Magnolia pest control

Magnolia Diseases: Anthracnose

Symptoms

Magnolia leaves are most susceptible to this disease.

The initial symptoms are irregularly shaped spots appearing on the leaf tips or edges, or nearly circular spots appearing on the leaf surface. The lesions initially appear as brown water stains with small black particles on the surface and raised dark brown lines on the edges, which are clearly demarcated from normal areas.

The high temperature and high humidity make summer the peak season for this disease. Failure to properly control the amount of water and fertilizer used for the plants and poor ventilation will also make the plants susceptible to infection by this disease.

Prevention and treatment methods

Control the amount of water and fertilizer to ensure the healthy growth of the plants and enhance their disease resistance.

Diseased leaves should be removed in time, and fallen leaves in late autumn should also be swept and destroyed in time.

If the plant has been infected by the disease, spray 800 times diluted 75% thiophanate-methyl wettable granules or 500 times diluted 70% anthracnose thiram (once every 10 days). Continuing for 3-4 times will effectively control the deterioration of the disease.

Magnolia Diseases: Chlorosis

Symptoms

The initial symptom is a reduction in chlorophyll in the leaves, causing the leaflets to turn green. Gradually, the other leaves will also turn yellow or light yellow, but the veins will still be green.

If the disease progresses further, all the leaves will turn yellow and then white, causing the plant's growth to decline continuously and eventually lead to death.

Prevention and treatment methods

Chlorosis is a physiological disease that can be caused by soil that is too sticky, excessive pH values, and insufficient iron supply.

Root irrigation with a 0.2 percent concentration of ferrous sulfate solution or spraying with a 0.1 percent concentration of ferrous sulfate solution can effectively prevent and control this disease. At the same time, more fertilizer should be applied.

Magnolia Diseases: Leaf Burn

Symptoms

The disease initially manifests itself as burnt edges on the leaves of the plant, which gradually shrink and dry up. When the disease worsens, new leaves will have difficulty expanding, and finally a large number of leaves will wither and fall off.

This disease can occur in areas with poor geological environments, such as large hardened areas and small green areas, as well as areas affected by high temperature, drought and strong light for a long time, and soil alkalinization.

Prevention and treatment methods

First, make sure the soil is moist by increasing watering.

Apply organic fertilizer frequently to enhance the disease resistance of plants.

Other measures include whitewashing the tree or wrapping its trunk.

Magnolia pests: Red wax scale

Symptoms

The nymphs and adults of the red wax scale suck the sap of flowers, and their excrement often induces the occurrence of sooty mold, which forms a layer of black mold or a thick black film on the leaves. The whole plant becomes black, the plant becomes weak, and rarely blooms or cannot bloom at all.

Prevention and treatment methods

In winter and early spring, combine pruning with removing some insect-infested branches.

If the number of affected flower plants is small or short, they can be removed manually in winter and spring.

During the peak period of nymph hatching, spray 1000 times diluted 25% phosmet emulsifiable concentrate or 1500 times diluted 40% oxydemeton-methyl emulsifiable concentrate, once every 4 to 6 days, for 3 times in a row.

Magnolia Pests: Red Spider Mites

Symptoms

Red spider mites mainly harm leaves and feed on leaf sap. When the disease occurs, reddish-brown spots will appear on the leaves. In severe cases, the leaves will wither and the branches will rot.

Prevention and treatment methods

Soak citrus peels in 10 times the amount of water for a day and night, filter and spray the plants.

Mix 15g of laundry detergent, 15ml of 20% caustic soda and 7.5kg of water and spray them on the plants.

Add 2.5kg water to 50g of wood ash, stir thoroughly, soak for two days and nights, filter, then add 3g of laundry detergent and mix well before spraying. Do this once a day for three times in a row, and then spray three more times after one week. This can eliminate the second generation of pests. Putting it into the soil can prevent and control maggots.

Light a plate of mosquito coils, place it in the pot of diseased plants, and then tie the pot tightly with a plastic bag. After 1 hour of fumigation, the eggs and adult insects can be killed.

Magnolia Pests: Cicadas

Symptoms

The nymphs of the cicada suck the sap from the roots of flowers in the soil, the adults suck the sap from the main leaves, and the females insert their ovipositors into the branches to lay eggs, causing the branches to wither and die.

Prevention and treatment methods

Kill the newly emerged mature nymphs promptly.

If the infestation is more serious, you can light a fire near the tree trunk on a hot summer night, shake the branches to drive the cicadas into the fire and burn them to death, and kill the cicadas that fall outside the fire.

Use boiled tung oil or a sticky dough made from spider webs to apply to the end of a bamboo pole to catch adult insects.

Check and cut off the egg-laying branches in time from April to August.