What are the common diseases of camellias? A detailed guide to disease prevention and control methods for potted camellias

Many people in the north grow camellias in their homes, yet there is a certain amount of skill involved in cultivating them. Today, the editor will tell you about the methods for growing camellias.

1. Root rot. The main cause of root rot is overwatering, or poor drainage in the potting soil, with water accumulating for too long without aeration, so the camellia roots cannot breathe. This leads to root rot.

The best way to solve this problem is to take the plant out of the pot, clear away the outer old soil, use scissors to cut off the rotten root parts from the base, then disinfect the wounds with a 0.1% potassium permanganate solution, or apply clean plant ash to the wounds, and then repot it or plant it in the ground.

2. No leaf drop, but the whole branch withers and dies. This phenomenon is mainly caused by watering camellias with tap water over a long period, which makes the potting soil alkaline and compacted, so that the water-absorbing function of the plant's root system is blocked, and the branches and leaves wither from water loss, causing the whole plant to die. Or it may be caused by exposure to strong sunlight, or during the shoot-sprouting and bud-setting period, when light and other conditions change suddenly; camellias find it hard to adapt to such changes, and the phenomenon of no leaf drop but the whole branch withering and dying also occurs.

Therefore, the watering of camellias is crucial and must never be done carelessly. The best water is rainwater or pond water; tap water must also be left in the sun for three to five days. Then add a little ferrous sulfate. In spring, summer and autumn, move the camellia to a semi-shaded place to grow. When keeping it indoors for viewing in winter, be sure to pay attention to air humidity; if the temperature is too dry, camellias will likewise not drop their leaves and the whole branch will wither and die.

3. The drainage holes at the bottom of the pot used for growing camellias must not be blocked. Clay pots are best, as they have good breathability. For soil, slightly acidic mountain soil is best, while field mud is the worst. It must be noted that the soil used for growing camellias should be one with high water-holding capacity, and soil with very strong permeability, such as pine needle soil, must absolutely not be used.

4. Repot once a year, with the repotting time after the flowers fade in spring.

5. In high temperatures and in the dry indoor season in winter, frequently spray water on the camellia leaves. When spraying, add a little edible vinegar to the water; this can both clean the leaf surface and increase the acidity of the potting soil, avoiding chlorosis.

The above are some methods for growing camellias. As long as we plant them according to the correct methods, camellias will bloom very beautifully.

How to grow camellias, and pest and disease control for camellias

The camellia plant has a very graceful form, and beyond that its flowers are gorgeous and richly colorful, making it beloved by the horticultural world. So next, let's take a look with the editor at how to grow camellias, along with related pest and disease control, in the hope that it can help everyone. Let's take a look!


How to grow camellias

I. Planting

  In areas north of the Yangtze River, camellias are best planted in spring, while in areas south of the Yangtze River, autumn planting is best. When planting in the ground, choose land with good drainage and strong water-holding capacity, a sandy loam rich in humus. If growing in pots, use: leaf mold, sandy soil and barnyard manure soil mixed at 1/3 each, or a mixed growing soil of 4 parts leaf mold, 5 parts peat soil and 1 part coarse sand.

  The pH should be between 5 and 6.5. The planting site should be chosen where water does not accumulate and the blazing sun does not reach. Potted camellias should be brought indoors in winter and placed in a ventilated, well-lit spot, and moved out in summer to a shade shed or other place where they can be shaded. Moving camellias around randomly is not good for their growth.


II. Light and temperature

  Camellia is a long-day plant. It can only form flower buds in an environment with 12 hours of daylight. The optimal growing temperature is 18 to 25°C, and the most suitable flowering temperature is 10 to 20°C. If the temperature is higher than 35°C, it will scorch the leaves.

  Camellias are not cold-tolerant, so in winter they should be brought indoors, with the temperature kept at 3 to 5°C; they can also endure a short period of -10°C low temperature, but must not be kept above 16°C for a long time, otherwise it will promote sprouting and cause leaf drop. During the growing period, they should be placed in a semi-shaded environment and should not receive overly strong direct sunlight. In particular, in summer and autumn, shading should be provided, or they should be placed in dappled shade under trees.

III. Watering and fertilizing

  Camellias have relatively high requirements for fertilizer and water, and both alkaline soil and neutral soil are unfavorable for camellia growth. In the north, special attention should be paid: alkaline water must undergo acidification treatment before it can be used to water the flowers. The specific method: store tap water for 2 days so that the chlorine in the water evaporates, then add an appropriate amount of ferrous sulfate (about 0.5% of the water). The amount of water must not be too large; too much water easily causes root rot.


  The potting soil must also not be dry; a lack of water easily causes the roots to shrink from water loss, so it is appropriate to keep the potting soil and surrounding environment moist. Do not spray water during the flowering period. For fertilizing, thin alum fertilizer water is good, and concentrated fertilizer should be avoided. Generally, after sprouting in spring, apply a thin fertilizer solution once every 17 days; in summer apply phosphorus and potassium fertilizers; in early autumn fertilizer can be stopped for about 1 month; before flowering apply alum fertilizer water again, and when flowering apply quick-acting phosphorus and potassium fertilizers, so the flowers are large and brightly colored and the flowering period is long.

