University of Maryland Extension

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Excess Water/Edema- Annuals, Bulbs, Groundcovers, Perennials, and Vines

Problems with excess water can result from poorly drained soil, prolonged periods of rain, or overwatering. Excess water reduces oxygen in the soil, which damages fine roots and renders the plant unable to take up water. Plants exposed to excess moisture show the same symptoms as plants under...

Excess Fertilizer/Salt Injury - Annuals, Bulbs, Groundcovers, Perennials, and Vines

Leaf tip browning from excessive fertilizer Salt injury may occur in connection with the application of fertilizers or ice melting products. Damage due to excessive fertilizer or salt application generally appears as marginal leaf browning or leaf scorch. Salts can be toxic to root tissues causing...

Leaf Yellowing/Environmental Stress - Annuals, Bulbs, Groundcovers, Perennials, and Vines

Back to Leaf Yellowing/Browning of Leaves Leaf yellowing is often one of the first symptoms of plant stress. If the stress causing condition is not alleviated, yellow leaves may turn brown. A prolonged period of environmental stress causes overall stunting and poor growth. Noticing the pattern and...

Drought - Annuals, Bulbs, Groundcovers, Perennials, and Vines

Drought Plants wilt when roots are unable to supply sufficient moisture to the stems and leaves. Wilting for short periods of time does not harm plants. Sometimes a plant wilts on a hot day because moisture is evaporating from the leaves faster than the roots can supply it. If there is ample soil...

Leaf Yellowing/Cultural Factors - Annuals, Bulbs, Groundcovers, Perennials, and Vines

Back to Leaf Yellowing/Cultural Factors Impatiens with nutrient deficiency A plant problem that is not caused by a living organism is called "abiotic" injury. Sometimes gardening practices (cultural factors), such as lack of soil preparation, improper planting procedures, planting too late in the...

Air Pollution - Annuals, Bulbs, Groundcovers, Perennials and Vines

Bronzy leaf spots on Rudbeckia foliage Air pollution damage is more common in urban areas but can also occur in suburban and rural areas downwind of industrial sites. The severity of plant damage caused by air pollution varies with the time of day and with environmental conditions such as heat,...

Whiteflies - Houseplants

Adult whiteflies resemble tiny white moths. They are about 1/16th of an inch long, white, with four wings, and may be covered with a powdery white wax. The nymphs or immature whiteflies resemble flat disks on the undersides of the leaves and may or may not be covered with wax. Whiteflies injure...

Thrips - Houseplants

Thrips damaged fuschia flower Thrips are very tiny insects, 1-2mm long. They are slender with narrow wings fringed with hairs. They may be white, yellow, brown or black. The immatures are smaller and usually white or yellow. There are several generations. Some species overwinter in the soil; others...

Spider Mites - Houseplants

Heavy mite infestation with webbing. Spider mites are very tiny plant pests that are related to spiders. They feed only on plants. The colors may be reddish or light green with two dark spots. They are about the size of a period on a page. Spider mites can be a problem all year indoors and have a...

Scale Insects - Houseplants

Fern infested with scale Soft scales are sucking insects that attack a wide variety of plants. Heavy infestations may cause leaf yellowing, stunting, and dieback. Soft scales such as brown soft scale and the hemispherical scale are common pests of houseplants. They appear as raised bumps on leaves...

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