|
| APPLE SCAB |
Description
Apple Scab is most severe where moisture of humidity is high, and temperatures are cool to moderate; typically in the spring to early summer. Olive green spots or lesions first appear on the leaves soon after bud break. The lesions begin on the underside of the leaf, but are more conspicuous on the upper surface. As the fungus progresses the entire leaf appears a dirty olive in color and falls to the ground.
Scab lesions affecting the fruit begin on the sepals (green portions) of the flower bud, but are difficult to detect because they are gray and indistinct. Once present on the fruit itself, the lesions are round, velvety and olive green tuning darker, scabby and often cracked. Twigs and blossoms may also be attacked, but this is very uncommon.
Apple scab fungus had two basic cycles, a primary cycle and a secondary cycle. The overwintering fungus is present on the previous years fruit and leaf matter beneath the tree. Fruiting structures form over the winter months, and the spores mature in the spring.
Spring rains swell the spore sacs and the internal pressure releases ascropspores a fraction of an inch above ground. Wind and air currents transport spores to susceptible plant tissue. Several hours of moisture is required for the spores to infect plant parts. Cool weather slows this process while warm weather accelerates infection. The ideal temperature range in 53 degrees to 58 degrees F.
A tree that hasnt been properly maintained, and has a crown that is too thick, increases the chances of contracting Apple Scab. A thick crown shades the sun blocks the winds that help prevent the prolonged moist conditions favorable to the spread of the fungus. The Apple Scab fungus itself dose not kill the tree, but repeated infection dose stress the tree and make it much more susceptible to other factors such as drought, insects, and other pathogens that can invade and kill the tree.
Apple scab infection results in fruit loss, reduction in fruit quality, and leaf loss. Even when fruit is not an important consideration, the leaf loss results in a very unappealing tree in the landscape. Many susceptible trees are severely defoliated by mid summer.
Apple Scab is most severe where moisture of humidity is high, and temperatures are cool to moderate; typically in the spring to early summer. Olive green spots or lesions first appear on the leaves soon after bud break. The lesions begin on the underside of the leaf, but are more conspicuous on the upper surface. As the fungus progresses the entire leaf appears a dirty olive in color and falls to the ground.
Scab lesions affecting the fruit begin on the sepals (green portions) of the flower bud, but are difficult to detect because they are gray and indistinct. Once present on the fruit itself, the lesions are round, velvety and olive green tuning darker, scabby and often cracked. Twigs and blossoms may also be attacked, but this is very uncommon.
Apple scab fungus had two basic cycles, a primary cycle and a secondary cycle. The overwintering fungus is present on the previous years fruit and leaf matter beneath the tree. Fruiting structures form over the winter months, and the spores mature in the spring.
Spring rains swell the spore sacs and the internal pressure releases ascropspores a fraction of an inch above ground. Wind and air currents transport spores to susceptible plant tissue. Several hours of moisture is required for the spores to infect plant parts. Cool weather slows this process while warm weather accelerates infection. The ideal temperature range in 53 degrees to 58 degrees F.
A tree that hasnt been properly maintained, and has a crown that is too thick, increases the chances of contracting Apple Scab. A thick crown shades the sun blocks the winds that help prevent the prolonged moist conditions favorable to the spread of the fungus. The Apple Scab fungus itself dose not kill the tree, but repeated infection dose stress the tree and make it much more susceptible to other factors such as drought, insects, and other pathogens that can invade and kill the tree.
Apple scab infection results in fruit loss, reduction in fruit quality, and leaf loss. Even when fruit is not an important consideration, the leaf loss results in a very unappealing tree in the landscape. Many susceptible trees are severely defoliated by mid summer.
Apple Scab is most severe where moisture of humidity is high, and temperatures are cool to moderate; typically in the spring to early summer. Olive green spots or lesions first appear on the leaves soon after bud break. The lesions begin on the underside of the leaf, but are more conspicuous on the upper surface. As the fungus progresses the entire leaf appears a dirty olive in color and falls to the ground.
