This disease is found in any region, but it is most widespread in the foothills of the North Caucasus, in the territories of western Ukraine, in Belarus, the Baltic states. This problem is also encountered in the regions of the Russian non-black earth zone, in the western regions of Siberia. And if there are heavy rains on the days when the grains are poured, get ready to fight this problem. This review will focus on the wheat disease called septoria, the causes and methods of dealing with this disease.
The Septoria fungus is considered a painful pathogen. It most often affects tomatoes, cereals, millet, vineyards, gooseberries, currant bushes, soy and hemp plants. Mainly the disease spreads over the remains of vegetation through the swelling of pycnidia on rainy days.
Stains of a rusty or brown hue, irregular in shape, are considered signs of the disease. They are surrounded by a yellow border. In the central parts of the spots, black dots, called pycnidia, can be observed. It is with them that the fungus multiplies.
After a certain time, the spot covers the entire sheet. With the full development of the disease, shoots are affected, foliage begins to dry out, stems wrinkle and become brown. Foliage often falls off prematurely.
Favorable conditions for the development of the fungus are considered high humidity and a temperature regime of twenty - twenty-five degrees Celsius.
The fight against wheat disease should be carried out in a comprehensive manner, taking into account the phytosanitary conditions of crops. They use not only agrotechnical measures, but also chemical treatments:
The main source of the disease is affected seeds and soil composition. Painful pathogens can persist for a long period in the ground and on the remains of vegetation. If the plant has sufficient immunity, then the disease will not manifest.
The disease can develop under unfavorable climatic conditions, on weakened plants damaged by insects.
Fusarium pathogen has a high level of resistance to weather conditions, which helps him to remain viable for a long time. It is most active if the temperature regime is twenty-five degrees Celsius, and the humidity level reaches ninety percent.
This disease can reduce yields and deteriorate the quality of the grains.
The main signs of this disease are:
Grains that appear healthy in appearance may contain microtoxins and fungal spores.
Plants affected by fusarium bloom poorly, turn yellow, lose leaves. The root system develops poorly; darkish vessels are distinguishable on the cut of the stem.
These include the following:
The yield is reduced by fifteen to twenty percent. Grain quality can be lost in full.
Today, advanced methods have been developed to combat this problem, in which fungicidal preparations are used. With their help, the disease is destroyed, and the quality of grain crops remains at the same level.
To minimize problems with septoria, do not take the plant out into the open air in rainy weather. It is necessary to control the level of moisture content in the room. It is recommended to ventilate the room, introduce nitrogen-containing preparations into the soil, and create sufficient illumination. Sowing crops are treated with special preparations.
For preventive purposes, it is recommended to use solutions based on Glyocladin, Trichodermin or Rovral.
If the plants get sick with fusarium, then it is necessary to remove and burn the affected parts, disinfect the soil. In case of massive lesions, it is recommended to change the sites for planting, use chemicals. Their effectiveness fully depends on the timely application. The speed and timeliness of ear processing will have a proper impact on the final performance.
Diseases of cereals are very serious and can lead to a loss in the quantity and quality of crops. Their timely identification and taking appropriate measures can save the situation.
Under the conditions of widespread introduction of methods of the minimum tillage system, as well as oversaturation of crop rotations with susceptible wheat varieties, an increase in wheat infestation with the yellow spot Pyrenophoratritici-repentis (Died) is observed. Drechs.) In 2012, it was found on 638.5 thousand hectares, or 53% of the surveyed area, which is 10 times higher than in 2005, in 2013 as of May 10 (http: // rsc26 .ru), the infected area reached 991.2 thousand hectares (59%) in 2014 - 936.7 thousand hectares or 60% of the surveyed area.
The fungus that causes yellow spot of wheat leaves is Pyrenophoratritici-repentis (Died). Drechs. The word "pyrenophora" means a core, bone or seed. The fungus was originally isolated from Agropyron repens in the 1850s and described as Pleosporatrichostoma Didike in 1902. Later he renamed it Pleosporatritici-repentis. The name Pyrenophoratritici-repentis was first used by Drechsler (1923) to describe the causative agent of yellow leaf spot on wheat .
Systematic position: kingdom Fungi, division Ascomycota, class Ascomycetes, subclass Dothideomycetidae, order Pleosporales, family Pleosporaceae .
