How to prevent larch seedling diseases and pests
Larch belonged to Pinaceae family of Larch, which is characterized by high light, cold resistance and strong adaptability. With long life, fast growth and high economic value of wood, it is a good tree species for artificially creating fast-growing and high-yield timber forests. The main tree species of Larix gmelinii in Heilongjiang Province are Larix gmelinii, Larix olgensis, and Japanese larch. They are widely distributed in Daxinganling, Xiaoxing'anling, and eastern mountainous regions. With the full start of key forestry ecological projects, larch seedlings have been widely developed in Heilongjiang Province in recent years and have become one of the main nursery stocks for afforestation in Heilongjiang Province. The occurrence and spread of plant diseases and pests in the seedling stage of the larch is closely related to the local climate, temperature, humidity, soil conditions, etc. The common diseases are blight (dumping type, root rot type). Insect pests have fleas (scarab larvae) and crickets. To prevent and control the pests and diseases of larch seedlings, it is necessary to implement the principle of "prevention as the main and eliminate it actively" and do a good job of prevention. Prevention work includes carefully selecting nursery nurseries, strengthening management, timely sowing, and doing a good job in soil preparation, watering, weeding, environmental sanitation, and pharmaceutical preventive measures. I. Larch Seedling Disease Larch seedling disease is mainly caused by blight, which is a common disease that occurs after seedling emergence. It usually occurs in May and June and lasts for a long time. The disease is divided into two kinds of cataplexy and root rot. The characteristics of the triploid type are as follows: the root and stem of the larch seedlings are rotten, and the seedlings are wilted and withered. The root rot characteristics are: root rotting, yellow stems and leaves. Some seed sprouts are rotted in the soil, and round the soil around the infected seedlings. For this disease, specific prevention and control measures are: 1. Seed disinfection method. Before the seed germination treatment was performed, the seeds were mixed and mixed with Saili Powder. 0.25 kg of Saili powder was added to each 50 kg of seeds. After mixing, the samples were tightly packed in sacks, and then germination was performed overnight. It is also possible to soak seed in copper sulphate water, applying a ratio of 50 kg of seeds to 0.5 kg of copper sulphate. 2. Soil disinfection method. Before the larch seedbed is covered with sand, stir the pentachloronitrobenzene into the sand and spread it evenly on the seedbed. The application rate is 18.75 kg-22.5 kg per hectare. 3. Spray control method. Bordeaux fluid is a commonly used drug for preventing and controlling diseases of larch seedlings. It should be applied regardless of whether the disease is occurring or not. The seedlings are sprayed immediately after weeding, and then sprayed once every 7-10 days. Continuous spraying is required 4-5 times. The concentration of drug solution is generally 1% -2%, the concentration is lower first - some later, with the increase in the number of spraying the concentration can be higher. Bordeaux mixture should be ready for use. It should not be stored for a long time. It should not be applied on rainy days or when there are water on the stems and leaves of seedlings, so as not to reduce the efficacy. In addition, the five-race mixture (pentachloronitrobenzene and Sairan San with a ratio of 3:1, plus 200 times the water), and the five-generation mixture (pentachloronitrobenzene and zeocin in a ratio of 3:1, Add 200 times of water to make), Dysonite (made 1000 times solution) and 0.5 of alum liquid, etc., to prevent and cure larch blight better. Second, larch seedling insects Larch seedling pests, there are two main, one is cockroaches (ie, chafer larvae), mostly in the permeability of water, good ventilation in sandy loam soil, when the soil is dry, lurking in the ground, when When the soil is too wet, it climbs to the surface.蛴螬 In the morning or in the evening, pecking the roots of larch seedlings causes the seedlings to die. The period of its damage is mainly from June to September every four years, and August to September is the heaviest. The second is crickets, hi habitat in wet areas. It often passes through small holes in the larch seedbed to dig up the soil, causing the roots of larch seedlings to be pulled up and causing seedlings to die. For these two kinds of pests, the specific prevention and control measures are as follows: There are two methods commonly used for the prevention and control of earthworm damage. The first is to use a 6% HBC powder solution (or 666 powder noodles) mixed with sand or soil in the seed bed before turning the larch seedlings. Turn it into the ground while turning the floor. The dosage per hectare is between 7.5 kg and 15 kg, not excessive, and it should not be applied consecutively to prevent phytotoxicity. The second is that when larch seedlings are infested, the seedbeds can be carefully inspected at about 9:00 a.m. daily. If the seedlings are found to be plunged into the surface or the tip of the seedlings, they must be traced around the infected seedlings. A small soil ditch is raised in the seedlings' gaps, and 0.5% dimethoate solution is poured along the ditch. Then watering in the ditch is needed in time to expand the penetration range of the liquid and achieve the effect of killing pests. With 0.1%-0.2% of dichlorvos, dipterex solution spraying seedling bed surface, the effect of poisoning to kill cockroaches is better. 2. Prevention of cockroach damage. There are two methods commonly used for the prevention and control of earthworm damage. One is that in the evening, the bait is placed on the channel or hole where it is digging, and you can't go back into the hole after you eat the bait. You can leave it early the next morning. Morning catch burn. Poison baits can be prepared with trichlorfon and dichlorvos. The second is to dig dozens of small pits on the trails of larch nursery land. The four sides of the pits are really smooth, with horse dung under the ground and grass covered on the ground. The use of trichlorfon and dichlorvos had a good killing effect.