What are the common pests of ginkgo trees?
Camphor silk moth
Distribution and damage: This pest occurs mainly in Fujian, Guangdong, Guangxi, Hunan, Hubei, Jiangxi, Zhejiang, Jiangsu, Henan and other provinces (autonomous regions). The larvae gnaw on ginkgo leaves, and in severe cases can eat all the leaves completely.
Biological characteristics: One generation occurs per year.
It overwinters as a pupa in a cocoon in branch trunks and bark crevices. For adult emergence, in Guangdong it begins in early January, with the peak in mid-February; in Fujian it begins in early February, with the peak from late February to early March; in Zhejiang emergence begins in early March, with the peak from late March to early April. Adults can mate shortly after emergence and have strong phototaxis. Eggs are laid on branches and trunks, forming egg masses of several dozen to over a hundred eggs; the eggs are arranged neatly in a single layer and covered with black fuzz, making them hard to spot. From February to April the larvae become active one after another; larvae of the 1st to 3rd instars gather to feed, and after the 4th instar they disperse to cause damage. From late May to early June the mature larvae successively spin cocoons and pupate, and by late July all have finished pupating.
Control methods
(1) Collect cocoons to destroy pupae: Taking advantage of this pest's long pupal period and dense cocoon spinning, organize manpower in winter to tear the cocoons off the trees and bury them deep in soil or burn them.
(2) Light trapping. During the peak adult emergence period from February to March each year, use black light lamps for trapping and killing.
(3) Chemical control. Use 741 dichlorvos tube-insertion smoke agent in the early morning or evening when the wind is calm, releasing it in the ginkgo orchard; it is fairly effective against 1st to 4th instar larvae. You can also spray 65% trichlorfon emulsifiable concentrate at 500-800 times dilution to control 1st to 3rd instar larvae. After the 4th instar, spray 90% trichlorfon crystal at 500 times dilution.
(4) Biological control. In the early rainy season, Beauveria bassiana can be used for control, with good results.
Ginkgo large silkworm moth
Distribution and damage
The ginkgo large silkworm moth, also known as the white fruit silkworm and commonly called the white-haired caterpillar, occurs mainly in Heilongjiang, Jilin, Zhejiang, Henan, Guangxi, Taiwan, China and other provinces (autonomous regions). The larvae are omnivorous; besides feeding on ginkgo leaves, they also feed on the leaves of Mongolian oak, walnut, willow, camphor, Chinese wingnut, Chinese sumac, cherry blossom, hackberry, crape myrtle, hazel, chestnut, persimmon, plum, plum, pear, apple and others. When outbreaks are severe, they can eat all the leaves of a whole tree, leaving the crown bare and reducing seed production. According to a survey in Haiyang Township, Lingchuan County, Guangxi, due to the damage by this pest, white fruit production dropped by more than 60%. Besides affecting the current year's yield, it also affects flowering and fruiting the following year. Individual severely damaged ginkgo trees die entirely.
Biological characteristics
The ginkgo large silkworm moth has one generation per year in Guangxi. The egg stage lasts from mid-September of the previous year to May of the next year, about 240-250 d. Late March to early April is the larval activity period; the larval stage lasts about 60 d, cocoon spinning begins in mid-July, pupation occurs after about a week, the pupal stage lasts about 40 d, and early September is the adult stage. The adult emergence period is about 10 d; after emergence they mate and lay eggs, with egg laying completed from early to mid-September. Generally they lay eggs 3-4 times, and one female moth can lay 250-400 or more eggs. The eggs are concentrated in piles or arranged in a single layer, mostly laid in bark cracks or sunken places on old tree trunks, at a position on the trunk below 3 m and above 1 m. Egg hatching is very uneven; newly hatched larvae gather at the egg mass, and after 1 h they begin climbing the tree to feed. Larvae like to gather before the 3rd instar, gradually disperse from the 4th to 5th instars, and act alone from the 5th to 7th instars, generally feeding during the day. During the day, feeding quantity is greatest from 10:00 to 14:00.
Control methods
(1) In winter, manually remove egg masses; in mid-to-late July, manually capture and kill mature larvae or collect cocoons and burn them.
(2) Light trapping. Adults have phototaxis and strong flying ability; before the female moths lay eggs in September, use black light lamps to trap and kill adults, with good results.