Yellow spot or pyrenophorosis affects leaves, stems and caryopsis of wheat. The first symptoms of the disease appear on wheat crops in the tillering phase - the beginning of tube emergence (29–31 according to Tsadox) . The disease manifests itself on both sides of the leaves and leaf sheaths of winter wheat and other cereals in the form of small single or numerous spots of an oval or round shape, yellow or light brown in color with a diameter of 2 to 5 mm. In the center of the spot, the epidermis is slightly raised. Sometimes a brown necrotic spot 1-2 mm in diameter forms in the center of the affected area. Over time, the spots grow in the longitudinal direction from 12 to 20 mm in length, sometimes take a diamond-shaped or lenticular shape, acquire a dark brown color. Usually spots are bordered by a zone of chlorosis.
Affected leaves die off as the affected area increases, starting from the top. Towards the end of the growing season, on highly overgrown spots and sometimes after the leaf has completely dried out, an olive-brown bloom of conidial sporulation appears. On the leaves of plants resistant to disease, the spots grow slightly or remain unchanged, especially on the flag leaf.
The fungus can infect the ear, which leads to discoloration of the scales and grains. On the spikelets, the spots are not growing, elongated or in the form of stripes 2-4 x 1-2 mm. The seed coat becomes reddish, the grains are covered with dirty-red spots - outwardly resembles the defeat of Fusarium [10 29].
On the stems of wheat, gray-brown and dark-brown stripes, spots (10x4 mm) with a chlorotic zone are formed .
The causative agent of pyrenophorosis is capable of producing strong toxins: emodin, catenarin, icelandicin , which cause chloroticity of leaves (similar chloroticity is observed with a lack or excess of nitrogen fertilizers) . The toxins determine the specificity of the interaction between the phytopathogen and the host plant. The PtrToxA toxin induces the formation of necrosis, PtrToxB - chlorosis due to inhibition of photosynthesis, and PtrToxC - causes the formation of chlorosis, but unlike PtrToxB on other wheat varieties. The strain of the fungus can have one, two or three toxins, on which the system of race differentiation is based.
Four pathotypes of the fungus have been identified based on the formation of chlorotic and necrotic spots on wheat varieties. The first pathotype forms both necrotic and chlorotic spots, the second only necrosis, the third only chlorosis, and the fourth does not form either necrosis or chlorosis .
The frequency of occurrence of physiological races varies from year to year. L.A. Mikhailova, I.G. Ternyuk and N.V. Mironenko (2007) note that in 1990 most of the population was represented by race 1 (90%), 9% of isolated isolates belonged to race 2, race 4 was less than 1%. Race 3 was isolated in 1994 only from durum wheat with a frequency of about 3%. The Canadian population of the pathogen is less virulent than the populations of the European part of Russia, Kazakhstan and Finland. Researchers associate this fact with the age of the population: the younger the population, the more virulent it is in relation to the host plant . O.S. Afanasenko (2010) notes that microevolutionary changes in the populations of the pathogen of wheat yellow spot during the colonization of new territories occur in the direction of expanding genetic diversity and increasing virulence in comparison with populations inhabiting the developed territories.
The first reports of the spread of yellow spot of wheat leaves appeared in Australia and North America in the 1970s, and in Europe in the 1980s [21-27]. Today it is a serious wheat disease in many countries .
In Russia, yellow spot was first recorded in 1985 in the North Caucasus [4 12]. Since then, it has been met annually . According to L.N. Shulyakovskaya (2010), in 1991 the area infected with pyrenophorosis was 10% with poor development mainly in the northern and southern parts of Krasnodar Territory, since 1998 the disease was noted everywhere with the development of 3-15%, and in untreated fields - up to 30– 40%. In 2006-2008. in the North Caucasus region, there was a weak development of septoria, but a significant damage to wheat crops by pyrenophorosis [2, 17]. Its share in the pathocomplex in 2006 reached 71% . According to A.G. Zhukovsky et al. (2012), yellow leaf spot is more common in warmer and wetter regions of the North Caucasus.
The study of the structure of the pathogen population showed that the most virulent phenotypes of pyrenophorosis from the southern foothill zone, and the statistical analysis revealed a greater diversity in the phenotypic composition of the southern foothill and central zones . L.A. Mikhailova, I.G. Ternyuk, N.V. Mironenko (2010) found the pathogen of yellow spot in Dagestan, Western Siberia, Altai, as well as the North-West, where the development of the disease in 2007 on some varieties reached 70%. According to T.S. Markelova (2011), over the past 10 years, pyrenophorosis, which was previously not typical for this agroclimatic zone, appeared and significantly spread in the Volga region. Yellow spot is a widespread disease of winter and spring wheat in the southern, southeastern and northern regions of Kazakhstan; the disease was first noted in the southeastern part of Kazakhstan in 1996 with a very rainy and cool spring .
