In the normal growth process, rice is blocked by growth due to external unfavorable factors, and abnormal symptoms appear. These abnormal symptoms are summarized as “four evils”, namely water damage, fertilizer damage, phytotoxicity, disease, in the actual production process. In the middle, it is often unclear and unclear, and the measures taken are counterproductive. The methods of identifying the “four evils” in rice fields in recent years and their effective defense measures are introduced as follows:

　　 1 field four damage identification method

　　 1.1 Water damage: The overall can be divided into three types:

　　 1.1.1 Water quality water hazard: Due to the pollution of the irrigation water source itself, it contains harmful substances that are not suitable for rice growth and is caused by pouring into the field. In the field, most of the performances are as follows: the seedlings are damaged and the degree is the same, the leaves are dark red or dark green, the heart leaves are not out, the new roots are not long, the water surface is covered with beads, the water is pale green or light brown, the soil is dark brown and Have an odor.

　　 1.1.2 Water-rich water damage: Mainly in the long-term irrigation of Putian without dehydration, especially in the large amount of organic fertilizer applied in Putian, combined with the continuous fine weather and the temperature above 35 °C, there will be water- rich water damage. Due to the deterioration of the soil environment, there are many reducing substances, and the purple spots that are densely covered by the leaves of the seedlings are gradually increased from top to bottom, the tip of the leaves gradually decreases downward, the roots of the roots are less, the black roots are more, and the soil of the fields is The body is soft and the color is dark black. Under the action of external force, bubbles rise out of the water and have a foul smell.

　　 1.1.3 Poor water-resistance: Mainly due to the excessively heavy land in Putian, the root water absorption is less than the transpiration of the leaves. The overall performance of the field is that the leaf color of the upper leaves turns from tender green to dark green, and the lower leaves die early, the topsoil cracks. More, and the surrounding area is heavier than the middle of the field.

　　 1.2 Fertilizer: It is caused by improper fertilization method or unfavorable fertilization environment. The main symptoms are:

　　 1.2.1 There are non-expanding white plaques on the upper leaves of the plants. In severe cases, the leaves are broken from the white plaques 2-3 days after the appearance of white plaques. This phenomenon is mostly caused by the application of ammonium bicarbonate without mixing appropriate amount of fine soil. Due to the burning of ammonia gas, the degree of local weight varies, and the extent of the field varies.

　　 1.2.2 The middle and lower leaves of the plant appear to die when they are not senescent, and the leaves are reddish yellow. Most of this phenomenon is shallow in the field water layer, even without water layer. When the temperature reaches about 35 °C, the nitrogen fertilizer is applied in one time, causing ammonia agglutination.

　　 1.3 phytotoxicity

Due to improper application or misuse of pesticides, sometimes the symptoms are confused with the disease, but the symptoms do not spread once they appear.

The overall can be divided into two types:

　　 1.3.1 Insufficient use of insecticidal fungicides: Most of them appear to be purple-red from the tip of the leaf tip and the degree is gradually reduced. In severe cases, the apex of the apex of the leaf tip appears to be large and small, and the shape is more similar to the fusiform shape. When found, the heart leaf is basically normal, and the most serious is the inverted 2 , 3 , and 4 leaves.

　　 1.3.2 Misuse of herbicides: Mostly misuse of glyphosate, in low concentration, rice is difficult to appear seedling death, but growth stops, the early leaf color is dark green, the late plant is dwarfed, the base appears more Late-stage tillers; at high concentrations, the leaves are brown and the entire plant gradually dies.

　　 1.4 Diseases

Rice seedlings are caused by pests.

　　 1.4.1 susceptible diseases: such as rice leaf mites, sheath blight, rice smut, etc., their common feature is the abnormal symptoms appearing on the field plants, first scattered, with time delay, spread to the surrounding and The degree is getting worse.

　　 1.4.2 refractory diseases: such as stripe leaf blight, dry tip nematode disease. After being infected by harmful organisms, it is difficult to achieve the desired effect of chemical control.

　　 2 field four evil defense measures

　　 2.1 Water damage:

　　 2.1.1 Water quality water hazard: First of all, we must understand the water quality of the irrigation water source. If the water body is contaminated, it should be prevented from being poured into the polder. If the seedlings appear abnormal after the accidental irrigation, the field water should be drained immediately to create conditions for no pollution. The water source is continuously irrigated 2-3 times.

　　 2.1.2 Water-rich water damage: Regardless of the growth period of the seedlings, the soil should be drained in time, and the water layer should be poured into the water layer 1-2 days after the soil is solidified to promote its growth.

　　 2.1.3 Water-poor water damage: Water should be poured into the field in time to meet physiological needs.

　　 2.2 Fatty:

　　 2.2.1 Eliminate the habit of spreading ammonium bicarbonate in the growing season of seedlings and field, and advocate deep application to improve fertilizer utilization and avoid the occurrence of fat damage.

　　 2.2.2 When the urea is applied in the field, there should be a water layer of about 1.5 inches in the field . Especially when the temperature reaches 35 °C, the water layer should not be shallow. If there is fat damage, it should be immediately poured into the field.

　　 2.3 phytotoxicity

　　 2.3.1 During the pest control period, it must be used according to the prescribed dosage. Do not arbitrarily increase the dosage, and avoid the medication at high temperature at noon.

　　 2.3.2 Before using the drug, it is necessary to look at the trademark to prevent the herbicide from being used as an insecticide. A small amount of pesticide stored in the farmhouse should be stored separately with pesticides, fungicides and herbicides, and clearly marked.

　　 2.4 Diseases:

　　 2.4.1 For the treatment of susceptible diseases, the principle of prevention should be adhered to, and the quality of prevention and treatment should be selected to control the quality of prevention and control.

　　 2.4.2 For refractory diseases, effective prevention and control measures should be taken, such as selecting resistant varieties, adhering to pesticide soaking and other methods, and eradicating the pathogenic organisms before the hazards.