Powdery mildew of Euonymus tomentosa

Symptom

It mainly harms young shoots and leaves, mostly on the back of leaves. During the onset of the disease, small white powder spots were first produced on the surface of the tender leaves, and then gradually expanded, the disease spots gradually expanded into a circular powdery layer, and the powdery layer on the old spot turned gray. In serious cases, the whole leaf is covered with white powder, the leaf shrinks, discolored patches appear, and even the diseased leaves roll vertically, and the new shoots are twisted and shrunk.

Pathogen

The pathogen is Alternaria thunbergii. The hyphae are superficial, colorless, septate, branched, 3.5-4.5 microns in diameter. Pairs of attached spores often appear on the mycelial cells, the shape is much cleft, the conidiophores are clavate, the basal cells are slightly twisted, 3 cells, the size is 73.4 ~ 43.9 × 6.3 ~ 10.1 microns. The conidia are solitary at the top of the stem and fall off immediately after maturation, often oval to rectangular orchard, with a size of 21.6 × 44.1 × 10.1 × 18.0 (14.2) microns. There is no sexual stage in the samples collected in the whole plant growing season, but the sexual stage can be induced artificially, and the sexual stage is Microsphaera sp.

Occurrence regularity

The infection of powdery mildew of Populus tomentosa is closely related to the development of host plant leaves, and generally only infects young leaves, so the peak value of the disease is mainly determined by the situation of shoots. The peak value usually occurs from April to May. At the same time, the development of disease spot is also closely related to the young and old leaves. With the aging of leaves, the development of disease spot is limited, and a limited near-garden-shaped disease spot is often formed on the old leaf, while on the young leaf, the disease spot expands almost infinitely, even covering the whole leaf. After that, the development of the disease stopped, especially from July to August, when the powdery mildew parasitic bacteria Cicinnobolus sp., was serious, the whole spot turned yellowish brown. During the disease period, the disease of Rain Water is serious; the disease of overgrown branches and leaves is serious; the planting is too dense, the hedge under the street tree shade, lack of light, poor ventilation, low-lying moisture and other factors can aggravate the occurrence of the disease, hedge disease is more serious than green ball disease.

Prevention and cure method

1. Strengthen management, control planting density, pay attention to ventilation and light transmission, in order to enhance the tree potential and reduce the humidity of the small environment; combined with pruning and shaping to remove diseased shoots and diseased leaves in time to reduce the source of infection.

two。 It is recommended that 20% Guoguang triadimefon EC 1500-2000 times or 12.5% uniconazole wettable powder (Guoguang black kill) 2000-2500 times, 25% Guoguang propiconazole EC 1500 times spray. Use it twice at intervals of 12-15 days.

Note: when using azole insecticides to control, young flowers and lawns must pay attention to the safe interval. Can not increase the amount and shorten the interval to avoid dwarfing effect.

Warm reminder of the four Seasons Plant Network:

Because this kind of diseases and insect pests are mainly distributed in Shanghai, Sichuan, Shandong, Jiangxi and other places. So friends in these places, if there is a big leaf boxwood breeding at home, we must pay more attention to it!

Control methods of powdery mildew of Euonymus tomentosa

In the growth process of Euonymus tomentosa, Populus tomentosa is easily affected by powdery mildew. Powdery mildew is widely distributed in Populus tomentosa. When it is damaged, a layer of white powdery mildew is formed on the leaves and shoots, which reduces its ornamental ability. The following editor shares with you the prevention and control methods of powdery mildew of Euonymus tomentosa.

Incidence regularity of powdery mildew of Populus tomentosa

The pathogen overwintered with mycelium in the damaged tissue of Euonymus tomentosa and produced gray membranous bacterial layer. In the leaf spreading and growing period of Euonymus tomentosa in the next spring, a large number of conidia were transmitted and infected by airflow, which became the bacterial source of the disease for the first time. The pathogen parasites on the surface of the branches and leaves of the host, produces haustorium and absorbs nutrients deep into the epidermal cells, and produces a large number of spores to infect leaves and new shoots every spring, summer and autumn. High temperature in summer is not conducive to the development of the disease. Rainy season and high humidity conditions are conducive to the occurrence of the disease. Cool and rainy autumn is conducive to the disease. The disease of Euonymus tomentosa planted in the shade is serious, the disease of young leaves and new shoots is serious, and the disease is more serious when the branches and leaves of Euonymus tomentosa are too dense.