The disease progresses, its development often reaches the level of epiphytoties, which are repeated 3-4 times in 10 years. Pyrenophorosis is a very harmful disease of cereals. Harmfulness is expressed in premature drying of leaves, grain faintness, and a decrease in the length and graininess of the ear. Crop losses in epiphytotic years can be 15-30% . Under optimal conditions for the development of the causative agent of the disease (high relative humidity and elevated temperature), as well as if the peak of development of yellow spot coincides with the phase of grain filling - milky-wax ripeness, grain losses can be 50–65% , while deteriorating grain quality .
The phytosanitary state of winter wheat crops is associated with all factors that determine the formation of yield and ensure the preservation and increase of the natural and acquired immunity of plants (increased soil fertility, balanced mineral nutrition, the introduction of resistant varieties, etc.) . Thus, for the development of tactics of integrated control, a comprehensive biocenotic study of agrobiocenoses is necessary, since it is agrobiocenology, according to M.S. Gilyarova, “is the fundamental biological basis of many areas of modern agricultural science” , including plant protection.
The aim of the study is to develop methods for phytosanitary stabilization of winter wheat agrocenosis based on accurate diagnostics, analysis of population dynamics of the causative agent of pyrenophorosis, and scientifically substantiated use of plant protection products.
Material and research methods. The studies were carried out in 2013–2014. at the training and experimental station of the FSBEI HPE "Stavropol State Agrarian University" (zone of unstable moisture). The land use of the training and experimental station of the FSBEI HPE "Stavropol State Agrarian University" is located in the zone of chernozems of the forest-steppe and steppe regions (leached chernozem, deep micellar-carbonate, medium-thick, medium-humus, heavy-loamy). This is a zone of temperate continental climate.
The experimental design, in addition to the control, included two drugs based on different active ingredients: cyproconazole + epoxiconazole (160 + 240 g / l) and epoxiconazole + azoxystrobin (160 + 240 g / l).
The phytosanitary state of winter wheat was studied in accordance with the Guidelines for registration tests of fungicides in agriculture .
Research results and their discussion. At present, the system of integrated protection of grain crops against diseases of fungal etiology, including yellow spot of wheat leaves, includes the use of fungicides as a mandatory element. During the growing season, preparations of the triazole group are mainly used, which very effectively control types of rust and powdery mildew.The effect of triazoles on leaf spot pathogens is somewhat weaker. Triazoles are characterized by the presence of a protective, curative and eradication effect, which allows them to be used at any stage of the infectious process.
Strobilurins have a high level of natural activity against many pathogens, however, due to the lack of a curative effect of treatment when plants are infected, they are not effective enough. Combining them with azoles or morpholines, which have a curative effect, increases their effectiveness.
Epoxy-, tebuco- and cyproconazole preparations have the longest effect on leaf diseases .
As a result of counts before the start of treatment, the development of spotting reached the economic threshold of harmfulness, equal to 5–10% for a planned yield of more than 4 t / ha. Within 14 days after the treatment, periodic precipitation was observed, which favored sporulation and the spread of phytopathogens, thus, the fungicidal treatment was aimed primarily at curbing the development of the disease.
Studies have shown that 14 days after treatment, the maximum biological effectiveness against winter wheat septoria in terms of "prevalence" and "development of the disease" was noted for the drug based on cyproconazole and epoxiconazole (the drug consumption rate is 0.3 l / ha), respectively, 44.4% and 47.3% (Table 1).
Infestation of winter wheat in the flowering phase with septoria and pyrenophorosis according to the variants of the experiment,% (2013–2014)
Protecting crops from disease
The past seasons have clearly demonstrated the need for mandatory fungicidal treatments on grain crops. Those who traditionally ignored this element of protection have lost a lot - both in quantity and quality of the crop. What is the best way to apply fungicides?
The crop protection system includes three treatments. The first (phase of spring tillering of the crop) - fungicide Benorad, the second (phase of culture, coming out into the tube) - herbicide set Bomba Mix (Bomba + Ballerina) + fungicide Spirit + insecticide Break + liquid fertilizers Izagri Vita and Izagri Azot third (flag phase -leaf - beginning of heading) - fungicide Racurs + insecticide Borey.
In the early spring period of development of winter wheat, when the protective effect of the dressing agent has already ceased, root rot, especially Fusarium rot, again begins to pose a danger to the crop.