(3) Biological control. During the female moth egg-laying period (September), Trichogramma can be released artificially, with a parasitism rate reaching more than 80%.
(4) Chemical control. During the larval stage, spray 90% trichlorfon at 1500-2000 times dilution, or 50% dichlorvos at 1500-2000 times dilution, or derris extract at 800 times dilution, or 25% dimehypo at 500 times dilution; all have good control effects. Control is especially obvious against 3rd instar larvae.
Ginkgo minute leaf roller
Distribution and damage
This pest occurs mainly in Guangxi, Zhejiang, Anhui, Jiangsu, Hubei, Henan and other provinces (autonomous regions). At present this pest has only been found to damage ginkgo. The larvae mostly bore into short shoots and current-year growth shoots, causing all the leaves and young fruits on short shoots to wither and fall off, and long shoots to wither and break.
Biological characteristics and the relationship between occurrence and environment
This pest has one generation per year and overwinters as a pupa in thick bark.
The adult emergence period is from early to late April of the following year,
mid-April is the peak emergence period, and the emergence period lasts 14-15 d.
Mid-April to early May is the egg stage.
Late April to mid-June is the larval damage period.
After late May to mid-June, mature larvae move into the bark to enter diapause,
and successively pupate in mid-November.
Adult emergence is mostly concentrated from 6:00 to 8:00 in the morning; after spreading their wings, adults have the habit of holding both wings upright on their backs. After about 30 min, they can crawl to rest in trunk crevices, making them easy to catch. After 9:00 they fly to the tree crown.
Adults mate the day after emergence and begin laying eggs after 2-3 d. Eggs are laid singly and scattered on 1-2 year old twigs, with 1-5 eggs per twig.
The egg stage lasts 8-9 d, and about 80% of eggs hatch.
Newly hatched larvae crawl to the sunken tip of short shoots to feed, eating little; after 1-2 d they bore into the shoot and feed horizontally. Larval damage is mainly on short shoots, followed by current-year growth shoots. When damaging short shoots, they often bore into the shoot through the sunken tip or the base of the leaf stalk.
From mid-May to mid-June, the larvae move from inside the shoots to dead leaves, roll up the side edges of the dead leaves, and rest and feed inside the leaves; afterward they bore into the bark. The larvae mostly make thin cocoons and pupate 2-3 mm below the surface of thick bark. This pest causes the most serious damage to old and weak-growing trees. Observations show that the population density of the ginkgo minute leaf roller gradually decreases from south to north.
Control methods
(1) Based on the characteristic that adults rest on tree trunks before 9:00 after emergence, manually capture and kill adults before 9:00 each day from early to late April.
(2) In areas where the pest has just appeared and damage is light, starting in April, when the leaves and young fruits on damaged branches begin to wither, manually prune off the damaged branches and burn them to eliminate the larvae inside the branches.
(3) Strengthen management to enhance tree resistance and reduce the degree of damage by this pest.
(4) Chemical control. During peak adult emergence, mix 50% fenitrothion emulsifiable concentrate at 250 times and 2.5% deltamethrin emulsifiable concentrate at 500 times in a 1:1 ratio and spray the trunk with a sprayer; the kill rate against newly emerged adults reaches 100%. During the damage period, focus on eliminating young larvae. Spray damaged branches with 80% dichlorvos emulsifiable concentrate at 800 times dilution, or 90% trichlorfon and 80% dichlorvos (1:1) diluted 800-1000 times, or 80% dichlorvos at 800 times mixed with 40% omethoate at 1000 times; all have good effects. Based on the habit of mature larvae moving into the bark to enter diapause, in late May to early June, spray 25% deltamethrin emulsifiable concentrate at 2500 times dilution, or mix 1 part each of 25% deltamethrin emulsifiable concentrate and 10% cypermethrin emulsifiable concentrate separately with 20 parts diesel, and brush it onto the trunk base, the soil area and scaffold branches to form a 4 cm wide toxic ring; the mortality rate against mature larvae reaches 100%.
Large bagworm
Lepidoptera, Psychidae. Also called the debt-avoiding moth, bagworm, bark worm, etc. Distributed in subtropical and tropical regions, omnivorous, damaging fruit trees, forest trees and crops. The larvae eat leaves, tender branches and young fruits. It is a disastrous pest.
