Orchid leaf tips turning black
Plant management knowledge, about the knowledge of flower clinic, orchid leaf tips turning black, next, the editor will explain in detail for you
There are many reasons for the blackening of orchid leaf tips, most of which are diseases, and a small part is caused by improper maintenance. This article analyzes the reasons for the blackening of orchid leaf tips from the perspective of diseases. In order to make it clear for orchid lovers, this article uses multiple disease maps from the Internet. Orchid lovers can refer to the pictures.
Let's first look at the pictures, and then analyze them:
Figure 1: Physiological burning tip symptoms
Figure 2: Brown spot disease symptoms
Figure 3: (T-J) disease symptoms
Figure 4: Black spot disease symptoms
Figure 5: Leaf blight symptoms
Figure 6: Blunt tip disease symptoms
Figure 7: Leaf blight with black spot disease
Figure 8: (T-J) disease and black spot disease occurring simultaneously
Figure 9: Black transverse lines at the junction of diseased leaves
Figure 10: Physiological burning tip, brown spot disease, (T-J) disease, blunt tip disease, leaf blight, and black spot disease
Figure 11: Cutting off diseased leaves
Let's now understand the main reasons for orchid leaf burning tips:
There are many reasons for orchid leaf burning tips, some of which are caused by natural factors, some by improper management, and others by diseases, among which diseases cause the most serious burning tip damage.
1. Burning tips caused by natural factors
(1) Low humidity: Orchid leaf burning tips are closely related to moisture. Especially in the case of long leaves of Cymbidium, if the moisture is not sufficient, it will inevitably cause leaf burning tips. The moisture of orchid leaves is supplied by the roots and absorbed from the air. Therefore, in addition to the excessive dryness of the potting soil, the low humidity of the air is also closely related to the cause of orchid burning tips. If the air humidity is too low and too dry, it will enhance the transpiration of orchid plants, resulting in an imbalance between supply and demand of leaf moisture and causing leaf burning tips. Generally speaking, the indoor cultivation of orchids has higher air humidity, and the situation of leaf burning tips is not serious. However, in outdoor cultivation, due to the difficulty in controlling air humidity, the situation of leaf burning tips is more serious.
(2) Sudden climate change: Taking 2007 as an example, people moved the orchids from the humid orchid house to the outdoors and encountered a drought that had not occurred for decades. The rivers dried up, and the air humidity was extremely low, resulting in more serious leaf burning tips in orchids. Although the plum rain season arrived late, it lasted for about 50 days. The leaves that had not seen the sun for a long time were thin and soft, and as soon as the plum rain season was over, they encountered high temperatures and strong sunlight, making the situation of leaf burning tips even more serious.
(3) Air pollution: Near sewage areas, industrial zones, or where someone is burning harmful substances near the orchid garden, causing harmful gases to fill the air and harm orchid leaves, leading to burning tips.
2. Burning tips caused by improper management
(1) Excessive sunlight: In summer, due to insufficient shading or not enough shading, the sunlight is too strong, causing leaf burning tips.
(2) Long-term shading: Excessive shading during the growth of orchids, weak sunlight, long-term shading, resulting in thin and weak leaves, if suddenly exposed to strong sunlight, it is easy to cause burning and leaf shrinkage in orchids.
(3) Water damage: Frequent watering can cause root rot and lead to burning tips. Spraying water in the sun can cause water to accumulate at the leaf tips and burn after being exposed to strong sunlight. If the quality of the water for watering is polluted, or if the orchids are rained on by acid rain, it can also cause leaf burning.
(4) Fertilizer damage: When fertilizing the roots, if the fertilizer concentration is too high and the frequency is too frequent, it can cause the roots to turn black and then cause leaf burning tips.
(5) Excessive pesticide concentration: Pesticides should be mixed in a certain proportion. If the concentration exceeds the standard and the amount of spraying is too much, pesticides will accumulate at the leaf tips, causing leaf damage and burning tips.