Benorad, whose systemic action is aimed specifically at combating fungi of the genus Fusorium, must be applied immediately after the plants leave wintering, in the early stages of culture development. This ensures maximum treatment efficiency against root and root rot. After spraying with Benorad, 0.6 kg / ha, there is a lower percentage of spread and development of the basal form of fusarium root rot under conditions of a high concentration of infection in the soil and on plant residues of the predecessor.
Further conditions of the spring growing season of wheat necessitate the prophylactic use of Spirit, 0.5 l / ha against a complex of leaf diseases. The fungicide is applied together with the herbicide.
20 days after treatment, the effectiveness of Spirit against powdery mildew will be 88%, against septoria - 66.7%.
In the flag-leaf phase - the beginning of wheat earing, the third fungicidal treatment with Rakurs at a maximum dosage of 0.4 l / ha will be required to protect plants from septoria and pyrenophorosis.
As a result, the system of protecting winter wheat with fungicides can provide an increase in yield of 5-6 c / ha and significantly improve the quality of grain.
Protection of cereals from leaf rust damage.
The biology of rust is such that it infects plants exclusively through the stomata. It takes some time for it to form a germ hypha from the spore, which sooner or later finds the stomata. And this is where you need to not waste time and apply the fungicide. A contact preparation is sufficient at this stage. If there is a protective fungicidal layer on the surface of the leaves, the mycelium will not be able to grow and will die. If this does not happen, the spore finds the stomata, and the mycelium begins to grow inside the plant tissue, penetrating with its haustoriums inside the cells. While the pathogen is inside, no symptoms of the disease are observed, this period is called latency. In rust, it lasts five to seven days, depending on the temperature. But now, to fight rust, systemic fungicides with a healing effect will be required, which kill the mycelium or prevent it from growing normally.
When pustules have formed on the leaves, there is no way to remove them, that is, the symptom will not disappear. But this does not mean that it is necessary to abandon the culture - by treating crops with fungicides, we disrupt the formation of new spores. This reduces the amount of inoculum.
Brown rust can develop both in a full cycle, with the participation of an intermediate host - a basil, and in an abbreviated form, moving to a fall crop of a spring crop, and later on to a winter one. Surface tillage or its absence with "zero" technology increases the amount of this overwintering infectious material in the form of teliospores. Previously, for example, straw affected by black linear and brown rust was not allowed to be used even on animal bedding.
In addition to the fact that rust in itself causes depletion of plants, a black ear begins on a weakened culture, saprophytic fungi settle. Timely application of a fungicide, such as Kolosal Pro, will save the crop. And even if you work it out with a delay, already according to the symptoms, the affected leaves will not die immediately, they will work for some time to fill the grain.
Unfortunately, farms often do not have enough time to cultivate the soil after harvesting the grain predecessor, so a volunteer remains on some of the fields in winter, and it is an excellent reserve for all kinds of infection. This is especially true for those pathogens that spread downwind, in particular powdery mildew. Only one diseased volunteer plant gives in the future a radius of damage of 4 km or more. The problem with this disease is that it is capable of infecting plants even in the absence of drip moisture, moisture content of 70 - 90% is sufficient for it, which is always achieved with dense standing of plants.
There is another danger factor - early sowing of winter wheat. A high tillering rate, a huge biomass - and even a three-component dressing agent will no longer be able to contain the spread of infection.
Septoria is another disease that affects leaves, but its pycnospores do not spread with air currents. In order for infection to occur, rain is imperative. With each drop of it, the spores are transferred one - one and a half tiers of leaves up. From the moment of infection, which also occurs through the stomata, until the appearance of pycnidia, it takes from 14 to 28 days. That is, if a pathogen is present on the dead leaves in the pycnidial stage, then approximately 14 - 20 days after the rain, wait for the infection of the next layer. The more precipitation falls and the higher the temperature, the faster the next stage of destruction of the next tier begins - after 14 days.
These pathogens can and should be fought! If they are present in winter wheat crops, it is necessary to carry out the autumn fungicidal treatment with Benorad, which, among other things, works very well against fusarium, somewhat weaker against septoria, but it has sufficient efficiency to significantly reduce the amount of infection.
In the fall, you can also use the Credo fungicide based on carbendazine, these drugs have a comparable effect. In the spring, it is still better to treat crops first with Benorad, it has a great systemic effect, and Credo can be used in the future as a contact-systemic fungicide. Do not wait for symptoms to appear, do not tie the application of fungicides to herbicidal and insecticidal treatments! We must always work proactively, because it’s impossible to predict everything. It should be understood that if you apply fertilizers, if the potential of your soil and variety is 40-50 centners per hectare of grain, in the case of rust epiphytotics, you can lose 50-70% of the crop. In the case of epiphytoty of powdery mildew, depending on the situation, the spread is from 20 to 80%, septoria also carries away in this case from 40 to 60% of the grain.
