Control of algal spot caused by coal fouling disease of mango

(1) mango coal fouling disease:

1. Symptoms: the disease mainly occurs in leaves and fruits. The leaves and fruits are covered with a layer of black fluff, like soot, so it is called soot disease. In severe cases, the whole leaf and fruit are covered with mycelium (soot). This kind of fungi mainly grows on the appearance of the leaves, is not easy to invade the leaf tissue, and is easy to be erased.

two。 Pathogen and occurrence regularity: the pathogen of this disease is named CapnodiummangiferaeP.Henn. This bacteria mainly depends on honeydew secreted by aphids and leafhoppers. Aphids and leafhoppers occur frequently, and soot disease is also serious. The germs are so wet that mangoes are planted too densely and are easy to get sick in the shade.

3. Control methods: the control of aphids and leafhoppers is an effective way to prevent the occurrence of this disease. After the onset of the disease can spray 0.3 Baume degree of stone sulfur mixture, dithiocarbamate has a certain effect.

(2) Mango algal spot:

1. Symptoms: the disease mainly occurs on the leaves, and can occur on both sides of the leaves. The primary white to yellowish brown needle-sized dots gradually expand radially around, forming round or irregular slightly raised felt spots with irregular edges, grayish green or orange. In the later stage, the surface is smoother and the color is darker.

two。 Pathogen and occurrence regularity: the pathogen of the disease is CephaleurosvirescensKunze, the orchard soil is barren, weeds are overgrown, the terrain is low-lying, wet and shady, and the growth is weak on the old trees, the old leaves and branches in the lower part of the crown. Absorbing water and mineral nutrients from mango trees has little direct effect on mango trees.

3. Prevention and treatment methods: rational fertilization, increasing application of phosphorus and potassium fertilizer, moderate pruning, paying attention to ditch drainage and so on can reduce the incidence of the disease. Remove and burn fallen leaves and reduce pathogens. In the orchard with serious disease, before the zoospores were formed in the gray-green spot in early spring, the effect was good when the orchard was sprayed with 0.5-100 Bordeaux solution for 2 times.

(3) Mango purple root disease:

1. Symptoms: the disease is mainly harmful to the base and roots of seedlings. The injured part turned purple and black, the cortex rotted and the xylem became dry and rotten. The growth of the aboveground part of the plant was weak, the leaf color was light to yellow, and finally the whole plant died. The surface of the underground disease part is covered by purplish red rhizomatous fungal cord, which forms a purplish red velvet membrane when it is wet, and the sclerotia can be formed in the later stage.

two。 Pathogen and occurrence regularity: the disease is caused by fungal infection (Helicobasidiumsp.). If the pathogen overwinters in the soil, the conditions are suitable to invade from the root or root neck of the plant. The disease is more serious in the nursery with heavy sticky soil, poor ventilation, easy hardening and poor drainage.

3. Prevention and treatment methods: remove the diseased plant in time, burn it centrally, and sprinkle some lime in the diseased point for disinfection; drench the root with 25% carbendazim 500 times or copper-ammonium mixture 400 times, and soak the soil thoroughly with 0.5 kg of 70% dimethazon. Mix well with 20 kilograms of fine soil and sprinkle it near the roots of the plant, or sprinkle the soil surface with 350 kilograms of water. Every 667 square meters, 40% pentachloronitrobenzene 3 kg and fine soil 10kg were used to make poisonous soil and spread it on the soil surface of the root of the plant.