中转料塔可大大降低病毒进入生产区的风险。 虽然非洲猪瘟杀伤性十足，但xx表示，非洲猪瘟是可防、可控的，养猪人不必过度恐慌，但也不能心存侥幸; 因为目前对于该病尚无有效的防治疫苗与药物，所以基于传染病控制的三个基本要素——“控制传染源、切断传播途径、保护易感群体”来看，养猪人应把防治重心放在前两项措施上，通过良好的生物安全体系来给猪场建立有效的防疫屏障，防止非洲猪瘟病毒进入场内。
非洲猪瘟防控强化措施指引 当前，我国非洲猪瘟防控工作取得了积极成效，但病毒已在我国定殖并形成较大污染面，疫情发生风险依然较高，稍有松懈就可能反弹扩散，必须建立健全常态化防控措施。各地要切实增强打持久战的思想认识，深入贯彻预防为主方针，在落实好现行有效防控措施基础上，着力解决瞒报疫情、调运监管不力等突出问题，全面提高生猪全产业链风险闭环管理水平，重点强化十二项工作措施。 一、组织开展重点区域和场点入场采样检测。农业农村部制定科学的入场检测技术规范和标准，组织对生猪调出大县、规模猪场和其他高风险区域进行入场采样检测。落实到人到场监督责任制，做好入场抽样检测。对年出栏2000头以上的规模猪场开展一次全覆盖检测，对年出栏500—2000头的规模猪场随机抽样检测。 二、建立疫情分片包村包场排查工作机制。县级畜牧兽医主管部门组织对非洲猪瘟疫情实施包村包场监测排查，确保不漏一场一户。逐村逐场明确排查责任人，建立排查对象清单和工作任务台账，发现异常情况即时上报。养殖场户要明确排查报告员，每天向包村包场责任人报告生猪存栏、发病、死亡及检出阳性等情况。对不按要求报告或弄虚作假的，列为重点监控场户，其生猪出栏报检时要求加附第三方出具的非洲猪瘟检测报告。农业农村部和省级、地市畜牧兽医主管部门成立相应专班，负责统筹协调疫情排查报告。各省级农业农村部门抓紧组织实施本省份动物防疫专员特聘计划，力争8月底前在全国498个生猪调出大县先配齐1万人的队伍，努力做到一个乡镇特聘一名动物防疫专员。 三、完善疫情报告奖惩机制。基层相关单位和工作人员及时报告、果断处置疫情是成绩，不得追责，绩效考核还应当加分。要推广一些地方县级人民政府进行及时奖励的好做法，对疫情报告、处置工作表现突出的给予表彰。明确瞒报、谎报、迟报、阻碍他人报告等情形认定标准，对生产经营主体瞒报的，依法从严追究法律责任;对各级政府和部门瞒报或阻碍他人报告的，从严追责;造成疫情扩散蔓延的，从重处罚并予以通报。 四、规范自检阳性处置。养殖场户自检发现阳性的，必须按规定及时报告。经复核确认为阳性且生猪无异常死亡的，按阳性场点处置，不按疫情对待，可精准扑杀、定点清除，只扑杀阳性猪及其同群猪，其余猪群隔离观察无异常且检测阴性后，可正常饲养。及时报告检测阳性的，扑杀生猪给予补助;不及时报告的，不予补助，并严肃追究法律责任。 五、健全疫情有奖举报制度。各级畜牧兽医主管部门要建立完善非洲猪瘟疫情有奖举报制度，及时核查举报线索，查实的及时兑现奖励。省级畜牧兽医主管部门要定期对有奖举报制度落实情况进行督查，有关情况按月报中国动物疫病预防控制中心。 六、建立黑名单制度。将瞒报、谎报、迟报疫情和检测阳性信息，以及售卖屠宰病死猪、违规调运生猪、逃避检疫监管的生产经营主体纳入黑名单，实施重点监管。特别是对恶意抛售染疫生猪的，一律顶格处罚，坚决追究有关主体的责任并通报。 七、加强养殖场户风险警示。建立养殖场户风险预警机制，根据疫情形势、生产安排、市场变化等因素，广泛运用讲座、视频、短信、微信、挂图等多种形式，加强生产和疫情风险警示。特别要提醒养殖场户不要引进价格异常便宜的生猪，不要采购没有动物检疫证明、
