ORIGIN.
Rice cultivation began nearly 10,000 years, in many humid regions of tropical and subtropical Asia. India is probably the country where first cultivated rice because it abounds in wild rice. But crop development took place in China since its lowlands to highlands. Probably there were several routes by which rice was introduced from Asia to other parts of the world. MORPHOLOGY AND TAXONOMY
Rice (Oryza sativa) is a monocotioledónea belonging to the family Poaceae.
ESTATE:
The roots are thin, fibrous bundles. There are two types of roots: seminal originating from the radicle and are temporary in nature and secondary adventitious roots, which are free and are branching from lower nodes of young stem. The latter replaces the seminal roots.
STEM:
The stem is formed of alternating nodes and internodes, with cylindrical, knotty, glabrous and 60-120 cm. long.
SHEETS:
The leaves are alternate, sheathing, with the linear blade, sharp, long and flat. At the meeting point of the sheath and the blade is a ligule membranous, erect bifida occurs in the bottom a number of long cirri and silky.
FLORES:
whitish green are arranged in spikelets, which together constitute a large panicle, terminal, hanging close and after flowering.
Inflorescence: panicle
is a given which is located on the stem end, being a unit spikelet of the panicle, and consists of two sterile lemmas, rachilla and floret.
GRAIN:
rice grain is the ripened ovary. The shelled grain rice (caryopsis) with brown pericarp is known as brown rice, rice grain shelled with a red pericarp is red rice.
ADAPTATION OF RICE TO Waterlogged soils.
flooded soils offer a unique environment for the growth and nutrition of rice, as the area around the root system is characterized by lack of oxygen. Therefore, to avoid root asphyxia, the rice plant has a special fabric, a well developed air spaces in the leaf blade in the sheath, stem and roots, which form a very efficient system for air passage.
air enters the plant through the stomata and leaf sheaths, moving toward the base of the plant. Oxygen is supplied to the tissues with the passage of air, moving into the roots, where used in breathing. Finally, the air leaves the roots and spreads into the surrounding soil, creating a redox interface.
ECONOMIC IMPORTANCE AND GEOGRAPHICAL DISTRIBUTION.
Rice is the staple food for more than half of the world population, although it is the world's most important when considering the extension of the surface on which it is grown and the number of people who depend on their crop. Globally, rice ranks second after wheat considering the harvested area, but considering its importance as a food crop, rice provides more calories per acre than any other cereal crop. Addition its importance as food, rice provides employment to as the rural sector of most of Asia, it is the typical cereal southern and eastern Asia, although it is widely grown in Africa and America, and not only widely but intensively in some parts of southern Europe, particularly in Mediterranean regions.
Rice Production and Yield worldwide
Country Production (tons) Yield (kg / ha)
World China 3863 592 873 253 190 389 160 135 000 000 3027 6241
India Indonesia
Vietnam 51,000,000 4426 32,000,000 Bangladesh
4183 29,856,944 2852 23,402,900 2340
Thailand Myanmar 20,000,000 Japan
3,333 11,750,000 10,940,500 3010 6528 Brasil
USA 3205 Philippines 12,500,000 6963 8,692,800 7,270,500
Rep. of Korea 6880
Colombia Peru 1,664,700 4773 2,100,000 5549 737,000 4913
Venezuela
Among the countries that produce more than one million tons per year are Cambodia (3.5 million), Iran (2.6), North Korea (2.1), Laos (1.6), Madagascar (2.4), Nepal (3.6), Nigeria ( 3.2), Pakistan (6.5) and Sri Lanka (2.7).
TRADE.
rice consumption and therefore trade is differentiated by the types of rice and the quality of them. We consider the following types of rice:
Long-grained indica profile: this in turn is classified according to the percentage of broken grains and whether they are aromatic. This type of rice represents 85% of world rice trade, including approximately 10-15% of aromatic rice (jasmine and basmatil types), 35-40% of high-quality rice (less than 10% of broken grains) and 30-35% of low quality rice.
