Control of orchid anthracnose and leaf blight

Anthracnose of orchid

Symptoms: anthrax symptoms of different orchid varieties, the symptoms are different, mainly harm to the leaves, the leaf tip leaf edge is more, the leaf tip disease spot expands to form the whole leaf to die. Leaf edge disease spot often into a semicircle or irregular shape, the middle of the leaf disease spot into a round or oval, the size of the disease spot 2mur20mm, the disease spot can be connected to form a strip or cause the whole leaf to die, some of the color of the disease spot is reddish brown in the first stage, dark brown in the later stage, and some become grayish white after turning dark brown, small black spots are born on the disease spot, sometimes the small black spots are arranged in a wheel, and the small black spots are the conidium disk of the bacteria.

Pathogen: COLLETOTRICHUM ORCHIDEORUM

Belongs to the subphylum Colletotrichum, Colletotrichum, conidium disk oblate, bristles with or without, peripheral, dark brown, with several septum, conidium cylindrical, colorless, unicellular, containing 1 Mel 2 oil balls.

According to the law of the disease, the hyphae overwintered on the diseased plants or soil residues, and the conidia could also survive the winter, but the germination rate was low, the pathogen began to infect in early April, stopped at the end of November, and reached the peak from April to August. The new leaves began to occur in late July and reached the peak from late August to September. The pathogen mainly invaded from the wound and could also invade from the epidermis at 25. C, when the relative humidity is more than 85%, the disease is favorable to the epidemic, the peak of the disease is in the typhoon season in the plum rain season, and the heavy rain is also beneficial to the disease after high temperature in summer. The disease degree of different varieties of orchids is obviously different, and the disease of Cymbidium is more serious. The incidence of Cymbidium is moderate.

Prevention and control measures

1. Agricultural prevention and control: outdoor cultivation should build sunshade equipment, adjust the distance between basins, not only ventilation and light, but also maintain a certain air humidity, use rotten organic fertilizer, do not use alkaline water, pour it from the edge of the basin when watering, reduce the time of water contact on the leaf surface, prevent storm and other mechanical injuries, reduce the chance of bacteria invasion, and remove and destroy the diseased body in time.

2. Chemical control: commonly used agents are chlorothalonil 75% wettable powder, 50% Dysenmeng zinc wettable powder, 50% carbendazim 800 times solution, 70% thiophanate 600 mi 800 times solution, and so on.

Orchid leaf blight

Also known as round spot disease, sometimes mixed with anthrax, it is easy to cause leaf wilt.

Symptoms: the occurrence site is mainly in the lower part of the leaf, watery, light brown at the beginning of the disease class, dark brown on the edge at the later stage, and gradually light brown in the middle, sometimes showing a small light brown ring pattern on both sides of the disease spot, showing small protuberances on both sides of the disease spot, breaking through the epidermis after ripening, showing a round, boat-shaped or irregular shape, surrounded by warped epidermis, showing yellowish brown protuberance when wet, and the disease spots can be connected to each other. Causing the leaves to wither in a large area.

Pathogen: CYLINDROSPORIUM DIOSCREAE

It belongs to the semi-known phylum, Styllosporium, conidium disk-shaped, conidium pedicel short, linear, straight or slightly curved, round at both ends, colorless, monospore, smooth surface.

The disease law, the pathogen overwintered in the diseased leaf, the pathogen was transmitted by Rain Water, the warm and humid weather was favorable for the transmission and invasion of the pathogen, the disease of the old leaf began in late April, the peak period was from late May to June, and the development stopped in November, the damage of the new leaf was heavier than that of the old leaf, the soil was hardened, the flowerpot was placed too dense, the ventilation and light penetration was poor, and the disease was aggravated by low temperature.

1: cut off the diseased leaves, improve the ventilation and light transmission conditions, and prevent rain in summer.

2: during the growth period, 70% chlorothalonil 500 Muthamel 600 times solution, 50% acetaminophen 800 times solution, 65% Dysen zinc 500 times solution is sprayed every 12 days. (it clears up when it snows fast)