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Oddities Appear As Leaves Fall

As leaves fall from our deciduous trees, you may notice some curious-looking growths. Typically hidden by foliage, here are some of the oddities you might be seeing.

Lichens

Lichens look menacing, but they are not harmful to the plants they grow on. Lichens are the crusty, leafy or hairy gray-green growth that you often see growing on the bark of trees and shrubs. You also see lichens growing on old figurines and old wooden fences.

Lichens are a symbiotic organism composed of an alga and a fungus. The alga in the lichen photosynthesizes and provides the food that the organism needs through the energy of the sun. The fungus provides the body of the organism.

They are not parasites or pathogens. They don’t attack or damage plants. But oftentimes, you see lichen growing vigorously on plants that appear sick or of low vigor. This is simply because a plant in low vigor typically loses its foliage and allows more light to penetrate its canopy. This gives the sun-loving lichen an advantage. They are not causing the problem they are simply taking advantage of the situation.

Lichens are not parasites nor pathogens. They can be an indication of a plant's failure to thrive.

Cottony Cushion Scale

This insect often appears in clusters at the tips of trees and shrubs. Cottony cushion scale is a strange-looking white insect that can infest many different types of plants but are often seen on citrus, maples, pittosporums and magnolia.

The mature females have bright orange-red, yellow, or brown bodies. The most conspicuous feature is the large fluted egg sac, which will frequently be two times longer than the body. The egg sac contains about 1000 eggs.

Like other scales, cottony cushion scale decreases the vitality of its host by sucking sap from the leaves, twigs, branches, and trunk. Feeding can result in defoliation and dieback of twigs and small branches when infestations are extremely heavy. Like other soft scales, cottony cushion scale excretes honeydew, which is usually accompanied by blackish, sooty mold growth and ants.

Horticultural oil kills all stages of scales that are present, and often provides good control. Oil products may be used on tolerant plants during either the growing or dormant seasons, depending on the product. Refer to the product label for guidelines on plant sensitivity and temperature limitations.

Cottony cushion scales are most commonly found on Citrus and Pittosporum

Galls

Galls occur on a wide variety of plants. These growths may be the result of fungi, bacteria, nematodes or mites, but insects are the prime cause. These growths are called galls because they contain large amounts of tannin, a substance which has a very bitter taste. Long ago, they were known as “gallnuts” because they tasted as bitter as gall.

Galls are found most commonly on the stems and leaves, but also occur on trunks. They occur in almost every conceivable form and color, and their shapes range from spheres to tubes. The surface may be smooth, hairy or covered with spines.

Galls seem to cause a lot of concern to the general public. Generally they do not seriously harm the plant. Most ornamental plants and trees are not apparently injured even by relatively large numbers of galls. After formation, it is impossible to eliminate the galls or the pests with insecticides because they are enclosed and well protected inside the gall.

Galls are abnormal growths

To prevent some of these oddities, remember to keep your plants healthy by performing appropriate cultural practices. For more information, contact your local Extension Office.

Permanent link to this article: http://santarosa.ifas.ufl.edu/blog/2012/01/24/oddities-appear-as-leaves-fall/