Integrated control techniques of small heart borer in pear orchard for export

Integrated control techniques of small heart borer in pear orchard for export

In recent years, the area of pear orchard at Botou export has been expanding, but with the prohibition of organophosphorus pesticides and the restriction of chlorpyrifos, as well as a large number of unreasonable use of drugs lead to the improvement of pest resistance and the reduction of natural enemies, the pear heart borer is becoming more and more serious. In recent years, the average fruit decay rate of bagged pears in the export garden has reached 7% to 8%, the fruit decay rate of naked pears is more than 70%, and the annual loss of the whole city is more than 50 million yuan. Once the pear is small, it will become a residual fruit, and a small amount of decay marks are not obvious. the processing of the fruit after picking mainly depends on manual removal, such as not removing the fruit before export, resulting in withdrawal, resulting in huge economic and reputation losses to exporters. The increase of times and dosage of drugs in prevention and treatment also brings great hidden trouble to the quality and safety of pear fruit. Oriental Pear Orchard and Yafeng Pear Orchard in Botou City greatly reduced the harm of small heart borer in pear from the use of sex attractant in 2012 combined with insect control cocoon control, insect shoot pruning, bagging, sugar and vinegar trapping and chemical control in critical period. At present, this technology is popularized in the pear orchard of the whole city.

1 Life habits and harmful characteristics of pear heart borer

1.1 Life habits

Pear heart borer overwintered with mature larvae under the old warped bark, root neck, branches, cut saw mouth, grass handle, shallow soil layer around the trunk, etc., and overwintering larvae were also found in main branches and fruit bags. the underground overwintering larvae mainly come from the ground insect fruit. By creating an overwintering place for it, it can achieve the purpose of trapping and destroying some overwintering larvae and depressing the population density of insects in the coming year, which is an effective control measure. Because the pear heart borer has the habit of transferring its host, the harm is more serious in the orchard where peach, apricot and pear are mixed. The adults lie still on the branches and leaves during the day, mate before and after sunset, and have a strong tendency to sugar and vinegar and black light. There is a specific tendency to sex attractants. According to the monitoring records for many years, from April 1 to September 30, more than 1 500 male adults were lured by 5 sex traps and more than 100 by one insecticidal lamp. through the trapping results of many kinds of traps, we can see that the effect of sex attractants is the best.

1.2 harmful characteristics of small heart borer in pear

The pear heart borer belongs to the family Lepidoptera. It is an important pest that harms pears and peach trees. Pear heart borer not only harms pears and peach trees, but also harms apricots and apples, seriously affects fruit quality and yield, and reduces the economic income of fruit farmers. The insect occurs for 3 to 4 generations every year in Botou City, and the fruit damage of the third and fourth generations is the most serious. bagged pears are mainly harmful to the fruit through the gap between the fruit stalk and the paper bag, and the naked pear is damaged from the fruit surface. From April to May, the larvae of pear heart borer mainly damage peach shoots (figure 1). From June to July, a small number of larvae harm peach shoots, most of them harm pear fruit, and from August to September, they mainly harm pear fruit. The larvae of the damaged shoots were eaten from the base of the 2nd ~ 3rd petiole of the damaged shoots and ate down to the semi-xylem. The tender tips of the damaged shoots wilted and drooped, and there were glue and insect dung at the boreholes, and soon the tip of the new shoots wilted and withered. The peak period of tip decay is from late May to early July. The newly hatched larvae often eat the fruit from the calyx and stem depression (figure 2). In the early stage, insect feces were excreted outside the holes of the damaged fruit, but no insect feces were found in the later stage. The damaged fruit is often rotten at the wormhole, showing the shape of black paste (figure 3). Bagged pear larvae eat the pulp around the stalk, resulting in fruit drop.

