Occurrence characteristics and control methods of the main insect pests of greenhouse asparagus (beet noctuidae moth and thrips).
Cheng Zhichao Jiang Hanshun
Asparagus, also known as stone cypress, dragon's whiskers, etc., belongs to the lily family asparton, perennial root herb, unique flavor, rich in nutrition, containing a variety of essential amino acids and trace elements, but also rich in rutin, polysaccharides, flavonoids and other medicinal active ingredients, with a variety of health care effects, known as the king of vegetables, loved by the majority of consumers, the market demand is increasing. The asparagus industry in Lianshui County, Huai'an City, has developed rapidly and the planting area has been expanding, but in recent years, the incidence of insect pests has also shown an upward trend, which has seriously reduced the yield and quality of asparagus. The occurrence characteristics of the main insect pests of asparagus and the green prevention and control measures are introduced as follows.
1 Beet nocturnal moth
There are many types of nocturnal moths on asparagus, and beet moths are more common and more harmful. Beet nocturnal moth eats the tender stem of asparagus with larvae, eats a large amount, and also eats the cortex of the old stem, when the harm is serious, only the dry light stalks are left in the aerial part of the asparagus, losing the assimilation function, unable to accumulate nutrients, resulting in serious yield reduction.
1.1 Morphological characteristics
Adults are grey-brown, 12 to 14 mm long, with a wingspan of 19 to 30 mm, the forewings have distinct kidney-like stripes and ring-shaped spots, the outer margin line consists of a series of black spots, the hindwings are silvery-white, and the outer edges of the wings are black-brown. The eggs are spherical, pale greenish-white, with radial lines on the surface. The eggs are in a lumpy shape, with more than 10 grains each, with single or multiple layers overlapping, with white villi on them. The mature larvae are 20 to 30 mm long, with a variety of body colors, green, dark green, yellowish brown, brown to black brown, the lower line of the abdominal valve is a clear yellow-white longitudinal band, each with a white spot on the valve, and the middle chest valve is located on the posterior edge of the anterior chest, with obvious external protrusions. The pupal is 12 to 13 mm long and yellowish brown.
1.2 Occurrence Characteristics
In the Jianghuai region, beet noctus moths occur in 5 to 7 generations per year, about 1 generation per month, and the generations overlap, and the hazard period is peak from July to September, and the pupae overwinter in the soil. Adults hide in the shade of weeds and plant stems and leaves during the day, are nocturnal, phototropism and chemotaxis, and lay eggs on asparagus stems, branches or pseudo-leaves after mating, with an egg stage of 2 to 6 days. The larvae are 5 to 6 years old, cluster hazards at the beginning of incubation, disperse hazards after 3 instars, and greatly increase the amount of food, and eat asparagus into light stalks in severe cases. The larval stage is about 18 days, the old mature larvae enter the soil for 0.5 to 3 cm as a chamber pupal, and the pupal stage feathers into adults after 8 to 9 days. Pupae and eggs are more tolerant of low temperatures, and the mortality rate of eggs after a short period of -20 °C low temperature is only 40%, but the larvae die in large numbers of days at 2 °C, and adults die after hours to days at 0 °C.
1.3 Green prevention and control measures
1.3.1 Agricultural control
Remove roadside weeds from the field, worsen the pest breeding environment, reduce the pest base [1], manually remove egg blocks and young larvae gathered more branches and leaves in combination with agricultural operations, collect the greenhouse film when the ground is partially dead, and clean the countryside before wintering.
1.3.2 Physical control
Field placement of sexual attractants, both timely grasp of insect conditions, but also can trap adult insects, pieces of asparagus field can be used to trap with black light; the food attractant and water in a 1:1 ratio into a medicinal solution, and according to every 1 000 mL of the liquid plus 5% chlorantraniliprole 2 mL, the liquid is poured into the mineral water bottle (cap hole), in mid-July, holding the mineral water bottle in the middle of July while walking between the rows to sprinkle the liquid on both sides of the plant, every 667 m2 spray solution 200 mL.