非洲猪瘟疫情应急预案 1 总则 非洲猪瘟是由非洲猪瘟病毒引起的猪的一种急性、热性、高度接触性动物传染病。世界动物卫生组织（OIE）将其列为法定报告动物疫病，我国将其列为一类动物疫病，是我国重点防范的外来动物疫病之一。 1.1 编制目的 及时扑灭突发非洲猪瘟疫情，保障生猪养殖业健康发展。 1.2 编制依据 依据《中华人民共和国动物防疫法》《中华人民共和国进出境动植物检疫法》《重大动物疫情应急条例》《国家突发重大动物疫情应急预案》和《国家中长期动物疫病防治规划（2012—2020年）》，制定本预案。 1.3 工作原则 按照属地管理的原则，实行政府统一领导、部门分工负责，切实落实防控工作责任制，联防联控，形成防控合力。 坚持预防为主，贯彻“加强领导、密切配合、依靠科学、依法防治、群防群控、果断处置”的防控方针。按照“早、快、严、小”的要求，及早发现，快速反应，严格处理，减少损失。 1.4 适用范围 本预案适用于我国突发非洲猪瘟疫情的应急处置工作。 2 组织管理 2.1 应急指挥机构 农业部在国务院统一领导下，负责组织、协调全国非洲猪瘟疫情应急管理工作，并根据突发疫情应急处置工作的需要，向国务院提出启动国务院重大动物疫情应急指挥部应急响应建议。 地方各级人民政府兽医主管部门在本级人民政府统一领导下，负责组织、协调本行政区域内非洲猪瘟疫情应急管理工作，并根据突发疫情应急处置需要，向本级人民政府提出启动地方重大动物疫情应急指挥部应急响应建议。 各级人民政府应急指挥部应明确组成部门，各有关部门要加强协调配合，建立健全多部门共同参与的联防联控协作机制。 2.2 职责分工 农业部负责组织实施突发非洲猪瘟疫情应急管理工作，并进行检查、督导；及时发布突发非洲猪瘟疫情信息，并向有关国际组织、国家和地区通报疫情；紧急组织调拨消毒药品等应急防疫物资；提出启动、停止疫情应急控制措施建议；组织对扑杀及补偿等费用和疫情损失的评估。各地兽医部门要积极配合出入境检
防非生物安全考试试题（不定项选择+问答题）ASF 相关： 1、下列哪些能感染非洲猪瘟（ AB ） A 野猪 B 家猪 C 人 D 牛 2、下列哪些可能成为传播非洲猪瘟的媒介（ ABCD ） A 人 B 物品 C 车辆 D 空气 3、非洲猪瘟病毒可通过以下哪些途径间接传播？（ ABCD ） A 饲喂污染的泔水 B 污染的饲料、垫草 C 污染的车辆 D 污染的衣物和设备 4、非洲猪瘟病毒自然感染的潜伏期一般为多少天？（C） 4~7 B、4~10 天C、4~19 天 5、关于非洲猪瘟存活时间，下列哪一项是正确的（ ABCD） A、冰冻肉中可存活数年；半熟肉以及泔水可长时间存活； B、腌制火腿中可存活数月； C、未经烧煮或高温烟熏的火腿和香肠中能存活 3~6个月； D、4C保存的带骨肉中至少存活5个月。 6、目前防控非洲猪瘟主要依赖（ C） A 疫苗 B 兽药 C 生物安全 D 无能无力。 7、急性性型非洲猪瘟会有以下哪些表现（ ABCD） A高热B食欲废绝C、皮肤发绀D网状内皮系统出血. 8、感染非洲猪瘟的急性病例死亡率可达多少（ D） A 30% B 50% C 80% D 100% 消毒类： 9、当前本场用于车辆喷雾消毒和衣物浸泡消毒的消毒药是什么（A）
