Mushrooms, illnesses a plant and stability to illnesses. Protection of plants against illnesses

you are: Mushrooms, illnesses a plant and stability to illnesses

Successful conducting agriculture assumes decrease in losses from illnesses of plants or the prevention of these illnesses. As well as in fauna, here there are two approaches: preventive and medical. Preventive actions there where they are possible, manage more cheaply and give usually the best effect. various agrotechnical receptions also can help to warn illness; the effect is obvious, for example, from destruction of any infected material or from alternation of various cultures in space and in time to limit a survival and distribution patogena in crops. Activators of some illnesses extend by means of other organisms (them name carriers or vectors); in these cases it is desirable to combat carriers also.

Fungitsidy. These preparations at their use or create a sheeting on a surface of plants, or get in a plant and have on its system an effect. The mushrooms developing on plants outside, like activators of false mealy dew, are sensitive to fungitsidam the first group and consequently to influence them slightly easier, than on the mushrooms growing in a vegetative fabric. biologically mushrooms are more removed from the person, than insects so fungitsidnye substances usually are not so poisonous for it as insektitsidy, but care in their application nevertheless should be observed. All fungitsidy can be subdivided into three main classes. The first class includes for a long time the known inorganic connections appreciably superseded now by other preparations, but still used. Ground sulphur concerns them - very much an effective remedy against some mushrooms developing on a surface of plants, for example. It is widely applied till now as well bordoskaja a liquid - a mix gidrookisi calcium and copper kuporosa. At mixing these two connections enter reaction in which result copper - the active component of a mix - appears in more ' accessible ' a condition; in this condition it suppresses mushroom growth, but does not operate on a plant. The Bordosky liquid has been applied to prevent for the first time grapes plunder; however it was thus found out that it well protects grapes from mildju, and since then it use in quality fungitsida. The second class fungitsidov are the organic connections operating on a surface of plants, but more effective, rather than inorganic fungitsidy. The major, most versatile and widely used group is made among them by the organic connections containing sulphur. It is very effective, in particular, kaptan, widely applied for protravlivanija seeds on purpose to protect shoots from the illnesses transferred through seeds.

In the field of protection of plants it is necessary to consider as the Most essential achievement occurrence of the third type of protective substances - fungitsidov or insektitsidov system action. These substances get into a plant and then are transported on ksileme or floeme, therefore they quickly liquidate a mushroom infection or invaziju insects-wreckers in the most different vegetative fabrics. Protective substances of system action should possess such chemical structure which would allow them to get into a plant and to move on spending fabrics together with transpiratsionnym a current or with a current of nutrients; these two requirements assume zhiro-solubility and water solubility. Besides, substances of system action should keep relative stability in a plant, otherwise they cannot provide reliable protection.

To the best new system fungitsidam belongs benomil, possessing a wide spectrum fungitoksicheskogo actions. To put it it is the most convenient on leaves; introduction in soil provides, the truth, long receipt fungitsida through roots, but the preparation expense thus strongly increases; injections in a tree trunk give some effect at the Dutch illness of an elm, but in such a way it is not possible to reach full treatment. Benomil it is transported on ksileme, therefore from the sprayed old leaves in the young its only small quantities arrive. It, of course, some lack given fungitsida as the new gain is required to be sprayed anew. However it means also that fungitsid does not get to fruits so from the trees processed before infructescence, it is possible to collect fruits without any fear. mechanism of action benomila is connected with formation infringement mitoticheskogo spindles, i.e. This fungitsid suppresses cellular division of a mushroom. As a whole benomil could be considered almost ideal fungitsidom, if not a problem of occurrence of stability at pathogenic mushrooms. At that stage of a cellular cycle on which this operates fungitsid, one gene mutation has enough to inform an organism stability. Such cases are known, and their number gradually grows. It is necessary to think therefore that benomilu it is not for long fated to play an appreciable role in practical protection of plants and that the further continuous work on creation of new connections of this kind is required.