1.3.3 Chemical control
In the larval hatching period to 3 years before the selection of biological pesticides or low-toxicity pesticides control, and pay attention to the alternating use of different types of pesticides. The recommended agents are 30 billion PIB/g beet nocturnal nucleotype polykeratovirus 9 000 times liquid, 5% chlorobenzenamide suspension 1 000 to 1 500 times liquid, 100 g/L trifluoromethirade emulsion 800 to 1 000 times liquid, 5% polycyclineicide suspension 1 200 times liquid, 1% methylamino avermectin benzoate emulsion 1 800 times liquid, 12% insect mite nitrile methyl salt suspension 1 000 times liquid, 20% fibrosis diamide water dispersion granules 2 000 times liquid, 15% Indatex suspension 3 000 times liquid [2], 24% methoxyhydrazide suspension 3 000 times liquid.
2 Thrips
The main thrips that harm asparagus are flower thrips and smoked thrips. Adult flower thrips are 1.3 mm long, brownish yellow; smoked thrips, also known as allium thrips, adults are 1.0 to 1.3 mm long, short-line, light brown.
2.1 Hazard Symptoms
Thrips mainly harm the young stems, leaves, quasi-leaves, flowers and other parts of asparagus with adult or nymphs, and use the sucking mouthpiece to aspirate the sap, so that the asparagus is stunted, causing the plant to be short, atrophied, curly, deformed, and the epidermis appears stained, especially causing the young stem tip to bend and deform, the harvested shoot tip is loose, and it is easy to scatter the head, which seriously affects the commerciality of asparagus. After the asparagus seedling stage is endangered by thrips, the leaves are rapidly yellowed, wrinkled and not stretched, and the plant is severely dwarfed and does not grow.
2.2 Occurrence Characteristics
Thrips overwinter as pupae and nymphs or adults on soil surfaces, asparagus root pomegrasses or other plants. Thrips occur in 10 to 12 generations in the Jianghuai River Basin, and can occur in April to November, with the heaviest occurrence in May to June, which is the peak of thrips. The suitable temperature of thrips is 20 ~ 25 °C, the hazard is heavy in the dry season, the harm is lighter when the high temperature and high humidity, and the adult insects are lively and flying, and can be spread by wind. Thrips have a habit of tending to green, afraid of light, generally concentrated on the back of the leaf during the day, rainy days, evening activities on the leaf surface. Thrips occur heavily when there are onion garlic crops or fieldside weeds around the asparagus field [3].
2.3 Green prevention and control measures
2.3.1 Agricultural control
The soil maintains a suitable water content, and the timely replenishment of water according to the soil moisture during the harvesting period can not only ensure the tenderness of the young stems, but also help to reduce the base number of thrips and reduce the degree of harm; the asparagus base should be far away from the field of onions and garlic crops to prevent mutual transmission; in early spring, timely remove weeds in the field and around, strengthen fertilizer management, promote the healthy growth of plants, and enhance plant resistance.
2.3.2 Physical control
Before the occurrence of thrips, 3 to 5 armyworm plates are suspended every 667 m2 to monitor the occurrence of worm mouths, and when there are a small number of thrips on the sticky worm boards, 30 pieces of blue armyworm boards (30 cm long and 25 cm wide) are suspended every 667 m2 for booby traps.
2.3.3 Biological control
When the density of thrips is low, new small plants such as sycamores are released to prey on thrips.
2.3.4 Chemical control
When there are an average of 2 to 3 thrips in the heart leaves, spray 2.5% ethyl polybactericide 1 000 to 1 500 times liquid, 24% spirant ethyl ester suspension 2 000 times liquid, 15% zoloftamide emulsion 1 000 to 1 500 times liquid control on cloudy or sunny afternoons, focusing on spraying the top part of asparagus. Fund Project: Jiangsu Modern Agriculture (Vegetable) Industrial Technology System Lianshui Promotion Demonstration Base, JATS (2018) 120.