In hot weather, intense insolation, the active ingredients of fungicides are susceptible to photolysis. Moreover, in the presence of water, they are destroyed much faster than usual. Sometimes the period of effective protection is reduced to two weeks instead of the declared three. If there is not enough money for a second fungicidal treatment, with a low or medium degree of infestation, you need to concentrate on protecting the flag leaf. If the "green fire" occurs at an early stage, then you just need to save the crops.
There are also questions about strobilurins - what time is the best time to use them. Let us consider this using the example of azoxystrobin, one of the active ingredients of the fungicide Spirit. In addition to the fact that it has a fungicidal effect, disrupting membrane synthesis and affecting the transport of electrons in the respiratory chains of fungi, it also reduces the amount of free radicals inside the plant that cause damage to plant cells. And to reduce this physiological "spotting", drugs based on azoxystrobin are used, which in this case act as prophylactic and growth-regulating drugs. So it is better to use Spirit in the first treatment - prophylactically, then Kolosal Pro or Racurs.
Fusarium spikes are infected during flowering through the anthers of cereals. In the future, this leads to white spike, premature ripening, and graininess. At the time of flowering, crops must be protected with a systemic fungicide!
All species of fungi of the genus Fusorium are characterized by the release of mycotoxins that reduce plant immunity. As a result, the fungus, and then other pathogens, colonize the weakened tissue. It can be difficult to determine when to apply a fungicide without special tests, but you can be guided by the weather conditions. If rains have passed or are expected, there is high humidity at night and in the morning, and the plants are in the heading - flowering stages, you need to work with fungicides.
Soil cultivation also plays an important role in preventing the spread of fusarium. For example, disking sharply increases the speed of decomposition of plant residues lying on the surface with the help of a whole complex of cellulolytic bacteria, saprophytic fungi, etc., which destroy, including the resting stages of pathogenic infection. Therefore, decomposition of the straw is, in the end, the improvement of the field.
Spike moles are usually caused by fungi that normally do not infect healthy plants. If they are weakened due to damage by aphids or other piercing-sucking pests, or there are traces of septoria infection, brown rust on the spikelet scales, humidity increases - all this contributes to the development of fungi such as Ctadosporium, Atternaria and Epicoccum. They have dark-colored mycelium, the growth of which leads to the mob of the ear. This infection, like a seed infection, is effectively removed by all fungicidal dressings.
Head of Science and Information Department
Ministry of Agriculture and Natural Resources
Pridnestrovskaia Moldavskaia Respublika
With fusarium, the vascular system (fusarium wilting) and plant tissues (rot of roots, fruits and seeds) are affected. With fusarium wilting, damage and death of plants occur due to a sharp violation of vital functions due to clogging of blood vessels by the mycelium of the fungus and the release of toxic substances by them. Infected plants have poor flowering, yellowing and leaf fall, darkened underdeveloped roots, general wilting. Dark vessels are visible on the cut of the stem and leaves. At temperatures below +16 ° C, diseased plants die quickly enough.
On the bulbs, more often at the bottom, reddish-brown spots appear depressed inward (therefore, fusarium in bulbous plants is very often called red rot), which, with high humidity, become covered with a pinkish-white bloom. During storage, the disease progresses rapidly and the bulbs rot, being at the same time a serious source of infection.
Fusarium wilts are especially dangerous for all bulbous plants, neoregelia, rose, chrysanthemum, echmea, anthurium, gerbera, cyclamen, balsam, zygocactus and other jointed cacti.
Fusarium spike. © MUExtension417
Fusarium wilting of strawberries is one of the most dangerous diseases of berry crops. A plant with root rot withers within six weeks and dries up. Dying off of roots and root collar is observed. It is easy to find traces of necrosis on the leaf blades. At an advanced stage, the leaves of the strawberry turn brown, like the petioles. The rosette disintegrates, and the bushes, due to the loss of turgor in the tissues of the stems and leaves, tilt to the ground.
