What are the two most common causes of plant diseases?

When growing garden plants, we often encounter many plant diseases, but many gardening enthusiasts are often unclear about exactly what causes plants to develop diseases. In fact, identifying the cause can also be a great help in treating plant diseases. The editor has summarized the two major causes of plant diseases for you.

Rose (details)

The causes of plant diseases generally fall into two major categories:

One is caused by unsuitable environmental conditions, called physiological disease, and its causes are mainly climatic conditions as well as water, soil, fertilizer, and so on.

The other is caused by biological infection, called infectious disease, and the factors that cause it include pathogens, susceptible plants, environmental conditions, and human factors. When a pathogen infects a plant, the plant does not necessarily become diseased; whether the disease occurs also depends on the strength of the plant's disease resistance. If the disease resistance is strong, the plant will not become diseased or will be only mildly affected. Therefore, selecting disease-resistant varieties and improving the disease resistance of plants is one of the main approaches to disease control. Given a pathogen and a host plant, whether the disease occurs still depends on environmental conditions, so we should actively create environmental conditions suitable for plant growth and development to reduce the occurrence of diseases. To improve plant resistance and create environmental conditions suitable for plant growth and development, it is necessary to use horticultural methods to strengthen management, mainly including the management of soil, fertilizer, water, pruning, and so on.

Control of common fern diseases

1. Anthracnose.It mainly harms the young leaves of the plant. The affected parts initially show water-soaked round or nearly round dark brown small spots at the leaf margins or leaf tips, and then gradually several lesions expand into irregular patches, and the color turns scorched yellow. Some lesions appear cloud-like, with a light red halo at the edges. In the later stage, the center of the lesion turns grayish white, with many tiny black dots, and in severe cases the entire leaf dies. At 25°C and humidity of 80% to 90%, it spreads rapidly.

Control method: This disease should be mainly prevented. During the plum rain season when new leaves form and during seasons of high temperature and high humidity, fungicides should be sprayed for prevention. In the early stage of the disease, spray 75% chlorothalonil at 500 times dilution, or 50% carbendazim wettable powder at 800 to 1000 times dilution, or 70% thiophanate wettable powder at 800 to 1000 times dilution for control.

2. Brown spot disease.Also called leaf spot disease or leaf blight. It often occurs at the tip of the leaf. The affected leaf initially shows small round black spots, which later expand into round or nearly round spots. The edges of the lesions are dark brown, and the center is grayish black with small black dots. After that, the lesions expand rapidly, and the leaf finally turns black, dries up, and dies. Its main route of transmission is fallen leaves. It can occur in spring, summer, and autumn, and is prone to epidemics in seasons of high temperature and high humidity.

Control method: If diseased plants are found, they should be immediately isolated and sprayed, and at the same time the diseased branches and leaves should be pruned off and burned in a centralized manner. For protective spraying, 50% carbendazim at 1000 times dilution, 50% thiophanate-methyl at 1000 times dilution, or 200 timesBordeaux mixturecan be used for control.

3. Rust disease.It can occur on species such as Selaginella uncinata, and in May the leaf surface gives off pale yellow powder.

Control method: 65% zineb wettable powder at 500 times dilution, or lime sulfur mixture at 0.3 to 0.4 degrees Baume, can be used, spraying once every 10 to 15 days, for 3 to 4 consecutive sprays, which can achieve a certaineffect。

Introduction to common diseases of Alocasia macrorrhizos

Alocasia macrorrhizos (details) is a relatively common indoor foliage plant, named because it drips water in humid environments. Although Alocasia macrorrhizos is not difficult to cultivate, it can still get sick. Generally, the diseases of Alocasia macrorrhizos are mainly reflected on the leaves, with two types: leaf spot disease and anthracnose.

Alocasia macrorrhizos (details)

1. For leaf spot disease, spray the leaf surface with chlorothalonil or carbendazim at 800 times dilution, 2-3 times in a row, with 7 days between each application. For anthracnose, 75% thiophanate-methyl at 500 times dilution must be sprayed on the leaf surface, once every 7 days, 2-3 times in a row, which can basically bring it under control. Because Alocasia macrorrhizos is a foliage plant, once the leaves become diseased, it will inevitably affect its ornamental effect, so prevention should be the main approach.

2. On the stem, there is a kind of wilt disease caused by bacterial infection. This disease is not easy to detect at first, and once discovered it is already very serious. If the stem is found to lean to one side, or there is a wilting spot, then it must be wilt disease. You can use a small knife to cut out the diseased part. The boundary between the diseased part and the healthy part is very obvious, and it can generally be broken off by hand. If the diseased part is less than one third of the stem, you can apply a layer of chlorothalonil solution to the healthy part and keep it dry, then apply it again after ten days, and after 20 days it can basically recover.