Identification and Control of Lily Grey Mold

Lilium, belonging to Liliaceae, is a perennial root plant. In recent years, the planting of lily is seriously threatened by diseases, such as lily gray mold (leaf blight), blight, base rot, virus disease and so on. Among them, Botrytis cinerea has the greatest effect on the growth of lily and the quality of cut flowers, and even affects the breeding of lily bulbs.

Botrytis cinerea is a common disease of lily. It mainly harms leaves and can also infect stems and flowers. Infected lily leaves and floral organs often show symptoms such as leaf scorching, bud deformity and petal wilting in the later stage. So how to identify Botrytis cinerea in actual production?

The leaf appears scorched when it comes to disease.

Initial symptoms of the disease

Grey mold disease of lily

First, symptom recognition

1. Stem: after the lily stem is infected by the pathogen of Botrytis cinerea, the damaged part will turn brown and the plant is easy to lodge; after the top of the stem and leaf of the young plant is infected, its growth point will become soft, rot and die.

two。 Leaves: the leaf disease is a transparent water-stained spot at the beginning, and then rapidly expands to brown or reddish brown round or oval spot, the size is different, and the edge is water-stained; in the environment of low temperature and high humidity, the surface of the disease spot will be covered with gray or grayish brown mildew, that is, the conidiophores and conidia of the pathogen. In severe cases, most of the disease spots heal, making the whole leaf scorch, like "fire", and even cause the whole plant to die.

3. Flowers: small brown spots appear in the early stage of flower bud damage, and then spread to cause flower bud rot; when the pathogen infects petals, it will first produce dotted water stains and fade spots, and then the disease spots will expand to light grayish brown in a short time, and only cause flower organ deformities in mild infections. in severe cases, it will cause the whole flower to wither. In the case of high environmental humidity, all the disease parts will produce a large number of grayish-brown mildew, which are conidia of bacteria.

II. Pathogenic bacteria

Botrytis cinerea is caused by BotrytiscinereaPers. Diseases caused by infection, but the pathogen causing Botrytis cinerea in lily except

BotrytiscinereaPers. Besides, it is mainly Botrytiselliptica (Berk.) Cooke, whose host range is limited to Lilium genus of Liliaceae. B.elliptica, known as oval grape spores, belongs to half-known fungi of the genus Botrytis.

Third, the regularity of the disease and the route of transmission

The occurrence of Botrytis cinerea in lily is closely related to climate. The pathogen of B.elliptica can survive and grow on the soil and various plant residues, and overwinter in the damaged part of the host or in the soil as sclerotia. When the temperature rises in spring, the overwintering hyphae will form a large number of conidia in a short time, and come into contact with lily leaves or petals by air, Rain Water and farm operations in the field. after germination, the mycelium bud tube can directly penetrate the cuticular layer and invade the lily host cells or invade through the wound and stomata to complete the primary infection; after the disease, the diseased part produces conidia for reinfection. In addition, Botrytis cinerea can also be transmitted by carrying seed balls, and the parts that are physiologically injured are also prone to Botrytis cinerea.

The optimum temperature for mycelial growth of Botrytis cinerea is 15 ℃ to 25 ℃, and the best temperature is 20 ℃. The air relative humidity above 90% is beneficial to the epidemic of the disease.

When the conditions are suitable, the whole process of spore formation, release and germination of Botrytis cinerea can be completed in a very short time; continuous rainy and foggy days, when there is moisture in lily leaves, it can lead to the outbreak and epidemic of the disease. For example, Yunnan Province in China is the main area of cut lily production. June, July and August every year is the frequent season of Botrytis cinerea, and it is also the key period for chemical control.

IV. Diagnosis

The affected part of Botrytis cinerea can produce a large amount of gray mildew in a humid environment, such as when this typical disease is observed in the field, the disease can be correctly diagnosed, but in the general lily growing season, this disease is not common. On the contrary, diseases similar to leaf spots are more common.

V. Prevention and control methods

Adopting protected cultivation facilities, paying attention to cultivation density and strengthening ventilation can effectively reduce the incidence of Botrytis cinerea.

Cultivate disease-tolerant varieties, advocate field irrigation, adopt drip irrigation to reduce relative humidity, and appropriately increase calcium and potassium fertilizer to enhance disease resistance.

Diseased leaves were removed in time and destroyed centrally.

Disinfect the bulb before planting: because the bulb may carry bacteria, it is best to disinfect the lily bulb before cultivation.

Chemical control: at the initial stage of the disease, Huiyou (Medallion), chlorothalonil and azoxicycline were alternately sprayed on the leaves every 7 to 10 days for prevention and treatment.

(note: Huiyou is a contact protective fungicide, which works by inhibiting the transfer related to glucose phosphorylation to inhibit the growth of pathogenic mycelia and eventually lead to the death of pathogens.)