Occurrence Patterns and Integrated Control Methods of Pests and Diseases in Goji Berry

Goji berry is a deciduous shrub of the genus Lycium in the Solanaceae family. Its fruit is called goji berry (Lycii Fructus), and its root bark is called Digupi (Lycii Cortex); both can be used as medicine. The tender stems and leaves are eaten as vegetables. It is distributed throughout China, mostly in the wild. The related species Lycium barbarum (Ningxia goji) is mostly cultivated; its fruit is called Xi goji or Gan goji and is used medicinally, mainly produced in Ningxia, Gansu and Inner Mongolia. Goji berry suffers from pests and diseases at every stage of growth, causing great economic losses to production. The occurrence and control methods of goji berry pests and diseases are introduced as follows:

1 Diseases

1.1 Black fruit disease (anthracnose)

It mainly damages green fruit, tender branches, leaves, buds and flowers. When green fruit is infected, small black spots or irregular brown spots first appear on the fruit surface. During continuous rainy weather, the lesions keep expanding, and half or the entire fruit turns black; when dry, the fruit shrivels. When humidity is high, many orange-red gelatinous dots grow on the diseased fruit. When tender branches, leaf tips and leaf margins are infected, brown semicircular lesions appear, which turn black after expanding; under high humidity they become wet rot, and sticky droplet-like orange-red dots appear on the surface of the diseased part, namely the pathogen's acervuli and conidia. Control measures: open ditches for drainage and remove diseased fruit. During the fruiting period, spray with 1:1:100 Bordeaux mixture; immediately after rain, spray 50% thiram wettable powder 600 times dilution. After harvest, promptly prune out diseased branches and fruit, remove diseased and residual fruit from the trees and the ground, and bury them deeply or burn them. Before the first rainfall in June, once again remove diseased and residual fruit from the trees and the ground to reduce the primary infection source. Before the first rainfall in June, first spray once, adding an appropriate amount of urea to the spray solution to kill overwintering pathogens and enhance the tree's disease resistance. After disease onset, focus on spraying after rainfall; spraying should be done within 24 hours after rain to prevent conidial germination and invasion. During the disease period, prohibit flood irrigation, and drain accumulated water from the goji orchard after rain. Watering should be done in the morning to control field humidity and reduce nighttime condensation on the fruit surface. During the disease period, promptly control aphids and mites to prevent pests from carrying pathogen spores to spread the disease and causing wounds. At the early stage of disease, begin spraying 75% chlorothalonil wettable powder 600 times dilution, or 70% mancozeb wettable powder 500 times dilution, 64% oxadixyl-mancozeb wettable powder 500 times dilution, 58% metalaxyl-mancozeb wettable powder 500 times dilution, 75% chlorothalonil wettable powder 1000 times dilution plus 70% mancozeb wettable powder 1000 times dilution, or 50% benomyl wettable powder 1500 times dilution. Apply once about every 10 days, for 2 to 3 consecutive applications. Stop applying chemicals 7 days before harvest.

1.2 Root rot

It mainly harms the roots and stem base of the plant. Affected plants show yellowing and wilting leaves. When diseased plants are dug up and the roots and stems are dissected, the affected parts are seen to turn brown to dark brown; in some cases the cortex rots and falls off, exposing the xylem. The vascular bundles inside the root and stem also turn brown. When moist, white to pink powdery fungal signs sometimes appear on the surface of the affected parts. The disease occurs in mid-to-late June and is more severe in July and August. In the early stage the roots turn black and gradually rot, after which the aboveground parts wither and the whole plant dies. Control measures: in frequently affected areas, crop rotation is advocated, preferably paddy-upland rotation. Level the land, cultivate on high ridges with deep furrows, lower the groundwater level, clear ditches and drain after rain, and prevent excessively wet soil. Use formula fertilization, apply more phosphorus and potassium fertilizer, and avoid applying inadequately decomposed farmyard manure. For leaf-type goji, when planting cuttings, a 1000 times dilution of potassium permanganate can be used as rooting water for drenching. After the cuttings survive and before disease occurs, or at the latest after symptoms appear, drench with chemicals at regular or irregular intervals to prevent and control the disease. In addition to potassium permanganate solution, drenching with 20% kangkuning aqueous solution 600 times dilution, or 15% mixed amino acid zinc-magnesium aqueous solution 500 times dilution, can also be used. Apply 3 to 4 consecutive times, once every 7 to 15 days, with shorter intervals first and longer intervals later, spraying enough to soak through. Irrigate the roots with 50% thiophanate-methyl 1000-1500 times dilution or 50% carbendazim 1000-1500 times dilution.