GRAIN MEDIUM / SHORT japonica:
trade of this type of rice represents only a 15% share.
world rice trade over the next 15 years (from 18 million in 1996 to 21 million in 2010), is estimated to grow at an annual rate of of 1.11%, a rate significantly lower than the current (8.82%) and reflects the fact that the major impact of global trade liberalization and worked.
world rice market.
Due to the nature of the world rice market, this contributes to price volatility. Thus we consider the following aspects in the international rice market: small quantities traded stand for the quantities produced or consumed, so small changes in production or consumption of any major producer / consumer or buyer countries Sellers , can lead to a big impact on the volume put on the market and therefore on prices.
Another aspect is the high degree of concentration among rice exporters in the world. Since 85% of export proceeds of 7-9 countries, therefore changes in the stock offerings of rice, due to the weather for example, is finally on prices. BREEDING
.
world rice yield for 1996 was 2.52 tonnes / ha, and is projected for 2010 will yield 2.87 tons / ha, an annual increase of 0.93%. Increase a little optimistic considering that the increase in the last 6 years was 0.68%, the basis for this performance "optimistic" projected responds basically to the development and increased use of improved varieties.
cultivated rice varieties have changed in recent years by a gradual replacement of older, based on the best features, causing the disappearance of certain varieties, as the new offer better yields, greater disease resistance , lower height, better grain quality and increased production.
breeding programs are based on rice production of dihaploid plants through anther culture of plants obtained from previous crosses. The use of haploid lines increases the efficiency of selection of polygenic origin and character facilitates the detection of recessive mutations. The continued cultivation in vitro anther culture lines originated gene variations, in this case called gametoclonales, which have given rise to new varieties of rice.
soil and climate requirements. WEATHER
.
is a tropical and subtropical crops, although most global production is concentrated in tropical humid climates, but can also be grown in humid regions of the subtropics and in temperate climates. The crop extends from 49-50 degrees north latitude to 35 degrees south latitude. Rice is grown from sea level to 2,500 m. altitude. Rainfall condition the system and cultivation techniques, especially when grown in the highlands, where they are more influenced by their variability.
TEMPERATURE.
Rice needs to germinate at least 10 to 13 ° C, considered optimal between 30 and 35 º C. Above 40 º C germination does not occur. The growth of stem, leaves and roots have a minimum of 7 º C, considered optimal at 23 º C. At temperatures above this, the plants grow faster, but the tissues are too soft, still more susceptible to attack by disease. The tall is influenced by temperature and by decreasing the duration days.
The panicle, usually called the spike by the farmer, begins to form about thirty days before bolting, and seven days after starting their training now reaches about 2 mm. From 15 days before the tall stem develops rapidly, and this is the period most sensitive to adverse environmental conditions.
Flowering takes place on the day of bolting, or the next day during the last hours of the morning. The flowers open their glumillas for one or two hours if the weather is sunny and high temperatures. Rainy weather and low temperatures impairs pollination.
The minimum temperature to flower is considered 15 ° C. The optimum of 30 ° C. Above 50 º C no flowering occurs. Respiration reaches its maximum intensity when the pin is in bag, decreasing after heading. High temperatures intensify the night respiration of the plant, so that the use of the reserves accumulated during the day by the function of chlorophyll is higher. For this reason, the overnight low temperatures favor the ripening of the grains.
FLOOR.
The cultivation takes place in a wide range of soil texture ranging from sandy to clay. Are often grown in soils with fine to medium texture, typical of the process sedimentation in the broad flood plains and river deltas. Fine textured soils work difficult, but they are most fertile to have higher clay content, organic matter and provide more nutrients. Therefore, the soil texture plays an important role in the management of irrigation and fertilizer.
PH.
