Integrated control of Sclerotinia sclerotiorum in coriander

Coriander, formerly known as coriander, alias: coriander, coriander, Latin name: Coriandrum sativum L. Annual or biennial strongly scented herbs of the family Umbelliferae and coriander, 20-100 cm tall. The root is fusiform, slender, with many slender branches. Stems Terete, erect, much branched, striate, usually smooth. Root leaves stipitate, style erect when young, retrorse outward when ripe. The fruit is round, and the main ribs and adjacent secondary ribs are obvious on the back. The ventral surface of the endosperm is concave. The tubing is not obvious, or 1 is located below the secondary edge. Native to the Euro-Mediterranean region, it is cultivated in Northeast China, Hebei, Shandong, Anhui, Jiangsu, Zhejiang, Jiangxi, Hunan, Guangdong, Guangxi, Shaanxi, Sichuan, Guizhou, Yunnan, Xizang and other provinces.

Morphological characteristics of coriander

It is an umbrella-shaped plant of the genus Zingiberaceae, an annual or biennial herb. In Shuowenjiezi, it is written: "if coriander is used as a clover, it can taste delicious." Its stem is soft, the leaf is thin and the root is bearded, and Sui Suiran is also. Zhang Qian made it possible to grow coriander in the western regions, hence the name coriander. Coriander is the appearance of stems and leaves. Shiller is secretive about Hu, so the Jin land is called coriander. "

Parsley originated in western Asia, Persia and Egypt, and was introduced into China by Arabs in the Tang Dynasty. Meng Xi's "Dietotherapy Materia Medica" and Chen Zang's "Materia Medica" record in detail the attributes, growth cycle and hydrological environment of this plant.

Control methods of Sclerotinia sclerotiorum in coriander

Sclerotinia sclerotiorum caused by Sclerotinia sclerotiorum has become a major obstacle in the production of parsley with the continuous expansion of coriander planting area in recent years, especially the difficulty of crop rotation in protected areas.

Symptom recognition of Sclerotinia sclerotiorum in coriander

Sclerotinia sclerotiorum mainly harms the base of stem, followed by leaves. At the beginning, the discolored waterlogged spot appeared, and then it became light brown and expanded rapidly. when the humidity was high, the disease had white cotton-like hyphae, showing soft rot, and in the later stage, the hyphae formed black sclerotia under the white mold layer, and when serious, the disease seedlings withered and died.

Main points of identification: when it is wet, there is a white cotton-like mildew layer on the surface of the disease, and a sclerotia is formed on the stem surface in the later stage, or black sclerotia can be seen on the stem.

Occurrence regularity of Sclerotinia sclerotiorum in coriander

1. Sclerotinia sclerotiorum is caused by Sclerotinia sclerotiorum of Sclerotinia sclerotiorum. The mycelium is white, the sclerotia is black on the outside and the inside is white. When sclerotia germinate, there are dozens of ascomycetes, usually 3-10. The ascus disc is cup-shaped at first, then a disk-shaped, yellowish brown, with a long handle under the disc. There are 8 ascospores on the surface of the ascomycete disc, which are club-shaped.

two。 The infection cycle bacteria overwintered with sclerotia in the soil or mixed with seeds and became the source of infection at the beginning of the second year. When the conditions were suitable in the following year, the sclerotia germinated, produced ascomycetes, ejected ascospores, spread by airflow, invaded the host, and then re-infected through hyphae in the field. In the field, it can also be transmitted to parsley through weeds infected with Sclerotinia sclerotiorum (such as Portulaca oleracea), which is repeatedly infected, and later, when the conditions deteriorate, the bacteria form sclerotia to overwintering.

3. Disease condition

1) the relationship between disease and temperature and humidity the temperature of the germ station is 0-30 ℃, the optimum temperature is about 20 ℃, and the relative humidity is more than 85%, which is conducive to the occurrence and development of bacteria. Therefore, the occurrence of Sclerotinia sclerotiorum is serious in winter and spring where the temperature is relatively low and the humidity is high.

