Control of common diseases and insect pests in lily cultivation

1. Disease 1. Penicillium: the disease is invaded by Penicillium through the wound on the bulb tissue and transmitted during storage. Symptoms: during storage, white spots grow on scale decay spots, and then fluffy green-blue patches grow. After infection, decay increases gradually throughout the storage period, even at a low temperature of-2 ℃. The pathogen will eventually invade the base of the bulb, making the bulb lose its value or slow the plant growth. Although the infected bulb looks unhealthy, the growth of the plant will not be affected during planting as long as the basal disc of the bulb is kept intact. After planting, the infection of Penicillium does not transfer to the stem, nor does it infect other plants from the soil. Prevention and control methods: do not plant those bulbs whose base plate has been infected; the susceptible bulbs should be planted as soon as possible. Before planting, they must be soaked in 1 / 1000 grams of carbendazim, chlorothalonil, carbendazim and other fungicides for 30 minutes, and then planted; before and after planting, maintain appropriate soil moisture; store the bulbs at the recommended minimum temperature. 2. Bulb, scale rot and stem disease caused by Fusarium: this disease is caused by Fusarium oxysporum and self-destructive Alternaria. These fungi infect the underground part of the plant through wounds or parasitic insects, which are mainly caused by the cracking of bulbs and stem roots. These fungi can expand on bulbs, bacteria can also be infected through the soil, and some varieties are particularly sensitive to infection. Symptoms: plants with rotten bulbs and scales grow very slowly and their leaves are light green. In the ground, brown spots appear on the top of the scales or at the junction of the scales and the root disc, and these spots gradually begin to rot (scales rot). If the root disc is infected, the whole bulb will rot. Stem rot is a symptom of Fusarium infection in aboveground parts, which is marked by the fact that the basal leaves turn yellow in adolescence and turn brown and fall off after yellowing. In the underground part of the stem, orange to dark brown spots appear, and then the spot expands, and finally extends to the inside of the stem. Then the stem rotted, and finally the plant died under age. Prevention and treatment: disinfect the infected soil; plant those lightly or moderately infected bulbs as soon as possible, and the soil temperature should be low. 3. Rhizoctonia: this disease is caused by Rhizoctonia solani. This fungus mainly infects plants from the soil and is most active when the temperature is higher than 15 ℃ and moisture. This fungus can harm many other plants, such as tulips, irises, chrysanthemums and tomatoes, so many soils are infected by Rhizoctonia. Symptoms: if the infection is mild, it only harms the leaves in the soil and the green leaves in the lower part of the buds, with sunken light brown spots on the leaves. Generally speaking, although the growth of the plant is affected, it can continue to grow. If the plant is seriously infected, the growth of the upper part of the plant will be hindered, and the white leaves in the underground part and the basal leaves in the upper part will rot or wilt off, leaving only brown scars on the stem. Young leaves and growth points are often harmed, and infected plants will inhibit rhizome development, which in turn hinders plant growth, resulting in poor or even non-flowering, because the flower buds have dried up at an early stage. Control methods: disinfect the suspected infected soil with soil disinfectants. After disinfection, the soil must not be infected again, especially when the soil temperature is high in summer. If the previous crops have been infected, general soil disinfectants should not be applied, and the soil should be pre-treated with Rhizoctonia control agents before planting (completely added to the depth of soil 10cm). 4. Phytophthora: this disease is usually caused by the fungus Phytophthora and its varieties. No Phytophthora was found in Dutch bulb cultivation. In the subtropical climate, it affects many kinds of plants, so it can be found in most cultivated soils. This fungus is common in the soil where tomatoes and Flowers have been cultivated, and can survive in moist soil for many years. Too moist soil and plants and high temperatures (above 20 ℃) will promote the occurrence of the disease. Symptoms: plant foot rot (Phytophthora) can hinder growth or cause it to wither suddenly. Soft rot occurs at the infected base of the stem, which becomes dark green to brown and expands upward, the leaves turn yellow and begin to lose color at the base of the stem. Similar soft rot infection often occurs on the stem on the ground, causing the stem to collapse or bend. Prevention and control methods: disinfect infected soil with general soil disinfectants; use fungicides to control Pythium during cultivation can also effectively control foot rot; ensure that the soil has good drainage conditions to prevent crops from being moist for a long time after watering; in summer, the soil temperature should be as low as possible. 