Disease and Pest Control Methods and Technical Key Points for the Medicinal Herb Panax notoginseng
Panax notoginseng has many diseases and pests, and the damage is relatively severe. The common main diseases include Panax notoginseng black spot, Panax notoginseng root rot, Panax notoginseng phytophthora blight, Panax notoginseng anthracnose, and Panax notoginseng rust, commonly known as "yellow greasy disease," Panax notoginseng powdery mildew, commonly known as "gray spot disease," etc.; common pests include short-bearded mites, slugs, red spider mites, aphids, etc.
1. Black spot: After the stem and flower axis are affected, the lesions are initially brown and elliptical, then the upper and lower parts of the lesions expand and become sunken, and finally the diseased part breaks off, causing the stem to wither or the flower stalk to droop, wither, and die. When leaves are affected, nearly circular or irregular water-soaked brown lesions appear, and the lesions tend to perforate and rupture. In wet weather the lesions expand relatively quickly, especially in the high-temperature and rainy season from June to August, when it is even more severe, ultimately causing the leaves to fall off. After the fruit is affected, irregular water-soaked lesions appear on the surface, the peel gradually shrinks and dries, and black mold-like matter grows on it. After the roots are affected, they become brown and wet-rotted, and then gradually rot.
Control methods: ① Select disease-free seedlings and do a good job of disinfecting the seedlings: soak the seeds for half an hour in a 1:500 solution of amobam or carbendazim, and soak the seedlings for 5-10 minutes. ② Strictly select the site. For Panax notoginseng gardens, virgin wasteland is generally preferred, and continuous cropping should be avoided, especially continuous cropping with peanuts. It can be rotated with non-host crops such as corn for more than 3 years. ③ Plant at a reasonable density, and the light transmittance in the field should be controlled at 25%-30%. ④ In addition to applying sufficient base fertilizer, topdress and water in a timely manner, pay attention to the appropriate ratio of nitrogen, phosphorus, and potassium, apply more potassium fertilizer, control nitrogen fertilizer, and apply manure water 4-5 times a year. ⑤ Chemical control: tests show that a mixed solution of amobam and zineb (1:300), or a mixed solution of zineb and thiram (1:300), or anthracnose thiram 1:800 has good control effects on this disease.
2. Panax notoginseng phytophthora blight: Also known as "leaf-drooping rot," it mainly damages leaves. Affected leaves look as if scalded, appearing dark green and water-soaked. The disease is severe in June-August when temperatures are high and humidity is high. It is generally also induced by cloudy and rainy weather in early spring or low-temperature and rainy weather in late autumn.
Control methods: ① Clean the field, gather fallen leaves and dead branches in winter, and burn them in a concentrated manner. ② Before onset, spray Bordeaux mixture at 1:1:50, once every half month, for 2-3 consecutive times; after onset, spray 65% zineb 500 times, or 50% thiram 1000 times, or dexon 500 times, once every 7 days, for 2-3 consecutive times.
3. Root rot: Also known as "chicken manure rot," it damages the roots. The affected roots become dark brown and gradually soft-rot into a grayish-white pulpy state, with a foul odor.
Control methods: ① Choose plots with good drainage for planting. For the planting site, it is best to choose virgin wasteland with loose soil and good drainage, and drain promptly during the rainy season. ② When transplanting, select robust, disease-free Panax notoginseng. ③ Promptly pull out diseased plants and disinfect the diseased holes with lime. ④ During the onset period, irrigate the diseased area with carbendazim 100 times or 50% thiophanate-methyl 1000 times.
4. Damping-off: Also known as "rotten foot plague," it damages seeds, seed buds, and the stem base of seedlings. Affected seeds rot into a milky-white pulpy state, affected seed buds turn dark brown and die; the base of the false stem (petiole) of affected seedlings becomes dark brown, ring-shaped, and sunken; the seedlings bend over and die.