2) the relationship between disease and soil moisture. The survival time of sclerotia in water was short, and the sclerotia died in 1 month. Therefore, sclerotia can survive for about 1 year in moist soil and more than 3 years in dry soil. It can be seen that the high soil moisture is not conducive to sclerotia survival and the incidence of disease is reduced.

3) the relationship between the disease and other vegetables due to Sclerotinia sclerotiorum disease can damage almost all vegetables, including cabbage, lettuce, celery, cucumber, tomato, eggplant, bean, fennel, cabbage and so on. After the occurrence of Sclerotinia sclerotiorum in these vegetables, there is sclerotia in the soil, and parsley can be infected by planting parsley.

4) the relationship between disease and seeds if the sclerotia is mixed in the seeds, the sclerotia enters the vegetable field with sowing and infects coriander.

Comprehensive control methods of Sclerotinia sclerotiorum in coriander:

At the initial stage of the disease, 50% Sukeling wettable powder 1000-1500 times liquid, or 50% Prometholide wettable powder 1000 times liquid, or 50% Promethrin wettable powder 1000 times liquid, or 50% Nongliling wettable powder 1000 times liquid, or 40% sclerotia net wettable powder 1000 times liquid, or 50% ammonium chloride wettable powder 1000 times liquid, or 40% Kuli wettable powder 1000 times liquid, once every 7 days for 3 times in a row. Those planted in protected areas can be fumigated with 10% Prochloraz or 15% tocopherol fumigant, 250g per 666.7 square meters each time, in the evening. After lighting the smoke, the fumigation is sealed and smoked once every 7 days for 4 consecutive times.

Other prevention and control measures:

1. Crop rotation or high temperature disease control should be carried out with food crops for 2-3 years, and high temperature control can be adopted to protect the diseased areas. the methods are as follows: during the period of high temperature in three summers, first clean the countryside, remove residual branches, diseased leaves and weeds, take them out of the field, bury them or burn them. Apply lime 50100kg every 666.7 square meters, add crushed wheat straw or wheat taro 500kg, evenly apply to the surface, immediately turn into the soil, ridge about 30cm, furrow irrigation, until saturated, in order to always have water in the furrow, irrigation every day; plastic film, sealed around with soil, closed shed, room for 15-20 days. This method can not only kill part of the sclerotia, but also kill Fusarium, root-knot nematode and other germs.

2. Large field soil or peat soil should be selected for raising seedlings in disease-free soil, and management should be strengthened to cultivate disease-free and strong seedlings. If there are conditions, the hotline can be used to raise seedlings in the seedbed where vegetables have been planted. The sclerotia in the soil of the seedbed can be killed by setting the temperature of the seedbed to 55-56 ℃ before sowing for 2 hours. Then cool down, sow, and raise seedlings normally.

3. Select disease-free seeds to leave seeds from disease-free plants. For seeds mixed with sclerotia, rinse the seeds with 10% brine and remove sclerotia. Then rinse the seeds repeatedly with clean water, dry them and sow them. The seeds can also be soaked in warm water for 50 ℃ for 10 minutes (keep the temperature) to kill the sclerotia mixed in the seeds.

4. To strengthen the cultivation of protected areas, we should strengthen the release of air, reduce the humidity, and create an environmental condition that is not conducive to the occurrence and development of Sclerotinia sclerotiorum.

5. Covering plastic film can prevent the ascomycete from being unearthed. If the ground is covered with ultraviolet blocking film, the effect is better, because this film can inhibit sclerotia germination.

6. when diseased plants are found in clean rural fields, they should be pulled out in time to reduce the spread of bacteria in the field.

7. for planting in protected areas for the prevention and control of pollution-free pesticides, 3.3% Tex smoke agent shall be used before the disease, 250g per 666.7 square meters, divided into 4-5 points, carried out in the evening, closed fumigation, fumigation once every 7 days, continuous fumigation 5-6 times. At the initial stage of the disease, 42% Tekedo suspension can also be sprayed 1000 times, once every 7 days, 3-4 times in a row.