which plants and animals get diseases by microorganisms and how to prevent this
Answers
Answer:
Bacteria and fungi (together with insects) play an important role in natural communities because they help break down material from dead plants into nutrients that benefit living plants. But non-native bacterial, viral and fungal pathogens can kill entire populations of plant species that have no natural resistance.
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Where Do Plant Diseases Come From?
Plant Diseases
Chestnut Blight
Butternut Canker
Dogwood Anthracnose
Dutch Elm Disease
Elm Yellows (Elm Phloem Necrosis)
Beech Bark Disease
Sudden Oak Death
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Where Do Plant Diseases Come From?
Many of the most threatening plant diseases spreading in the U.S. today were brought there on plants or wood products from around the world. (In the same way, some of the most threatening plant diseases spreading in Asia today were brought there from the U.S.!) Ecobit: Why are catastrophic plant diseases usually non-native?
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Plant Diseases
Chestnut Blight
American chestnut was once the dominant tree in mid-Atlantic hardwood forests—comprising as much as 35 percent to 50 percent and sometimes more of the canopy.1 2
Today, there are virtually no mature American chestnuts remaining in these forests.
What killed the chestnuts? A fungus called chestnut blight (Cryphonectria parasitica).
Before the blight, the fast-growing American chestnut provided foliage, fruits, and living wood as food for bears, turkeys, and native insects and many more animals. Its dependable, abundant crops of chestnuts were an important food for Native Americans, and later, European immigrants who incorporated them into Christmas traditions.
It easily survived wildfires and outbreaks of native insects and diseases. Its durable, high quality wood was widely used in construction and carpentry. But since the 1930s, it has all but disappeared. Store-bought chestnuts today come from European stock or hybridized strains.
The chestnut blight fungus was apparently unwittingly brought to the U.S. on highly resistant Japanese and/or Chinese chestnut trees in the late 1800s, and spread undetected for many years throughout the U.S. via the nursery trade.
The fungus enters wounds on the tree and grows in and under the bark, forming cankers on the stems. The tree eventually dies back to the roots. Chestnut blight is easily spread on the feet of any insect or other animal that walks across the cankers.3
In some cases the roots continue to send up sprouts, which succumb to the fungus before they are old enough to reproduce. After the loss of American chestnut, drought-tolerant oaks appear to have increased where American chestnuts once grew.4 5 Oaks can host the fungus without getting sick, so there is a continual source of the fungus to infect new chestnut sprouts.
Scientists are working to develop blight controls and to breed a resistant strain of American chestnut, with the goal of restoring the majestic chestnut to eastern forests of North America.
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Butternut Canker
Butternut canker (Sirococcus clavigignenti-juglandacearum) is currently eliminating entire populations of butternut trees (also called white walnut) throughout its range in the United States.
The origin of the fungus is unknown, but it was probably introduced from outside the United States in the mid 1900s.6
Infected trees typically have dead branches or a dying top. Cracked, sunken, discolored bark may ooze black inky fluid in spring, or appear sooty with whitish margins in summer. Where the bark has come loose, dark oval stains may be visible on the wood beneath.7 Controls currently do not exist.8
Rain splash and wind (and possibly insects and other animals) spread the spores to other butternut trees and to black walnut. However, black walnut, which is related to butternut and overlaps part of its geographic range, appears to be resistant to the fungus.
Butternut has prized edible nuts. Never a very common tree, butternut is becoming hard to find. Since some trees in the U.S. seem to display resistance, there is hope that the species can outlive the disease
Dogwood Anthracnose
Dogwood anthracnose (Discula destructive) is a fungus that appeared simultaneously on both coasts of the United States in the mid-1970s, origin unknown.
It forms purple-rimmed tan blotches on the leaves, and cankers on the twigs of our beautiful flowering dogwood. Lower branches often die first, and the trunk may produce a lot of sprouting as a last-ditch (but ill-fated) attempt to survive.9