Exploration on the Problems of Orchid Leaf Scorched Tip and Other Diseases (Illustration)

(1) the main reason for the scorched tip of orchid leaves

There are many reasons for the scorched tip of orchid leaves, some are caused by natural factors, some are caused by improper management, and some are caused by diseases. Among them, the damage of coke tip caused by disease is the most serious.

1. The focal point caused by natural factors

(1) the humidity is too low: the focal tip of the orchid leaf is closely related to the water supply, especially the Huilan leaf is longer, if the water supply is not high, it is bound to cause the focal tip of the orchid leaf. The water supply of orchid leaves is transported by the roots and absorbed from the air. Therefore, the reason for the focal tip of orchids has a lot to do with the low air humidity, in addition to the excessive dryness of the potted soil. If the humidity in the air is too low and too dry, the transpiration of orchid plants will be strengthened, and the imbalance between water supply and demand of orchid leaves will lead to the scorched tip of orchid leaves. Generally speaking, the indoor orchid cultivation air humidity is larger, the orchid leaf coke tip situation is not serious, while the outdoor orchid cultivation air humidity is difficult to control, the orchid leaf coke tip situation is more serious.

(2) sudden climate change: in 2007, for example, people just moved orchids out of the orchid houses with high humidity, that is, they encountered a drought that occurred once in decades, the rivers dried up and the air humidity reached the bottom, so the coke tip of orchids was more serious. Although the plum rain season comes late, but it takes a long time, about 50 days, the orchid leaves that have not seen the sun for a long time are both thin and soft, and immediately encounter the hot sun just out of the plum rain season, so the Jiaojian situation becomes more and more serious.

(3) Air pollution: near the sewage area, industrial area, or someone burns harmful substances near Lan Yuan, causing harmful gases in the air to harm the orchid leaves and cause coke tips.

2. Focal point caused by improper management

(1) excessive light: lack of shading or insufficient shading in summer, resulting in too strong light, resulting in the scorched tip of orchid leaves.

(2) long-term shading: orchids grow in excessive shade, weak light and long-term shading, resulting in thin and weak orchid leaves. if orchids suddenly see strong light, it is easy to cause orchid scorched heads to shrink leaves.

(3) Water injury seedlings: watering too often, causing rotting roots and leading to scorched tips. Spray water in the sun, the water gathers the leaf tip, and the focal tip is illuminated by strong light. The water quality of the watering is polluted, or the orchids exposed to acid rain can also cause scorched leaves.

(4) Fertilizer damage to leaves: the concentration of fertilizer in the root system was too high and the frequency was too frequent, resulting in the scorched black of the orchid root and the scorched tip of the orchid leaf.

(5) excessive concentration of pesticide: the proportion of pesticides has a certain proportion, if the concentration exceeds the standard, the spraying amount is too much, resulting in the accumulation of pesticides in the leaf tip of orchid, causing damage to the leaf tip and causing coke tip.

(6) the plant material is too dry: lazy watering causes the plant material in the basin to be too dry to meet the water demand of the orchid plant, forming the empty root, the orchid leaf can not get the normal water supply, and the coke tip of the orchid leaf is caused by the loss of water.

The above several kinds of orchid leaf focal tips caused by natural factors or improper management are usually called physiological focal tips, which are usually black, and there are no black horizontal lines in the pathogeny, so they will not move forward rapidly, the course of the disease is relatively slow, and the harm degree is not great. (figure 1: physiological focal tip symptoms) as long as the cause is identified and symptomatic management, the harm of orchid leaves can be controlled.

