Common Problems in the Cultivation Process of Phalaenopsis Orchids
This article provides information on common problems encountered during the cultivation of Phalaenopsis orchids. Detailed introductions are provided below.
Symptom 1: Root rot and yellowing of leaves.
Causes: Mainly caused by excessive watering leading to root rot, heavy fertilization, and low temperatures. Poor ventilation inside the pot can also cause these symptoms. It is important to note that the permeability of the growing medium is crucial when caring for Phalaenopsis orchids. Some caregivers might switch to a relatively larger pot, thinking it provides a spacious environment for the plant roots. However, this can make it harder for the sphagnum moss to dry out, significantly reducing root aeration and leading to root rot. Moreover, watering with water that is too cold can also cause root rot.
Solution: Trim the rotting roots, spray the entire plant (including roots) with a 1500x solution of Metalaxyl and apply wood ash. Fertilization should be kept within a concentration of 3000-7000x, and avoid heavy fertilization. If the temperature drops below 13°C, it is necessary to increase the temperature of the plant's environment. The pot used for cultivation should be small rather than large. The water temperature should not be too low; generally, if it feels cold to the touch, it is too low; if it feels cool, it is suitable. Avoid watering when the temperature is below 10°C.
Symptom 2: Around the Spring Festival, after purchasing and caring for Phalaenopsis orchids for a period, the plant's growth tends to weaken. Some may not bloom even after a year of good care.
Causes: Mainly caused by low temperatures. The time when Phalaenopsis orchids are available on the market often coincides with the Spring Festival. After purchasing, caregivers usually place them in living rooms and other areas to admire, where the daytime temperature is sufficient, but the nighttime temperature is somewhat low. Additionally, professionally cultivated orchids are mostly grown in well-equipped greenhouses, and plants coming from greenhouses cannot adapt well to the harsh conditions at home, leading to worsening growth.
Symptom 3: After autumn, slow growth, leaf bleaching, and even bud drop.
Causes: If the temperature remains below 18°C during the flowering induction and flowering stages, the above symptoms will appear.
Solution: Improve the environment and increase the temperature, which can be achieved by adding heating facilities. Raising the temperature can prevent further deterioration of the above symptoms.
Symptom 4: Bud drop during autumn and winter.
Causes: Due to insufficient light accumulation in the early stages or poor root growth, possibly even root rot.
Solution: During the care process before flowering, make sure to avoid direct strong sunlight while allowing the plant to receive scattered light to accumulate more light. Also, water rationally to prevent root rot.
Symptom 5: Small brown凹陷 points that expand into circular or irregular lesions, sometimes with a yellow halo. In severe cases, it can spread to the entire leaf, with blackish-brown or pink concentric small dots on the lesions.
Causes: Caused by (T-J) disease in conditions of high temperature, high humidity, and poor ventilation.
Solution: Spray a 1000x solution of Prochloraz, every 7 days, for 3 consecutive times. Improving the care environment and ensuring good ventilation is very important for preventing this disease.
Symptom 6: Yellowing of old leaves or black spots on leaves, followed by leaf drop.
Causes: Long-term temperatures below 15°C may lead to the above symptoms.
Solution: Improve the environment and increase the temperature, which can be achieved by adding heating facilities. Raising the temperature can prevent further deterioration of the above symptoms.
Symptom 7: Rust spots on the petals.
Causes: Temperature below 13°C.
Solution: Same as symptom six.
Symptom 8: Initially, water-stained spots appear on the leaves, then turn black and rot, sometimes spreading to the leaf tips, turning yellow in the later stage. In severe cases, the center rots, with a yellowish liquid oozing out from the squeezed, rotten part, emitting a foul odor.
Causes: This symptom mainly occurs in the summer when it is hot and humid. It is caused by bacterial infections when water droplets splash onto the leaves or when there is poor ventilation.
Solution: The disease is mainly transmitted through water droplets. Improve ventilation, be careful with watering, avoid spraying water, strengthen management, prevent plant wounds, and spray 3000x Agricultural Streptomycin, once every 7 days, for 3 consecutive times. Trim and destroy the infected leaves and keep them away from the plant.
Symptom 9: Yellowing, wilting, and shedding of leaves, with obvious discoloration near the base of the leaves. The growing point is easily shed, and there are irregular wet lesions on the lower surface of the leaves. The central part of the older and larger affected areas is blackish-brown or black, oozing moisture when squeezed, and the affected part appears water-stained, without an odor.
Causes: High temperature, high humidity, poor ventilation, excessive nitrogen fertilization, and insufficient light, leading to disease.
Solution: Trim the infected leaves, improve the care environment, fertilize rationally, avoid excessive darkness, and use a 1500x solution of Metalaxyl and a 3000x solution of hymexazol alternately every 15 days. During the outbreak, spray once every 7 days, usually for 3 times.
Symptom 10: Black spots appear on the leaves and stems initially and gradually spread to the entire leaf, forming a thick and loose black mold layer.
Causes: Insufficient light, excessive nitrogen fertilization, poor ventilation, and scale insect infestation can cause the above symptoms. This symptom is the manifestation of sooty mold disease, and if not treated in time, it will lead to rapid deterioration of the plant's growth and eventual death.
Solution: First, brush off the mold, then spray a 2000x solution of Jianlei or an 800x solution of carbendazim. Move the plant to a location with sufficient light and good ventilation, fertilize rationally. If there are scale insects, remove them promptly, as the honeydew they secrete can lead to sooty mold disease.
Symptom Eleven
The lower leaves first show abnormal signs, with yellow spots appearing on the leaves, gradually turning black, then perforating, with the surrounding tissue gradually yellowing, while the other parts continue to grow, causing bending towards the lesion, resembling a sickle. When it occurs at the roots, it will lead to black root rot.
Causes: Excessive watering, weak plant growth, poor ventilation at the care location, and insufficient light. In addition, excessive nitrogen fertilization can exacerbate the degree of plant damage. The above symptoms are the manifestation of Fusarium wilt.
Solution: Control the moisture in the growing medium, improve the care environment, trim the infected parts, and can spray and water with a 600-800x solution of Fosetyl-Al. This disease is mainly controlled through daily management by the caregiver rather than relying on chemicals.
Symptom Twelve
The affected part appears water-stained, with irregular black or brown spots on the leaves. As the disease progresses, white mycelium will grow on the affected part and the growing medium, later turning into brown sclerotia.
Causes: Caused by incomplete disinfection of the growing medium, high temperature, high humidity, and poor ventilation.
Solution: If there are two or more Phalaenopsis orchids being cared for, it is recommended to remove the infected plants and spray uninfected plants with a 1000x solution of copper sulfate or an 800x solution of carbendazim to prevent further infection. Once this disease occurs, it is basically impossible to save the plant.
The above is the complete content of common problems in the cultivation process of Phalaenopsis orchids. I hope it can help you, and at the same time, I hope everyone comes to see more green plant and flower experience and common knowledge!