1. Diseases such as root rot or stem and leaf rot often occur due to poor management, leading to symptoms like leaf shrinkage, dark spots, and overall plant wilting. This is commonly caused by high humidity, excessive temperature, poor air circulation, or overly dense seedlings. To treat this, you can spray the plants with fungicides like *Bacillus subtilis* or carbendazim (diluted 800–1000 times). However, avoid frequent spraying to prevent overuse.
Sudden leaf drop in a short period is usually due to a sharp temperature change or insufficient light exposure.
If leaves turn yellow and fall off quickly, it's typically a sign of underwatering. This issue may also occur during winter if the temperature is too low.
Leaf tips or edges turning brown or scorched can be caused by excessive sunlight, dry air, over-fertilization, or dry soil in the pot.
Long, leggy branches and leaves are usually the result of inadequate light, excessive nitrogen fertilizer, or improper watering. Move the plant to a brighter area and prune the affected parts to encourage healthier growth.
Yellow or brown water-like spots on leaves may indicate overwatering or splashes from muddy water hitting the leaves.
2. Soil that is too alkaline can cause stunted growth, yellowing leaves, and even premature death of the plant. High alkalinity in the water can also contribute to this problem. Salt buildup often appears on the surface of the potting soil. To reduce alkalinity, regularly remove the top layer of soil and replace it with fresh soil. Additionally, apply a small amount of 0.2% ferrous sulfate solution periodically to help neutralize the soil pH.
3. For drought-related issues like dehydration and leaf wilting, place the pot in a tray of water so it can slowly absorb moisture. However, avoid overwatering at once, as this can damage the roots.
4. Viral diseases are difficult to detect with the naked eye. They consist of tiny, granular particles made of nucleic acids and proteins, visible only under an electron microscope. These viruses live inside the plant’s living tissues, interfere with its metabolism, and cause various symptoms. To prevent the spread, always use healthy, disease-free plants for propagation.
5. Pest control
(1) Soil pests include grubs and beetles. The adult stage is known as "golden beetles" or "white grubs," which curl into a "C" shape. They feed on plant roots, causing the plant to wilt. They are most active at night, especially between May and June. Manual removal is effective during plowing or when inspecting pots. You can also use a 50% phoxim EC solution diluted 1000–1500 times and pour it around the roots (50–100 ml per plant).
(2) Cutworms appear as dark brown or brownish worms that create crisscross tunnels in the soil, lifting it and separating roots from the soil. This leads to dehydration and wilting. They are most active in spring and autumn. Manual removal is one option, or you can mix wheat bran with 90% trichlorfon (30 times dilution) and sprinkle it around the base of the plants in the evening. Alternatively, use a 50% phoxim EC solution (1000–1500 times) to water the root zone.
(3) Small tigers, also called cutworms, are gray-brown in color, measuring 16–23 mm long. They hide in the soil during the day and emerge at night to feed on roots. April is the peak season for this pest. Manual removal or applying a 50% phoxim EC solution (1000–1500 times) directly to the roots can help control them effectively.
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