Figure 1: physiological focal tip symptoms

3. The focal point caused by bacteria

(1) bacterial brown spot: the brown spot of orchid is caused by bacteria infecting orchid leaves, which is the most ferocious scorched tip disease in orchid leaf diseases. It is easy to identify, and its disease spot is brown. At the initial stage of the disease, the leaves have watermarked discoloration spots that seem to be scalded by boiling water, and quickly push forward, resulting in the death of the whole leaf, which is highly contagious, spreads rapidly and does great harm. (figure 2: symptoms of brown spot)

Figure 2: symptoms of brown spot

(2) anthrax: anthracnose of orchid is caused by fungi, which is the most common scorch tip disease of orchid leaves, which is easy to identify. it is characterized by a number of wavy transverse black belts after the leaf tip is damaged and withered, and if the focal tip leaves are not treated, it will continue to move forward, which is a serious scorch tip disease. (figure 3: anthrax symptoms)

Figure 3: anthrax symptoms

(3) Black spot: the black spot of orchid is caused by fungi, which is one of the most common scorch tip diseases of orchid leaves, which is easy to identify. Its remarkable characteristic is that the disease spot is round, scattered on the leaf surface and leaf edge, and can also be connected into one piece when it is serious. so that the whole orchid leaf loses its ornamental value. (figure 4: symptoms of black spot)

Figure 4: symptoms of black spot

(4) Leaf blight: orchid leaf blight is caused by fungi, which is one of the more ferocious scorch tip diseases, which is easy to identify. Its remarkable characteristic is that in the later stage, the leaf tip turns gray and white, the whole leaf dies, the junction of the diseased leaf is dark brown, and it advances continuously, even making the whole leaf dry up rapidly and do great harm. (figure 5: symptoms of leaf blight)

Figure 5: symptoms of leaf blight

(5) Blight tip disease: orchid tip blight is caused by fungi and is the most common scorched tip disease, which is easy to identify. It is characterized by grayish yellow dead parts, no banding marks (different from anthracnose) and dark brown markings at the junction. (figure 6: symptoms of tip blight)

Figure 6: symptoms of tip blight

The above diseases sometimes occur alone, and sometimes several diseases occur at the same time. For example, orchids suffer from not only leaf blight but also black spot, which still exists after the leaves die. (figure 7: leaf blight and black spot on the leaves).

Figure 7: leaf blight and black spot on the leaves

For example, the orchid leaf suffers from both anthracnose and black spot, and the two diseases exist at the same time after the death of the leaf. (figure 8: anthrax and black spot damage at the same time)

Figure 8: anthrax and black spot damage at the same time

The focal tip of the orchid leaves caused by the pathogen is generally more serious, the disease usually has black stripes, and the black stripes are constantly moving forward (figure 9: black stripes at the junction of the diseased leaves). In serious cases, the whole leaf is scorched, and even if it is cut off, it will continue to scorch, and then cut and scorch again until bald. It even constitutes a deterrent to the life of the orchid plant.

Figure 9: black stripes at the junction of diseased leaves

(2) accurate diagnosis of orchid leaf scorch tip disease.

Although the symptoms of all kinds of focal point disease have been clearly explained before, it is difficult to distinguish what causes the focal point of Lanyou in general. In fact, it can be identified as long as you pay attention to observation. (figure 10: physiological focal tip, brown spot, anthracnose, blight, leaf blight and black spot) the significant difference between them can be seen clearly from this picture.

Figure 10: physiological focal tip, brown spot, anthracnose, blight, leaf blight and black spot

1. Physiological focal tip: (water injury, fat injury, drug injury, etc.) the injured place is all black, and there are no black stripes at the junction; the pathological scorched tip leaves are not black after withered, and there are black striped disease spots at the junction.

2. Disease spots caused by bacteria: at the initial stage, there were waterlogged brown plaques scalded by boiling water, while the withered tips caused by fungi did not have yellowish brown plaques.

3. Diseases caused by fungi: there are generally black spots at the junction. On the withered tip damaged by anthrax, there are several horizontal wavy black stripes, which are not found in other diseases; the diseased leaves damaged by leaf blight are gray-white; the leaves damaged by leaf blight are grayish yellow.

To sum up, the injured parts of the physiological focal tip are all black, and there are no black stripes at the junction of the diseased leaves; the damaged parts of bacterial brown spot begin to have brown patches, the later diseased spots are black, and there are black horizontal stripes at the junctions of diseased leaves; there are several transverse wavy black stripes on the leaves damaged by anthracnose, and there are black stripes at the junction of diseased leaves; the damaged parts of leaf blight are gray-white, and there are black horizontal striations at the junction of diseased leaves. The affected part of the blight tip disease is grayish yellow, and there are black stripes at the junction of the diseased leaves.

