How to prevent and treat stem rot in orchids? A detailed guide to practical methods

Symptoms

The disease mainly occurs onorchidnew shoots, followed by the leaves. In the early stage of the disease, a lesion the size of a mung bean appears at the base of the shoot, and after 2 to 3 days it rapidly spreads upward and downward, becoming a large dark green patch that extends to the outside of the shoot tip and turns dark brown. When the newly emerged orchid shoots are affected, the disease is quickly transmitted to the orchid plants from the previous year; 1- to 2-year-old seedlings are susceptible, while the pseudobulbs of old plants are highly lignified and not easily affected.


Pathogen

The pathogen issoft rotErwinia carotovora. The optimum temperature for this bacterium is 25°C to 30°C, and it can grow at pH 5.3 to 9.2, with pH 7.2 being the most suitable; this bacterium can infect many kinds of orchids.

Prevention and control measures

During periods of high temperature, cooling measures should be taken to keep the temperature of theorchid-growingarea below 25°C; at the same time, reduce the amount of watering to lower the water content of the potting soil; reduce the frequency of misting to lower the relative humidity of the air; and strengthen ventilation to create an environment unfavorable for the infection and reproduction of the pathogen.

Strengthen chemical prevention

Disease prevention: According to the author's investigation, when this disease occurs in spring, autumn and winter, if measures are taken early, some orchid plants may still be saved, but in the hot summer, once orchid plants are infected, it is very difficult to treat them. Therefore, doing a good job of chemical prevention of this disease is very important. The following chemicals can be used to prevent this disease: 53.5% Kocide dry flowable 1000-fold solution; 72% agricultural streptomycin wettable powder 800-fold solution; 50% Ruanfuling powder 800-fold solution.

How to use: once every 7 to 10 days, use continuously 2 to 3 times, then spray according to the situation.

Pest control: After pests in the orchid garden or orchid pots harm the orchids, the pathogen invades the orchid bodies and the orchid plants are damaged. Therefore, preparations for pest control should be made.

In short, in the prevention and control of orchid diseases, the principle of prevention first and control second must be followed. Secondly, in routine management, an environment suitable for orchid growth should also be created, so that orchids do not grow in a hot, humid and poorly ventilated environment. In the use of fertilizer, nitrogen, phosphorus and potassium should also be used in combination, and nitrogen fertilizer should not be applied alone, so as to enhance the ability to prevent and resist disease.