How to control pests on Chinese knotweed? Latest technical method tutorial

Chinese knotweed (Polygonum capitatum) is a herbaceous plant with creeping stems, growing in clumps, belonging to the phylum Angiospermae, class Magnoliopsida, family Polygonaceae, genus Polygonum, also known as red sour stem, green shadow, stone vegetable, sour berry grass, etc. The whole plant is used as medicine and can treat urethral infection, pyelonephritis and other conditions. In Yuping County, Guizhou Province, it is the second largest Chinese medicinal material, with a planting area second only to blackberry lily. However, as the planting area of Chinese knotweed grows larger and larger, the problem of its pests and diseases has gradually become prominent. Below are four common pests and diseases of Chinese knotweed and their control measures introduced for herb growers:

Black cutworm

Also known as soil silkworm and root-cutting worm, belonging to the order Lepidoptera, family Noctuidae, it reproduces 2 to 3 generations a year, and the larvae overwinter in soil chambers. The first-generation larvae damage Chinese knotweed seedlings in late April and early to mid-May, causing missing plants and broken rows, and newly planted seedlings are especially severely affected by this pest.

[Control measures] 1. Manual capture: when new broken seedlings are found in the field in the morning, a tree branch can be used to dig the larvae out of the soil chamber at the broken seedling site and kill them. 2. Spraying pesticides: spray the seedling roots with 59% phoxim emulsifiable concentrate at 500 times dilution or 2.5% deltamethrin at 2000 times dilution. 3. Applying poisoned soil: mix 0.5 kg of 25% trichlorfon powder with 20 kg of fine soil evenly, and spread it into the soil before the seedlings emerge.

Two-spotted leaf beetle

Also known as four-eyed leaf beetle, belonging to the order Coleoptera, family Chrysomelidae, it occurs 1 generation per year, lays eggs in late October and overwinters in the soil in egg form. Although it only hatches in early to mid-May, the larvae damage the roots of Chinese knotweed in the soil, causing the plants to wilt and die. It pupates in late June and emerges in mid-July. The adults damage the leaves of Chinese knotweed, biting the leaves into holes or notches, and in severe cases can eat all the leaves. Drought favors the occurrence of this insect.

[Control measures] 1. Promptly remove weeds along field edges, field ridges and canal sides, and deep-plow before winter to eliminate eggs. 2. During the peak adult occurrence period, spray 1 to 2 times with 4.5% beta-cypermethrin at 1500 times dilution plus abamectin at 1500 times dilution.

Striped flea beetle

Also known as ground flea, flea worm and vegetable louse, belonging to the order Coleoptera, family Chrysomelidae, it occurs 4 to 5 generations per year and overwinters as adults lurking on stems, leaves and weeds. It begins feeding when the temperature rises above 10°C, its food intake increases greatly at around 20°C, and decreases greatly above 30°C. In early April it lays eggs in the soil at the plant roots, and after hatching the larvae feed on the root epidermis and young roots, causing the plants to die. In mid-to-late May the adults damage the leaves, causing many tiny holes and thus affecting photosynthesis.

[Control measures] 1. Clean the field, remove residual plants and fallen leaves after harvest, remove weeds, and bury or burn them in a concentrated way. 2. During the larval damage period, spray and drench thoroughly with 90% trichlorfon crystal at 1000 times dilution or 40% pyrethrin and malathion emulsifiable concentrate at 2000 times dilution. 3. During the adult occurrence period, spray 2 to 3 times with 50% phoxim emulsifiable concentrate at 1000 times dilution, with an interval of 10 days.

Tobacco cutworm

Also known as night thief worm and aconite worm, belonging to the order Lepidoptera, family Noctuidae, its source is generally migrated in from other places. It occurs 4 to 5 generations per year, and the larvae damage crop leaves, petioles or young stems. It likes high temperatures and fears cold, so high temperature is an important reason for its outbreak. Newly hatched larvae gather near the egg mass, begin to disperse at the 2nd instar, enter the gluttonous stage at the 4th instar, and mature larvae pupate in soil cracks and on fallen leaves.

[Control measures] 1. Clean the field and promptly remove weeds and residual branches and fallen leaves in the field. 2. Taking advantage of the adult's phototaxis, install insect-killing lamps in the field to trap and kill them. 3. Set up sex pheromone lures in the field to trap and kill adults. 4. During the young larval stage, spray with insect plague No. 1 virus at 1000 times dilution or 25% diflubenzuron No. 3 at 2000 times dilution.