Only by accurately grasping the symptoms of all kinds of scorch tip disease, can we have a clear idea and a definite target in the treatment of coke tip disease, so we must make efforts to study it and really prescribe the right medicine to the case in the treatment.

(3) measures for radical cure of scorch tip disease

It is difficult to fundamentally eliminate the orchid leaf scorch tip disease caused by the disease, but as long as active treatment, careful management and comprehensive control, remarkable results will be achieved.

1. The diseased leaves should be cut off: since the leaves have been scorched, they are not enough to be cut off. They must be cut off resolutely, and there is no need for nostalgia at all. Cut off the diseased leaves thoroughly, and the cut mouth should be more than 1 cm away from the diseased spot. If the disease of the old plant is serious, the whole plant can be cut off mercilessly. (figure 11: diseased leaves are cut off) and sprayed with methyl topiramate. After the diseased leaves are cut off, they should be burned or buried deeply. Never leave the diseased leaves in the Orchid Garden, and the diseased leaves that fall on the ground during pruning should also be picked up to prevent them from becoming the source of the disease again.

Figure 11: removal of diseased leaves

2, the use of medicine should be symptomatic: since the orchid leaf has been scorched, what is the cause to find out? If it is the physiological focus caused by improper management, then strengthen the management of the symptoms. If it is the focal point caused by the disease, it is easy to distinguish whether it is caused by bacteria or fungi, that is, the brown spot caused by bacteria has an obvious symptom: at the beginning of the disease, the spot looks like a waterlogged mark of boiling water. Diseases caused by bacteria can be prevented and treated with agricultural streptomycin and Yekuning, while diseases caused by fungi are treated with methyl topiramate, chlorothalonil, Shigao and other agents. If it is difficult to distinguish what kind of disease it is, the mixture of bactericidal agents and fungicidal agents can also achieve twice the result with half the effort.

3. Treatment should be timely: once the condition is found, it should be treated with medicine in time, and there must be no paralysis thought that "the focal tip of the orchid leaf has nothing to do with it", let alone the wrong idea that the focal tip of the orchid leaf is normal, and delay the treatment, resulting in aggravation of the disease and expansion of the scope. It is necessary to clearly realize that the infection rate of orchid leaf disease is very fast, although it is not fatal, it loses its ornamental value.

4. Prevention should always be grasped: "Prevention is more important than cure". Prevention work should be carried out unremittingly, liquid medicine should be sprayed regularly, preventive medicine should be used from early spring, and drugs for killing bacteria and fungi should be served together every 10 to 15 days, even if no illness is found, prevention should be taken in the bud, and the disease should be eliminated in the bud.

5. Water spraying should be strictly prohibited: once the focal point caused by germs appears in the orchid leaves, water spraying must be strictly prohibited. Because spraying water will moisten the leaves and accelerate the reproduction of bacteria, at the same time, spraying water will accelerate the spread of bacteria, resulting in malignant spread. If there is too much dust on the leaf surface, which affects the photosynthesis and respiration of the orchid, it can be sprayed together with other fungicides immediately when the leaf surface is dry after spraying water to prevent the spread of bacteria.

6. Management should be strengthened: not only the physiological focal point of orchid leaf is related to management, but also, in the final analysis, the focal tip caused by bacteria also has a lot to do with management. therefore, we should think more and study more in management and do a good job in the management of orchids. Try to put an end to man-made coke tips of orchid leaves.

7. Be cautious in buying grass: resale grass and greenhouse seedlings almost grow in potions because they grow in high temperature and humidity for many years. Once they are transplanted to the natural environment, they will quickly cause scorched heads to shrink leaves due to increased light, reduced humidity and other reasons.

8. Pesticides should be rotated: any pesticide used for a long time will produce drug resistance, so one pesticide must not be used for a long time to control diseases. Pesticides should be rotated frequently, generally speaking, each pesticide can be exchanged after three consecutive uses, so that a better control effect can be achieved.