Often, the disease is activated during the period when ovaries appear or when berries are ripening. It is practically impossible to cure the plant. It is better to remove bushes from the garden and be sure to burn outside the garden. The causative agent of the disease, living in the soil, affects not only strawberries, but also garden strawberries. The degree of damage depends on the age of the bushes, the climatic conditions of the region where the crop is grown, and compliance with agricultural practices. To stop the spread of the pathogen, the following drugs are used: trichodermin, trichoplant, glyocladin. The soil and roots of the seedlings are treated with a solution of these drugs. The variety Zenga belongs to strawberry varieties resistant to fusarium wilt. To protect planting from infection, process seedlings before planting.
Fusarium blight of melons is widespread in the countries of Central Asia, where favorable conditions for the development of the pathogen are recognized. Depending on the variety and growing conditions, this fungal disease can destroy up to 70% of melon plantations.
The development of the disease begins with roots and shoots. They turn brown. On the root layers, hairs disappear, and the base of the root becomes covered with reddish spots or stripes. Affected bushes quickly die. If the pathogen touched the bushes during the period of fruit laying, then the melon will not fully ripen, it will lose its taste and will no longer be edible. The fruits will become watery and tasteless and will fit only for livestock feed. On days when the temperature outside fluctuates between 23-25 degrees, and the humidity is about 80%, the fungus on the melon develops faster.
The danger to the cereal culture is not only various diseases, but also pests. Their main representatives can be found below.
Small insects (1 mm long) of brown or black color with a tapering segmented belly. They often settle on the lower parts of flag leaves and eat the stem.
Thrips lay eggs inside or on the surface of tissues. They are characterized by a short period of development, so they can give several generations a year. The larvae are really dangerous, because they first suck the juices from the spikelet scales, and then eat the contents of the grains, because of which they lose their seed qualities and become puny.
With a large invasion of pests and larvae, plant tissues are deformed and acquire a silvery color. As a result, leaves, stems and young ears are damaged.
In the fight against thrips, it is necessary to use insecticides of systemic action or combined preparations containing substances of contact and systemic action (Angio 247 SC).
Aphids are almost translucent soft-bodied sucking insects that are considered one of the most dangerous pests for wheat, especially two of them - large cereal (Sitobion avenae F.) and common cereal (Schizaphis graminum Rond).
These insects feed on wheat from the moment of germination to the waxy ripeness of the grains. Their number gradually increases and reaches a maximum in the grain filling phase. Aphids give 10-12 generations per season.
The following signs indicate the defeat of this pest:
Aphids can not only cause significant damage to plants, but also become a carrier of viruses, so modern systemic drugs must be immediately used against them.
Adult insects (butterflies) do not harm the plant, but only feed on flowering vegetation, but caterpillars can cause significant harm to it.
Females lay eggs on wheat ears in clutches of 10-25 eggs. Their embryonic period lasts 1-2 weeks. After this, caterpillars appear, which have 8 instars. At each stage, they are dangerous in their own way:
The harmfulness of the caterpillar increases gradually:
|Age||The amount of grain eaten|
|1 to 4||less than 50 mg|
Over the entire period of development, one caterpillar is capable of destroying 2 g of grain, which is equivalent to 2 ears. To prevent such consequences, it is necessary to fight the scoop in phase 3 of age, using combined insecticides to treat wheat.
The insect is capable of infecting the plant throughout the entire growing season. The culture is harmed by both adult bugs and their larvae. Females lay 14 eggs each after 1-2 weeks of active feeding. This process takes 10 to 20 days. The larvae appear on average 9-16 days and also begin to feed on the plant.
The pest causes significant harm to wheat:
In the fight against bedbugs, wheat must be treated with insecticides twice: the first treatment is against overwintered insects, and the second is against the larvae. In the case of winter wheat, treatment is best done against an overwintered bug in the tillering phase.
These are insects that look like small fly-like wasps. For wheat, two of their representatives are dangerous - ordinary bread (Cephus pygmaeus L.) and black (Trachelus tabidus F.).
If the first sawfly is found in any zones of wheat cultivation, then the second - mainly in the central regions. In any case, they cause the same harm to the cereal crop, affecting as follows:
For this reason, the grain yield is reduced by about 1 centner / ha.
In some years, sawflies can cause significant harm to crops, so it is better to cultivate the varieties that are most resistant to their attacks. These are wheat species with dense or semi-dense stems filled with parenchyma.
May or June beetles lay eggs in the soil, and the hatched white larvae with three pairs of legs on the belly infect wheat.
These pests partially or completely gnaw through the roots of plants, which leads to the following consequences:
The signs of damage outwardly resemble the manifestations of root rot, however, upon a detailed examination of the area with dying plants in the soil, white larvae can be identified. As they mature, they reach 2-3 cm in length and almost 1 cm in thickness.