A、卫可 B、百胜-30 C戊二醛 D、烧碱 10、消毒药卫可常用的配比浓度为（ B ），雨天卫可配比浓度（ A）。 A、1:100 B、 1:200 C、 1:300 D、 1:400 11、中转站的车辆停靠，说法正确的是（ A）。 A、场内车停靠在靠近猪场一侧，外部拉猪车停靠远离猪场一侧 B、场内车停靠在远离猪场一侧，外部拉猪车停靠靠近猪场一侧 C场内车可以停靠在中转站的任一侧 D、外部拉猪车可以停靠在中转站的任一侧 12、员工场外穿衣服，若需要拿入生活区，则通过（ A）。 A、卫可1： 200浸泡消毒30分钟 B、卫可1： 200浸泡消毒30分钟或臭氧消毒60分钟 C、卫可1： 400浸泡消毒60分钟或臭氧消毒30分钟 D、卫可1： 400浸泡消毒60分钟或臭氧消毒60分钟 13、关于消毒药的使用，说法错误的是（ D）。 A、消毒药和石灰水需要现配现用 B、雨天，消毒液浓度加倍 C、消毒药避免在阳光下直射 D、车辆清洗完后最好立即用消毒药进行消毒 14、中转站的场内运猪车辆要坚持每用（ A ）消毒（）。 A、一次，一次 B、两次，一次 C 一周，一次 D、一月，一次 管理类： 15、任何人（A）从场外带入偶蹄动物类相关制品。 A、禁止 B、随时可以C经批准可以D、偶尔可以 16、下列哪些描述是符合防非生物安全要求的（ ABC）。 A、送菜车和猪精车禁止开进场区，只允许在大门口特定区域停留、卸货； B、内部转猪车司机禁止下车
建议严格的生物安全体系对于新建猪场，张桂红表示如果猪场能够做到分区饲养管理、批次化生产同时还建立隔离栏舍的话，将对非洲猪瘟的防控有很大的帮助。 有些猪场建立已久，要在这些方面做优化可能较为伤筋动骨，那么这些猪场又该如何在现有的基础上来防控非洲猪瘟呢? 在猪的方面，养猪人在引种时一定要注意隔离和检测，且平时要做好相关的排查工作，如果发现猪只出现体表发绀、耳朵或体表出现紫斑、毛孔出血、厌食、腹泻等症状时，要提高警惕，最好是采样送到相关的非洲猪瘟检测实验室进行检测。 对于当前的非洲猪瘟疫情猪场主要措施就是预防；非瘟清，主要用于防治猪的病毒性传染病（瘟疫病，如非洲猪瘟、蓝耳、圆环、流感等）用于非洲猪瘟、蓝耳、圆环、链球菌、流感、附红体、弓形体及混感等引起的猪发热性（瘟热性）疾病的治疗与预防。症见：高热神昏、精神萎顿、结膜潮红、充血；皮肤发红，体表出血、瘀血，四肢、下腹、会阴、臀部等部位尤其严重；咳嗽、喘气、呼吸困难；呕吐，食欲减退或废绝，粪便干硬、便秘或排脓性血便；母猪伴有不孕、流产、死胎。剖检病死猪可见脾脏、肝脏、肺脏等脏器和淋巴结严重肿大，并广泛性出血瘀血。本病急性发病时死亡率很高，尤其是母猪、大猪死亡更快。 预防拌料 预防量（2-3公斤非瘟清/吨料），每月使用7-14天；治疗量（4-5公斤非瘟清/吨料），连用7天； 常规投药，猪只免疫力、抵抗力强，可有效抵御野毒侵袭；抗应激能力强，消化功能好，生长速度快；疫苗免疫后抗体产生迅速而整齐；重大疫情时，不发病或发病少，病情轻，易于治疗。 对于当前的猪场流行疫病，本产品已经有很好反馈。多家猪场与公司的试验结果表明，用本产品进行预防性、保护性投药，体现出显著的“三减一降”效果，即：减缓发病、减轻病情、减少死亡；降低损失。“三减”给猪场留下了宝贵的时间，为实质性控制疾病与降低损失创造了条件。 “猪场要慎重剖检疑似猪只!”张桂红特别强调，剖检有可能会成为传染源，风险极大，所以她建议猪场不要轻易剖检疑似病猪。 至于人员方面，要注重员工和外来人员的隔离，规范人员进场的流程，同时要做好相关的科普宣传工作和加强对员工的培训。 相关文献显示，猪源产品、原粮存在一定携带非洲猪瘟病毒的风险，所以猪场做好饲料的运输安全管理非常重要，如果能在场内建设中转料塔可大大降低病毒进入生产区的风险。 虽然非洲猪瘟杀伤性十足，但张桂红表示，非洲猪瘟是可防、可控的，养猪人不必过度恐慌，但也不能心存侥幸;
