Disease and Pest Control of Peony

Dicentra leaf spot

In the early stages of leaf spot disease, many small dark brown spots will appear on the leaf surface, which will then gradually expand and form irregular rings, and finally black mold spots will appear.

Causes

When attacked by pathogens, local necrotic diseases will appear on the leaves. The diseases are mainly caused by fungi, bacteria and nematodes. Germs can be spread through wind, rain and air currents. The infection continues throughout the growing season. Leaf spot occurs in climatic conditions with heavy rainfall, high precipitation, and moderate temperatures.

Prevention and treatment methods

Reasonable fertilization and watering, ventilation and light transmission, improve the disease resistance of plants;

Spray 0.5% to 1% Bordeaux mixture for prevention before the disease occurs;

Remove diseased leaves promptly at the early stage of the disease and destroy them in batches to reduce the source of infection; then spray 65% ​​mancozeb wettable powder 600 times diluted, once every 10 to 15 days, and repeat 3 to 4 times;

During the disease period, spray 500-800 times diluted 80% Mancozeb and 1000 times diluted 70% Thiophanate-methyl wettable powder for prevention and control.

Dicentra scale insect

Direct spraying of scale insects with chemicals is not effective. It sucks the sap of plants crazily, causing flowers and trees to wither and become damaged; the affected plants will experience poor growth and gradually turn yellow. The excrement of this insect often causes sooty mold disease, which can turn leaves and branches black.

Causes

The disease is caused by poor ventilation, weak light and improper fertilization.

Precautions

Strengthen plant lighting, maintain ventilation, place in an appropriate position, increase water and fertilizer management, and pay attention to frequent pruning for prevention.

Prevention and treatment methods

The main approach is to utilize natural enemies, supplemented by medicines. There are many natural enemies of scale insects, the most common ones include the big red ladybug, Australian ladybug, small red ladybug and red-ringed ladybug. They can kill scale insects in large numbers. It is most appropriate to use medicine in winter and spring when there are more nymphs. Use 1000-1500 times diluted 50% cypermethrin emulsifiable concentrate or 1000-1500 times diluted 40% oxydemeton-methyl emulsifiable concentrate for spraying for control; during the dormant period of scale insects in winter, use 1% lime sulfur mixture of Baume for spraying for control.