During the growth process of rice, it is often damaged by various pests such as aphids, mites and bacterial blight, and various kinds of dead seedlings appear in the field. How to correctly judge and distinguish these dead seedlings is of great significance for investigating the occurrence of pests and diseases and guiding the prevention and treatment of pesticides. Here are some common dead seedlings in the field:
The bitterness caused by locusts
The aphids that harm rice are mainly mites, mites and cockroaches. (1) In the rice seedling stage and tillering stage, the ants are plucked into the base of the rice stem, impairing the heart leaf or stem tissue of the rice plant, causing the heart leaf to lose water and roll vertically, and the appearance is onion tubular, and the leaf color is chlorotic. Or it is blue-gray. If the curled heart leaves are taken out at this time, it can be seen that the incision is neatly cut at the bite, but the heart leaf or growth point has not been completely destroyed. This is called “false heart†in the measurement report. With the further damage of the anthill, the heart of the plant is dead, but the other leaves are still green and green, forming a dead heart seedling. The mites harmed by the rice mites are small, and there are no worms outside the holes, but there are white granules in the rice stems. (2) After hatching, the ants are first clustered on the inner side of the leaf sheath to take food hazard, so that the yellow-stained water-stained macula appears in the leaf sheath or vein, called the color-changing leaf sheath. The larvae continue to be harmed, and the tip of the leaves turns yellow. On the newly extracted leaves of the damaged plants, a row of holes can be clearly seen. When the damage is serious, the heart leaves are yellow and die, and there are pupils on the stems. The worm in the stem is yellowish white. (3) In the case of a large number of rice cultivars, there are more rice in the field, and there are fewer harmful plants in the middle of the field. Datun invaded rice plants have large pupils and many worms, and most of the worms are trapped between the rice stalks and the sheaths. The broken heart is a tear-like hemp, which is the main difference between the cockroaches and other mites. .
枯 caused by the heart
The cockroach harms rice, and the rice plexus is often bitten off from the base, and it is twisted and hemp-like. The whole plant of the rice plant is chlorotic, causing the rice heart to yellow and die. The damaged rice is easy to pull up, and there is no wormhole on the rice stem, and there is no insect feces. This type of dryness is generally more likely to occur in rice fields or due to prolonged drought and waterless rice fields.
Heartlessness caused by rodents
It usually only occurs at the booting stage of rice. The characteristic is that the stalk is bitten, and the dead heart is not easy to pull up. The hazard is generally light and does not require prevention.
The heart of the disease
A variety of rice diseases can cause dry heart seedlings: (1) bacterial blight. Common types are acute and wilting strains. Below the heart leaf or heart leaf, 1 and 2 leaves lose water and curl, showing symptoms of green and dry, similar to the "fake heart" caused by the damage of the mites, but the pupils and worms can not be found on the diseased plants. It is not easy to pull up, and other leaves are gradually dead after the onset. When the weather is wet or the dew is not dry, yellow sticky viscous dewdrops (ie, pus) can be seen on the diseased plants, and after drying, they are like fish-like small micelles. Take a small piece of fresh diseased leaves and squeeze it in the glass piece. For the light, you can see the yellow pus out of the vein. (2) Viral disease. The symptoms of heartlessness are similar to those of Sanhuai. There is no pupil on the stem of the victim, no insect feces, and the heart leaf is not easy to pull up. It is also sterile and pus. The leaves are clamped in the glass piece and can not be seen. (3) bacterial brown streak disease. Most occur in low-lying flooded fields. Symptoms are characterized by crushing the diseased tissue by hand. There is a yellow-white pus overflow, which has a foul smell and peels off the leaves. It can be seen that the growth point is watery and rotten, and the dead heart is difficult to pull up. (4) Bacterial base rot. It usually occurs in the tillering stage of rice. The symptom is characterized by crushing the diseased tissue by hand. There is a yellow-white fungus pus overflowing, which has an odor. The base of the stem of the dead heart seedling becomes dark brown and rot, which is easy to pull up. (5) Stripe leaf blight. The bitterness caused by stripe leaf blight, the stem of the rice plant has no wormholes, does not rot, and the heart is not easy to pull up. The heart leaves have yellow-white streaks, and the curls are drooping. The heart of this dead seedling is weak, bent and drooping to death. Pulling up the heart, there is no trace at the break.
Rice control measures
To prevent and control rice seedlings, we must do a good job in investigation and research. The type of Lintian observation is the type of insecticide caused by the disease, and then the insecticide or fungicide is used to prevent and treat the disease. There are many experiences in the prevention and control of rice aphids, but the rice farmers are a little overwhelmed by pests such as cockroaches, and the effect of spraying with organophosphorus pesticides such as phoxim is not good. Spraying deltamethrin in the evening (enemy) Killing), S-Fenvalerate (Rifampicin) and other pyrethroid pesticides have a better control effect. After the carbofuran pesticide is banned, it is trapped with trichlorfon. Use 90% crystal trichlorfon 100~150g per acre, 1.5~2kg heating water, mix with sauteed wheat bran, etc., and make it bait around the edge of rice paddy in the evening when there is no wind in the evening, focus on è¼è›„The trapping effect is better in the areas where the damage is more serious and the field. After the rice fields are rehydrated, the cockroaches will no longer enter the rice field. If the paddy field is about to rehydrate, no preventive measures can be taken. The disease caused by the heart, found symptoms of medication, generally difficult to control, especially bacterial brown streak disease, bacterial base rot disease incidence field, once the disease occurs, that is, the use of drug control has little effect. It is mainly required to do a good job of disinfecting the seeds, to prevent the seeds from carrying bacteria into the field, and to alleviate the pressure of prevention and control in the field.
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