Control methods: ① Before sowing, disinfect the soil with carbendazim or comfrey liquid. ② Promptly pull out diseased plants when found, spread lime powder around the diseased plants, and spray 50% thiophanate-methyl 1000 times or 50% methyl pyrazophos 1000 times. ③ After emergence, promptly adjust the height or width of the shade frame, and maintain a light transmittance of 30%-35% in the garden as appropriate;
5. Anthracnose: It mainly damages the aboveground parts. Leaf lesions are yellowish-brown with obvious brown edges, and later small black spots form on the lesions, which easily perforate; lesions on petioles and stems are sunken yellowish-brown diamond-shaped spots in the center; lesions on fruit are circular, slightly sunken brown spots. The disease is severe in June-July when temperatures are high and humidity is high.
Control methods: ① Clean the field and promptly burn fallen leaves and dead branches. ② Select disease-free Panax notoginseng as seed stock, dip briefly in Bordeaux mixture at 1:1:200 before transplanting, and transplant after drying. ③ Disinfect seeds by soaking in 100-150 times 40% formalin for 10 minutes, rinse with clean water, and sow after drying. ④ During the onset period, spray 65% zineb 500 times, or 50% thiram 1000 times, once every 7 days, for 2-3 consecutive times.
6. Rust: Local names "yellow greasy" and "yellow blister disease." The pathogen is a basidiomycete among fungi. It mainly damages leaves. The diseased areas on the leaves initially appear as small yellow needle-tip-like raised spots, and when they expand they are circular or radial, with irregular edges. After the pathogen spore piles rupture, yellow powder is released.
Control methods: ① In winter, cut off the stems and leaves of diseased plants, and spray lime sulfur mixture at 1-2 degrees Baume. ② During the onset period, spray 200-300 times dinitro scattered, or 0.3 degrees Baume lime sulfur mixture, or 300 times dinocap, once every 7 days, for 2-3 consecutive times.
7. Powdery mildew: The pathogen is a deuteromycete among fungi, mainly damaging leaves. Diseased leaves are covered with grayish-white powder.
Control methods: ① In winter, clean the garden and cut off diseased plant leaves, and spray lime sulfur mixture at 1-2 degrees Baume. ② In the early stage of onset, spray 0.3 degrees Baume lime sulfur mixture or 50% thiophanate-methyl 1000 times, once every 7 days, for 2-3 consecutive times. Pests
1. Short-bearded mite: Also known as fire spider, belonging to the order Acariformes, family Tetranychidae, class Arachnida. Adults and nymphs gather on the underside of leaves to suck sap and spin silk webs. This causes leaves to turn yellow and finally fall off. After the flower disc and red fruit are affected, they become shrunken and withered.
Control methods: ① Clean the garden in winter, gather fallen leaves and dead branches and burn them, and after cleaning the garden spray lime sulfur mixture at 1 degree Baume. ② Starting in April, spray 0.2-0.3 degrees Baume lime sulfur mixture, or use 20% tetradifon wettable powder 1500-2000 times, or 25% chlordimeform aqueous solution 500-1000 times for spraying, once a week, for several consecutive times.
2. Slug: Also known as dry snail or slug, it is a mollusk. It bites and feeds on seeds, stems, and leaves, causing notches. It feeds and causes damage at night and in the early morning.
Control methods: ① In winter, turn and sun-dry the soil. ② Before planting, apply 300-375 kg of tea seed cake per hectare as base fertilizer. ③ During the occurrence period, spread lime powder on the bed surface or spray with 3% lime water to kill them.
3. Red spider mite: Nymphs and adults overwinter hidden on the ground surface. They become active in March-April, and the damage is severe from June to October. Affected leaves turn from green to yellow and fall off; damage to the flower disc and tender fruit causes early shrinkage, failure to bloom, and failure to set fruit.
Control methods: Carefully clean the Panax notoginseng garden in winter, burn weeds and fallen leaves and dead branches in a concentrated manner, and spray the bed surface with lime sulfur mixture at 2-3 degrees Baume; before they become active from March to April, spray lime sulfur mixture at 0.2 degrees Baume, once every 7 days, for 2-3 consecutive times; when damage is found, promptly spray 40% dimethoate 1000 times, once every 7 days; during the peak damage period, spray 20% tetradifon 800 times, once every 5 days.