(6) Dry potting soil: Lazy watering can cause the potting soil to be too dry, failing to meet the water requirements of the orchid plants, forming empty roots, and the leaves cannot get normal moisture, resulting in burning tips due to water loss.
The above-mentioned burning tips caused by natural factors or improper management are usually called physiological burning tips. This type of burning tip is usually black and does not have black transverse lines at the edge of the lesion. It does not quickly advance and the disease progresses slowly, causing relatively minor damage. (Figure 1: Physiological burning tip symptoms) As long as the cause is identified and the management is targeted, the situation of leaf damage can be controlled.
2. Burning tips caused by diseases
(1) Bacterial brown spot disease: Orchid brown spot disease is caused by bacterial infection of orchid leaves and is the most vicious burning tip disease among orchid leaf diseases. It is relatively easy to identify, with brown lesions. In the early stage of the disease, the leaves have a boiled watermark-like discoloration that quickly spreads and causes the entire leaf segment to wilt. It has strong infectivity, spreads rapidly, and is highly harmful.
(2) (T-J) disease: Orchid (T-J) disease is caused by fungi and is the most common burning tip disease in orchid leaves. It is relatively easy to identify, with a characteristic feature of several wavy transverse black bands after the leaf tip dies. If the diseased leaves are not treated with medication after cutting, they will still continue to advance, making it a more serious burning tip disease.
(3) Black spot disease: Orchid black spot disease is caused by fungi and is one of the most common burning tip diseases in orchid leaves. It is relatively easy to identify, with round lesions scattered on the leaf surface and edges. In severe cases, they can also merge and cause the entire orchid leaf to lose its ornamental value.
(4) Leaf blight: Orchid leaf blight is caused by fungi and is one of the more vicious burning tip diseases. It is relatively easy to identify, with the characteristic feature of the leaf tip turning gray-white and the entire leaf segment drying up in the later stage. The junction of the diseased leaf is deep brown and continues to advance, causing significant damage.
(5) Blunt tip disease: Orchid blunt tip disease is caused by fungi and is the most common burning tip disease. It is relatively easy to identify, with a characteristic feature of gray-yellow dead parts without band-like marks (different from (T-J) disease), and black-brown patterns at the junction.
The above diseases sometimes occur singly and sometimes simultaneously. For example, orchids may not only have leaf blight but also black spot disease, with black spots remaining after the leaves die. (Figure 7: Leaf blight with black spot disease) Similarly, orchid leaves may have both (T-J) disease and black spot disease, with both symptoms present after the leaves die. (Figure 8: (T-J) disease and black spot disease occurring simultaneously)
Burning tips caused by diseases generally cause more serious damage. The lesion edges usually have black transverse lines, and this black transverse line lesion continues to advance (Figure 9: Black transverse lines at the junction of diseased leaves), causing the entire leaf segment to burn and dry up. Even if cut, it will continue to burn, cut again, and burn again, until bald. It can even threaten the life of the orchid plant.
(II) Accurate diagnosis of burning tip diseases
Although the symptoms of various burning tip diseases have been explained relatively clearly earlier, it is still difficult for ordinary orchid lovers to distinguish the cause of the burning tips at once. In fact, as long as you pay attention and observe carefully, you can identify them. (Figure 10: Physiological burning tip, brown spot disease, (T-J) disease, blunt tip disease, leaf blight, and black spot disease) The picture clearly shows their significant differences:
1. Physiological burning tips (water damage, fertilizer damage, pesticide damage, etc.) are completely black at the affected site, with no black stripes at the junction; pathological burning tips are not black after the leaves die, and there are black stripe lesions at the junction.
2. Bacterial lesions have boiling watermark-like brown patches in the early stage, while fungal burning tips do not have yellow-brown patches.
3. Fungal diseases generally have black transverse bands at the junction. (T-J) disease has several horizontal wavy black lines on the burned leaf tip, and other diseases do not have this wavy pattern; leaf blight has a gray-white lesion; blunt tip disease has a gray-yellow lesion.
