Symptoms and prevention of botrytis cinerea of rose

Rose is a common flowering plant in China, originated in China, due to the long-term cross-breeding by horticulturists, it has developed to more than 20,000 varieties. Although the cultivation difficulty of rose is relatively low, we can not ignore the common diseases of rose. The editor will introduce the grey mold of rose to you in detail. Friends who like rose can learn it together.

Rose

1. Characteristics of symptoms

The pathogen is Botrytis cinerea. The pathogenic fungus infects the flower, bud and tender stem of rose, and the disease spot mainly occurs on the flower. At first, it was waterlogged irregular spot, slightly sunken, and then became brown and rotten. The disease on the bud also produces waterlogged irregular spots, which can be extended to the whole bud, and finally the whole bud becomes soft and rotten. The diseased buds withered and hung over or near the diseased tissue. In a warm and humid environment, the disease can produce a large number of gray mildew layer.

Second, the law of the disease.

The pathogen overwintered by mycelium or sclerotia.

Conidia infection occurred in the following year, and gray mildew appeared on the surface of the disease. High temperature and heavy rain are beneficial to the formation and spread of conidia. After contact with the host, the conidia germinated into the germ tube and invaded. It is easy to occur if the planting is too dense, the humidity is high, the light is insufficient or nitrogen fertilizer is applied, and the plant growth is weak.

III. Prevention and control measures

In autumn, litter should not be used to protect the root, so as to avoid excessive dampness at the base of the stem, which is conducive to the survival of bacteria. In greenhouse cultivation, we should pay attention to ventilation and light transmission, avoid excessive humidity, prevent spray watering, not partial application of nitrogen fertilizer, not excessive close planting. The infected flowers should be removed and the diseased buds should be cut off and destroyed together with the stem a few centimeters below the bud.

During the onset of the disease, 75% chlorothalonil wettable powder can be sprayed with 700x solution, or 1purl 1vir 12x to 160x Bordeaux solution, or 50% carbendazim wettable powder 900x solution, or 65% methylcarbendazim wettable powder 1000 times, or 70% methyl thiophanate wettable powder 1500 times.

Symptoms of Botrytis cinerea of rose and its control measures

Botrytis cinerea mainly harms flowers and twigs. After the bud is infected, it is waterlogged and irregular at first, and the spot expands continuously, so that the whole bud becomes soft and rotten. When the diseased buds wither and hang on the diseased tissue, the pathogen will also invade the branches that have been plucked flowers. Under warm and humid conditions, a large number of gray mildew layers occur in the diseased part.

Symptoms of disease:

Botrytis cinerea of rose is mainly harmful to leaves, buds, buds and flowers, as well as young stems. When the leaf margin and leaf tip occur, at first there are water-stained light brown spots, smooth and slightly sunken, and then expand and rot. The flower bud is sick, the disease spot is gray and black, which can prevent the flower from blooming, and the diseased bud turns brown and dies. When the flowers are invaded, some of the petals turn brown, wrinkled and rotten. Botrytis cinerea also invades the tip of the branch after folding, and the black part of the disease can infect the lower edge of the point to a few centimeters. In a warm and humid environment, the gray mildew layer can completely cover the infected parts.

Prevention and control measures:

1. Timely removal of diseased flowers, removal of withered presbyopia, and concentrated burning.

two。 Greenhouse cultivation pay attention to ventilation, reduce air humidity, so that indoor rose has a good growth environment to prevent excessive humidity.

3. During the onset of the disease, 65% Dysen zinc wettable powder, 75% chlorothalonil wettable powder or 70% methyl topiramate wettable powder 1500 times can be sprayed.

Symptoms and control methods of rose downy mildew

Symptoms: downy mildew harms leaves, tender shoots, pedicels and flowers. In the early stage, irregular light green markings appeared on the leaf surface, then expanded in yellowish brown and purple, and then grayish brown, with a dark edge and no obvious boundary with healthy tissue. Finally, the leaves are twisted and deformed. When the weather is humid, a sparse gray-white downy mildew layer can be seen in the leaf back disease spot. Leaflets often turn yellow, some disease spots are purplish red, the center is grayish white, similar to pesticide damage and chemical fertilizer burn. When the new shoots and flowers were infected, the disease spots were similar to the leaves, but the disease spots on the tender shoots were slightly sunken. In severe cases, the leaves atrophy and fall off, and the new shoots die.

Pathogen: rose downy mildew is caused by a rose downy mildew infection in fungi. The bacteria overwintered in the diseased tissue with oospores or mycelia. Under the condition of low temperature, high relative humidity and water droplets on the plant surface, the disease is easy to occur and spread. When the greenhouse has poor ventilation, too dense plants, high humidity and too much nitrogen fertilizer, the disease is serious. The fungus only infects rose.

The pathogen overwintered and overwintered with oospores and infected with conidia. The spore germination temperature was 1: 25 ℃, the optimum was 18 ℃, the germination rate decreased above 21 ℃, the spores did not germinate at all above 26 ℃, the spores died in 24 hours at 26 ℃, the spore transmission needed 100% air humidity, 10-25 ℃ temperature, spore germination needed water droplets, open-field cultivation mostly occurred in rainy season, and greenhouse mainly occurred in March-April and September-October. It happened in a greenhouse. When the seedbed is dense, poorly ventilated, wet and too much nitrogen fertilizer, the disease is serious.

Prevention and control methods: avoid high temperature and humidity, reduce leaf moisturizing time, control air humidity, open more windows for ventilation, use 20000 times mancozeb or mancozeb, but the latter is easy to pollute leaves.