Morphological characteristics
(1) Adults: Females and males are different in form. Females are wingless, 17-20 mm long, maggot-shaped, stout, with a small head, degenerated mouthparts, and a well-developed thorax; the front edge of the pronotum projects forward, and abdominal segments 7 and 8 have yellow down. Male moths have a wingspan of 35-44 mm, and the body is blackish brown. Antennae are bipectinate, with the pectinations gradually becoming smaller at the upper 1/3; the thorax dorsum has 5 dark longitudinal stripes.
(2) Eggs: block-shaped, pale yellow, laid inside the female moth's protective case.
(3) Larvae: 5 instars in total. From the 3rd instar, females and males are clearly distinguishable. Female larvae are 32-37 mm long, with a dark brown head, ring-shaped markings on the top of the head, and strongly sclerotized thoracic tergites; the abdominal dorsum is dark brown, each segment surface has wrinkles, there are large reddish-brown spots near the subdorsal line and spiracular upper line, and there are markings alternating reddish-brown and pale yellow. The crochets on the abdominal prolegs are arranged in a ring. Male larvae are smaller and yellowish-brown.
(4) Pupae: Female pupae are 22-23 mm long, nearly cylindrical, brown, with 3 thoracic segments tightly packed, and the posterior ends of abdominal segments 2, 3 and 5 each have a transverse row of small spines. Male pupae are thinner, 17-20 mm long, with a protruding thorax and a slightly curved abdomen, and the posterior end of each segment has a row of small spines. The protective case is spindle-shaped, about 62 mm long for females and about 52 mm for males. The protective case is often adorned with small twigs and leaves.
Occurrence pattern
Usually one generation occurs each year. Adults overwinter in the protective case. They pupate in May of the following year, mate and lay eggs in late May, hatch after about 3 weeks, and begin overwintering in early November. The larval stage lasts 310-340 days. Male moths mate inside the protective case, and females die on the ground after laying eggs. Fecundity is 1000-5000 eggs. The larvae spin silk and spread by wind. They have phototaxis. After the S instar, food consumption increases, and damage is severe from July to September.
Control methods
(1) Capture and kill: Collect overwintering protective cases and burn them in a concentrated manner.
(2) Biological control: Spray with a Bacillus thuringiensis solution containing 100 million spores per milliliter.
(3) Chemical control: After the larvae hatch, spray with 2.5% trichlorfon powder or 90% trichlorfon at 1000 times solution.
Control methods for four common ginkgo pests
Ginkgo grows very, very slowly and is a very precious plant.
Ginkgo is a deciduous tree of the Ginkgo family and genus, also known as white fruit, palm-leaf fan, etc. Ginkgo is the oldest relict plant among extant seed plants. All other plants in the same class have become extinct, and it is known as a living fossil. Ginkgo is a precious tree species with ornamental, economic and medicinal value. However, the threat of pests and diseases to ginkgo is also considerable. Below, the editor will explain how to control the common pests and diseases of ginkgo.
1. Minute leaf roller
(1) Adult emergence is mostly concentrated from 6-8 o'clock and adults rest on tree trunks after emergence; therefore, from early to late April before 9 in the morning is a good time for manually catching adults and eliminating eggs.
(2) Prune off damaged withered branches, and burn the fallen branches and leaves on the ground together.
(3) During the key period of larval damage (early April to early May), spray the tree crown twice with 2.5% deltamethrin emulsifiable concentrate at 3000 times dilution, or mix 80% solution with 40% omethoate at 1000 times dilution and spray; the effective rate reaches 100%.
(4) After the larvae bore into the bark, use a mixture of undiluted dichlorvos, omethoate and diesel at 4:5:10 as an oil mist agent and spray the trunk, which can effectively eliminate the larvae. To kill adults by applying medicine, before early pupae emerge in late March, mix 50 kg quicklime, 1 kg dichlorvos emulsion, 10 kg salt and 190 kg clean water and brush it on the bark, which can effectively prevent adult emergence.
2. Large bagworm
(1) After leaf fall in autumn and winter, in combination with pruning, the insect bags can also be removed and burned.
