Latest Technical Methods Tutorial for the Prevention and Control of Pests and Diseases of Cornus officinalis

Cornus officinalis is a medicinal herb favored in medical practice through the ages, and it has been introduced and cultivated in Sichuan. The main diseases harming Cornus officinalis include anthracnose, angular leaf spot, and grey felt fungus disease, among others. The main insect pests harming Cornus officinalis include the green-tailed moon moth, the large bagworm, the Cornus fruit-boring moth, the yellow slug moth, the geometrid moth, the green-legged grasshopper, the large green leafhopper, the small green leafhopper, and the spotted lanternfly, among others. Let us take a look together below!

Anthracnose

[Damage characteristics] Anthracnose is also known as black spot disease, black fruit disease, and black scar dysentery. When young fruit is affected (fruit anthracnose), it mostly invades from the fruit apex, and the lesion spreads downward from the fruit apex. The diseased part is black with a reddish-brown edge, and the lesion gradually spreads to the entire fruit. The fruit turns black and shrinks, and mostly does not fall off. When mature fruit is affected, the lesion first appears as small brownish-red dots, and the lesion gradually expands into round or oval black sunken spots, with a reddish-brown edge and a red halo on the outer periphery. When the pathogen attacks leaves (leaf anthracnose), it first appears as small reddish-brown dots, which then expand into brown round lesions with a diameter of about 1-4 mm. The lesion edge is reddish-brown, with a faded halo on the outer periphery, and the lesion often perforates and falls off. The peak period for fruit anthracnose is from June to August, and the peak period for leaf anthracnose is from May to June.

[Prevention and control methods] Choose sandy loam soil with deep soil layers and good drainage for cultivation. Do not plant too densely. Strengthen management. During the disease period, apply less nitrogen fertilizer and more phosphorus and potassium fertilizer to promote robust plants, improve the disease resistance of the plants, and reduce damage. Clear away fallen leaves and diseased mummified fruit by deep burying or burning to reduce sources of infection. In the early stage of the disease, spray with 1:2:200 Bordeaux mixture.

Angular leaf spot

[Damage characteristics] Angular leaf spot mainly harms leaves and fruit. When leaves are affected, small dark purple-red spots first appear on the upper surface of the leaves. The lesion edge is not obvious, and only the epidermal cells are discolored, with no symptoms on the underside of the leaves. When fruit is affected, there are small rust-brown round dots with a diameter of about 1 mm. When there are many lesions, they connect into patches, making the fruit apex partly rust-brown, and only the fruit skin is harmed, with the lesions not penetrating into the flesh. The disease starts in May and continues to cause damage until the end of October, with July being the peak period.

[Prevention and control methods] Strengthen management at the seedling stage, and interplant with leguminous plants, which can strengthen the plants and reduce damage. Clear away diseased leaves, improve ventilation and light penetration, and reduce sources of infection. Apply more phosphorus and potassium fertilizer and farmyard manure to improve the disease resistance of the plants. In May, spray the tree canopy with 1:2:200 Bordeaux mixture as a protective agent, once every 10-15 days, for 3 consecutive times, or spray with 50% wettable Tuzet 800-1000 times dilution.

Grey felt fungus disease

[Damage characteristics] Grey felt fungus disease generally occurs on the trunks or branches of old trees more than 20 years old. The lesions attach to the branches and trunk and form irregular thick films, like a plaster, hence the name felt fungus disease. Where the soil is poor, drainage is bad, soil moisture is high, ventilation and light penetration are poor, and plant growth is weak, the disease is severe.

[Prevention and control methods] Strengthen maintenance and management, adjust tree density. Where density is too high, remove the weak and keep the strong, remove the small and keep the large, so as to regulate light conditions and improve the disease resistance of the plants. Reasonably prune diseased old plants, remove diseased old branches, renew the plants, retain growing branches sent out from the inner canopy, and gradually replace heavily diseased branches and trunks to reduce sources of the pathogen. Use a knife to scrape off the mycelial film, and apply 5 degrees Baume lime sulfur mixture or lime milk to the diseased parts. During the occurrence period of scale insects that accompany the pathogen, spray the tree canopy with 1000 times dilution of dichlorvos emulsifiable concentrate for control. In the early stage of the disease, spray 1:1:100 Bordeaux mixture for protection, once every 10-14 days, for multiple consecutive times.

Green-tailed moon moth

[Damage characteristics] The green-tailed moon moth is also known as the water-green moth, swallowtail moth, and large green caterpillar. The larvae feed on leaves, causing translucent spots, holes, and notches, and in severe cases can eat all the leaves bare. Older larvae can also eat the leaf stalks, greatly affecting the normal growth of Cornus officinalis medicinal trees and the yield and quality of the medicinal material. It often occurs from mid-May to early October.

[Prevention and control methods] Cornus officinalis medicinal trees should avoid being interplanted with other forest trees and medicinal materials such as Chinese wingnut, elm, walnut, or Eucommia, peony, and Chinese peony, so as to facilitate management and control. During the adult occurrence period, use black light lamps to trap and kill them. In the early stage of the disease, spray with 800 times dilution of 90% crystalline trichlorfon. During the peak egg-laying period, manually remove eggs, or manually capture larvae during the peak larval period.

Large bagworm

[Damage characteristics] The large bagworm is also known as the large bag moth, skin worm, debt-avoiding moth, bag worm, and cloth-bag worm. The larvae mainly feed on leaves, and can also damage tender branches and young fruit. When feeding on leaves, they can bite holes and notches, and even eat the leaves bare leaving only branches, seriously affecting flowering and fruiting and the growth of the medicinal material. In August and September, the larvae enter the older-instar heavy-feeding stage, and the damage is severe.

[Prevention and control methods] Manually remove the larval bags. During the peak larval period, spray 800-1000 times dilution of 90% crystalline trichlorfon. Take care to protect various parasitic and predatory natural enemies during the larval and pupal stages, such as birds, parasitic wasps, and parasitic flies.

Cornus fruit-boring moth

[Damage characteristics] The Cornus fruit-boring moth is also known as the stone jujube worm, Cornus flesh worm, and medicinal jujube worm. Its larvae bore the flesh inside the fruit into crisscrossing tunnels, and the hollowed fruit is filled with insect frass. The damage worsens as the fruit matures. From late September to early October, when the fruit matures, is the peak period of damage.

[Prevention and control methods] Promptly clear away early fallen fruit. When the fruit matures, harvest at the appropriate time, which can reduce the overwintering insect population base. Treat the soil around the tree trunk with 2.5% trichlorfon powder, which can achieve the purpose of killing pupae and larvae that enter the soil.