Most soils tend to change their pH toward neutrality few weeks after the flood. The pH of acid soils increases with the flood, while for alkaline soils the opposite happens. The optimal pH for rice is 6.6, because with this value the microbial release of nitrogen and phosphorus from organic matter, and availability and phosphorus are also high concentrations of substances that interfere with absorption of nutrients, such as aluminum, manganese, iron, carbon dioxide and organic acids are below the toxic level.
SPECIAL CROP.
Land preparation.
soil tillage rice wetland or dry land depends on the technique of crop establishment, moisture and machining resources. In tropical countries of Asia wetland tillage is a common procedure. The traditional method of farming to lowland rice is the plow and the cement, the latter being very important because allows easy transplant. Sowing
.
TYPES OF RICE PLANTING METHOD OF MAXIMUM WATER DEPTH (cm)
rainfed rice lowland rice transplantation 0-50 superficial temporal
lowland rice transplantation 5-15
temporary lowland average depth Transplantation 16-50
deepwater rice in dry soil to broadcast Rice 51-100
floating 101-600 broadcast on dry upland rice
broadcast or in rows on dry with no standing water
Source: Barker and Herdt .
PAID.
nitrogen:
Much of the soil nitrogen is in organic forms part of the organic matter and debris harvest, but the rice plant only absorbs nitrogen from the solution in an inorganic form. The passage of the organic form of nitrogen to inorganic forms takes place through the process of mineralization of organic matter, with the final products of this process differ according to soil conditions.
anaerobic In a soil, lack of oxygen causes nitrogen mineralization stops at ammonium form, which is the stable form in soils with these conditions. This form of nitrogen is found in two ways: dissolved in soil solution and absorbed by the clay-humus, forming both the fraction of nitrogen readily available land for rice.
Nitrogen is considered the nutrient that most directly impact on production, it increases the percentage of filled spikelets, increases the leaf surface and also contributes to increased grain quality. Rice needs
nitrogen in two critical moments of the crop:
1.-At the tillering stage (35-45 days after sowing), when plants are developing the vegetation needed to produce rice.
2.-Since the beginning of the elongation of uppermost internode until it reaches 1.5-2 cm.
nitrogen must be provided in two phases: first as basal dressing, and the second, at the beginning of the reproductive cycle. The dose of nitrogen depend on the variety, soil type, climatic conditions, fertilizer management, etc. In general, the dose of 150 kg of nitrogen per hectare distributed twice (75% as basal dressing, 25% at panicle initiation).
In the basal dressing fertilizer should be used ammonium and buried about 10 cm. depth, before the flood, with a harrowing task. The top dressing is applied to the panicle initiation, using ammonium nitrate. Nitrogen fertilizer used, are generally ammonium sulphate, urea and complex fertilizers that also contain nitrogen, other nutrients.
MATCH:
also has a positive impact on productivity of rice, although its effects are less dramatic than those of nitrogen. Phosphorus stimulates root development, promotes tillering, contributes to the earliness and uniformity of flowering and maturity and grain quality improvement. Rice needs to find
available phosphorus in the early stages of development, so it is important to provide the subscriber phosphorus as basal dressing. The amounts of phosphorus to apply range from 50-80 kg P2O5. The first figures are recommended for silty clay soil, while the latter figure applies to light loose terrain. POTASSIUM
:
Potassium increases resistance to lodging, disease and unfavorable weather conditions. The absorption of potassium during the growing season runs similar to that of nitrogen. The dose of potassium to apply range from 80-150 kg K2O. The higher figures are used in loose and when using high doses of nitrogen.
IRRIGATION:
The irrigation system used in rice fields are different from static systems of circulation and collection of water. Taking into account the advantages and disadvantages of each system and its potential impact on water quality, allow rice to choose the system best suited to their farming operations, and then describe each briefly and concisely:
SYSTEM FOR CONTINUOUS FLOW IRRIGATION:
is conventional, being designed for self-regulation: water flows from the top of the rice paddy to the lower, regulated by a wooden box. The spill is from the latest "cash drain" that is used to maintain the water level of the table. The disadvantages of this system include the discharge of pesticides to public waters, the constant supply of cold water through the top of the table produces the delay in maturity date and hurts yields in areas near the entrance water and the introduction of water at the time of herbicide application, resulting in less control of weeds
WATER RECOVERY SYSTEM FOR WASTE DISPOSAL.
