What is Wrong With My Herbaceous Peony Leaves？

Herbaceous peony is a common plant, which has been loved by people since ancient times. However, herbaceous peony can also be sick, the following introduction to the common symptoms of herbaceous peony and prevention and treatment methods.

How to Prevent Herbaceous Peony from Leaf Mould？

Cardinal symptom: Near-round purple-brown spot appeared on the early stage of the disease, and the diameter was 1-5 mm and then expanded to an irregularly large spot, the diameter was 7-12 mm, the center was pale yellow-brown, the edge was purple-brown, and the lesion was marked with a clear concentric wheel pattern. The diseased spots spread and connected into pieces, and the whole leaves were scorched when they were severe. Dark green mildew is produced on the surface of the diseased spot when wet, that is, the conidia peduncle and conidia of the pathogen. The green stem is purple-brown round dots, some protruding and the diseased spot expands slowly, the size is only 3-5 mm. The petiole symptom is similar to the spot on the stem, but it is long striped and has dark green mildew on it.

The onset of conditions: The disease starts from late April to early May, and the peak period is in August and middle. In July and August, there is a lot of rainfall and high humidity, which is beneficial to disease expansion. Planting is too dense, and the garden with poor cultivation management is more serious. In general, the plant has weak resistance and serious disease after frost damage. There is a difference in the degree of incidence between varieties.

Prevention and control methods:

1. Remove the diseased leaves and branches in time, and concentrate on burning or burying in the soil below 15cm, so as to reduce the source of bacteria for the first infection in the next year.

2. Strengthen management, planting should not be too dense, keep plants ventilated and transparent. 

3. At the beginning of the disease, 40% carbendazim suspension 600 times solution or 50% methyl-tobuzine 800 times solution could be sprayed every 10 to 15 days for a total of 3 times.

How to Prevent Herbaceous Peony from Gray Mould？

Cardinal symptom: There are two kinds of pathogenic bacteria: the first is Botrytis paeoniae Oudem, the spot on the leaf is nearly round or irregular, most of which occur in the tip and thin leaves, brown or purple brown, with irregular wheel lines, and grow gray mildew when the air humidity is high. When infecting the stem, the diseased spot is brown. The flowers are brown, soft rot, gray, mildew and the black granular sclerosomes are sometimes produced at the lesion. The second pathogen is Botrytis cinerea, which not only harms herbaceous peony, but also infects peony, chrysanthemum, cyclamen and so on.It causes brown rosette wrinkle at the edge of the leaf. Petiole and pedicel soft rot, outer coat rotting, pedicel killed, often affecting seed maturity.

The onset of conditions: The above two pathogens overwintering in the soil by sclerotinia. The incidence of multiple continuous cropping plots was serious. High temperature and rain were beneficial to the formation and transmission of conidia, conidia were in contact with the host. Under the condition of water and humidity, the bud tube germinates and invades the host body, excessive application of nitrogen fertilizer, the plants too close, high humidity, lack of light, plants with weak growth are vulnerable to bacteria.

Prevention and control methods:

1. Avoid continuous cropping and plant in aseptic soil.

2. Use aseptic seedling and use 65% wettable zinc powder 300 times solution before planting, soak for 10 minutes.

3. Pay attention to ventilation, light transmission, proper application of nitrogen fertilizer, timely drainage after the rain, and remove the diseased leaves and diseased plants at any time.