In summary: Physiological burning tips are completely black at the affected site, with no black transverse lines at the junction; bacterial brown spot disease has brown patches at the beginning and black lesions later, with black transverse lines at the junction; (T-J) disease has several horizontal wavy black lines on the leaf, with black transverse lines at the junction; leaf blight has gray-white lesions, with black transverse lines at the junction; blunt tip disease has gray-yellow lesions, with black transverse lines at the junction.
Only by accurately grasping the symptoms of various burning tip diseases can we have a clear target and effective treatment. Therefore, we must put in the effort to study them and truly target the symptoms when treating.
(III) Measures to radically cure burning tip diseases
It is relatively difficult to completely eliminate burning tip diseases caused by diseases, but as long as we take a positive attitude,认真管理, and adopt comprehensive prevention and treatment measures, we will certainly achieve significant results.
1. Diseased leaves should be cut off. Once the leaves have burning tips, there is no need to feel sorry for cutting them off. It is necessary to cut them off彻底, with the cut edge more than 1 cm away from the lesion. If the old plant is severely affected, the entire plant can be cut off without hesitation. (Figure 11: Cutting off diseased leaves) Then spray with methylthiophanate. The cut diseased leaves should be burned or buried deep, and absolutely not left in the orchid garden. Any diseased leaves that fall on the ground during pruning should also be picked up to prevent them from becoming a source of infection again.
2. Medication should be targeted. Once the leaves have burning tips, you need to find out the cause. If it is caused by improper management, then strengthen the management accordingly. If it is caused by a disease, then first distinguish whether it is caused by bacteria or fungi. This is easy to distinguish. Bacterial brown spot disease has an obvious symptom: the lesion in the early stage of the disease looks like a boiled watermark. Bacterial diseases can be prevented and treated with agricultural streptomycin, leaf blight宁, and Kasil; while fungal diseases can be prevented and treated with methylthiophanate, carbendazim, and Shihigh. If it is difficult to distinguish the type of disease at once, a mixture of bacteria-killing and fungus-killing agents can be used, which can achieve twice the effect with half the effort.
3. Treatment should be timely. Once the disease is discovered, it should be treated with medication promptly. Never have the idea that "orchid leaf burning tips are not a big deal" or the wrong idea that "orchid leaf burning tips are normal," which can delay treatment and worsen the condition, causing the disease to spread. It should be clearly recognized that the transmission speed of orchid leaf diseases is very fast. Although it is not fatal, it can make the orchid lose its ornamental value.
4. Prevention should always be emphasized. "Prevention is better than cure," and preventive work should always be emphasized. Regularly spray the leaves with medication, starting from early spring, alternating between bacteria-killing and fungus-killing agents every 10～15 days, even if no disease is found, medication should be used to prevent potential diseases.
5. Spraying water should be strictly prohibited. Once orchid leaves have burning tips caused by bacteria, it is strictly forbidden to spray water. Because spraying water can make the leaf surface moist, accelerating the reproduction of bacteria, and at the same time, spraying water can accelerate the spread of bacteria, causing恶性传播. If there is too much dust on the leaf surface, affecting the photosynthesis and respiration of orchids, you can spray water and then immediately spray杀菌剂 such as Kasil and other fungicides to prevent the spread of bacteria.
6. Management should be strengthened. Not only are physiological burning tips related to management, but bacterial burning tips are also related to management. Therefore, we need to think and study more about management and do a good job in managing orchids to minimize burning tips caused by human factors.
7. Caution when buying plants. Resale plants and greenhouse seedlings have been growing in a high-temperature and high-humidity environment for a long time and have almost been soaked in medicine water. Once they are transplanted to a natural environment, they can quickly cause burning and leaf shrinkage due to increased sunlight and reduced humidity.
8. Pesticides should be rotated. Any pesticide will develop resistance if used for a long time. Therefore, it is not advisable to use the same pesticide for a long time. Pesticides should be rotated regularly. Generally, each pesticide should be used for three consecutive times before switching to another one. This can achieve better control results.
The comprehensive knowledge about orchid leaf tip blackening (with multiple images) is hoped to help you.