Bacteria and viruses. Some illnesses of plants are caused by bacteria and viruses. Protection of plants against bacterial illnesses is completely similar to their protection against pathogenic mushrooms; stability of plants to viruses (not being cellular organisms) depends on ability of a vegetative cage to prevent virus to take advantage of the cellular device of synthesis of nucleinic acids. In agriculture protection against virus illnesses is reached partially by means of isolation of plants from a source of an infection and partially by means of struggle against insects-carriers of viruses (by spraying insektitsidami).

In gardening for disposal of virus infections there are two ways. The first of them-\is thermal processing of vegetative fabrics. The plants which are in a condition of active growth, maintain for a long time at 35 °s, and fabrics at rest warm up during 30 mines at 55°С; such way possible to reach destructions of a virus without appreciable damage of the most vegetative fabric (though a safety limit thus easily enough to cross). More safe way consists in use meristematicheskih cultures (see gl. 14), but this way is suitable only for separate kinds of plants. At some plants, for example at the chrysanthemums, the separated ends of runaways quickly grow in culture. Virus reproduction lags behind thus growth of a vegetative fabric owing to what the runaway top appears through any time free from a virus; this top separate and grow up from it the whole plant which has been not infected with a virus.

The Chemotherapy of virus illnesses of plants does for the present only the first steps though and in this area one obvious success is noted already. It is a question of a virus of the western jaundice of salad-latuka. Leaves of the plants infected with this virus, turn yellow and fall down; illness can destroy all crop. However if to bring in soil a preparation of system action karbendazim it will be absorbed by roots that will prevent destruction of a chlorophyll caused by a virus. Thus, though in cages the virus also will remain, leaves of salad-latuka will look like absolutely healthy, i.e. Will keep the commodity qualities.

In the future we, probably, will learn in the same way to combat and with other viruses. Parasitic higher plants. To parasites from among the higher plants of great value usually do not give, however at strong defeat they can take from vascular system of a plant-owner such quantity of water and nutrients that their lack becomes already rather notable. Omela (Phoradendron ftavescens), used for a traditional ornament of the house for Christmas, is a dangerous parasite of an oak and the coniferous breeds, capable it is essential to slow down growth of these trees. The dodder (Cuscuta gronovii), a twisted plant-parasite, too can do considerable harm, especially in areas with warmer climate (fig. 15.11).

Two parasites from this group amaze roots of plants: striga (Striga) meets on subtropical cereals, such as the corn and sorgo, and zaraziha (Orobanche) parasitizes on many kinds of plants, including on bean cultures, tomatoes and tobacco. In some areas of globe striga makes a serious problem in agriculture. Corn poor harvests in the North Africa, attributed usually poverty of local soils, actually often speak that corn crops are infected strigoj. In the USA, especially in an average part of the Atlantic coast, the cargoes intended for sea transportations, often are late quarantine inspection of that grain contains an impurity of seeds of this root parasite. Striga - an incomplete parasite; it has small green leaves (usually they are visible at the basis of the infected plant of corn). Therefore striga can carry out in some measure photosynthesis, but nevertheless it very strongly exhausts the plant-owner. Struggle with strigoj by means of herbicides has not given while results. The main link of life cycle cut, on which it is necessary to direct blow, it is possible to consider germination of seeds. Simeon cut long time remain in soil at rest and sprout only under stimulating influence of some connections developed by roots of plants-owners. Recently it was possible to find out chemical structure of these stimulators of germination. The active substance, strigol, has appeared somewhat similar with gibberellinami. It is possible, obviously, to synthesise this substance and to try to struggle with strigoj, bringing it in soil to cause germination of seeds cut when corn plants in the field are not present; young sprouts of a parasite cannot survive without additional pitany which they receive from a plant-owner, and will be, possibly, are doomed to  destruction. To process soil such stimulators of germination, to destroy in it seeds cut, it is necessary, apparently, within several years on end because it is improbable that all seeds of this parasite sprouted simultaneously.