{"id":27103,"date":"2021-08-05T07:34:28","date_gmt":"2021-08-05T11:34:28","guid":{"rendered":"https:\/\/extension.umaine.edu\/publications\/?page_id=27103"},"modified":"2024-05-24T09:44:08","modified_gmt":"2024-05-24T13:44:08","slug":"5059e","status":"publish","type":"page","link":"https:\/\/extension.umaine.edu\/publications\/5059e\/","title":{"rendered":"Bulletin #5059, Too Much Water or Not Enough Light? Irregular Growth Commonly Seen on Plants Grown Indoors"},"content":{"rendered":"\n

Developed by Dr. Alicyn Smart, Assistant Extension Professor & Extension Plant Pathologist, University of Maine Cooperative Extension, and Nick Goltz<\/span>, Graduate Student, University of Florida.<\/em><\/p>\n\n\n\n

For information about UMaine Extension programs and resources, visit extension.umaine.edu<\/a>.<\/strong>
Find more of our publications and books at extension.umaine.edu\/publications\/<\/a>.<\/strong><\/p>\n\n\n\n

Edema (Oedema)<\/strong><\/h2>\n\n\n\n

Abiotic Disorder: <\/strong>Swollen growths or corky lesions on leaves and\/or stems.<\/p>\n\n\n\n

Introduction<\/h3>\n\n\n\n

Edema is a symptom of excessive watering. It is most common with houseplants, plants grown in greenhouses or under plastic, and plants grown too close to one another. With plants grown outdoors, it is usually seen following cloudy, humid, or low-light conditions when the plant is not able to transpire quickly enough to relieve itself of excess moisture.<\/p>\n\n\n\n

Symptoms & Signs<\/h3>\n\n\n
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\"Leaf
Photo: Bruce Watt<\/span>Fig. 1. Corky lesions on a geranium leaf caused by edema.<\/figcaption><\/figure><\/div>\n\n\n

Edema usually manifests as raised bumps on stems or the lower side of leaves. These bumps are initially clear or greenish but will become tan and corky over time. Sometimes (particularly with succulents), the corky areas will not be raised and will appear as spotty lesions instead. See figure 1.<\/p>\n\n\n\n

To learn more about edema, see University of Maine Cooperative Extension Bulletin #5060, Edema<\/a>.<\/p>\n\n\n\n

Etiolation<\/h2>\n\n\n\n

Abiotic Disorder:<\/strong> Long, spindly plant with pale leaves.<\/p>\n\n\n\n

Introduction<\/h3>\n\n\n\n

Etiolation is very common among houseplants and plants grown outdoors in constant or near-constant shade. Genetics and overwatering do not appear to have an impact on etiolation.<\/p>\n\n\n\n

Symptoms & Signs<\/h3>\n\n\n\n

Etiolation is the term used to describe plants with insufficient chlorophyll, elongated, spindly stems and pale leaves due to being grown in low-light conditions.<\/p>\n\n\n\n

Intumescence<\/h2>\n\n\n\n

Abiotic Disorder:<\/strong> Swollen growths on surfaces (especially veins) of leaves.<\/p>\n\n\n\n

Introduction<\/h3>\n\n\n\n

Unlike edema, intumescence does not appear to be caused solely by excess watering. Researchers have not arrived at a consensus on what causes intumescence development, but it is likely caused by a combination of excess water, not enough ultraviolet (UV) light and a genetic predisposition.<\/p>\n\n\n\n

Symptoms & Signs<\/h3>\n\n\n
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\"A
Photo: Dr. Cheryl A. Smith.<\/span>Figure 2. Intumescence symptoms along veins of a tomato leaf. Photo: Dr. Cheryl A. Smith.<\/figcaption><\/figure><\/div>\n\n\n

Symptoms of intumescence are similar to those of edema and the two terms are sometimes used interchangeably. The raised bumps that characterize intumescence are sometimes corky and are found on the leaf surface and along leaf veins. See figure 2. Intumescence is most common on solanaceous crops (tomato, sweet potato) grown in greenhouses.<\/p>\n\n\n\n

Neoplasm<\/h2>\n\n\n\n

Abiotic Disorder:<\/strong> Improper planting or natural occurrence overtime<\/p>\n\n\n\n

Introduction<\/h3>\n\n\n\n

While there is not much definitive evidence on the exact causes of neoplasm growth, they are likely caused by lack of ultraviolet (UV) light and a genetic predisposition. Excess watering does not seem to increase the likelihood of neoplasm formation, but they are more commonly found during cloudy, humid and low-light conditions.<\/p>\n\n\n\n

Symptoms & Signs<\/h3>\n\n\n\n

Like intumescence, neoplasms are also swollen growths observed on a plant, usually on fruit or new growth. See figure 3 and Figure 4.<\/p>\n\n\n\n

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<\/p><\/div>\n\n\n\n

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\"Pea
Fig. 3. Neoplasm development on the pods of pea plants grown closely together under a high tunnel. Saprophytic fungi are growing on the neoplasms on the right. Photo: Nathalie Forster <\/figcaption><\/figure>\n\n\n\n
\"Pea
Fig. 4. Neoplasm development on the pods of pea plants. Photo: Nathalie Forster<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

Management<\/h3>\n\n\n\n