This system facilitates the reuse of runoff water and allows no pesticide residues are dumped on the public channels. Has the advantage of providing maximum flexibility by requiring a shorter period of water retention after application of plant protection products than conventional systems. Is to raise the water drain from the last table to the highest level table using a low power pump through a pipe or channel. The costs of construction and use of a recirculating system depends on the area covered by the system, the slope and terrain.
IRRIGATION SYSTEM STATIC. Keeps
waste waters with pesticides outside the public channels and eliminates the need for a pump system as used in the recirculating also be independently controlled water inlet to each table, limiting water loss through evapotranspiration and percolation. This system consists of a drainage canal that runs perpendicular to the drains of the tables. The canal is separated from each plot for a series of valves that control the depth within each table. Not suitable for saline soils and also reduces arable land due to construction of drainage channel.
RECOVERY THROUGH IRRIGATION WATER.
water recovery pipe is made by using the flow due to gravity to carry water from one table to another, avoiding the landfill to public water channels with pesticide residues. This system is very effective and has reduced costs, as well as during periods of water retention, allows great flexibility in handling. Even when connected multiple tables due to the large area, it is difficult to accurate and efficient management, taking into account also the saline-sodic salt accumulation can be a problem.
WEEDS.
Competition from weeds in rice varies with the type of crop, planting method, variety and cultivation techniques (soil preparation, seeding, fertilizing, etc.).. This competition is more important to the early stages of crop growth, therefore, early control is essential for optimal performance.
flooded soils favor the abundance of viable weed seeds in the rice field, giving rise to a specific adventitious flora of aquatic habit, which requires appropriate methods of control. The massive presence of weeds can reduce rice yields up to 50%. Among
agronomic methods to control weeds include tillage (depth and time of completion), irrigation (control of flood water layer as the growing season), rotations and planting (age, type and density .) The determination the limit depth of water is very important to maximize weed without risk, since for example, increased water depth increases the effectiveness in controlling and Cyperus difformis oryzoides Achinochloa. Heteranthus
limosa is a common weed of rice, which grows best in dense cultures, but because of its low elevation, exercises little competition in crops with normal densities.
Chemical control is the most effective method, also including weed of cultivation, irrigation channels, embankments, loins, etc., The latter being a source of primary invasion of weeds and seed source pest and diseases. The control of annual dicotyledonous Bensulfuron was made using 0.08% + 8% Molinate presented as granules at doses of 50-60 kg / ha. Against annual grasses apply Propanil 35%, presented as emulsifiable concentrate at doses of 8-12 l / ha. The following table shows the active ingredients, dosage and presentation of products from dicots: ACTIVE MATTER
DOSE PRODUCT PRESENTATION 60% Bensulfuron
80-100 g / ha microgranule
Bentazone 48% (sodium salt) 3-5 l / ha Concentrate 87% soluble
Bentazone 1.5-2.5 kg / ha Grain
water soluble The following table shows the active ingredients, dosage and presentation of the product to be sedges: These treatments are usually given after drying rice from tillering and jointing stage. ACTIVE MATTER
DOSE PRODUCT PRESENTATION 50%
Azimsulfuron 40-50 g / ha water dispersible granule
Bensulfuron Molinate 0.08% + 8% 50-60 kg / ha 60% granule Bensulfuron
80-100 g / ha water soluble Grains
Bentazone 87% 1.5-2.5 kg / ha microgranule
Below is the active ingredients, dosage and presentation of the product against Alismataceas: post-emergence applied early, you should cut the water to make the application and return to flood at 24-48 hours, maintaining level to cover the weeds in 10-15 days. Used until the state of weed with two leaves. ACTIVE MATTER
DOSE PRODUCT PRESENTATION 50%
Azimsulfuron 40-50 g / ha water dispersible granule
Bentazone 40% (sodium salt) + 6% acid MCPA (amine salt) 3-5 l / ha Concentrate
Propanil 35% soluble 8-12 l / ha emulsifiable concentrate
to combat aquatic weeds 5% is used as granule Dimepiperato dose of 50-60 kg / ha and oxadiazon applied against Herantera 2% granule at a dose of 1-2 l / ha. Echinochloa
SP.
