Reasons Why Azaleas Die and How to Prevent and Treat Them

Azaleas suffer from many common diseases and pests. Having grown flowers for many years, the author has summed up eight causes from practical experience.

1. Diseases

Black spot is the main disease of azaleas, with outbreaks being more serious from June to August, and most severe when the temperature is between 25°C and 32°C. When the temperature is below 10°C, the disease can stop spreading. After infection, black spots form on the leaves, which gradually dry up and fall off. This is the main cause of azalea death.

Prevention and treatment: 1. Burn the diseased leaves. 2. Chemical control. ① Spray the leaves with a 600-800 times dilution of 50% wettable carbendazim or tuijunte, with an effective rate of over 95%; ② Spray with a 600-800 times dilution of phosethyl aluminum. Spray one of these three chemicals once every 7 days, for a total of 3-5 sprays, and the plant will recover, with an effective rate of 100%.

2. Pests

The main pests of azaleas are red spider mites, mealybugs and short-whiskered mites, which occur from May to October. After being damaged, brownish-red spots appear on the leaves, disrupting the metabolic function, causing the leaves to fall off and leading to death.

Prevention and treatment: 1. Ensure good ventilation and a cool temperature. 2. Chemical control. ① Use a 1200-1400 times dilution of 50% dimethoate emulsion, spraying 3-4 times in a row, once every 7-10 days, with an effective rate of 100%. Use a 1800-2000 times dilution of 50% dichlorvos emulsion, spraying 3 times in a row, with an effective rate of 100%. ② Spray with a 3000-4000 times dilution of 50% triazophos emulsion, covering both the upper and lower surfaces of the leaves. ③ Spray with a 2000 times dilution of dicofol, with an effective rate of 100%. When spraying, seize the right timing and target the treatment specifically to achieve satisfactory results.

3. Soil damage

Apart from diseases and pests, the main cause of azalea death is soil damage.

1. Alkalinization of potting soil. Alkalinization of the potting soil leads to root rot, yellowing and falling leaves, and death of the plant. Prevention and treatment methods: First, water with a 0.1%-0.2% ferrous sulfate solution, once a week, for 4-5 times, and the plant will recover; second, change the soil, with a pH value between 6 and 6.5 being suitable; third, water with a 0.1% sugar solution or water from fermented fruit; fourth, regularly measure the pH of the potting soil, and if it is on the alkaline side, immediately change the soil or water with ferrous sulfate solution, etc.

2. Acidification of potting soil. Acidification of the potting soil causes the plant to die within 7-10 days. Prevention and treatment methods: 1. Immediately change the potting soil, keep it clean, and do not casually throw debris, fruit peels or fruit flesh into the pot; 2. Loosen the soil frequently to keep the soil well aerated, regularly measure the pH value, and adjust the potting soil in time; 3. Never drip salt water or cooking oil into the pot, and never water flowers with water used to wash pots, dishes or fish; if any of the above has happened, it is best to change the potting soil promptly.

4. Fertilizer damage

Azaleas are afraid of concentrated fertilizer and raw fertilizer. First, they are afraid of raw, concentrated human manure and urine, rotten eggs, dead animals, etc. These fertilizers are certainly good fertilizers, but once they ferment after use, they burn the roots, rot the roots and cause death. Fertilizer must be fermented and decomposed, and when applied it must be diluted with 10-20 times water before use, and each application should be small and dilute. Fertilizing from February to May is better; second, they are afraid of fertilizing at high temperatures, as the roots rot easily afterward. Azalea fertilization is generally done in spring and autumn, and it is best not to fertilize in July and August of summer; third, besides applying organic fertilizer, inorganic fertilizer can sometimes also be applied in appropriate amounts, by application or spraying, but the ratio must follow the instructions, and it should be dilute rather than concentrated.

5. Water damage

Azaleas can also be killed by water. If the potting soil is waterlogged for 4-6 days, the roots will suffocate from lack of oxygen and die, and the leaves will fall and the branches will wither. If the water-holding capacity of the potting soil is only 18% or less, the plant will also certainly die in about 20 days. Watering should be appropriate, keeping the potting soil at 50%-60% moisture. In summer, water 1-2 times a day; in winter, water once every 4-5 days. Do not water when the soil is not dry, and water when it is dry, keeping the potting soil normally moist. Loosen the soil frequently to keep the potting soil loose and breathable, facilitate drainage, and promote good root growth.

6. Root damage

In a suitable growing environment, the roots of azaleas can grow into a tangled mass. If the pot is not turned and the soil is not changed for two years, the roots cannot absorb nutrients and water, causing death. Therefore, the roots should be cut every autumn and winter to encourage new root growth. Prune the roots every year to promote the plant's vigor, with more and larger flowers. You can also move it from a small pot into a larger pot for cultivation.