非洲猪瘟疫情防控工作方案 篇一 11 月以来我省发现多处非洲猪瘟疫情，全省已进入非洲猪瘟防控应急状态防控形式愈发严重，为进一步做好我县非洲猪瘟疫情防控工作，根据《省住房和城乡建设厅关于进一步加强非洲猪瘟防控工作餐厨废弃物处置监管的紧急通知》要求，应全面禁止使用泔水喂猪，为扎实做好全县餐厨废弃物处置监管工作，结合城管工作职能，现制定应对非洲猪瘟疫情工作方案如下。 一、总体要求 猪肉是人民群众的生活必需品，食品安全事关人民群众的身体健康，来不得丝毫马虎。此次疫情来势凶猛、事态紧急，县城管系统必须迅速贯彻国家和省县的部署要求，紧扣“餐厨泔水” 这一关键环节和目标任务，采取切实有效措施，构建包含产生源头、全面收集、及时运输、规范处置、执法保障等各方面、全链条的工作体系，为全县疫情防控大局作出城管部门应有的贡献。 二、组织领导 县城管局建立疫情应对工作班子，局长王军同志任总指挥，副局长马永剑任副总指挥，机关各处室、各直属事业单位、负责人为成员，从即日起进入临战状态，切实抓好疫情防控各项工作。
三、工作措施 （一）专题研究部署。11 月26 日上午召开紧急会议，进行专题会商，制订工作方案；9 月27 日前后，召开县城管系统动员会，进行全面部署。 （二）开展调查摸底。11 月26 日开始，通过市场监管、工质局等系统，对县产生餐厨泔水的餐饮服务企业、食品加工企业和集体供餐单位进行登记造册，做到底数清、情况明，为下一步工作打好基础。 （三）全面宣传发动。统一印制面向餐厨泔水产生单位的告知书和相关法律法规的承诺书，要求其全面履行动物疫病防治法、环境污染防治法、城县市容和环境卫生管理条例等法律法规规定的义务，签订餐厨废弃物承诺书，要求餐厨泔水不得流向生猪饲养企业和农户，不得排入河道、污染水体，不得擅自排入下水道等，并告知相应的法律责任。按照属地管理的原则，由县城管局牵头，执法大队具体负责，逐一上门送达、告知。 （四）逐一签订承诺书。安排属地城管部门，协助处置企业，逐一签订餐厨废弃物承诺书，做好收集容器投放等工作，并及时报县城管局备案。
防非生物安全考试试题（不定项选择+问答题）ASF相关： 1、下列哪些能感染非洲猪瘟（AB） A野猪B家猪C人D牛 2、下列哪些可能成为传播非洲猪瘟的媒介（ABCD） A人B物品C车辆D空气 3、非洲猪瘟病毒可通过以下哪些途径间接传播？（ABCD） A饲喂污染的泔水 B污染的饲料、垫草 C污染的车辆 D污染的衣物和设备 4、非洲猪瘟病毒自然感染的潜伏期一般为多少天？(C) 4~7 B、4~10天C、4~19天 5、关于非洲猪瘟存活时间，下列哪一项是正确的（ABCD） A、冰冻肉中可存活数年；半熟肉以及泔水可长时间存活； B、腌制火腿中可存活数月； C、未经烧煮或高温烟熏的火腿和香肠中能存活3~6个月； D、4℃保存的带骨肉中至少存活5个月。 6、目前防控非洲猪瘟主要依赖（C） A疫苗B兽药C生物安全D无能无力。 7、急性性型非洲猪瘟会有以下哪些表现（ABCD） A高热B食欲废绝C、皮肤发绀D网状内皮系统出血. 8、感染非洲猪瘟的急性病例死亡率可达多少（D） A 30% B 50% C 80% D 100% 消毒类： 9、当前本场用于车辆喷雾消毒和衣物浸泡消毒的消毒药是什么（A）。
