Center Drill Bit is also known as Slocombe Drills, Centre Drills were originally designed to create the countersink required to locate a tailstock centre when turning between centres. They have a point angle of 60° to match the angle of a Tailstock Centre.
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Minimize the use of pesticides. The selection of pest-resistant varieties is the most economical, safe and effective method for controlling pests and diseases. Secondly, in the summer or in the winter, the cultivated land can be used to kill some germs and eggs, and cooperate with the application of fully decomposed organic fertilizer. After strengthening the field management and creating environmental conditions suitable for crop growth and not conducive to the occurrence of pests and diseases, it can effectively reduce the occurrence of pests.
Specify the scope of use of pesticides. According to the chemical nature and toxicity of pesticides, it is forbidden to use pesticides with high toxicity, high toxicity, large accumulation and long residual period on some crops. Among them, alfalfa, phorate and carbofuran can only be used for seed treatment or soil treatment of cottonseed, wheat, corn, sugar beet, etc. Other crops should not be sprayed. Parathion is used to control fruit tree pests and must be used 30 days before fruit harvest.
Strictly control the application concentration, application amount, dosage form, frequency and application method of pesticides. In the agricultural dosage form, the amount of the emulsion oil is large, the milk powder and the wettable powder are the second, and the water agent is lower. From the application method, seed treatment, soil treatment, and tree dressing have higher residues than spraying and dusting. Special attention should be paid to the application of pesticides close to the harvest period of crops. It is necessary to select the variety of drugs with low toxicity and rapid decomposition, strictly control the dosage, concentration, application method, frequency of application and time of disabling.
Strictly follow the last application time before harvest. According to the safety interval of various pesticides, and according to the principle of early treatment, the pesticides can be greatly reduced in the growth period of crops and in the early stages of pests and the initial infection of the bacteria.
A Centre Drill can also be used to provide a start location for a drill when drilling down the centre of a bar held in a Lathe chuck. Centre Drills are short and rigid enough to mark the bar centre without wandering off if they are carefully offered up to a rotating work-piece.
After applying pesticides to various crops, some residual or excessive residues may remain on the surface, fruits and grains of crops for a certain period of time, and some may penetrate into the waxy layer or tissue of the epidermis of the crops. Some systemic drugs can also be absorbed by crops and moved to other parts, so that trace or excess pesticides or toxic metabolites are inevitably left in the harvested agricultural products. Over time, it may endanger the health of humans and animals.
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