Control methods of Populus tomentosa powdery mildew

1. Improve the cultivation conditions, planted in dry, sufficient light, no stagnant water, deep and fertile soil.

two。 Strengthen the management of fertilizer and water, increase the application of phosphorus and potassium fertilizer and appropriate amount of nitrogen fertilizer, and pay attention to drought and drainage to make seedlings grow strong and improve disease resistance.

3. Combined with pruning, diseased branches and leaves are cut off.

4. Rational use of chemicals for timely prevention and control, pay attention to the alternate use of agents, so as to avoid drug resistance of powdery mildew; spray carefully and thoughtfully, pay attention to spraying the inner chamber and leaf back. It was treated twice with 3-degree stone-sulfur mixture in winter, with an interval of 1 month. During the leaf development and growth period of Euonymus tomentosa, especially from April to May and September to October, the following chemicals can be used for control: 1500 to 2000 times of 25% fenbuxine wettable powder, or 1000 to 1000 times of methyl thiophanate wettable powder, or 1000 to 1500 times of 50% benzoate wettable powder, or 1000 to 1000 times of 50% benzoate wettable powder, etc., as soon as the disease begins to appear and sprayed once every 7 to 10 days. Spray 4 to 5 times in a row.

The above is the article on the prevention and control of powdery mildew of Euonymus tomentosa, which is shared by the editor. I hope the above can help you.

Control of powdery mildew of Euonymus tomentosa

Powdery mildew of Populus tomentosa is a common disease on Populus tomentosa, which is widely distributed. when damaged by it, there is a layer of white powdery mildew on leaves and shoots, which reduces its ornamental ability.

Morbidity regularity

The pathogen overwintered with mycelium in the damaged tissue of Euonymus tomentosa and produced gray membranous bacterial layer. In the leaf spreading and growing period of Euonymus tomentosa in the next spring, a large number of conidia were transmitted and infected by airflow, which became the bacterial source of the disease for the first time. The pathogen parasites on the surface of the branches and leaves of the host, produces haustorium and absorbs nutrients deep into the epidermal cells, and produces a large number of spores to infect leaves and new shoots every spring, summer and autumn. High temperature in summer is not conducive to the development of the disease. Rainy season and high humidity conditions are conducive to the occurrence of the disease. Cool and rainy autumn is conducive to the disease. The disease of Euonymus tomentosa planted in the shade is serious, the disease of young leaves and new shoots is serious, and the disease is more serious when the branches and leaves of Euonymus tomentosa are too dense.

Prevention and cure method

one。 Improve the cultivation conditions, planted in dry, sufficient light, no stagnant water, deep and fertile soil.

two。 Strengthen the management of fertilizer and water, increase the application of phosphorus and potassium fertilizer and appropriate amount of nitrogen fertilizer, and pay attention to drought and drainage to make seedlings grow strong and improve disease resistance.

three。 Combined with pruning, diseased branches and leaves are cut off.

four。 Rational use of chemicals for timely prevention and control, pay attention to the alternate use of agents, so as to avoid drug resistance of powdery mildew; spray carefully and thoughtfully, pay attention to spraying the inner chamber and leaf back. Three degrees of stone-sulfur mixture was used to prevent and cure it twice in winter, with an interval of one month. During the leaf development and growing period of Euonymus tomentosa, especially from April to May and September to October, the following chemicals can be used for control: 25% trimethoprim wettable powder 1500 to 2000 times, or 70% methyl topiramate wettable powder 8 to 1000 times, or 50% benzoate wettable powder 1 to 1500 times, or 50% chlorpheniramine 8 to 1000 times, etc. As soon as the disease begins to appear, it is sprayed once in seven to ten days and four to five times in a row.