A、卫可 B、百胜-30 C、戊二醛 D、烧碱 10、消毒药卫可常用的配比浓度为（B ），雨天卫可配比浓度（A）。 A、1:100 B、1:200 C、1:300 D、1:400 11、中转站的车辆停靠，说法正确的是（A）。 A、场内车停靠在靠近猪场一侧，外部拉猪车停靠远离猪场一侧 B、场内车停靠在远离猪场一侧，外部拉猪车停靠靠近猪场一侧 C、场内车可以停靠在中转站的任一侧 D、外部拉猪车可以停靠在中转站的任一侧 12、员工场外穿衣服，若需要拿入生活区，则通过（A）。 A、卫可1：200 浸泡消毒30分钟 B、卫可1：200 浸泡消毒30分钟或臭氧消毒60分钟 C、卫可1：400 浸泡消毒60分钟或臭氧消毒30分钟 D、卫可1：400 浸泡消毒60分钟或臭氧消毒60分钟 13、关于消毒药的使用，说法错误的是（D）。 A、消毒药和石灰水需要现配现用 B、雨天，消毒液浓度加倍 C、消毒药避免在阳光下直射 D、车辆清洗完后最好立即用消毒药进行消毒 14、中转站的场内运猪车辆要坚持每用（A ）消毒（）。 A、一次，一次 B、两次，一次 C、一周，一次 D、一月，一次 管理类： 15、任何人（A）从场外带入偶蹄动物类相关制品。 A、禁止 B、随时可以 C、经批准可以 D、偶尔可以 16、下列哪些描述是符合防非生物安全要求的（ABC）。 A、送菜车和猪精车禁止开进场区，只允许在大门口特定区域停留、卸货； B、内部转猪车司机禁止下车
非洲猪瘟疫情应急实施方案 （年版） 为有效预防、控制和扑灭非洲猪瘟疫情，切实维护养猪业稳定健康发展，保障猪肉产品供给安全，根据《中华人民共和国动物防疫法》《中华人民共和国进出境动植物检疫法》《重大动物疫情应急条例》《国家突发重大动物疫情应急预案》等有关规定，制定本实施方案。 一、疫情报告与确认 任何单位和个人，一旦发现生猪、野猪异常死亡等情况，应立即向当地畜牧兽医主管部门、动物卫生监督机构或者动物疫病预防控制机构报告。县级以上动物疫病预防控制机构接到报告后，根据临床诊断和流行病学调査结果怀疑发生非洲猪瘟疫情的，应判定为可疑疫情，并及时采样送省级动物疫病预防控制机构进行检测。相关单位在开展疫情报告，送检、调查等工作时，要及时做好记录备查。 对首次发生疑似非洲猪瘟疫情的省份，省级动物疫病预防控制机构根据检測结果判定为疑似疫情后，应立即将样品送中国动物卫生与流行病学中心确诊，同时按要求将疑似疫情信息以快报形式报中国动物疫病预防控制中心。 对再次发生疑似非洲猪瘟疫情的省份，由省级动物疫病预防控制机构进行确诊，同时按要求将确诊疫情信息以快报形式报中国动物疫病预防控制中心，将病料样品送中国动物卫生与流行病学中心备份。
对由中国动物卫生与流行病学中心确诊的疫情，中国动物卫生与流行病学中心按规定同时将确诊结果通报样品来源省级动物疫病预防控制机构和中国动物疫病预防控制中心。中国动物疫病预防控制中心按程序将有关信息报农业农村部。农业农村部根据确诊结果和相关信息，认定并发布非洲猪瘟疫情。 在生猪运输过程中，动物卫生监督检查站查到的非洲猪瘟疫情，其疫情认定程序，由农业农村部另行规定。 各地海关、林业和草原部门发现可疑非洲猪瘟疫情的，要及时通报所在地省级畜牧兽医主管部门。所在地省级畜牧兽医主管部门按照上述要求及时组织开展样品送检、信息上报等工作，按职责分工，与海关、林业和草原部门共同做好疫情处置工作。农业农村部根据确诊结果，认定并发布疫情。 二、疫情响应 （一）疫情分级 根据疫情流行特点、危害程度和涉及范围，将非洲猪瘟疫情划分为四级：特别重大（级）、重大（级）、较大（级）和一般（级）。 ．特别重大（Ⅰ级）疫情 全国新发疫情持续增加、快速扩散，天内多数省份发生疫情，对生猪产业发展和经济社会运行构成严重威胁。 ．重大（Ⅱ级）疫情 天内，个以上省份发生疫情，疫区集中连片，且疫情有进一步扩散趋势。