is the most important weed in rice cultivation, can significantly affect performance. Its emergence is staggered, requiring repeated treatments for the low persistence of the control products. The treatments were performed in pre-and post-emergence early, before seedling emergence of this weed, the treatments can be done dry, 1-2 days before the flood for sowing, or after the flooded field . If the application is dry before planting, herbicide must be buried with the latest work at a depth of 4-5 cm. The following table shows the active ingredients, dosage and product presentation against Echinocloa:
DOSE ACTIVE MATERIAL PRODUCT PRESENTATION
Cicloxidin 10% 2-3 L / ha emulsifiable concentrate
cyhalofop-butyl 20% 1.5 l / ha emulsifiable concentrate
Dimepiperato 5% 50-60 l / ha granule Molinate
thiobencarb 4.5% + 4.5% 50-60 l / ha granule Molinate
7.5% 55-65 l / ha quinclorac
Granule 25% 2.5-4 l / ha Concentrated suspension
thiobencarb 10% 40-50 l / ha granule
WILD RICE.
wild or wild rice is one of the main problems of rice cultivation, along control of weeds, thus resulting in great economic losses. This type of rice comes from the species Oryza sativa varieties as well, but this has arisen because of the ease of retrogradation to their genetic origins of the cultivated varieties. The presence of wild rice in rice cultivation has been steady increase in recent years due to several factors: tillage, increased crop varieties, crop rotation failure and use of uncertified seed.
The appearance of wild rice is similar to cultivated varieties differing only in detail: more robust, green color intense in leaves and cane, easy threshing, awned spikes and great power of germination conditions. Chemical control is complicated by the genetic similarity with cultivated rice, so there are no specific herbicides. Manual weeding is only possible when the size of the wild rice plant is greater than that of cultivated rice.
CONTROL OF ALGAE.
flooded paddy field in the present microscopic and macroscopic algae that live in associations, which vary and evolve at different rates depending on environmental conditions, in addition to their own culture techniques determine variations in these associations. The damage caused by algae depend on the species, the importance of the mass of weed and crop stage, they compete for light and oxygen, causing chlorosis and wilting of seedlings and even boot from the ground, making it difficult to feed and roots. Also prevent any herbicide treatments, reducing their effectiveness, to cover the mass of algae also bad
HERBS.
most damaging species belong to the group of green algae or Chlorophyceae and belong to the genera Oedogonium, Vaucheria, Hydrodictylon, Spirogyra and Cladophora. The development of algae is faster the higher the water temperature and air and the higher the difference temperature between surface and bottom water layer. Current methods of control are chemical seed treatments with fungicides containing algaecides effects, application of products in the irrigation ditches and the water inlet sluices and conducting field sprays. One of the active substances that are used today is Propanil 35%, presented as emulsifiable concentrate at a dose of 8-12 l / ha.
COLLECTION.
The optimal time to harvest is when the panicle reached physiological maturity (when 95% of the grains are straw color and the rest are yellow) and grain moisture is 20 to 27%. Collection is recommended machined using a combine equipped with tracks.
The price of rice has a special interest in the whole kernel percentage of the total harvested, since this value depends mainly on the variety, but also varies depending on the time of harvest, because if the rice harvest very green, the period of handling increases in the dryer, resulting in a decrease in that percentage. After threshing the rice may have a humidity of 25 to 30%, so it must be dried to a moisture content below 14%.