IV. Shaping and pruning

  For ground-planted camellias, mainly cut off dead branches, diseased and weak branches, crossing branches, overly dense branches, and branches that clearly affect the tree shape, and thin out excess flower buds. For potted camellias, in addition to the above work, shaping and pruning should also be done according to personal preference, but heavy pruning is not suitable, because their growth vigor is not strong.

V. Flowering period control

  Camellias are not cold-tolerant, and generally methods such as selecting varieties, temperature control and hormone treatment are used to control the flowering period. If you want camellias to bloom on "National Day" (October 1), in mid-July or early August use a writing brush dipped in 0.1% gibberellin and dot it on the flower buds once every 3 days, with normal fertilizer and water management. In September, decide whether to apply it to the flower buds based on their growth; if it is estimated that blooming on "National Day" is not assured, increase the number of applications to the buds and increase the amount of fertilizer and water to promote rapid growth of the flower buds, so that flowers can be seen on "National Day."

VI. Winter management of potted camellias

  (1) Freeze protection and warmth. When the temperature drops below 0°C, move potted camellias outdoors to a warm, sunny, wind-sheltered place, or place them in a plastic shed sealed on three sides and facing the sun on one side. They can also be placed indoors, but the place where they are put must have good light and ventilation. In severe cold and frosty weather, attention should be paid to keeping them warm; before a sudden temperature drop, it is best to move outdoor camellias indoors. If left outdoors, at night cover them with plastic film, newspaper, cloth or other materials.

  (2) Water and fertilizer management. Camellias like a warm, humid environment and are afraid of water accumulation. In winter, spray the leaf surface once every 3 to 5 days with clean water at a temperature close to room temperature, to increase humidity and wash dust off the leaves. During the flowering period, the amount of watering should be such that the potting soil alternates between dry and moist, and the suitable time for watering is noon on a sunny day. Winter is the period when camellia flower buds swell; each month, along with spraying water on the leaves, apply 0.1% to 0.3% potassium dihydrogen phosphate solution once, or apply a thin liquid fertilizer based mainly on phosphorus and potassium to the roots once (fertilizer-to-water ratio 1:4).


  (3) Other matters. When potted flowers overwintering indoors bloom (early-flowering varieties begin blooming at the end of November, and ordinary varieties bloom from February to April), do not place them in a place with too strong light or too high a temperature, otherwise the flowers will fade early. Removing excess flower buds can promote larger flowers and brighter color, and can extend the flowering period.

  When watering, do not spray water on the flowers, otherwise it will cause the flowers to rot and shorten the flowering period. After the flowers fade, promptly remove the withered flowers.

Pest and disease control for camellias

  The main diseases of camellias include ring spot, shoot blight, anthracnose, leaf spot and sooty mold. The main control agents are: carbendazim at 500 times, chlorothalonil at 800 times, thiram at 800 times, and prochloraz at 800 times for regular control. Before flowering, pay attention to the control of gray mold and flower blight.


  The main insect pests of camellias are red spider mites, aphids, scale insects, leaf-rolling moths and bridge-forming caterpillars. The main control agent is 15 mL cypermethrin + 20 mL isocarbophos or 25 mL monocrotophos mixed with 30 jin of water for spraying.

Summary: The above is an introduction to how to grow camellias, as well as pest and disease control. Different flowers have different meanings, and the differences in cultivation can let us better care for the flowers. The editor's information is not comprehensive enough, so please forgive me.

Common pests and diseases of camellias

        I. Camellia gray leaf spot: Camellia gray leaf spot harms plum blossoms, tea plants and others, and is a relatively common disease on camellias, occurring repeatedly on nursery and potted plants.
        Symptoms: It harms leaves and tender shoots. The pathogen mostly invades from the leaf tip or leaf edge; at first it appears as small yellow-green spots, gradually expanding into nearly round, semicircular irregular large spots, dark brown, with the edges clearly raised, and the lesions can heal together with each other. The lesion diameter is generally 10-20 mm. In the later stage, dense black small dots are produced on the lesions, scattered or arranged in inconspicuous concentric rings; in severe cases the diseased leaves dry up, crack and fall off.
        Control methods: 1. Remove diseased leaves to reduce the source of infection.
        2. Appropriately increase the application of organic fertilizer, phosphorus and potassium fertilizers and ferrous sulfate, to promote robust plant growth and enhance disease resistance;
        3. In June, when the disease is relatively severe, use 1:1:100 Bordeaux mixture, or 50% thiram wettable powder at 1000 times, spraying once every 10-15 days, for a total of 4-5 sprays.
        II. Camellia anthracnose symptoms: It is a common disease harming camellias, mostly occurring on leaves formed in the current year, and occasionally on new shoots. On the leaves, the lesions mostly start from the leaf tip or edge; at first they are water-soaked dark green round spots, later expanding into irregular large spots, yellow-brown to brown. Finally, the center of the lesion appears grayish-white with many small black dots scattered on it, and the edge of the lesion is slightly raised.
        Control methods: In the early stage of occurrence, spray for control with 70% thiophanate-methyl wettable powder at 1000-1500 times, or 50% benomyl wettable powder at 1000 times, or 75% chlorothalonil wettable powder at 600 times, or 65% zineb wettable powder at 600 times.