Scab lesions affecting the fruit begin on the sepals (green portions) of the flower bud, but are difficult to detect because they are gray and indistinct. Once present on the fruit itself, the lesions are round, velvety and olive green tuning darker, scabby and often cracked. Twigs and blossoms may also be attacked, but this is very uncommon.
Apple scab fungus had two basic cycles, a primary cycle and a secondary cycle. The overwintering fungus is present on the previous years fruit and leaf matter beneath the tree. Fruiting structures form over the winter months, and the spores mature in the spring.
Spring rains swell the spore sacs and the internal pressure releases ascropspores a fraction of an inch above ground. Wind and air currents transport spores to susceptible plant tissue. Several hours of moisture is required for the spores to infect plant parts. Cool weather slows this process while warm weather accelerates infection. The ideal temperature range in 53 degrees to 58 degrees F.
A tree that hasnt been properly maintained, and has a crown that is too thick, increases the chances of contracting Apple Scab. A thick crown shades the sun blocks the winds that help prevent the prolonged moist conditions favorable to the spread of the fungus. The Apple Scab fungus itself dose not kill the tree, but repeated infection dose stress the tree and make it much more susceptible to other factors such as drought, insects, and other pathogens that can invade and kill the tree.
Apple scab infection results in fruit loss, reduction in fruit quality, and leaf loss. Even when fruit is not an important consideration, the leaf loss results in a very unappealing tree in the landscape. Many susceptible trees are severely defoliated by mid summer.
Apple Scab is most severe where moisture of humidity is high, and temperatures are cool to moderate; typically in the spring to early summer. Olive green spots or lesions first appear on the leaves soon after bud break. The lesions begin on the underside of the leaf, but are more conspicuous on the upper surface. As the fungus progresses the entire leaf appears a dirty olive in color and falls to the ground.
Scab lesions affecting the fruit begin on the sepals (green portions) of the flower bud, but are difficult to detect because they are gray and indistinct. Once present on the fruit itself, the lesions are round, velvety and olive green tuning darker, scabby and often cracked. Twigs and blossoms may also be attacked, but this is very uncommon.
Apple scab fungus had two basic cycles, a primary cycle and a secondary cycle. The overwintering fungus is present on the previous years fruit and leaf matter beneath the tree. Fruiting structures form over the winter months, and the spores mature in the spring.
Spring rains swell the spore sacs and the internal pressure releases ascropspores a fraction of an inch above ground. Wind and air currents transport spores to susceptible plant tissue. Several hours of moisture is required for the spores to infect plant parts. Cool weather slows this process while warm weather accelerates infection. The ideal temperature range in 53 degrees to 58 degrees F.
A tree that hasnt been properly maintained, and has a crown that is too thick, increases the chances of contracting Apple Scab. A thick crown shades the sun blocks the winds that help prevent the prolonged moist conditions favorable to the spread of the fungus. The Apple Scab fungus itself dose not kill the tree, but repeated infection dose stress the tree and make it much more susceptible to other factors such as drought, insects, and other pathogens that can invade and kill the tree.
Apple scab infection results in fruit loss, reduction in fruit quality, and leaf loss. Even when fruit is not an important consideration, the leaf loss results in a very unappealing tree in the landscape. Many susceptible trees are severely defoliated by mid summer.
Apple Scab is most severe where moisture of humidity is high, and temperatures are cool to moderate; typically in the spring to early summer. Olive green spots or lesions first appear on the leaves soon after bud break. The lesions begin on the underside of the leaf, but are more conspicuous on the upper surface. As the fungus progresses the entire leaf appears a dirty olive in color and falls to the ground.
Scab lesions affecting the fruit begin on the sepals (green portions) of the flower bud, but are difficult to detect because they are gray and indistinct. Once present on the fruit itself, the lesions are round, velvety and olive green tuning darker, scabby and often cracked. Twigs and blossoms may also be attacked, but this is very uncommon.
Apple scab fungus had two basic cycles, a primary cycle and a secondary cycle. The overwintering fungus is present on the previous years fruit and leaf matter beneath the tree. Fruiting structures form over the winter months, and the spores mature in the spring.