SELECTION MECHANICS.
Following completion of harvesting operations and drying, each consignment intended for seed, carry out the determinations of regulatory quality (impurities, humidity, red beans, germination, etc..), eliminating those that do not meet the necessary conditions. The selection mechanism is to separate those materials or types of grains that are not worth preserving along with the selected seed, improving the quality of it. This operation is done by cleaning and sorting machines, which remove unwanted material (chaff, straw, broken grains, weed seeds, etc.)..
NUTRITIONAL VALUE. RICE
.
Composition of rice per 100 g of substance
Water (%) 12
Protein (G) 7.5
Fat (g) 1.9
Carbohydrates (g) 77.4
Fiber (g) 0.9
Ash (g) 1.2
Calcium (mg) 32
Phosphorus (mg) 221
Iron (mg) 1.6
Sodium (mg ) 9
Potassium (mg) 214
Vitamin B1 (Thiamine) (mg) 0.34
Vitamin B2 (Riboflavin) (mg) 0.05
Niacin (nicotinic acid) (mg) 4.7 Calories 360
WHITE RICE. Composition
white rice 100 g of substance
Water (%) 15.5
Protein (g) 6.2
Fat (g) 0.8
Carbohydrates (g) 76.9
Fiber (g) 0.3
Ash (g) 0.6
Calcium (mg ) 6
Phosphorus (mg) 150
Iron (mg) 0.4
Sodium (mg) 2
Vitamin B1 (Thiamine) (mg) 0.09
Vitamin B2 (Riboflavin) (mg) 0.03
Niacin (nicotinic acid) (mg) 1.4 Calories 351
PEST.
PEST.
WORMS RED AND WHITE RICE
is Ortocladius species sp. Larvae (red) and Cricotopus sp. (Brownish white grubs). They overwinter as larvae, but at the start of spring appear first generation adults. The female makes putting on calm waters and clear. The answer is mucilaginous, and when the rice is emerged, the stakes remain attached to the stems. The larvae go through four stages to reach 12-16 mm. length, being characterized by their different shades.
larvae 3 and 4 Older cause heavy damage in the fields, feeding on small roots of seedlings, can also lead to lodging early, which occurs when the treatments do not achieve sufficient efficacy or begun the attack first generation. The white larvae eat the seed inside the grain.
CONTROL:
The timing of insecticide application is determined by the time between the flooding of the land and planting. -Make
early treatment.
-Making sprays or dusts against adults in flight. Apply
-water treatments against larvae that develop in it, a few days after planting, leaving standing water 48 hours.
paddy Pudent OR BUG:
insects are called Eusarcoris inconspicuus and Eusarcoris perlatus, causing serious damage to rice and some even in milled rice. Adults are between 5-6 mm. long, with its color, recently made the move, pink, after a few hours, depending on light exposure, acquire brown. The female makes the start several times on the aerial parts, leaves and ears of the rice plant, or some adventitious herbs present in the rice fields. The Pudenta passes through five larval stages, all devoid of functional wings. The first age larvae feed on the ears of rice, causing severe damage due to the need for food to complete development. It is a migratory insect, whose migration begins in late September to mid November, as the insect is reaching adult status.
occurs in spring revival rolling overwintering insects, addressing the rice-growing areas, developing maximum activity at dawn and dusk, because in times of high luminosity and temperature, are hidden in the lower parts of plant near the water surface, where temperatures are milder. The damage is caused by the larvae of 4 th and 5 th age and adults through its stylet extracted juices of the green parts of the plant, its main power supply rice grains.
