The epidemic disease of national orchid and its control

Blight is the most common disease in Guolan. Guolan has been cultivated in greenhouse facilities with high temperature, humidity and poor ventilation for a long time, and it is most likely to suffer from epidemic disease. It is also the period with the highest frequency of epidemic disease, especially from the budding stage to the growing period. The pathogen of Phytophthora can be divided into Phytophthora and Rhizoctonia, which belongs to soil-borne diseases.

After the pathogen of Phytophthora infects the tissue of the orchid plant, the disease spot is dark green at first, and the spot expands very rapidly, which can occur in any part of the orchid plant. From the young bud stage to the leaf expansion, because the cultivation manager carried out the watering work, did not immediately keep the aboveground part of the orchid plant dry, the bud core and bract stagnant water, the pathogen of the disease waited for an opportunity to invade and harm, and the leaf core rot was like water immersion. At this time, if the cultivation manager is unable to take immediate prevention and control work and eliminate the diseased leaves, the disease spot will expand rapidly and spread to the false corm and root base, and in serious cases, it will spread to other healthy orchid plants. In the mature stage of the orchid plant, due to the maturity of the leaves and tissue fibrosis, the disease will not rot and lodge, but only yellowing of the leaves.

In severe cases, yellowing extends to the finger ring (detachment), and the leaf door falls, endangering the root. Sometimes diseased plants that lose their leaves will sprout from the bulbs. If the root is infected by the pathogen of the blight, the root tissue will rot, and the pathogen will spread upward, endangering the bract and the growth point, causing serious necrosis of the bract and the growth point.

Route of transmission:

The occurrence of the pathogen of Phytophthora is the most serious in the environment of high temperature, humidity or poor ventilation. The disease spreads rapidly when the relative humidity reaches 100%, and the pathogen slows down with the decrease of humidity, and stops growing when the relative humidity is 50%. The pathogen of the disease is transmitted by reliable water, wind and medium. During the rainy season, the incidence of epidemic disease is relatively high, and insects will also spread the disease.

Prevention and control methods:

(1) keep the orchid chamber gong well ventilated, avoid excessive watering and leaching, and make the medium acidified. The choice of medium requires good drainage and fast re-wetting.

(2) the leaves should be kept dry immediately after watering to avoid stagnant water in the bracts and bud centers. A small number of wandering spores, that is, invade and harm infection without passing through the wound.

(4) pay attention to insect pests at all times to avoid the spread of the disease.

(5) cultivate healthy and strong orchids and do not apply excessive nitrogen fertilizer. More plant growth promoters with low nitrogen and high potassium organic matter should be applied to enhance the disease resistance of orchid plants.

(6) remove the affected site immediately, treat with appropriate leaf agent and move the place with low humidity to prevent the spread of pathogenic bacteria.

(7) whenever the PH value of the medium is lower than the critical point for the growth of the national orchid, plant ash or bitter lime should be added, the pH value should be adjusted to moderate, the bitter soil lime should be soaked in water for more than 1000 times for more than 12 hours, and properly poured into the bowl medium, the PH value can be adjusted and the spread of pathogenic bacteria can be restrained.

(8) if it is found that the orchid plant is infected with Phytophthora, it is better to change the medium immediately and immediately treat it with medicament. if it is treated a few days after planting or by plant impregnation, it will be very difficult to achieve the desired control effect.

At present, some of the cultivation media used in national orchid cultivation often carry the pathogen of Phytophthora. Orchid plants are often prone to disease if cultivation managers do not make proper treatment in advance or accumulate sufficient fermentation before planting.

On the other hand, the blight pathogen in the pathogen of Phytophthora generally uses chemical pesticides such as Edeli or Pucela, which is difficult to achieve the therapeutic effect, which often troubles the cultivation managers in the management of the cultivated national orchid.

Therefore, the cultivation manager should thoroughly clean the environment one month before the Guolan plant, spray the whole orchid room with chemicals to reduce the number of pathogens, and irrigate the orchid plant and pot medium with Edeli mixed metoprolol after planting, so as to inhibit the occurrence of pathogens, which can be used in turn at ordinary times:

(a) 25% Edeli emulsion 1500 times

(B) 30% Edeli wettable powder 2500 times

(C) Metoprolol wettable powder 2000 times

(d) 75% metoprolol wettable powder 1000 times

Add 1500 times of exhibition water exhibition agent to increase the effect. It is used in turn every 14 days in summer and every 30 days in winter. If you have suffered from the epidemic disease, you can use 35% Edelicol wet powder 1500 times mixed with 75% chlorphenamine 1000 times, add water exhibition agent 1500 times, spray the whole plant, including leaf surface, leaf back, bract, stem base, medium, inside and outside the pot, etc., in order to carry out disinfection by the most particulate spray to ensure the control effect. Try to keep the humidity and the whole plant dry for two days. It should be applied every seven days until the disease is reduced.

There are many kinds of pesticides sold in the market, which have excellent effects on the prevention and control of epidemic diseases. However, the national orchid plant is a higher plant, and its tolerance to certain pesticides is more sensitive, which will affect the growth of the national orchid after use. When some agents are mixed with other chemicals or chemical fertilizers, organic fertilizers, or even plant growth regulators, it is easy to cause drug damage or growth disorders.

When the cultivation managers are engaged in disease prevention and control work, they should be more careful when choosing chemicals and mixed use, so as not to cause serious damage to the orchid plant, then the loss outweighs the gain.