非洲猪瘟的综合防控措施 发表时间：2019-09-12T11:19:28.720Z 来源：《基层建设》2019年第17期作者：郭金良 [导读] 摘要：非洲猪瘟能在短时间内快速传播，导致猪出现高热、器官出血和呼吸障碍等症，继而死亡，如果不能有效防控，将会给养殖户带来严重的经济损失及食品安全问题。 汶上县汶上街道办事处山东济宁 272500 摘要：非洲猪瘟能在短时间内快速传播，导致猪出现高热、器官出血和呼吸障碍等症，继而死亡，如果不能有效防控，将会给养殖户带来严重的经济损失及食品安全问题。目前，我国一些地区出现了数次非洲猪瘟，急需动物卫生研究人员提供有效的防控措施，在全国范围内推广。 关键词：非洲；猪瘟；综合防控 引言： 自2018年以来，我国境内多次出现了非洲猪瘟的疫情，不仅给养殖户造成了巨大的经济损失，还造成了一定的社会恐慌，严重威胁到了经济的发展和社会的稳定。因此非洲猪瘟引起了国家和地方政府的高度重视。如何做好非洲猪瘟的综合防控工作，已成为广大畜牧兽医工作者的首要任务。 1.流行特点 非洲猪瘟（ASF）的致病原是非洲猪瘟病毒（ASFV）。本病呈常年发病，发病无明显季节性，家猪和野猪均属于ASF高度易感对象，发病畜是主要传染源。传播途径广泛，可经直接接触传染，或经感染动物的排泄物、分泌物、污染物、带毒机体组织等间接性接触传播，各种寄生于动物体表的寄生虫（节肢动物，软蜱、蚊蝇等）也可携原散播疾病。由于ASFV在动物耐受值范围内环境条件下存活时间极长，猪场一旦感染发病将长期难以净化，发病场可呈周期性发病、反复发病。传播主要经上呼吸道侵入感染，近代兽医临床研究证明阳性猪分泌物、排泄物中含有大量高致病性ASFV，尤其是在口鼻分泌物中浓度更高。经临床观察发现，给猪喂泔水，或生物安全防范及保洁消毒不到位，中间传播媒介控制不严（节肢动物、蚊蝇、鼠类等）的猪场发病风险最高。 2.非洲猪瘟的严重性 2.1病原体对环境的抗性非常强 非洲猪瘟的病原体属于非洲猪瘟病毒科，是一种传染性非常强的病毒。这种病毒的诱惑性非常强。一旦有细胞被感染，被感染的细胞内会出现至少100种以上的病毒去诱导蛋白，致使蛋白发生异变。而且这种病原体还具有吸附猪红细胞的特性，致病毒性非常强，其严重性在目前尚未出现中和抗体。不管是被自然感染还是人工接种都不会出现抗体。而且这种病原体对外界环境的抗性非常强。即使是被冰封多年依然可以保持病原体的活性。这种病原体对干燥的环境或酸性物质都有一定抵抗力，但比较害怕高温，要想杀死这种病原体可以在60°C 的高温下进行30min的杀菌即可将其杀死。 2.2传染性非常强 非洲猪瘟的传染性非常强。虽然非洲猪瘟仅发生于猪和野猪。但患有非洲猪瘟的猪和野猪体液、各种组织器官、分泌物及排泄物里都含有这种病毒。这些病毒可以通过寄生虫传播，且传染性非常强。因为非洲猪瘟可以在猪和寄生虫之间传播，导致这种疾病很难被根除。因为非洲猪瘟还有一定的潜伏期，如果患有非洲猪瘟的猪没有被发现患病，和病猪接触过的猪群都会感染这种疾病，因为这种疾病的传染性非常强。一旦被感染，患有非洲猪瘟的猪群发病率和死亡率都非常高。 2.3疾病特点 非洲猪瘟有急性发病和潜伏期发病。患有急性非洲猪瘟的猪群会在患病后迅速死亡，甚至都不会表现出明显的临床特点。患有急性非洲猪瘟的病猪在患病后没有食欲，先是体温非常高，然后体温开始下降，持续一段时间会有昏迷症状。昏迷一段时间后，病猪心率增加，呼吸急促，体表出血，最终死亡，患有急性非洲猪瘟的病猪死亡率非常高。拥有潜伏期的病猪在患有非洲猪瘟之后会慢慢出现临床症状，患有慢性非洲猪瘟的病猪传染性非常强。因为这些病猪在出现临床反应前会通过一些接触使其他猪群感染这种疾病。 3.