5. Pythium: this kind of root rot is caused by Pythium. The fungus is active in humid conditions and at temperatures of 20-30 ℃. They exist in soil and bulb roots, and unsuitable cultivation conditions, such as poor soil structure, high soil salinity or too wet soil, can promote the occurrence of the disease. Symptoms: this kind of bacteria can invade the roots of plants in an area, causing root rot, dwarfing susceptible plants, yellowing lower leaves, narrowing upper leaves, lighter leaves and often wilting, especially under high temperature transpiration. When the plant is affected by root rot, the flower bud shrinks. These plants often have buds falling in winter. And the flowers are small and often cannot be fully opened, or the flowers are not easy to color. If the plants are pulled up, transparent, beige rot spots can be seen on the bulbs and rhizomes, or they have become completely soft and rotten. Control methods: disinfect infected or suspected infected soil with general soil disinfectants; keep the soil temperature low at the beginning of cultivation and adopt correct cultivation steps throughout the cultivation period; fungicides that are easy to spray on crops to control Pythium can be used after crop growth or when Pythium infection may occur, preferably in the evening If infection has been observed, keep the greenhouse and soil temperature as low as possible to limit crop transpiration, which can be achieved through ventilation and shading, and the soil is kept as moist as possible. 6. Staphylococci: "fire" spots caused by staphylococci. In a humid environment, staphylococci develop and produce spores, which can quickly spread to neighboring plants through the wind or Rain Water. Spores do not germinate on dried plants, so dried plants do not become infected. Symptom: small dark brown dots with a diameter of 1~2mm can be seen on the leaves. Under wet conditions, these dots quickly develop into larger round or oval well-defined spots. The spot is visible to the naked eye on both sides of the leaf. The infected tissue gradually dies (withered into paper). Infection can start not only from the middle of the leaf, but also from the edge of the leaf, making the leaf deformed and hindering the growth of the leaf. The stem can also be infected, resulting in complete decay or abnormal development of the bud. In the early stages of infection, protuberant areas appear on the outer petals of the newly infected buds. Blooming flowers are extremely sensitive to infection and show gray, water-soaked, round spots that become "fire spots". Control methods: keep the plant dry as far as possible, reduce the planting density, increase ventilation and heating; in the disease-prone season, you can alternately use staphylococcal fungicides (such as benate) in the early stage; remove weeds and plant residues to ensure cleanliness and hygiene. 2. Insect pest 1. Aphid symptoms: the leaves at the bottom of the infected plants develop normally, while the upper leaves are curled and deformed at the early stage of development. Aphids only harm young leaves, especially downward leaves, as well as buds, producing green spots, and flowers become deformed and some are still green. Control method: remove weeds, because weeds are often the host of aphids; if aphids appear, spray crops with pesticides every week. Use drugs alternately to prevent aphids from developing drug resistance. Physiological diseases 1. Leaf burning: when the balance between water absorption and evaporation of the plant is destroyed, the leaves will scorch. This is the result of calcium deficiency in young leaf cells when water absorption or transpiration is insufficient. The cells are damaged and die. At the same time, the poor roots, the high salt content in the soil and the rapid growth relative to the roots, the sharp change of relative humidity in the greenhouse will affect this process. Big balls of sensitive varieties are more likely to occur. Symptoms: first, the young leaves curl slightly inward, and a few days later, yellow to white spots appear on the scorched leaves. If the leaf scorch is light, the plant can continue to grow normally, but if the leaf scorch is very serious, the white spot can turn brown, where the injury occurs, the leaf bends. In very serious cases, all leaves and buds will fall off and the plant will not develop further, which is called "the most severe scorch". Control methods: ensure that the plant has a good root system; keep the soil moist before planting; it is best not to use sensitive varieties or small balls; the planting depth should be appropriate, there should be a soil layer of 6~10cm above the bulb; in the time of increasing sensitivity, avoid large differences in temperature and relative humidity in the greenhouse, try to keep the relative humidity level around 75%; prevent excessive growth Ensure that the plant can maintain a steady transpiration. 