Rice is an important field crop in China. However, in the process of rice growth, it often suffers from some diseases and insect pests, such as aphids, cockroaches, and bacterial blight. In addition, various types of dry crops appear in the fields. seedling. How to correctly judge and distinguish these dead seedlings is of great significance in investigating the occurrence of pests and diseases and in guiding the control of pesticides. Several common dead seedlings in the field are now described as follows:

Rice seedlings

Dead rice caused by aphids

The aphids that are harmful to rice mainly include rice stem borer, rice stem borer, and large borer. (1) In the rice seedling stage and tillering stage, the saponaria indica enters the base of the rice stem, damages the heart or stem tissue of the rice plant, causes the heart lobe to lose water volume, the appearance of onion tube, leaf color chlorosis Or blue-gray, at this time if the curling of the heart out, visible insect bite at the incision is neat, but the heart or the growth point has not been completely destroyed, which is called "false dead heart" in the forecast. With the further damage of the anthill, the heart and leaves of the plant have died, but other leaves are still green and form a dead heart seedling. The rice borer borer is harmful to the rice borer, and there is no insect excrement outside the hole, but there are white fine insects in the rice stem. (2) After larvae hatched, the ants first clustered to feed on the inner side of the leaf sheath, causing grayish-yellow water-stained macules at the leaf sheath or veins, called the discolored leaf sheath. The larvae continue to harm and the tips of the leaves turn yellow. A row of holes can be clearly seen on the newly extracted leaves of the damaged plants. When the damage is serious, the heart leaves are yellow and die, there are pods on the stems, and a small amount of insect feces is outside the holes. , Insect faeces yellow white. (3) Large numbers of rice plants were found in the rice field in the field, and there were fewer plants in the middle of the field. The larvae infested rice plants with large pod bores and many insect excrements. Most worm excrements were sandwiched between rice stems and leaf sheaths, and the gnawed heart was broken at the broken heart. This is the main difference between larvae and other aphids. .

Rice seedlings caused by earthworms

Aphid damages rice, often bite off the rice stalks from the base part or all, and is in a tangled form of torn silk. The whole plant of the rice plant chlorotic, causing the yellow leaves of rice leaves to die. Damaged rice is easy to pull up, there are no wormholes on rice stems, and no insect feces. This type of dry heart is generally prone to occur when the rice is in the field or because of prolonged drought and water in the rice fields.

Rice dead rice caused by rodent damage

Usually only occurs in the booting stage of rice. The characteristic is that the ear of panicle is crushed and the dead heart is not easy to pull up. The general hazard is lighter and no control is required.

Disease caused by dead rice seedlings

A variety of rice diseases can cause dead heart seedlings: (1) bacterial leaf blight. Common acute and wilting diseased strains. The following 1 or 2 leaves of the heart or leaf lose water, curl, and show symptoms of blight. They are similar to the "false dead heart" caused by the damage of Sanhua, but they cannot find wormholes and insect feces on the diseased plants. Not easy to pull up, and after the onset of other leaves also gradually died of dry blue. When the weather is wet or when the dew is dry, yellow sticky dewdrops (ie, pyothelium) can also be seen on the diseased plants. After drying, they appear like fish-like small micelles. A small piece of fresh diseased leaf was squeezed and squeezed in a piece of glass. When the light was observed, there was a yellowish pus exudate from the leaf veins. (2) Viral disease. The symptoms caused by dry heart are similar to that of Sanhuan, and there are no holes in the culms on the damaged plants, no insects, and the heart leaves are not easy to pull up. They are also sterile and pus. (3) Bacterial brown strip disease. Occurs in low flooded fields. Symptoms are characterized by the hand squeezing the diseased tissue, yellow-white bacteria pus overflow, with foul odor, stripping out the leaves, visible water spots growing point is rotting, dead heart seedlings is not easy to pull up. (4) Bacterial base rot. Generally occurs in the rice tillering stage, the symptoms are characterized by hand-squeezing the diseased tissue, there is a yellow-white bacteria pus overflow, with odor, dead heart seedling stem base dark brown rot, easy to pull up. (5) Stripe leaf blight. The dead heart caused by stripe leaf blight has no wormholes in the stems of rice plants. It does not rot, the dead heart is not easy to pull up, the heart leaves have yellowish-white streaks, and the curls are drooping. The heart of this dead heart seedling is thin, and it sags to death. Pull up the dead heart and break it without any traces.

The Preventive Measures of Rice Dead Heart Seedlings

To prevent and treat rice withered, it is necessary to do a good job of investigating and researching. What kind of field is Lintian's observation and discrimination? Is it caused by insect pests or diseases, and then use insecticides or fungicides to prevent and treat the disease? The prevention and control of rice aphids has accumulated more experience, but rice farmers are a bit overwhelmed with the prevention and control of pests such as cockroaches. Phosphor pesticides such as phoxim and other organophosphorus pesticides have poor control and are sprayed with deltamethrin in the evening. Killing) and S-fenvalerate (Ryforin) and other pyrethroid pesticides have a better control effect. After the carbofuran pesticide was banned, it was baited with trichlorfon and mixed baits. 90% crystals of trichlorfon 100-150 grams per acre, heated water 1.5-2 kilograms, mixed with sauteed wheat bran and other baits, spread in the sunny evening when no wind, scattered around the edge of the paddy fields, focus on the In areas with severe hazards and field ridges, culling and killing effects are better. After the paddy field has been reclaimed from the field, the alfalfa no longer enters the paddy field. If paddy fields are about to be rehydrated, no preventive measures can be taken. Disease caused by dry heart, found that the symptoms of drug use, generally more difficult to control, especially bacterial brown bar disease, bacterial base rot disease onset, once the disease, that is, the use of drug control has little effect. The main requirement is to do a good job of disinfecting the seeds and prevent the seeds from entering the field, so as to reduce the pressure on the prevention of future fields.

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