Spring rains swell the spore sacs and the internal pressure releases ascropspores a fraction of an inch above ground. Wind and air currents transport spores to susceptible plant tissue. Several hours of moisture is required for the spores to infect plant parts. Cool weather slows this process while warm weather accelerates infection. The ideal temperature range in 53 degrees to 58 degrees F.
A tree that hasnt been properly maintained, and has a crown that is too thick, increases the chances of contracting Apple Scab. A thick crown shades the sun blocks the winds that help prevent the prolonged moist conditions favorable to the spread of the fungus. The Apple Scab fungus itself dose not kill the tree, but repeated infection dose stress the tree and make it much more susceptible to other factors such as drought, insects, and other pathogens that can invade and kill the tree.
Apple scab infection results in fruit loss, reduction in fruit quality, and leaf loss. Even when fruit is not an important consideration, the leaf loss results in a very unappealing tree in the landscape. Many susceptible trees are severely defoliated by mid summer.
Apple Scab is most severe where moisture of humidity is high, and temperatures are cool to moderate; typically in the spring to early summer. Olive green spots or lesions first appear on the leaves soon after bud break. The lesions begin on the underside of the leaf, but are more conspicuous on the upper surface. As the fungus progresses the entire leaf appears a dirty olive in color and falls to the ground.
Scab lesions affecting the fruit begin on the sepals (green portions) of the flower bud, but are difficult to detect because they are gray and indistinct. Once present on the fruit itself, the lesions are round, velvety and olive green tuning darker, scabby and often cracked. Twigs and blossoms may also be attacked, but this is very uncommon.
Apple scab fungus had two basic cycles, a primary cycle and a secondary cycle. The overwintering fungus is present on the previous years fruit and leaf matter beneath the tree. Fruiting structures form over the winter months, and the spores mature in the spring.
Spring rains swell the spore sacs and the internal pressure releases ascropspores a fraction of an inch above ground. Wind and air currents transport spores to susceptible plant tissue. Several hours of moisture is required for the spores to infect plant parts. Cool weather slows this process while warm weather accelerates infection. The ideal temperature range in 53 degrees to 58 degrees F.
A tree that hasnt been properly maintained, and has a crown that is too thick, increases the chances of contracting Apple Scab. A thick crown shades the sun blocks the winds that help prevent the prolonged moist conditions favorable to the spread of the fungus. The Apple Scab fungus itself dose not kill the tree, but repeated infection dose stress the tree and make it much more susceptible to other factors such as drought, insects, and other pathogens that can invade and kill the tree.
Apple scab infection results in fruit loss, reduction in fruit quality, and leaf loss. Even when fruit is not an important consideration, the leaf loss results in a very unappealing tree in the landscape. Many susceptible trees are severely defoliated by mid summer. |
|
How
to Treat
TO CONTROL APPLE SCAB FUNGUS, several steps must be taken. First, all leaf and fruit matter should be removed from under the tree before winter sets in. since only 1% of the fruiting spores under the tree are necessary to produce severe infection, this alone in not enough to protect your tree. Second, two or more preventative fungicide sprays are required to achieve control. In the event of prolonged periods of cool and damp weather, additional applications maybe necessary. The timing of these applications is determined by weather patterns.
As is the case with any stressed tree, a fertilization program is strongly recommended to keep energy reserves up and improve the overall vigor of the tree. Thinning the crown of your Crabs and Apples is recommended to reduce shading which allows dampness to linger. Resistant varieties of Crabs and Apples should also be considered in any future landscape plans.
Apple Scab is often confused with natural summer leaf drop in fruit trees such as Apple, Crabs, Cherries, and Plums. Most fruit tree species produce an overabundance if leaves during the spring, and shed those extra leaves in June or July. The leaves which are shed are yellow, or pale, orange-pink in color. They are usually located on the underside of the plant, or within the canopy of the tree itself. The plant naturally sheds those leaves which receive the least amount of sunlight, while making optimal use of those leaves which receive the most sun.
Another distinguishing characteristic is the lack of olive green lesions on the shed leaves. This summer leaf drop is a natural process, and process, and poses no threat to your valuable tree. |
|