综合防控措施 我国是全世界最大的猪肉生产和消费国，做好非洲猪瘟防控工作意义极为重大，只有进一步强化非洲猪瘟防控措施的落实，才能有效防止疫情的扩散和蔓延，才能实现对非洲猪瘟的彻底根除。特别是在2018年诸多地区先后暴发疫情的情况下，各地一定要按照《中华人民共和国动物防疫法》和《非洲猪瘟疫情应急预案》的要求，来对疫情进行实时监测，如发现不明原因生猪死亡、野猪异常死亡等情况，应立即向上级部门报告，对确认疫情的地区进行第一时间的封锁，禁止所有生猪及易感动物和产品运入或流出封锁区。在封锁区范围的把控上，基层畜牧兽医站要积极配合农业农村部及相关部门的工作，在疫点周围3km范围内扑杀所有生猪，并做好无害化的处理；在疫区外围设立检验检疫站和消毒站，控制动物运输车辆的移运，对出入的人员和车辆进行消毒；在疫区、受威胁区及周边地区开展疫情筛查、防控措施准备和知识的普及工作，同时要注意对野猪和蜱的监控，最大限度地阻滞疫情传播。具体要做好如下工作： 3.1严格控制他国产品入境 目前已查明，导致非洲猪瘟传入我国的主要原因之一就是生猪及相关产品的跨区域调运。因此，在研究有效防控非洲猪瘟技术手段的同时，相关部门必须加大对入境产品及生猪的检验检疫力度，从根源上切断病原，防治病菌侵入。 3.2严格落实生猪免疫 在一些较为偏远的地区，生猪养殖户的免疫意识不强，甚至为了节省资金故意避开免疫，最终导致疾病肆虐，造成巨额经济损失，也容易在当地引起社会恐慌。尽管目前对非洲猪瘟还未研究出有效的防治疫苗，但定期接种常规疫苗，对提升猪群免疫力，降低染病率也能起到有效作用。动物卫生部门要严格落实免疫制度，深入基层，确保所有养殖户都定期为猪群接种疫苗，落实奖惩。派遣专员到基层地区进行走访调查，了解免疫落实情况，抽样检测，向养殖户普及基本的养殖和疾病防控常识[1]。 3.3宣传科学养殖知识 为了提高基层养殖户的科学化养殖水平，起到对非洲猪瘟的防控作用，基于当前许多养殖户盲目养殖，一味关注成本的错误化养殖方法，应加强对养殖技术和常识的推广。高温和消毒剂能有效杀灭非洲猪瘟病毒，因此，应定期对猪舍内外进行消毒，及时清理粪便和剩余的饲料，不给病菌提供繁殖和生存空间。此外，出入养殖场内的人员和车辆也要严格控制和检查，做到出入消毒。不用来路不明的泔水、
黑人原本生活在非洲,他们是怎样到达美洲大陆的?其中可有一段悲惨的历史,悲惨的历史是什么? 哥伦布发现了美洲，后来，英法先后在北美建立殖民地，西班牙葡萄牙在南美建立殖民地。注意，这4个国家都是小国，没多少人口。他们在欧洲本土还有很多矛盾，所以，殖民地的人口并不多。因此，不论是挖矿，建立大型种植园都需要大量奴隶，努力从哪来？非洲！！！殖民地的人需要奴隶，欧洲人就有专卖奴隶的，他们坐船从欧洲向南到非洲抓黑人，再向西到美洲把黑人买了，再向东回欧洲，然后向南到非洲抓黑人，再向西到美洲把黑人买了，再向东回欧洲这样不断的贸易，因为这条路是三角形，又被称为罪恶的三角贸易。 说悲惨是因为黑人的地位是奴隶数以千万计的非洲黑人背井离乡，漂洋过海，被贩卖到美洲以及印度洋、亚洲由殖民者开办的种植园和矿井中工作，另一些黑人在捕奴、掠奴战争及贩运途中死去。非洲人民及其社会经济生活受到空前浩劫。生产力遭到严重破坏。而万恶的殖民主义、资本主义制度却随着贩卖和奴役非洲黑人而兴盛起来。黑奴贸易大约经历了四个世纪。除奥地利、波兰和俄国等少数国家外， 几乎所有的欧洲国家以及美国都先后参与了这一罪恶活动第一，对非洲社会生产力起了极大的破坏作用。损失了大量人口，黑奴贸易大量毁灭了生产力的首要因素——劳动者本身，并在非洲内部造成连续不断的政治纷争和军事动乱，致使社会动荡，农村凋蔽，田园荒芜，直接破坏了农业生产。 