A Detailed Guide to Pest and Disease Control Methods for Cymbidium Hybrids
Fungal anthracnose
Mostly occurs at the tips of the leaves, with dark brown lesion margins and a grayish-white center, mostly caused by high temperature, high humidity and poor ventilation. The lesions should be cut off promptly along with spraying. Commonly used chemicals include 1000x mancozeb and 1000x copper hydroxide.
Other fungal diseases are commonly controlled with the following chemicals: 1000x chlorothalonil, 800x metalaxyl, and 800x metalaxyl-M.
Pest and Disease Control for Cymbidium Hybrids
1. Fungal anthracnose
Mostly occurs at the tips of the leaves, with dark brown lesion margins and a grayish-white center, mostly caused by high temperature, high humidity and poor ventilation. The lesions should be cut off promptly along with spraying. Commonly used chemicals include 1000x mancozeb and 1000x copper hydroxide.
Other fungal diseases are commonly controlled with the following chemicals: 1000x chlorothalonil, 800x metalaxyl, and 800x metalaxyl-M.
2. Bacterial diseases
Commonly used chemicals include 6000x agricultural streptomycin sulfate, 300 ppm agricultural streptomycin, and 800x validamycin. When grown continuously on the same soil or over a long period, soft rot can become severe. This disease does not occur at the seedling stage; generally by the third year, when the flower buds reach a height of 20 to 30 cm, the pseudobulbs are suddenly found to have all rotted away, and it also occurs on the mountains. At this point the plants can only be destroyed entirely, otherwise the disease can easily spread to healthy plants. If the surrounding environmental sanitation is dealt with promptly and chemical control is carried out, the disease can be suppressed.
3. Pests
The main pests are slugs and spider mites. Commonly used chemicals: slug bait (for trapping and killing) and trichlorfon miticide. From June to September, when ventilation is poor, slugs become a serious problem; they mostly hide on the undersides of the leaves and also damage the root system. For control, lime can be scattered in the gaps between bricks and then watered, which can kill large numbers of adult slugs; meanwhile, Kalanchoe leaves and granular slug bait can be used for trapping and killing. Spider mites occur on the undersides of the leaves, so when spraying, start from the undersides of the leaves.
The above is an introduction to the price of Cymbidium hybrids and their pest and disease control. We hope it can help everyone. For more home knowledge, please stay tuned.
Common Pests and Diseases of Cymbidium Hybrids and Their Control
1. Diseases: mainly including phytophthora rot, soft rot, root rot, anthracnose, leaf blight, and virus diseases.(1) Phytophthora rot: Because it occurs in different parts and produces different symptoms, it is also divided by some into black rot, heart rot, stem rot, and damping-off, and it can occur in all four seasons in the Xiamen area. Under greenhouse cultivation with high temperature, excessive watering and poor ventilation, a large amount of water accumulates in the leaf axils, and over time this most easily triggers the disease. June to August each year is the peak period of incidence. It can affect plants from seedlings to flowering plants, and the clustered seedling stage as well as new shoots and young leaves are most susceptible. It is caused by two closely related fungi - Phytophthora cactorum and Pythium ultimum. Phytophthora cactorum easily causes root rot, damping-off and crown rot, while Pythium ultimum also easily causes root rot and damping-off in plants. Once these diseases occur and are not dealt with promptly, they quickly spread to the root system and pseudobulbs, so they are terrifying, destructive diseases of Cymbidium hybrids. Their route of infection is through spores spread and dispersed by water droplets splashed during watering. Control methods:
1. Environmental control: The orchid shed must be well ventilated and have sufficient light. During outbreaks, water must be strictly controlled, diseased leaves and plants removed promptly, and watering from above downward should be avoided.
2. Once an infected plant is found, immediately remove the diseased tissue, and at the same time cut away about 1 inch of uninfected tissue as well; if the damage is severe, remove the entire plant.
3. Tools such as scissors must be strictly sterilized.
4. Chemical treatment: Spray with 80% zineb at 500x dilution. Alternatively, spray with 8-hydroxyquinoline sulfate at 1:2000, or soak the diseased plant in sodium o-phenylphenate solution for 1 hour, and if necessary repeat the treatment within 3 to 7 days.
(2) Soft rot: Soft rot usually attacks the leaves, buds and pseudobulbs of Cymbidium hybrids, and can occur from spring to autumn throughout the year, though it is less often seen in winter. It sometimes occurs together with phytophthora rot, but is not too serious. It is caused by a bacterium called Erwinia chrysanthemi, which has a very wide host range and can cause damage to all orchids. Its main routes of entry are through wounds or natural stomata. In orchid sheds with high temperature and high humidity, this disease spreads extremely quickly. At 100% relative humidity and a temperature of 30°C, after artificial inoculation it completes the invasion process in just three hours. Its symptoms are somewhat similar to those of phytophthora rot, making it very difficult for beginner orchid growers to distinguish. Because the nature of these two diseases is different, the chemicals used are also different.
In the field, our distinction is mainly based on pulling out the rotted diseased part for observation: the rotted tissue of phytophthora rot has no sap or little sap, no fishy stench, and when a drop of the sap is squeezed into a glass of clear water, no cloudy turbidity is seen spreading; whereas in soft rot, the cells inside the epidermis of the diseased part are all broken down into watery liquid containing countless white bacterial ooze, with copious sap that flows out at the slightest touch, along with a fishy stench, and when a drop of the sap is placed in a glass of clear water, a cloudy turbidity can be seen spreading in all directions. Control methods:
1. Environmental control and handling of diseased plants: The same as item (1) above, with special care not to let the sap of the bacterial ooze contaminate healthy plants.
2. Chemical treatment: General pesticides are ineffective against soft rot, so once the disease occurs the diseased plants have to be discarded. Therefore, preventive measures are mainly adopted, and spraying with 40% copper hydroxide at 400x dilution gives good results. You can also use 68.8% oxytetracycline-streptomycin complex or 18.8% streptomycin at 1000x dilution, spraying once every 7 to 10 days for 3 to 4 consecutive times. These chemicals can be used in rotation to prevent the plants from developing resistance.