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44 Cards in this Set
- Front
- Back
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What is a plant disease? |
Any condition that interferes with normal plant development. |
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Examples of symptoms include, but not limited to: |
e.g. stunted growth, curled leaves, mottled coloring, spots, wilting, chlorosis, distorted flowers, etc. |
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Parasites are... |
...biotic causes for plant diseases. They are infectious and transmissible. |
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Bacteria is an example of a) a biotic or b) an abiotic cause for a disease? |
A) a biotic |
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Fungi is an example of a) a biotic or b) an abiotic cause for a disease? |
A) a biotic |
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Nematodes are an example of a) a biotic or b) an abiotic cause for a disease? |
a) a biotic |
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Viruses are an example of a) a biotic or b) an abiotic cause for a disease? |
a) a biotic |
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Mycoplasmas are an example of a) a biotic or b) an abiotic cause for a disease? |
a) a biotic |
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Viroids are an example of a) a biotic or b) an abiotic cause for a disease? |
a) a biotic |
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Insects are an example of a) a biotic or b) an abiotic cause for a disease? |
a) a biotic |
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Mineral deficiencies are an example of a) a biotic or b) an abiotic cause for a disease? |
b) an abiotic |
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Water stress is an example of a) a biotic or b) an abiotic cause for a disease? |
b) an abiotic |
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Extreme temperatures are an example of a) a biotic or b) an abiotic cause for a disease? |
b) an abiotic |
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Chemical toxiticy is an example of a) a biotic or b) an abiotic cause for a disease? |
b) an abiotic |
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Mechanical and electrical agents are an example of a) a biotic or b) an abiotic cause for a disease? |
b) an abiotic |
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Abiotic causes for plant disease are... |
...noninfectious and non-transmissible environmental conditions. |
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Abiotic stress: Cold damage... |
...occurs most often in early spring and late fall from frost and bitter winter from low temperatures. |
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Sunscalding is... |
...when bark is damaged by rapid freezing and thawing damaging the cambium. |
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Abiotic stress: Mechanical damage... |
...occurs from storms, excavation, vehicles, lawn mowers and other physically damaging conditions. |
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Environmental scorch can... |
...be a good indicator of an abiotic issue, taking into consideration patterns, timing, weather, species... |
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Winter scorch... |
...affects evergreens in the winter when they do not receive enough water to replace that used in transpiration. Most common in north or west wind exposure. |
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Abiotic stress: Overwatering... |
...damages roots by suffocation, disallowing oxygen. Common in compact soil and poor drainage (standing water), under thick shade, excessive rains, etc. |
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Abiotic stress: Chemical damage... |
...from poorly applied chemical agents, often results in curling of foliage. |
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Abiotic stress: Poor soil conditions... |
...lead to compaction and poor drainage, insufficient nutrients and oxygen deficiencies. |
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Abiotic stress: Thatch... |
...is the organic layer of decomposing matter, predominantly from old stolon and rhizomes from turfgrass. If left alone to thicken, it will prevent water and nutrients from reaching the roots of other plants. |
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Abiotic stress: Chlorosis... |
...is nutrient deficiency. Common examples include deficiency in iron, calcium and molybdenum. |
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Mobile nutrients can move from older to younger leaf tissue, so deficiency occurs... |
...in the oldest leaves of the plant. |
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Immobile nutrients can not relocate, so deficiency occurs... |
...in the youngest leaves of the plant. |
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A sign of iron deficiency is... |
...the leaf tissue is green-yellow while the veins remain dark green. As seen in the pin oak leaves. |
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A sign of calcium deficiency is... |
...brown or black scorching of new leaf tips and fruit. As seen in the picture with the brown hole on the tomato. |
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A sign of nitrogen deficiency is... |
...restricted growth of tops and roots and especially lateral shoots. Plants become spindly with general chlorosis of entire plant to a light green and then a yellowing of older leaves which proceeds toward younger leaves. Older leaves defoliate early. As seen on the yellowing geranium. |
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Iron deficiency is a result of... |
...a high pH soil, whereby iron is likely there but unattainable by the plant. |
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Abiotic stess: Toxicity... |
...from fertilizers, winter salt, herbicides, or animal blight, etc. |
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Plant abnormalities: SGR stands for.... |
..stem girdling roots. |
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Plant abnormalities: girdled roots are... |
...roots that have wrapped around the trunk of the tree or plant and have caused the cambium to be compromised (i.e, the outer layer of phloem is damaged). |
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Plant normalities to be aware of for a plant species include... |
...blossom timing, needle drop, and exotic colors. |
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Abiotic stress: Incorrect planting... |
...is a common cause for the decline of a tree or plant. Cases include: planting too deep or shallow, roots not properly placed causing girdling, burlap or other container left intact, etc. |
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Clues to look for when diagnosing abiotic stress... |
...plant species and variety, planting date and age, weather patterns, watering patterns, soil factors such as drainage and compaction, chemical usage, spatial distribution, and timing. |
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Knowing a plant species can clue you in on.... |
...its normal growth habit, site requirments, susceptibility to disease or insects. |
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Pathogens are... |
...host specific. They do not make "patterns". |
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Consider the site location of the planting... |
...for example, near a sidewalk or fence-line, edge of a garden, along a road, in a low or high area, near an area of pesticide spraying, in an area where animals or insects feed (deer or moths, for example). |
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A symptom is... |
...an expression of a disease by the plant. Example: leaf spots, galls, branch dieback, cankers, wilt, etc. |
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A sign is... |
...visible presence of the pathogen, its structure. Examples: lateral fungi, powdery mildew, etc. |
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Most plant diseases are caused by... |
...parasites as they obtain the plant's nutrients, depriving the plant. |