第二，在一定程度上造成了非洲长期落后，受压迫的窘境。 第三，种族歧视是黑奴贸易带来的直接恶果。在古代和中世纪，世界上并不存在种族优劣论。种族歧视是奴隶贸易时代最丑恶的遗产 新航路开辟后，欧洲开始了殖民掠夺，开始了资本的原始积累，黑奴贸易是其主要手段之一，欧洲殖民者占领美洲并，大量屠杀印地安人，为了增加劳动力从非洲贩卖黑人到美洲充当劳动力，这样原本生活在非洲的黑人就到了美洲，悲惨的论成为奴隶。 美国黑人共一千九百余万人，约占美国人口的百分之十一。他们在社会中处于被奴役、被压迫和被歧视的地位。绝大部分黑人被剥夺了选举权。他们一般只能从事最笨重和最受轻视的劳动。他们的平均工资只及白人的三分之一到二分之一。他们的失业率最高。他们在许多州不能同白人同校读书，同桌吃饭，同乘公共汽车或者火车旅行。美国各级政府、三K党和其他种族主义者经常任意逮捕、拷打和残杀黑人。在美国南部的十一个州，集居著美国黑人的百分之五十左右。在那里，美国黑人所受到的歧视和迫害，是特别骇人听闻的。 美国黑人正在觉醒，他们的反抗日益强烈。近几年来，美国黑人反对种族歧视、争取自由和平等权利的群众性斗争，有日益发展的趋势。 一九五七年，阿肯色州小石城的黑人，为了反对当地公立学校不准黑人入学，展开了剧烈的斗争。当局使用了武装力量来对付他们，造成了震动世界的小石城事件。 一九六零年，二十多个州的黑人举行了静坐示威，抗议当地餐馆、商店和其他公共场所实行种族隔离。
非洲猪瘟疫情防控工作应急预案 为及时有效预防、控制和扑灭非洲猪瘟疫情，保障全区经济持续稳定发展,保障人民群众身体健康，维护社会稳定，依据《中华人民共和国动物防疫法》、《中华人民共和国传染病防治法》、《江苏省动物防疫条例》等法律法规，以及省、市、区当前应急管理工作相关要求，特制定预案如下。 一、应急指挥系统 （一）区政府负责统一领导全区非洲猪瘟疫情防治工作，决策有关疫情的重大事项。区非洲猪瘟疫情防控应急指挥部（以下简称区指挥部）负责具体指挥全区疫情防控工作，区指挥部办公室设在区商务局,负责疫情防控日常工作。 1、区指挥部职责 指挥协调全区非洲猪瘟疫情防控应急管理等工作；拟定非洲猪瘟疫情有关政策；审定各项工作预案,分析研判疫情,提出紧急应对措施,研究并进行重大工作布署；组织实施、指挥扑灭本区发生的疫情；监督管理全区疫情防控工作。 2、区指挥部办公室职责 收集疫情和分析预测发展态势；及时调配疫情处理和损失补助的资金和物资；组织协调并监督各街道、各有关部门落实本预案；解决防控工作中遇到的实际问题,对各部门、街道的防控工作进行指导、检查和督促；提出启动、停止(解除)相应等级的疫情控制应急措施建议。
3、部门职责 （1）区委宣传部 按照有关规定要求，负责做好非洲猪瘟疫情防控新闻宣传工作。 （2）区公安分局 协助做好疫点封锁、生猪产品无害化处理和生猪产品来源调查等工作，做好疫点社会治安管理，维护社会稳定。 （3）交警五大队、六大队 负责做好各生猪产品运输检查工作，优先安排紧急防疫物资的调运；协助做好疫点的封锁工作和病害生猪产品无害化处理的运输等工作。 （4）区教育局 负责在校学生防控非洲猪瘟疫情知识的科普宣传教育工作。对全区中小学食堂的生猪产品进行来源检查，防止疫点生猪产品进入校园，加强学校食堂的餐厨垃圾管理。 （5）区民政局 制订并实施疫点救灾救济工作方案，组织协调救灾工作，指导疫点、灾区重建和生产自救，管理和分配救灾款物并监督检查使用情况。 （6）区财政局 负责筹集、划拨紧急防疫储备金，并做好应急工作经费的管理和监督。 （7）区环保局