Fig. 1 pear shoot shape with small damage

Fig. 2 Pear fruit spoilage from the stem depression

Fig. 3 the small pear makes the hole of the injured fruit in the shape of black paste

2 Life history

According to the continuous investigation of the monitoring sites of pear borer in Botou City for many years, through the analysis of the number and peak period of adults trapped by sex attractants and insecticidal lamps, it was found that the occurrence regularity of pear borer in Botou was as follows: three or four generations a year. The overwintering generation adults first appeared on March 22, the peak period of overwintering adults was from mid-April to late April, and the first generation larvae were harmful to peach shoots at the beginning of May. The peak period of adult occurrence of the first generation was from mid-May to early June, and the peak period of adult occurrence of the second generation was from mid-May to early June. The peak period of adult occurrence of the second generation was from late June to mid-July, and the larvae continued to harm pear and peach shoots and began to eat pear fruit. The peak period of adults of the third generation was from late July to early September (figure 4) [Jishan Huayao].

Fig. 4 occurrence dynamics of pears in Yafeng pear orchard detected by sex attractants

The larvae do a lot of harm to pear fruits. After that, the number of larvae decreased gradually, and it basically ended in mid-October. The mature larvae gradually shed their fruit and transferred to the overwintering place after the middle of September. The occurrence algebra of pear heart borer is more, and the overlap of later generations is obvious. Under the condition of temperature 23-28 ℃ and relative humidity 60%-70%, the egg stage is 3-5 days, the larva stage is 10-14 days, the pupa stage is 7-10 days, the life span of adults is 4-7 days, and each female adult lays 70-80 eggs. When the monthly rainfall is more than 150 mm and the air relative humidity is 80% to 90%, the adults lay a large number of eggs, the hatching rate is high, and the larvae are seriously harmful.

3 integrated prevention and control technology

Pear has strong reproductive ability, more generations and more overwintering places; after larvae eat into new shoots and fruits, the effect of medication and control is poor, so a variety of measures should be taken to control it.

The main results are as follows: (1) Scientific establishment of pear orchard, new pear orchard as far as possible to avoid multi-host mixed planting or to avoid adjacent pear orchard and peach orchard, in order to reduce the harm of pear heart borer transferring each other.

(2) in February, the old warped skin on the trunk and branches was scraped off to eliminate the overwintering cocoon of pear heart borer.

(3) in late March, 50% phoxim EC 300 times was sprayed on the ground to kill overwintering cocoons; film mulching on the ground could prevent adults from being unearthed and kill adults.

(4) all pears and fruits should be bagged, and the mouth of the bag should be tied tightly. Prevent the larvae from drilling into the harm from the mouth of the bag.

(5) cut off the injured shoots in time in the growing season, remove the fruits of the pests on and under the trees and bury them deeply, so as to reduce the population density of the next generation.

(6) using sex attractants, sweet and sour liquid pots (5 pots per mu, evenly distributed) and insecticidal lamp trapping (one per 3.3 to 4 hectares) to release Trichogramma parasitic pear heart borer larvae.

(7) isotropic control is suitable for pear orchards with continuous planting, relatively independent and regular shape of the garden. Isotropic filaments are suspended in the middle and lower part of the pear tree crown, with about 60 per mu, 2 per tree at the periphery of the pear orchard or at the edge of the high slope and the main wind direction, and 1 per plant in the garden. The control needs to be hung twice in the whole year, the first time is in early April (before the overwintering generation Eclosion), and the second time is in mid-late June. In order to monitor the effect of isotropy control at any time, a set of sex traps should be placed per hectare in pear orchards, and the control countermeasures should be adjusted in time.

(8) Pesticide control as a supplement to isotropic control, when the insect population density is high, the key is to master the prevention and control of the second and third generation larvae before hatching, and the control is more targeted and the auxiliary effect is better. To do a good job of city-wide sex attractant prediction and joint prevention and control can effectively control the harm of pear heart borer to pear fruit. Through the experiment, it was found that 48% chlorpyrifos 1 500 times solution and 1% methamectin EC (aminoavermectin benzoate cypermethrin) 2000 times solution had better control effect.

(9) pick up the exterminator fruit in time and bury it deeply. Before freezing, turn over the tree plate and kill the overwintering larvae under the tree plate.

(10) the overwintering larvae were trapped in the trunk of pear trees in late August and destroyed in December to reduce the population density of overwintering insects.