Diseases and insect pests of Morinda officinalis

The main diseases and insect pests of Morinda officinalis are stem rot, root-knot nematode disease, purple root disease, soot disease, grub (beetle larva) and mole cricket, scale insects, whitefly, aphids and red spiders. The performance and control methods of its diseases and insect pests are introduced in detail below.

1. Morinda officinalis disease

1. Stem rot: it is the most widely distributed and most serious destructive disease. The stem base, root and seed of Euphorbia officinalis may be infected with stem rot. The pathogen is Fusarium oxysporum, Fusarium oxysporum (Fusarium oxysporum). The parasitic specialization of bacteria is strong. It can occur in all growth stages of Morinda officinalis. Most of them occurred on the plants of 2-3 years after planting. The initial period is from late March to early April (the temperature rises to more than 15 ℃), the general period begins from the first ten days of April to the middle of May, and there are two peak periods from the middle of May to the last ten days of October.

Control methods: select the ecological environment similar to the wild Morinda officinalis for planting, with the next year of burning soil and calcium superphosphate as the base fertilizer, can not be traced to nitrogen fertilizer. In order to avoid germs invading from the wound, it is not suitable to plough and loosen the soil, it is better to pull grass in spring and autumn and shade with grass in summer to reduce the surface temperature and protect the cortex of the rhizome from damage. In Rain Water season, stagnant water should be eliminated in time. Seriously diseased plants should be removed and disinfected. In the initial period of the disease, 60% carbendazim 800 times solution can be used to spray the base of the stem or irrigate once, and another 2-3 times in the peak period of the disease. Or the application of 1:1 yin and yang ash (plant ash and lime) and sulfur powder (1-1.5g per plant) was also effective in the control of stem rot.

2. Root-knot nematode disease: the disease is common and the damage is slow. After the plant was damaged, the growth was poor, and the aboveground part withered or withered. After the root was damaged, round nodules of different sizes and rough surfaces were formed on the main root and lateral root. When the small tumor is cut, there are white granules in the tumor, and the pear-shaped female adult can be seen under the microscope. The disease is caused by root-knot nematodes. Root-knot nematode overwinters in the root or soil, infecting the young tissue of the root, especially the root tip tissue. Mainly through seedlings, fertilizers, farm tools and water transmission.

Prevention and control methods: Morinda officinalis is a deep-rooted plant, if the use of chemicals to control root-knot nematode disease, it is difficult, high cost and little effect. The main purpose is to put an end to the source of infection and carefully select the site. Seedlings are raised to choose wasteland or former as paddy land. The planting land should choose the wasteland with better fertility of red soil or yellow mineral soil. Seedling quarantine should be strengthened and diseased seedlings should be eliminated to prevent the spread of harm.

3. Purple root disease: also known as purple feather disease, which causes serious harm in local areas. The surface of the infected root was purple. When the surface of the diseased root is surrounded by dark purple velvet mycelium, the cortex is rotten and easy to peel off, and the xylem is initially yellowish brown and wet rot. The disease is caused by basidiomycetes. The pathogen lurks in the soil by its mycelium and sclerotia on the diseased root. Soil moisture or poor drainage is conducive to the growth of pathogens.

Purple root disease

Prevention and control methods: introduce healthy seedlings for planting; pay attention to drainage to promote the healthy growth of Morinda officinalis. Diseased plants should be dug up and burned in time. The soil around the diseased plant can also be irrigated and disinfected with 20% lime water or 2.5% ferrous sulfate, and sundries such as roots and litter should be removed from the newly reclaimed land. Purple root disease

4. Soot disease: it is caused by ascomycetes in fungi. The hyphae, conidia and ascospores of the pathogen can survive the winter and become the source of infection at the beginning of the next year. It mainly harms leaves and twigs and forms a black mildew layer on the host, which is like soot. In severe cases, the surface of leaves and twigs is covered with black bituminous coal, which hinders the normal photosynthesis of Morinda officinalis and can wither the whole plant in serious cases. Its occurrence is closely related to the harm of aphids, shell insects and planthoppers. The more insect pests are, the more serious the disease is. Therefore, pests should be eliminated in time.

Prevention and treatment methods: after the onset of the disease can be used 0.3% 0.5 Baumetu stone sulfur mixture, or Dysenamine 800-1000 times liquid spray.

Second, Morinda officinalis pest

Grubs (beetle larvae) and mole crickets are common underground pests. The soil can be irrigated with more than 1000 times of trichlorfon. Use 90% trichlorfon 50 grams plus bait 0.5 kg (stir-fry rice bran or wheat bran; then add trichlorfon to mix well) to make poison bait. It is best to put 2 grains at the mouth of the cave in the evening after a few days of rain, or dip a little peanut oil with pine needles, vegetable leaves or Xunpi, and then stick insecticides into the hole, so that the pests die after eating.

Mole cricket

Grub

Scale insects, whitefly, aphids and red spiders: all harm leaves. The scale insects were sprayed with 40% dimethoate emulsion 0.5 kg, kerosene 0.1 kg and water 750 kg or 0.2 Baomedo stone sulfur mixture once every 7-10 days for 2-3 times in a row. The aphids were sprayed with 1500 times of dimethoate EC. The whitefly larvae suck the leaf sap to control the same scale insects. Red spiders were sprayed with 1000-1500 times of 25% insecticidal amidine or 1000-1500 times of triclofenac EC, once every 7 days, several times in a row.