| Popis: |
Nematodes are invertebrate roundworms that inhabit most environments on earth. They comprise one of the largest and most diverse groups of multicultural organisms in existence. Plant parasitic nematodes spend at least some part of their lives in soil, one of the most complex environments. Their activities are not only influenced by variation in soil physical factors such as temperature, moisture and aeration but also by a vast array of living organisms, including other nematodes, bacteria, fungi, algae, protozoon’s, insects, mites and other soil animals. The biological component of the soil ecosystem is particularly important in limiting and more or less stabilizing nematode populations. For biological control to be successful, it must be supported by a backbone of basic ecological research. Nematophagous fungi can be fungal egg-parasites, nematode-trapping fungi that capture nematodes using modified hyphal traps, or endoparasitic that parasitizes the nematode by means of small conidia or zoospores. The history of attempts to use predaceous fungi to control plant- parasitic nematodes had been the subject of several reviews. Most research on microbial agents that attack nematodes in soil has concerned fungi, especially those that form traps to ensnare their prey. There are many attempts to production and formulation of the nematophagous fungi to plant nematodes. Many factors affecting for nematophagous fungi enhancement as Indigenous Nematophagous Fungi Present in the Soil, Time after Nematicide Application and Ecological Habitat. Duration of Cover Crop for Enhancing Nematophagous Fungi in Field Conditions. Biological control agents are generally produced in commercial quantities by one of two fermentation methods. The oldest and perhaps the simplest is solid substrate fermentation, which involves growing the microorganism on the surface of a substrate (e.g. bran) that has been impregnated with nutrients. However, for most other applications, it has been largely superseded by submerged culture fermentation, in which micro-organisms are grown in a liquid medium. A number of types of formulation, including dusts, granules, wet table powders and liquids have been used in biological crop protection products, but granular formulations are generally considered to be most suitable for micro-organisms that are to be applied to soil. The dry nature of these formulations means that an antagonist of nematodes needs to have the capacity to survive desiccation, if it is to be seriously considered for commercial development as a biological control agent. Granular biological products have traditionally been produced by blending the organism with a carrier such as clay or ground corn cobs and alien introducing a material to bind the organism to the carrier, but in recent years there has been considerable interest in encapsulating biological control agents in gallants such as sodium alginate. Formulation of microbial products in forms which have extended shelflives and which can be applied to soil using conventional farm equipment is likely to present a major challenge to those interested in commercializing antagonists of nematodes. Organisms which cannot be dried without loss of viability are likely to be difficult to formulate and are unlikely to retain their activity in storage for more than a few months unless expensive storage conditions are employed. |