To prevent pest attacks, it is important to subject the site to competent pre-sowing treatment.
In spring, click beetles lay eggs in the soil, from which hatch larvae with three pairs of legs, called wireworms. In length, they reach 2-3 cm, and their color varies from milky cream to brown.
Wireworms consume the endosperm of the grain, causing wilting or death of seedlings in a row or small bed. Seedlings of damaged seedlings, on which larvae can be found, are eaten right above the seeds.
To prevent wireworms from ruining the wheat crop, the crop should not be sown in the same area for several seasons in a row or after perennial grasses.
It is considered one of the most dangerous pests for cereals. It is a small insect (up to 3-4 mm in length) of dark gray or brown color with a pink or yellow-brown belly. It is widespread in different regions of the world, but occurs annually in the United States and North Africa.
Such a fly lays eggs, from which larvae, dangerous for wheat, hatch. They suck life juices from plant tissues, penetrate into the leaf sheath and eat the stem. All this is accompanied by the following signs:
Carrion after the last harvest contributes to the intensive reproduction of the Hessian fly, so it needs to be plowed up as soon as possible. This will help the rapid death of the larvae and stop their mass reproduction.
In case of severe damage by the Hessian fly, wheat can be chemically treated using special preparations (Hexachloran, Chlorophos, Metaphos, Phosphamide).
Wheat can be affected by various diseases and attacked by dangerous pests. Knowing the reasons for their appearance, you can take all the necessary measures in a timely manner to protect your crop from such misfortunes. If the plant shows signs of lesions, then you need to timely establish their cause and begin to improve your site.
When growing adaptive varieties of grain crops with the smallest fluctuations in yield over the years, it is possible to control the quality characteristics of the grain. For high yielding varieties, the protein and gluten content of the grain is largely determined by the correct choice of plant protection system during the growing season. The producer faces two tasks: quantitative (how many centners per hectare are planned to be obtained) and qualitative (the expected class of grain and the likelihood of mycotoxin accumulation).
The most important factors affecting yield
To solve the first problem, it is necessary to carefully monitor the parameters that determine the quantitative indicators of yield:
Each of these parameters is laid down in a certain phase of plant development and, with a competent approach, can be easily controlled.
1. The first vulnerable phase of development of winter wheat begins at the emergence of seedlings and continues until the appearance of three leaves. It was during this period that such a yield parameter was laid as the number of plants per unit area. The density of plants is formed by a complex of factors: the quality of the seed material, the rate and timing of sowing, the depth of seeding, as well as the level of basic mineral nutrition. Let us emphasize that the number of plants per hectare is the main factor in yield! If you miss it, further struggle for high performance will be meaningless. That is why it is so important to choose the right drug for protecting seeds, because during this period seed and soil infections, as well as seedling pests, are harmful. For high-yielding winter wheat varieties, MAXIM® FORTE is a good solution. It provides protection against a full range of smut and root rot. If, in the fall, plants have a poorly developed root system and cereal flies harm the field, SELEST® MAX will be an excellent solution.
2. In the tillering phase, the next most important indicator of productivity is laid - the number of productive stems. Lack of any nutrients or moisture can seriously reduce the productive tillering. Of the harmful objects that can reduce the number of productive stems, during this period, cereal flies and pathogens of root and root rot are also active, powdery mildew and septoria blight appear. To control rhizoctoniasis, we recommend treating seeds with VIBRANS® INTEGRAL, complex protection with MAXIM® FORTE (seed treatment) and AMISTAR® EXTRA (at the beginning of tube emergence) will work against the root rot.
3. The number of grains in an ear is formed in the phase of the end of tillering - the beginning of stemming. It is this period that is the most important and at the same time the most vulnerable, since it lasts a very short time (from 5 to 12 days, depending on the temperature). Nitrogen fertilization during this period contributes to the preservation of the productive stalk and the full realization of the grain content of the ear, laid down by the potential of the variety. For the successful passage of plants of this critical phase, we recommend using the fungicide AMISTAR® EXTRA at the end of tillering - the beginning of emergence into the tube at a consumption rate of 0.65–0.75 l / ha. This will save from 10 to 30% of the harvest even in the absence of infections in the field due to the preventive action. If the sowing is tall or thickened, the growth regulator MODDUS®, 0.3–0.4 l / ha should be added to AMISTAR® EXTRA. This will reduce the risk of lodging and maintain productive bushiness.
