Pest control methods of thrips in blueberry planting

Pest control methods of thrips in blueberry planting

Flower thrips is one of the most common pests in blueberry cultivation. Feeding on leaves will hinder the growth of new shoots, bend leaves, shorten leaf nodes, and have wounds on stems (figure 1) [Yoshanayama Huayao]. The pest of thrips will cause the decrease of pollination rate and fruiting rate of blueberry fruit, resulting in the loss of yield. The monitoring and control of flower thrips pests in blueberry orchards should be strengthened to prevent them from causing serious damage.

Fig. 1 Blueberry leaves damaged by thrips

1 characteristics

The flower thrips are about 1-1.3 mm long and orange (figure 2). They feed on plant tissue cell sap. Flower thrips have a short life cycle, only 18-22 days under ideal conditions, and can complete several generations in a year. Flower thrips like to live together. It takes four stages for thrips to change from egg to adult, of which the first and second stages will harm plants, and the third and fourth stages of larvae will fall into the soil or do not feed on plants in litter.

Fig. 2 Adult of thrips

Flower thrips harm blueberries mainly in two ways, one is to directly feed on pollen, ovary, petals, fruits, etc. (figure 3), resulting in the reduction of fruit quality and yield. The second is that the female lays eggs in the flower, which harms the growth and development of the flower. The number of flower thrips is related to the degree of flower bloom, and about 90% of the flowers are in full bloom when the population is at its peak.

Fig. 3 blueberry fruit damaged by flower thrips

2 Monitoring

There are many methods to monitor thrips. White stickboard or blue stickboard can be used to monitor adults. Sticky board should be placed in the tree and one stickboard should be used every 3 mu, because the population of thrips can increase in a short time and should be checked once a week. For direct sampling and analysis in the field, 10 trees can be selected in each sampling area, the new shoots of each tree can be selected for analysis, and the number of thrips can be counted directly with a magnifying glass.

For rabbit-eyed blueberries, prevention and control measures should be taken when there are more than 2 thrips in each flower, or when the sticker captures more than 45 thrips [Yoshima Huayao].

3 methods of prevention and control

Insecticides such as Malacion, spinosad, acetamiprid and novalon can effectively control flower thrips, but it has been reported that flower thrips are prone to drug resistance, so it is recommended to rotate different pesticides to prevent them from developing drug resistance. Furosemide is an internal insecticide that can be used after flowering to prevent accidental injury to pollinating insects.