Depending on the state of the grain at the time of suction, appear different damage. If it occurs when the grain is milky, in collecting these grains appear deformed, less weight than the rest. If the attack occurs in advanced stages, the deformations are lighter and almost imperceptible. In the mature grain, as in previous cases, no one can see by the hole chopped. In the latter case, once prepared can see a spherical depression of 0.2-0.3 mm., Sometimes, depending on the weather, about the injury saprophytic fungal growth, which cause brown discoloration noticeable to the naked eye. Therefore, the damage affects the quality and performance-percentage of grains susceptible to market developed.
CONTROL.
"Given the evolution of the pest, it is recommended to track parcel by parcel, starting this control plots provided by the most advanced. While larvae are observed first age should not intervene. It is advisable to wait for larvae show only 2 nd and 3 rd age.
-Destruction of natural vegetation after harvest and on the margins surrounding the rice field. Performing
-catching adults by hunter manga insects.
"The treatments are usually air, except in small plots, where the farmer makes treatments backpack. If the invasion of overwintering adults is intense, there will be two applications: one from the 1st generation in late July or early August and a second application in early September on the 2nd generation. The following table lists the most commonly used active ingredients:
DOSE ACTIVE MATERIAL PRODUCT PRESENTATION
Carbaryl 10% 15-25 kg / ha powder for dusting
0.10 to 0.20% Carbaryl 85% wettable powder
Etofenprox 30% 0.50 to 0.75 l / ha
Fenitrothion emulsifiable concentrate 100% 0.75-1.25 l / ha Liquid ultra low volume application Malathion 97%
1-2 l / ha Liquid ultra low volume application
Trichlorfon 5% 20-30 kg / ha powder for dusting
RICE DRILLING:
(Chilo supressalis), is a native of lepidopteran Asian countries. Adults are small butterfly of 11-25 mm. long, yellowish white with perforations distributed unevenly, they live between eight and ten days, two days after mating their transformation into adults. Spawning takes place on the underside of the leaves and rarely on the stem, always in the shade, protected from light and dry winds. The larvae develop entirely on the crop, moving five times, running between each molt five to six days. In the first stage, live outside the plant, then enter it. We present three complete generations on the rice field, taking three top flight of adults.
Damage caused by larvae of the 1st generation are not very important, because only slight cause rot do not affect the further development of the plant. Especially important are the damage caused by larvae of the 2 nd, as the drill stem and penetrate to impair the heading.
CONTROL.
Chemical control is based on making two or three aerial treatments, one per generation, the first of these ultra low volume, using as Piridafention products in the areas close to wetlands and Fenitrothion on the other, both to dose of 1.7-1.8 l / ha. In
have different biological control methods: the release of natural parasites of the genus Trichogramma and Apanteles, and sometimes with parasites ovífagos. Another method is the use of pheromone mass trapping (deleted by capturing males so that the females are unfertilized) and sexual confusion (based on disruption of male sexual behavior, the high concentration of synthetic pheromone vapors in the atmosphere close to the crop). Earwigs
paddy
:
These pupae of dipterous family Ephydridae, these pupae are found in the leaves of rice seedlings in their early stages. The most important feature, which derives its name, is the presence of an appendix bifida chitinous, remaining when the root is fixed by a prehensile organ formed by the last three segments. The larva is thickened, noting support and changing color from gray to yellow, this time lasting between 4-5 days. Earwigs harmful to the development of the crop only when large quantities are fixed.
CONTROL.
As the cycle coincides with that of red worms, to treat these, earwigs are removed, no specific treatment is frequent.
DONUT:
(Mythimna), Lepidoptera of American origin are very geographical distribution. The larvae can reach up to 4 cm. Length completing their development in 25-30 days, are greenish brown with three white dorsal lines. In early July spawning took place on the underside leaves, the larvae reach their maximum development at 25-30 days, forming the cocoon between the stem and leaf sheath. The caterpillars eat the leaves from the margins of the field or in stands where rice is more receptive to the start.
CONTROL. Capture
adults with lamps that have a great attraction.
sprays in the twilight hours at the first signs of plaga.Se recommends applying a dose of 1.5-2 kg / ha of Trichlorfon and 30 l of broth by aerial application.
