® EXTENSION Know how. Know now. EC1270 Common Signs and Symptoms of Unhealthy Plants Amy D. Timmerman, Associate Extension Educator James A. Kalisch, Entomology Extension Associate Kevin A. Korus, Assistant Extension Educator Stephen M. Vantassel, Wildlife Program Coordinator Ivy Orellana, Extension Assistant Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture. University of Nebraska–Lincoln Extension educational programs abide with the nondiscrimination policies of the University of Nebraska–Lincoln and the United States Department of Agriculture. © 2014, The Board of Regents of the University of Nebraska on behalf of the University of Nebraska–Lincoln Extension. All rights reserved. Common Signs and Symptoms of Unhealthy Plants Amy D. Timmerman, Associate Extension Educator James A. Kalisch, Entomology Extension Associate Kevin A. Korus, Assistant Extension Educator Stephen M. Vantassel, Wildlife Program Coordinator Ivy Orellana, Extension Assistant Plant symptoms may be caused Along with the type of a plant part may be a sign of a by biotic (living organisms) or symptoms being expressed by the saprophyte (a nonparasitic fungus abiotic (nonliving) agents. Many plant, it can be important to observe growing on nutrients and organic abiotic factors can cause symptoms the colors that are associated with matter on the plant surface) and thus in a landscape or garden. These those symptoms. When making a might not be related to the actual factors include nutrient imbalances, diagnosis, description of color can be cause of disease. drought or excess soil moisture, a useful tool, such as the yellowing limited light, reduced oxygen of leaves associated with chlorosis. When working on diagnosing a availability, air pollution, soil Being able to correctly define or plant problem, remember to examine pH extremes, pesticide toxicity, describe the abnormal appearance the surrounding area to observe compaction, cultural practices, of an affected plant strengthens the the presence of any patterns. Biotic mechanical damage, and low or high ability of a gardener or landscape problems typically have an uneven temperatures. manager to correctly identify the margin between the affected tissue cause. and healthy tissue, are randomly Insects, mites, fungi, bacteria, distributed, affect one plant species nematodes, viruses, parasitic higher In addition to the symptoms or related plant species, and progress plants, protozoa, and grazing or observed on the plant, there also may to related plants nearby. An example browsing animals are all examples of be signs of the problem. Signs are of a biotic problem pattern is the biotic agents that damage plants. visible, direct evidence of the causal movement of black spot from one agent on the affected plant part. rose to another. Abiotic problems Symptoms of an unhealthy plant Signs may include tracks, bite marks, typically have distinct margins are expressed as visible changes chemical residue, honeydew, egg between healthy and affected plant in its appearance. When whole- masses, frass (insect fecal excrement), tissue, have a uniform pattern to the plant symptoms such as wilting are fungal mycelium and spores, or distribution, affect multiple species, observed, 100 percent of the plant bacterial ooze. and do not spread to related plants. has visible symptoms. Plant part An example of an abiotic problem symptoms can affect any portion of Signs can be very useful when pattern is the uniform browning the plant, including flowers, fruits, making a diagnosis but must be of turf resulting from a plugged or leaves, stems, or roots. interpreted with care. For example, leaking sprinkler head. fungal growth on the surface of © The Board of Regents of the University of Nebraska. All rights reserved. 3 Whole Plant Symptoms Damping-off: Seedling damage near or below the soil line that causes emergence failure or death shortly after emergence. Damping-off of a corn plant infected with a root pathogen. Groove: The linear depression in the soil or turf caused by animals repeatedly walking or foraging on the same strip of land. Groove 1 to 2 inches wide caused by voles foraging. Stunting: Hindering of normal growth or overall development of a plant. Chrysanthemum stunted due to chrysanthemum stunt viroid infection. (Photo courtesy of J. Dunez, Bugwood.org) 4 © The Board of Regents of the University of Nebraska. All rights reserved. Wilt: Loss of rigidity and drooping of plant parts. b Whole zucchini plant wilting due to squash vine borer. Plant Part Symptoms Bleaching: White coloration on leaves. Leaf Bleaching of lilac leaves. Blight: General and rapid death of a plant part. Leaf, Flower, Stem Blighted tomato stem and leaves caused by late blight infection. © The Board of Regents of the University of Nebraska. All rights reserved. 