A Detailed Guide to Common Pests and Diseases of Trichosanthes kirilowii and Their Control Methods

Trichosanthes kirilowii, also known as yaogua or gualou, is a relatively good Chinese medicinal herb. Its roots, stems, leaves, seeds, and fruit rind can all be used as medicine, and it has a very wide range of applications. During the cultivation of Trichosanthes kirilowii, pest and disease infestations are very likely to occur. Let us take a look below at what are the common pests and diseases of Trichosanthes kirilowii and their control methods?

I. Common Pests and Diseases of Trichosanthes kirilowii

1. Diaphania indica

It mainly damages leaves and fruits. Young larvae feed on the leaf mesophyll on the underside of leaves, appearing as grayish-white spots. After the 3rd instar, they spin silk to join leaves or tender shoots together, living inside and feeding, causing the leaves to become perforated or notched, and in severe cases only the leaf veins remain. The larvae often bore into the fruit, affecting yield and quality.

2. Root-knot nematode disease

Caused by root-knot nematodes, it mainly occurs on the lateral roots and fine roots of the root system, forming many small yellow galls, and the main root is weak. In mild cases, the plant grows slowly and the leaves are small; in severe cases, the plant is stunted, thin and weak, with poor growth, and bears few and small fruits.

3. Anthracnose

Anthracnose is the most troublesome disease among Trichosanthes kirilowii diseases, and it may occur during the seedling stage and the final maturity stage. It threatens all parts of the plant. When the disease develops rapidly, it causes great harm to the fruits and stems and vines, and may even directly cause the fruits to rot and drop, and the stems and vines to shrivel. After the leaves are infected, many spots appear on the leaf surface. These spots gradually expand and extend, then slowly merge with each other, forming huge patches, causing the leaves to turn yellow, die, and then drop.

4. Viral disease

Viral disease mainly harms the leaves of Trichosanthes kirilowii, especially the old leaves. After the old leaves are infected, they begin to shrink and wrinkle at a rate visible to the naked eye. The leaves begin to appear raised and, as if they had lost water, become dry and brittle. The growth of the branches is also greatly affected. The branches are weak and take on a drooping shape, causing growth to be hindered, reducing the fruit-setting rate of the fruits, and affecting yield.

II. Common Control Methods for Pests and Diseases of Trichosanthes kirilowii

1. Control methods for Diaphania indica

(1) Clean the field. After harvesting the Trichosanthes kirilowii fruit, collect the dead vines and fallen leaves, compost and bury them or burn them, which can reduce the population base of the next generation or overwintering pests.

(2) Chemical control. It is recommended to use Guoguang Dujian at 600-800 times dilution for control before Diaphania indica reaches the 3rd instar. The best time to control this pest is in the evening after the sun has set.

1. Control methods for root-knot nematode disease

(1) Carry out soil disinfection in a timely manner. Before planting, use Guoguang Sanmie 1000-1500g/mu + Guoguang Duojunling 500-1000g/mu for soil disinfection to reduce the breeding of pathogenic bacteria.

(2) Chemical control. It is recommended to use Guoguang Jinmeigen 1000g/mu mixed with soil and broadcast, or use Guoguang Bihaike at 1000-1500 times dilution for root drenching control.

2. Control methods for anthracnose

The onset of anthracnose follows a pattern. It is most likely to occur during the month of the seasonal transition from summer to autumn each year, so we should spray an appropriate amount of chemicals for control before this time arrives. After the disease occurs, chemicals such as Duojunling can be sprayed continuously, once a week, for at least three weeks.

3. Control methods for viral disease

The main transmission route of the viral disease pathogen is aphids, so if we want to control viral disease, we need to control the reproduction of aphids well. Start using chemicals preventively when the young buds emerge, strengthen orchard management, clean the orchard regularly, remove diseased remains, fallen leaves, and fallen fruits from the orchard in a timely manner to reduce the presence of insect eggs in the orchard. When controlling aphids, a little oligosaccharin and similar substances can also be added to the chemical spray to control viral disease. The timing and frequency are the same as for anthracnose control.