The pathogen of sclerotinia disease

The pathogen of Sclerotinia sclerotiorum mainly harms the bracts of orchid plants. The function of bracts of orchid plants is mainly to protect the meristem growth point, if the bracts are damaged by Sclerotinia sclerotiorum, the growth point is generally easy to necrosis, affecting the chance of lateral bud germination. At the initial stage of bract damage caused by Sclerotinia sclerotiorum, irregular brown spots will appear at the tip or at the edge of the leaf, which will gradually turn gray and the tissue will die. Most of the round black sclerotia will grow on the dried bracts, and when the sclerotia matures, the sclerotia will form nuclei and fall into the medium. when the environment is suitable, the sclerotia will reinfect other healthy bracts.

Prevention and control methods:

(1) if Sclerotinia sclerotiorum is found to be infected with Sclerotinia sclerotiorum, the diseased leaves of bracts should be cut off, the diseased leaves removed by the disease should be burned immediately, and the water moss and medium should be replaced to prevent the spread of bacteria.

(2) the phenomenon of stagnant water in bracts should be avoided as far as possible by water supply.

(3) during the period of rooting and sprouting, the bracts are more likely to be injured, and the pathogens are easy to invade and infect from the wound, so more chemical control should be applied.

(4) maintain a good ventilated environment and do not be too close between plants.

(5) to avoid man-made or mechanical injury.

(6) choose the medium with good aeration, no miscellaneous bacteria and full accumulation fermentation as the cultivation medium, such as Lanbaole, orchid four-in-one special organic plant materials, etc. Immediately after the ramet was changed, the 75% metoprolol wettable powder was applied a thousand times, and the Zhanshui exhibition agent was added 1500 times. Spray bracts, stem base and perfusion medium. Put it in a cool place and do not use wave perfusion to feed water within two days.

(7) after the diseased leaves are removed during ramet, the fungicide shall be applied immediately to kill the germs. When the general cultivation managers plant the national orchid, the bracts are more easily infected by pathogens, and the reasons for the decay or withering of the bracts are as follows:

(a) the orchid plant itself carried the pathogen of Sclerotinia sclerotiorum, and the cultivation managers did not remove it and do a good job of prevention and control during planting, and the pathogen again infected other healthy bracts.

(B) caused by poor ventilation between plants and in orchid rooms

(C) improper watering and prolonged accumulation of water in the bracts

(d) during the period of growing roots and new buds, the bracts were cracked and injured, and the pathogens were waiting for an opportunity to invade from the wound, and the cultivation managers did not carry out pesticide control in time to prevent the bacteria from spreading.

(e) when planting, the orchid plant is planted too deep or the water moss is too big and too tight, resulting in poor ventilation and poor water accumulation.

(F) without adequate accumulation and fermentation in the cultivation medium, the population density of beneficial microorganisms is too low to inhibit the growth of harmful pathogens, resulting in a large room for survival and reproduction of Sclerotinia sclerotiorum pathogens.

The presence or absence of bracts is closely related to the beauty of the whole orchid plant, the commercial value and the protection of the growing point. Bract necrosis, relative growth point is also easy to necrosis, affecting the yield of national orchid reproduction. Therefore, if the cultivation managers want to cultivate the national orchid with high yield, good quality and good price, the most prerequisite is to keep the bracts strong. At ordinary times, it is necessary to regularly use agents to inhibit the proliferation of bacteria and remove the causes of bract disease, and it is most necessary to apply microbial additives to antagonize the growth of Sclerotinia sclerotiorum.