On the root rot of orchids

The pathogen of root rot is Rhizoctonia solanacearum (Rhizoctoina solani), which mainly lives in the cultivation medium and harms the root tissue of Orchid in the environment of proper temperature and humidity, resulting in the decrease of water and nutrient absorption capacity of roots. There is disharmony between evapotranspiration and absorption, and the orchid plant weakens day by day, which affects the normal growth of the orchid plant. The pathogen of root rot mainly infected the root system, and the injured orchid root had brown disease spot, depression and necrosis in the initial stage. Several severe spots will ring around the base of the stem and new roots or roots will grow, and finally the whole root will rot. Furthermore, the water transport was blocked and supported, and the orchid plant was gradually wilted or yellowed, dwarfed and so on.

The pathogen of root rot mainly harms the newspaper tissue, which can not be detected by the naked eye. In addition to the Philippines, the managers often pour out the orchid plant for observation. When the root tip or root rot, the orchid plant growth is slow, the leaf tip scorched, the leaf withered, the bract turned black, the new root Fei black after looking for a solution, it is too late! It has caused great damage to the future growth of the orchid plant.

Therefore, cultivation managers should pay more attention to whether the water moss is dead, whether the medium is acidified, whether the medium permeability is good, whether the chemical fertilizer is applied properly, whether the water is drenched excessively, whether the air in the orchid room is circulating and convective, whether the medium is clean and free of pathogens, whether the medium is fully accumulated and fermented, and whether the chemical control is thorough. Whether the plant is disinfected, whether there is pest control in the process of cultivation and management, and whether the main planting medium is proper, these problems are the inducement of root rot, cultivation managers have to be careful.

Route of transmission:

Root rot is a medium-borne disease. Mainly through the adverse environment with dormant hyphae or sclerotia. In the cultivation media used in national orchid cultivation, some media have been detected to carry this pathogen, which should be paid attention to by cultivation managers. It occurs most seriously in the old medium with poor wet ventilation, especially in the out-of-date medium, and sometimes the whole root system decays.

Prevention calendar:

(1) persist in changing the medium from one year to one and a half years, and choose excellent media with half particle size, good ventilation, strong water retention, moderate PH value, good buffer capacity, light texture, clean and non-toxic.

(2) after fully accumulating and fermenting for six months before the medium was used, the content of toxic powder compounds decreased and beneficial phenolic compounds were synthesized to promote the growth of orchid plants. The high temperature produced by Huaiji can kill pathogens, nematodes and other important factors affecting the growth of Cymbidium. After accumulation, the beneficial microbial population will increase greatly, reduce soil-borne diseases such as Sclerotinia sclerotiorum, medical disease and root rot, and promote root growth in a healthy medium environment.

(3) when the medium is accumulated, it can be added full point 18 or after planting, which can inhibit the pathogen of root rot disease, and the root growth and development has a very significant effect.

(4) regular detection of the PH value of the medium and the concentration of the base, and the verification of the PH value may be used:

(a) the saturated paste method. The ratio of medium to distilled water is 1:3, which is determined by S47TEXPHmeter after stirring for an hour.

(B) determination of base concentration: the ratio of medium to distilled water is 1:3, after fully stirring for one hour, if the PH value determined by HananH18820Ecmeter is less than 1.0, lime and phosphate fertilizer should be added. The supply of fertilizer and the application of phosphorus-solubilizing bacteria were strengthened to facilitate the growth of root group and the development of stem and leaf.

(5) usually pay attention to the harm of root mites, root thrips, roundworms and cockroaches.

(acupoint) apply beneficial microbial additives to achieve the effect of bacteriostatic and antibacterial control.

(7) at the initial stage of new bud growth after planting, the flowers that supply appropriate amount of phosphate fertilizer and promote rapid root growth are very prosperous, and promote early rooting, independent living function separated from the mother plant, exuberant root group development and strong plant growth.

(8) regular application of 75% metoprolol wettable powder to dilute 1000 times.

(9) the diseased plant should immediately change the medium, the rotten root system of the orchid plant should be removed before planting, the medium should be quasi-accumulated and fermented, and 75% metoprolol wettable powder should be used immediately after planting to irrigate the medium and root system. After planting, move to a cooler place, and apply amino acid 2,000 times every three days to spray the foliar surface, so that due to the lack of photosynthetic capacity, the nutrients needed to grow new roots are decomposed from the plant cell storage, thus affecting the germination of buds. Ten days after planting, the application of Huaganwang + Shengshang phosphate platform into enzyme can promote root formation and root tip elongation, and the hydraulic absorption and nutrient absorption can be balanced.

(10) do not use irrigation water supply within two days after spraying, but spray water supply instead, keep the medium as dry as possible and accelerate the healing speed.

[editor's note] in the past two years, the large-scale orchid fields and courtyard orchid rooms in the delta generally reported the occurrence of serious root rot and serious losses, especially in some old orchid fields. Therefore, the above prevention and control materials are specially selected for Lanyou's reference.