(2) Larvae hatched in June are mostly concentrated on the underside of leaves, which is exactly the key period for spraying. Spray with 90% trichlorfon at 1000 times solution, or 50% dichlorvos at 1000 times solution; the effect reaches 95%.
3. Yellow stinging moth
(1) In winter, remove the cocoons in combination with pruning.
(2) Based on the phototactic habit of adults, black light lamps can be used for trapping and killing.
(3) During the larval occurrence period, spray with 90% trichlorfon or 40% omethoate emulsion or 50% dichlorvos at 1000 times solution, or fenvalerate at 2000 times solution; all are effective.
(4) Natural enemies include small black wasps, five-toothed green wasps, etc. The cocoons of the yellow stinging moth parasitized by parasitic wasps all have a brown sunken part at the neck; special attention must be paid to protecting them, and they must not be removed.
4. Large silkworm moth
(1) Adults lay eggs in rough bark cracks or sunken places on trunks 1-3 m up, so removal is easy. You can also capture mature larvae and remove cocoons in July.
(2) Use black light lamps to trap and kill adults.
(3) Spray with 2.5% deltamethrin at 3000 times solution or 50% malathion at 1500 times solution. For mature larvae, increase the dosage; the insecticidal effect reaches more than 95%.
5. Glabrous spotted longhorn beetle
(1) Hatched larvae are between the xylem and phloem; you can make an iron wire into a shovel shape and dig them out tree by tree.
(2) Because adults are gregarious, when they appear after rain and clear skies in June-July, seize the opportunity and organize manual capture and killing.
(3) Before adults lay eggs, in early to mid-June, use 1 part lime-sulfur sediment and 2 parts clay, or 10 parts quicklime, 1 part sulfur, 40 parts water plus a small amount of salt, mix into a paste, and apply it evenly to the main trunk or main branches, which can effectively prevent adults from laying eggs.
(4) Insert 1-2 toxic sticks into new frass holes and seal the openings with yellow mud; the control effect reaches 98%.
The editor hopes everyone will control ginkgo pests and diseases early, and never let precious ginkgo be destroyed by the threat of pests and diseases.
Common pests of ginkgo and their control
Common pest of ginkgo: ginkgo large silkworm moth
Damage
In severe pest outbreaks, the leaves will be eaten completely, resulting in a bare tree crown, which affects yield and is also unfavorable for flowering and fruiting the following year.
Control methods
(1) Generally in mid-to-late July, manually capture and kill mature larvae, and collect cocoons and burn them; in winter, egg masses can be manually removed.
(2) Generally in September, that is, before the female moths lay eggs, black light lamps can be used to trap and kill adults.
(3) For larvae, spray with 25% dimehypo at 500 times solution, etc.
Common pest of ginkgo: ginkgo minute leaf roller
Damage
Generally the larvae bore into short shoots and growth shoots, causing all the leaves and fruits on short shoots to wither and fall off, and long shoots to wither and break.
Control methods
(1) In April, adults can be manually captured and killed in the early morning.
(2) Manually prune off damaged branches and burn them in a concentrated manner to eliminate the larvae within and reduce damage.
(3) Strengthen management and improve tree resistance.
(4) During the damage period, spray a mixture of 80% dichlorvos at 800 times and 40% omethoate at 1000 times.
Common pest of ginkgo: termites
Damage
Termites are pests of the main trunk, boring into and feeding on the trunk xylem, preventing ginkgo from obtaining a normal water supply.
Control methods
First, the location of the termite nest must be determined, which can be based on termite deposits, ventilation holes, etc. Then drill holes and inject about 10 milliliters of insecticide plus 10% mirex. Generally 3-7 days after application, the entire termite colony can die.
Common pest of ginkgo: tea yellow thrips
Damage
It occurs mostly from June to August. Adults often gather on the underside of leaves to suck the sap of tender leaves, causing the leaves to lose green and turn gray-white; in severe cases, the leaves dry up and fall off.
Control methods
You can spray 50% phoxim, or use fenvalerate at 3000 times solution, or 40% omethoate emulsifiable concentrate at 1000 times solution, etc. Generally the first spraying is carried out in mid-June, and the second in mid-to-late July. If the pest infestation is not severe, spraying twice is sufficient.