4. With a fully unfolded flag leaf, when the process of photosynthesis is especially active, the formation of the next factor of productivity begins - the mass of 1000 grains. Since the intensity of photosynthesis directly depends on the presence of diseases in the upper layer of leaves, during this period, protective measures are decisive for the future harvest. At the first signs of the appearance of pathogens in the middle tier, when the flag leaf can still be preserved, it is recommended to use ALTO® TURBO, 0.3-0.4 l / ha (if rust develops), or ALTO® SUPER, 0.4-0.5 l / ha, with septoria or helminthosporiosis.
5. Fusarium, septoria, rust and other similar diseases, actively developing during the growing season, significantly weaken the plants, leading to a catastrophic decrease in yield or significantly deteriorating the quality of grain. So, the initial loss of yield in the field when the ear is affected by Fusarium is up to 30%, which may not seem like a very big problem. However, almost always the remaining 70%, even with a slight presence of mycotoxins (waste products of Fusaria), make the grain completely unusable. Neither protein content, nor IDC values, nor nature matter if the grain contains negligible amounts of mycotoxins. Often, even a distillery will not accept such a batch.
6. When the ear is damaged by septoria, the technological indicators of grain quality deteriorate significantly. The grain in the spike of such a plant becomes puny or completely absent. Such underdevelopment of the ear leads to yield losses of 20-30% or more.
7. Fusarium head blight is the most dangerous disease of cereal crops. The accumulation of mycotoxins can occur in the ear even if there are no visible symptoms of massive plant damage. Since field diagnostics do not provide a complete picture, a mycotoxin test is necessary to ensure that grain is exportable or suitable for use as forage.
Spores on affected plant debris
pycnidia and mycelium on seedlings of winter crops
drip moisture for 17-19 days
resting structures on diseased plant debris
precipitation in the phase of earing and milky-wax ripeness
8. Fusarium spike control. Since the future harvest is already established at the time of pollination, the timing and technology of fungicidal treatment is critical. Anthers serve as an entrance gate for the causative agent of the disease, therefore, fungicidal treatment against Fusarium head blight must be carried out when 75% of the ears have completely appeared on the main stem. And finish before the phase when 50% of the ears have faded (BBSN 55-65). Earlier or later treatments are ineffective.
Undoubtedly, the weather conditions during the flowering period, the stock of infection in the field, the agricultural technology used and the varietal composition of the plants are important factors in the infection of the ear with Fusarium. Remember that the correct use of fungicides can only reduce the risks of serious mycotoxin build-up. To reduce the stock of infection of pathogens, including pathogens of fusarium, it is necessary to incorporate crop residues, destroy carrion, and also use stubble biodestructors in crop rotations saturated with grains. For example, the acceleration of the decomposition of plant residues is facilitated by the introduction of ammonium nitrate (10 kg a.i. / ha) or trichodermine (5.0 l / ha) immediately after harvesting.
We present to your attention MAGNELLO ™ - an innovative fungicide specially created for ear protection!
MAGNELLO ™ has the following advantages:
3 golden rules for grain quality control with MAGNELLO ™
Grain quality and mycotoxin accumulation.
Infection with any pathogens capable of accumulating mycotoxins occurs mainly during the flowering phase, until the anthers dry out. This period takes no more than 5 days, so the most important thing is to treat with the right fungicide at the right time. Treatments after the anthers are dry have practically no effect on the accumulation of mycotoxins, but they can only restrain the development of external infection on the ear. Treatments on the flag leaf (when the ear has not yet appeared) also do not have any effect on the ear infections.
For spike treatment against the main spike pathogens, Syngenta presents a novelty for the 2018 season - the fungicide MAGNELLO ™, developed specifically to control spike infections. MAGNELLO ™ equally well controls both fusarium head blight and septoria blight, and black embryo (internal infections) at a rate of 1.0 l / ha. It is recommended to apply MAGNELLO ™ prophylactically, from the moment when the first "beacons" appeared on the field (completely emerging ears) to the moment when the anthers on them begin to dry out. We do not recommend using MAGNELLO ™ before the spike appears, or if the field already has symptoms of Fusarium or Septoria spike.
MAGNELLO ™ also controls well all leaf diseases during this phase. Its use is especially effective in areas with constant precipitation during the flowering period, where the risk of Fusarium infection of the ear is high, in seed plots, on varieties susceptible to Fusarium and Fusarium-prone predecessors, such as corn, beets, soybeans, rapeseed.
Still have questions? We are ready to answer: call the hotline of agronomic support of the company "Syngenta" at the toll-free number 8-800-200-82-82, and you will receive answers to the most difficult questions!