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Problem Solver Plant Marquee

Plant:

Magnolia
Image of Magnolia
Flowering
Late winter to fall, depending on the species.
Adaptation
From the Mid-Atlantic or central Midwest down to most of the Gulf Coast.
Pruning
Magnolias do not require pruning, except to remove deadwood. When planting, allow enough room for growth.
Soil
Well drained, rich in organic matter. Magnolias will not tolerate salts in the soil or compacted soil. Avoid digging around their roots.
Water
Magnolias prefer moist growing conditions. Water when the soil is moist but not wet.
Fertilizer
Fertilize plant food formulated for acid-loving plants.
Light
Full sun (partial shade in desert areas).
Related problems

Algal Spot - Magnolia

Image of Algal Spot - Magnolia
Algal Spot

Iron Deficiency - Magnolia

Image of Iron Deficiency - Magnolia
Iron Deficiency

Magnolia Scale -

Image of Magnolia Scale
Magnolia Scale

Summer Leaf Scorch - Magnolia

Image of Summer Leaf Scorch - Magnolia
Summer Leaf Scorch

Tulip Tree Scale -

Image of Tulip Tree Scale
Tulip Tree Scale
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Algal Spot - Magnolia

Image of Algal Spot - Magnolia
Algal Spot
Description
Leaves and twigs are covered with greenish brown or velvety reddish spots. Twigs may be stunted or die back.
Analysis

Algal spot, also called green scurf, is caused by algae (Cephaleuros virescens) that are common on magnolias and other ornamentals in the southern parts of the country. During moist weather, cells of the algae enter the leaves or the other tissue of twigs and spread rapidly. The invaded twig tissue may swell and crack. If the crack encircles the twig, the twig dies. The infected magnolia leaves turn greenish brown at first. If the algae develop spore-producing bodies (tiny round heads on fine, dense reddish hairs), the patches appear reddish brown and velvety or cushiony. The algae spread rapidly when rains are frequent and heavy. Trees weakened by drought or poor growing conditions are most susceptible to algal spot.

Solution

Control measures are rarely necessary. If trees are weak, improve growing conditions by watering and fertilizing regularly. Prune dead twigs.

Close

Iron Deficiency - Magnolia

Image of Iron Deficiency - Magnolia
Iron Deficiency
Description
Some of the leaves turn pale green to yellow. The newest leaves may be completely yellow, with only the veins remaining green. On older leaves, only the leaf edges may be yellowing. The plant may be stunted.
Analysis

This is a common problem with acid-loving plants such as magnolia that grow best in soil with a pH between 5.5 and 6.5. The soil is seldom deficient in iron, but iron is often found in an insoluble form that is not available to the plant, especially in soil with a pH above 7.0. A high soil pH can result from overliming or from lime leached from cement or brick. Regions where soil is derived from limestone or where rainfall is low also have high-pH soils. Plants use iron in the formation of chlorophyll in the leaves. When iron is lacking, new leaves are yellow.

Solution

Fertilize with a plant food formulated for acid-loving plants.

Close

Magnolia Scale -

Image of Magnolia Scale
Magnolia Scale
Description
Twigs and stems are covered with powdery white or shiny brown crusty bumps, 1/2 inch in diameter, or soft masses of purple insects. Stems that are normally light green may appear enlarged and purple or whitish. The crusty bumps can be scraped or picked off; the undersides are soft. Leaves may be yellowing and smaller than normal; trees may be weakened or killed. A shiny, sticky substance usually coats the leaves. A black sooty mold often grows on the sticky substance.
Analysis

Neolecanium cornuparvum This is the largest scale insect found in the United States. The immature purple insect spends the winter on the twigs and branches of the tree. Starting in spring, it feeds by inserting its mouthparts and sucking the sap and nutrients from the bark tissue. The scale is unable to digest fully all the sugar in the plant sap, and it excretes the excess in a fluid called honeydew. A sooty mold fungus may develop on the honeydew. The scales mature in August, and the female lays her eggs beneath her powdery white or shiny brown shell. In the fall the young scales, called crawlers, settle on the twigs to spend the winter. Repeated heavy infestations kill branches and possibly the whole tree. Several other types of scales also infest magnolia.

Solution

Spray with an insecticide labeled for scale. Early the following spring, before new growth begins, apply a dormant oil spray to control overwintering insects, following label instructions.

Close

Summer Leaf Scorch - Magnolia

Image of Summer Leaf Scorch - Magnolia
Summer Leaf Scorch
Description
During hot weather, leaves turn brown around the edges and between the veins. Sometimes the whole leaf dies. Many leaves may drop during late summer. This problem is most severe on the youngest branches. Trees do not generally die.
Analysis

Leaf scorch is caused by excessive evaporation from the leaves. In hot weather, water evaporates rapidly from the leaves. If the roots can''t absorb and convey water fast enough to replenish this loss, the leaves turn brown and wither. For optimum growth, magnolias require moist soil. Leaf scorch is most severe when water is unavailable because the soil is dry. If the weather is extremely hot, scorch may also develop when the soil is moist, however. Drying winds, severed roots, limited soil area, or low temperatures can also cause scorch.

Solution

To prevent further scorch, deep-water trees during periods of hot weather to wet down the entire root space. Apply a thick layer of mulch over the root system. Water newly transplanted trees whenever the root ball is dry near the surface. If possible, shade trees during very hot weather. Plant trees adapted to your climate.

Close

Tulip Tree Scale -

Image of Tulip Tree Scale
Tulip Tree Scale
Description
The twigs and branches are covered with brown, turtle-shaped, crusty bumps 1/3 inch in diameter. Leaves turn yellow and may drop. A shiny, sticky substance, sometimes covered wtih black mold, coats the leaves. Branches die back, starting at the bottom of the tree. The tree may be killed by severe infestations. Lady beetles may be feeding on the scale.
Analysis

Toumeyella liriodendri The tulip tree scale is a serious pest of tulip trees, lindens, and magnolias. The immature insect spends winter on twigs and branches. Starting in spring, it feeds by sucking the sap and nutrients from bark tissue. The scale cannot digest all the sugar in the sap, and it excretes the excess in a fluid called honeydew, which drops onto objects below. Sooty mold grows on the honeydew, making the tulip tree leaves appear black and dirty. Honeydew also attracts bees, wasps, flies, and ants, which feed on it. Scales mature in August, and females lay up to 3,000 eggs underneath a brown shell. Young scales, called crawlers, settle on twigs in the fall. Crawlers are dark tan, looking like tiny aphids. Repeated heavy infestations kill branches or the whole tree. Several other types of scales also infest magnolias.

Solution

Apply an insecticide labeled for scales, following label directions.

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