5 Plant Symptom Part(s) Photo Blotch: Lesions with irregular margins, Leaf, Stem, tunneling by leafminers. Fruit Apple leaf with blotches. Bottle-brushing: Major roots of a plant with Roots numerous short, stubby secondary roots. Bottle-brush symptom on corn roots. Bronzing: Bronze discoloration of leaves. Leaf Overall browning and/or yellowing of bean leaves, caused by twospotted spider mite feeding. Canker (stem, root): A necrotic, often sunken, Stem, Root lesion on the stem of a plant. Canker on dogwood. 6 © The Board of Regents of the University of Nebraska. All rights reserved. Plant Symptom Part(s) Photo Catfacing: A deformity of fruit induced by Fruit initial scars caused by insect punctures or plant disease lesions, followed by continued fruit growth. Catfacing on apple, caused by apple maggot. Chlorosis: Spotty, striped, or mottled yellowing Leaf, Stem of normally green tissue due to chlorophyll destruction or reduced chlorophyll production. Mulberry leaf with chlorosis. Clipping: Animals nibbling or biting the end of Stem, a stem or branch into short sections. Branch Clipping by rabbit. Crooking: Growing stems curl or bend over to Stem, form a hook. Branch, Shoot Curling of candles (new growth) caused by European pine shoot moth larvae. (Photo courtesy of David McComb, USDA Forest Service) © The Board of Regents of the University of Nebraska. All rights reserved. 7 Plant Symptom Part(s) Photo Dieback: Progressive death of shoots, branches, Leaf, Stem, and/or roots, generally starting at the tip and Root gradually moving down the plant. Dieback on tips of pine branches caused by pine tip moth larvae. Erineum: Shallow, dense, granular growth on Leaf leaf blades. Can be green, pink, or red. Erineum on underside of viburnum leaves, caused by eriophyid mites. Flagging: Limited, non-progressive death of Leaf leaves or branch tips caused by rather sudden injury. Dieback on tips of red oak caused by a flatheaded borer, the oak twig girdler. Flecking: Small, pale, irregular leaf speckles that Leaf can coalesce to form necrotic spots. Ash plant bug feeding damage on green ash. 8 © The Board of Regents of the University of Nebraska. All rights reserved. Plant Symptom Part(s) Photo Gall: An abnormal growth or swelling of plant Leaf, Stem, tissue. Flower, Fruit, Root Oak bullet gall, caused by a gall wasp. Gnawing: Animal biting or chewing. Stem, Fruit, Root Gnawing caused by rabbit on branch. Hole: Removal of plant tissue caused by biotic Leaf, Stem agents such as insect feeding, or openings caused by abiotic agents such as hail. Holes chewed in pea leaf by a cabbage looper. © The Board of Regents of the University of Nebraska. All rights reserved. 9 Plant Symptom Part(s) Photo Lace-like injury: Numerous small holes Leaf between leaf veins caused by chewing insects, thus creating an intricate lace-like appearance. Bean leaf beetle lace-like injury. Leaf mining: Fine, serpentine, or looping Leaf patterns caused by insect feeding between the upper and lower epidermal layers. Leafminer damage to columbine leaf. Lesion: Localized area of necrotic tissue. Leaf, Stem, Flower, Fruit, Root Lesion on potato leaves infected with late blight. (Photo courtesy of Gerald Holmes, Valent USA Corporation, Bugwood.org) 10 © The Board of Regents of the University of Nebraska. All rights reserved. Plant Symptom Part(s) Photo Mildew: Fungal disease of plants in which the Leaf, Stem, mycelium and/or spores of the pathogen form a Flower fuzzy growth on plant tissues. Powdery mildew on gerbera daisy. Mosaic: Diffuse light and dark green or yellow Leaf, Stem, and green mottling of tissue. Flower Mosaic on hosta from Hosta Virus X infection. Necrosis: Localized death of tissue. Leaf, Stem, Flower, Fruit, Root Necrosis of viburnum root. Notch: Margins of leaves with generally Leaf uniform, chewed out notches. Large, circular notches in rose leaves caused by leafcutter bees. © The Board of Regents of the University of Nebraska. All rights reserved. 11 Plant Symptom Part(s) Photo Pruning: The complete removal or Stem, Twig, disconnection of a plant stem or branch. Branch Pruned twigs that have been cleanly cut by a roundheaded borer beetle. Pustule: Small blister-like elevation of Leaf, Stem, the epidermal layer created as spores grow Flower, Fruit underneath and push outward. Soybean rust pustules, highly magnified. Ringspot: Circular, colored area surrounding a Leaf, Stem, normal colored area, usually as a result of a virus Fruit infection. Ringspot on tomato fruit infected with tomato ringspot virus. 12 © The Board of Regents of the University of Nebraska. All rights reserved. Plant Symptom Part(s) Photo Rot: Softening, discoloration, or disintegration Stem, of succulent plant tissue. Flower, Fruit, Root Geranium stem rotting from blackleg infection. Rugosity or Puckering: The rough, wrinkled Leaf appearance of a leaf that failed to fully extend during leaf expansion. Red oaks with puckered leaves due to thrips feeding. Sand-blasting: Random trails of fine, whitish Leaf or silvery speckling caused by insect mouthparts superficially scraping plant leaf surfaces. Onion thrips feeding damage on green tops of onions. © The Board of Regents of the University of Nebraska. All rights reserved.