2. Falling buds and dry flower buds: falling buds occur when the plant can not get enough light. Under the condition of lack of light, the stamens in the flower bud produce ethylene, which leads to flower bud abortion. If the living condition of root system is poor, it will increase the risk of bud shrinkage. Symptoms: falling buds occur when the buds reach 1~2cm. The color of the bud changes to light green, at the same time, the pedicel connected to the stem shortens, and then the bud falls off. In spring, the low buds are affected first, while in autumn, the high buds will fall off first. Dry shrinkage of flower buds occurs throughout the growing season. The flower buds turn completely white and dry. These dried flower buds sometimes fall off, and if the flower buds dry and shrink in the early stages of development, tiny white spots will appear in the leaf axils later. Control methods: do not cultivate varieties that are easy to drop buds in poor light; in order to prevent flower buds from drying and shrinking, the bulbs can not be dried during cultivation; to ensure good root growth of the plant. 3. Element deficiency: in the process of lily cultivation, one or more symptoms of element deficiency may be encountered, some of which can be judged by the change of leaf color. If the corresponding elements are added in time, these symptoms can be prevented or alleviated. 1) symptoms of nitrogen deficiency (N): the growth of the plant is slow; the leaves are uniform light green to yellow. Solution: use available nitrogen fertilizer to adjust quickly, such as calcium nitrate (Ca (NO3) 2), urea (CO (NH2) 2) or potassium nitrate (KNO3). These fertilizers can be mixed with irrigation water or sprayed and then leached. 2) symptoms of calcium deficiency (Ca): the growth of the plant is slow, the leaf color becomes lighter, the leaf tip bends downward, sometimes the tip turns brown, the leaf is sometimes light green with white spots, and the root is stunted. Solution: lime can be added to the soil before planting to prevent it; there are other fertilizers that can also help alleviate the symptoms of calcium deficiency: magnesium carbonate (MgCO3), magnesium oxide (MgO), magnesium hydroxide (Mg (OH) 2). 3) symptoms of phosphorus deficiency (P): the growth of the plant was slow, the leaves were light green and dull, and the tips of the old leaves turned reddish brown. Solution: it is difficult to remedy phosphorus deficiency during cultivation. The content of phosphorus in soil should be suitable before cultivation, and calcium hydrogen phosphate (CaHPO4) can be used to supplement it. The fertilizer does not contain fluorine. Can be sprinkled on the soil before preparing the soil. 4) symptoms of potassium deficiency (K): plants grow slowly and somewhat short; growth rate is lower than normal plants; young leaves are dark yellowish green, leaf tips are brown; small white necrotic spots are distributed on the whole leaves; further, leaf tips wither. Solution: potassium nitrate and other fertilizers can be used to make up for it, which can be mixed in irrigation solution. 5) symptoms of magnesium deficiency (Mg): the expression of magnesium deficiency was faster, and that of the oldest leaf was the most obvious. It is mainly characterized by slow plant growth, light green leaves and downward bending, and sometimes brown-white spots along the longitudinal direction of the leaves. Solution: magnesium sulfate can be used to remedy, dissolve it in irrigation water and provide it to the plant, or spray it directly on the ground between the plants. 6) Iron deficiency (Fe) symptoms: iron deficiency symptoms can occur in any type of soil, and iron deficiency symptoms are easy to occur in lilies, especially oriental hybrid and iron cannon hybrids. They are as follows: yellowing between leaf veins; symptoms are mainly concentrated in the upper part of the plant; it is easy to occur when the growth rate is fast; in severe cases, the top leaves of iron cannon hybrid lilies will turn white. Solution: chelate iron can be used for prevention. Their effect mainly depends on the pH value in the soil. The two commonly used chelating iron are EDDHA and DTPA. Because EDDHA is suitable for soil pH in the range of 3.5 to 9, it can be used in any type of soil. The range of soil pH suitable for DTPA is from acidity to 7, and its effect will be greatly reduced when the pH value in the soil is higher than 7. According to the severity of the symptoms shown by the plant, 3-5 grams of chelated iron can be used per square meter. After use, if it is not completely washed, EDDHA will leave dark brown spots on the leaves. DTPA can be used with fertilizers, and the chelated iron comes in 3 and 6 per cent forms. Because the sun will decompose the chelated iron, the dissolved chelated iron should pay attention to avoid the exposure of sunlight. 7) Manganese deficiency (Mn) is not obvious in lily, and it has little effect on plant growth. Symptoms: the new leaves at the top of the plant become lighter in color; the leaf tips sometimes turn yellow or light brown. Solution: it can be solved by providing plants with chelated manganese or manganese sulfate (MnSO4H2O). 4. During the planting of lily, excessive amounts of potassium, magnesium, iron, copper, boron and molybdenum will not show any symptoms on the leaves. However, excessive manganese will make the veins turn purple, and at first there will be purplish red spots on the tip of the old leaves. Excessive manganese will occur after soil steam disinfection, especially when the soil pH is low. This can be balanced by adding lime to the soil (at least one week before planting), raising the pH value of the soil to above 6.5, or waiting at least three weeks before planting. If the level of calcium in the soil is high, it will cause the plant to suppress the absorption of iron, phosphorus and magnesium.