2 Insect pests

2.1 Fruit fly

Distributed in **, Ningxia and Qinghai, China. Its larvae mainly feed on goji fruit; after being bored into, the fruit has no medicinal value. It has 2 to 3 generations a year and overwinters as pupae in the soil. Control measures: use 80% dichlorvos emulsifiable concentrate 1000 times dilution or 40% dimethoate emulsifiable concentrate 1500 times dilution, spraying once every 7 to 10 days for 3 to 4 consecutive sprays; poisoned soil can also be used to kill newly emerged adults in the soil, or maggot-infested fruit can be removed manually.

2.2 Aphids

They harm young buds, leaves and young fruit. They have multiple generations a year. They overwinter as eggs on branches. Generally, damage begins after goji sprouts in April, with an outbreak in May, when large numbers of adults and nymphs gather on tender shoots and buds to cause damage. After entering midsummer, the population rate declines, then rises again in autumn, with a second peak appearing in September. In production, excessive nitrogen fertilizer application and overly vigorous growth lead to more severe damage. Damage is most severe from late May to mid-July. Control measures: use 40% dimethoate emulsion 2000 times dilution, spraying once every 7 to 10 days for 3 consecutive sprays. Strengthen goji orchard management, adopt formula fertilization techniques, prohibit excessive nitrogen application, and water at the proper time. When aphids multiply, immediately spray 50% pirimicarb, Bacillus thuringiensis suspension concentrate, or 10% imidacloprid wettable powder. Protect and utilize natural enemies, such as ladybugs, green lacewings and hoverflies.

2.3 Gall mites

They occur commonly in goji production areas and cause severe damage. Goji leaves, flowers, young fruit, tender stems, petals and flower stalks can all be affected, causing blue-black raised galls and bending. When leaf deformity is severe, the whole plant's vigor declines, leaves fall early, and yield decreases. This mite has multiple generations a year. In mid-to-late April, adults begin to lay eggs, after which larvae invade tissues, causing tissue deformity and turning them into blue-black nevus-like galls; new shoots are damaged the following year. Control measures: in the early stage of occurrence, spray with 40% dimethoate emulsion 1500-2000 times dilution. Promptly remove branches with galls and take them out of the orchard for disposal. Before overwintering, overwintering adult mites inside the scales and branch crevices of the current year's growth can be controlled with 3 degrees Baume lime-sulfur mixture.

2.4 Lily leaf beetle

Adults and larvae feed on leaves, causing irregular notches or holes, and later leaving only leaf veins. Lightly damaged leaves are contaminated by excrement, affecting growth and fruiting; when leaves and tender shoots are severely damaged, yield and quality are affected. Adults like to rest on branches and leaves and lay eggs on the upper or lower leaf surface in a herringbone pattern. The larvae carry their own excrement on their backs, hence the name lily leaf beetle. It has 3 generations a year, with the most severe damage in June and July. Control measures: from July to August, use 40% dimethoate emulsifiable concentrate 1500-2000 times dilution, or 80% dichlorvos emulsifiable concentrate 1500 times dilution, spraying once every 7 to 10 days for 3 to 5 consecutive sprays.