Aphids:
are hemipterans Aphidae family, considered a sporadic pest transient in the rice field. The damage is manifest from flowering, was observed on leaves and ears. If attacks occur in rice milk stage, distortions occur in spikes and grains.
Control.
chemical treatments are performed using Fenitrothion 60%, presented as ultra low volume liquid at doses of 1.25-2 l / ha.
DISEASES.
Pyricularia oryzae (see Pyricularia oryzae in rice paper).
RHIZOCTONIA SOLANI:
This disease is considered the second in economic importance after the blast. This increase is due to the intensity of cultivation, the widespread use of varieties early or semi-early and increased use of nitrogen fertilizers. The lesions occur mainly in the sheath, and these are at first ovoid, gray-green, with a length ranging between 1 and 3 cm. long. The center of the lesion becomes gray-white with a brown margin. The presence of different injuries that come to join causing the death of leaves or even the entire plant.
disease is accentuated in conditions of high humidity and temperature. The moisture is strongly influenced by the density, therefore high density and high fertilizer application rates tend to increase the effect of this disease. Development of this disease can be vertical or horizontal, the latter being faster and more severe, especially during the wet season and in plots with a high content of nitrogen fertilizers.
CONTROL. Collect
-affected plants.
-sound water management, draining 5-7 days in the state of maximum tillering.
-planting is recommended in line instead of the manual and the application of calcium superphosphate.
STEM ROT:
(Fusarium moliniforme. Sarocladium oryzae), this decay occurs in the leaf that surrounds the panicle. These stains can get together and can cover most of the leaf surface. The panicles only suffer a partial decay, but you can see a whitish powder inside the sheath and panicle.
CONTROL. Sanitation
ground.
Using high doses of potassium and nitrogen balanced doses.
Some genetically improved cultivars resistant to stem rot.
Burning stubble after harvest. Disinfection of seed
BROWN STAIN:
(Cochliobolus miyabeanus. Drechslera oryzae), this disease causes spots and oval brown with white or gray center. Sometimes, many spots on a leaf cause them to turn white. These besides appearing spots on leaves can be seen in glumes, pod and bracts of the panicle. Infected kernels are lighter weight and lower quality result.
Control.
Employment of certified seed, as this disease is spread primarily by seed. Check
soil conditions (drainage and nutrients).
tungro:
This is one of the most destructive diseases of rice, the symptoms appear on leaves, as these will turn yellow or orange. This disease is caused by a viral complex formed by the spherical virus (RTSV) and baciforme virus (RTBV), being transmitted this complex virus by several species of Homoptera. The increase of this disease is associated with increased vector population.
CONTROL.
Planting too early or too late is associated with the absence of tungro.
Early implementation of systemic insecticides.
additional applications of nitrogen.
NEMATODES:
Hirschmaniella oryzae, is an abundant nematode in rice fields since the flooding of the land is necessary to complete its cycle. Ditylenchus angustus, is present mainly in deepwater rice. Aphelenchoides besseyi is present in all ecosystems rice, feeding ectoparasite form of stem apical meristem. Then migrates to the developing panicle, penetrating the spikelets before anthesis feeding on the ovaries and stamens. During ripening of the grain, the nematodes enter a state of anaerobiosis and can survive on grains to more than three years.
Meloidogyne graminicola, M. incognita, M. and M. javanica arenaria, are the most important species of root nematodes. Symptoms include chlorosis, reduced growth, delayed flowering and increased the number of empty grains.
Pratylenchus indicus and Pratylenchus zeae damage to the root cause and are migratory endoparasites that cause necrosis in the roots, reducing the effect of plant height and number of children.
CONTROL.
remove debris from previous crops.
Treat the seeds with hot water at 52-57 ° C for 15 minutes after soaking the seeds in cold water for 3 hours.
Crop rotation can reduce population levels.
