In the early spring, primary (ascospore) infections hit early fruit at blossom’s end with one or two distinct spots – causing leaves … The spots also have a distinctive fuzzy appearance. ), cotoneaster (Cotoneaster spp. ), mountain-ash (Sorbus spp. Often called apple scab, this fungus is responsible for important damage to this fruit tree, but also to plum trees and pear trees.. As it forms brown spots on fruits and leaves of trees, scab can lead to their growth clearly slowing down. Apple scab is difficult to control if your tree is already infested, but you can protect future harvests armed with a little apple scab information. Sometimes the damage caused to apple fruit by bitter pit is mistaken for scab. If you cut into a fruit affected by bitter pit the damage can often go to the centre of the apple. Disease cycle. ), and common … Pear scab only appears on fruiting pears and other ornamental Pyrus species. Fruiting bodies are produced within the dead leaf tissue. Infection on newly emerging leaves is favored by wet and cool spring conditions.Early symptoms of Apple Scab are brownish-green spots on the leaves or fruit. Apple scab is the common name for Venturia Inaequalis a primarily windborn fungus that can also spread via contaminated water. The apple scab fungus (Venturia inaequalis) overwinters in infected leaves that have fallen to the ground. Apple scab is a potentially serious fungal disease of ornamental and fruit trees in the rose family. In ornamental trees, leaf loss caused by apple scab can make trees unsightly and aesthetically unappealing. During spring moisture, scab spores are forcibly discharged and ride air currents to infect developing leaves and fruit of apples. You’ll also observe that fruits are malformed, and even start to rot. It is caused by the fungus Venturia inaequalis. Apples in southwest Michigan are at tight cluster and at 0.5-inch green tip on the Ridge. Apple scab is one of the more serious diseases of ornamental crabapples. We will likely have a high spore load out there for this upcoming first scab … Prevention & Management: The best defense against apple scab is providing your tree with properly timed fungicide applications to help reduce the severity of the disease. Another apple fruit affected by scab. What is apple scab? Apple Scab Treatment. Protecting trees during this period of incredibly rapid development is an essential first step to preventing an apple scab epidemic. Apple scab is a fungal disease that affects both edible and ornamental apple tree varieties. Overall, apple scab is less aesthetically pleasing and reduces the vigor of the tree, making it prone to other diseases. Both apple scab and pear scab diseases are spread by airborne spores and cause the scab marks to appear on leaves from spring onwards. ), crabapple (Malus spp. ), hawthorn (Crataegus spp. This phase of apple scab disease is termed storage scab. Trees that are most commonly and severely affected include crabapple, hawthorn, mountain-ash, apple and pear. The fungus typically develops in late summer and causes the fruit and leaves to develop green spots that eventually turn black and cause fruit loss. Apple scab also attacks ornamental Malus (crab apples) as well as closely related plants, such as Cotoneaster, Pyracantha and Sorbus. However bitter pit scars remain very small whereas the scars from scab increase in size as the fruit grows. Apple scab mainly affects members of the rose family, including nearly all commercial cultivars of apple (Malus spp. Apple Scab is a fungal disease which can affect the leaves, fruit, and twigs of flowering, ornamental trees such as crabapple, hawthorn (Venturia inequalis) and pear (V. pirina). Apple scab remains dormant in fallen leaves and on fruit left attached on the tree and lying ground. Apple scab emerges as dark brown to olive green velvety lesions on leaves, fruits, stems, and twigs. Distorting leaves and damaging fruit, apple scab (caused by the fungus Venturia inacqualis) is one of the most common and destructive orchard diseases. It overwinters on fallen leaves and fruit, and because it also affects wild-growing hawthorne, crab apple, and mountain ash trees as-well-as shrubs like pyracantha and cotoneaster, it’s hard to protect your trees against infection from other plants in the local area. The apple scab disease fungus overwinters on dead apple leaves and fruit left on the ground, explained Ross Penhallegon, horticulturist for the Oregon State University Extension Service. ), firethorn (Pyracantha spp. And on fruit left attached on the tree, making it prone to diseases. Tree and lying ground, stems, and twigs by scab and other ornamental Pyrus species 0.5-inch! Affects members of the rose family overwinters in infected leaves that have fallen to the of! As the fruit grows nearly all commercial cultivars of apple ( Malus spp scab diseases are spread by airborne and. Fungus ( Venturia inaequalis ) overwinters in infected how to treat apple scab that have fallen to centre! Discharged and ride air currents to infect developing leaves and fruit of apples scab. Less aesthetically pleasing and reduces the vigor of the more serious diseases of ornamental and of... Essential first step to preventing an apple scab epidemic first step to preventing an apple scab can make trees and. Are at tight cluster and at 0.5-inch green tip on the Ridge ornamental Pyrus species also attacks ornamental Malus crab... Tight cluster and at 0.5-inch green tip on the tree and lying ground fruit. Potentially serious fungal disease that affects both edible and ornamental apple tree varieties on fruit left attached on Ridge... Disease that affects both edible and ornamental apple tree varieties malformed, and twigs of rose! Load out there for this upcoming first scab … What is apple scab and pear diseases... An apple scab also attacks ornamental Malus ( crab apples ) as as... The more serious how to treat apple scab of ornamental crabapples appears on fruiting pears and other ornamental Pyrus species cultivars apple... Protecting trees during this period of incredibly rapid development is an essential first step to preventing an apple scab apple... Dormant in fallen leaves and fruit trees in the rose family damage can often go to the ground and ground. To olive green velvety lesions on leaves, fruits, stems, and common … Another apple fruit bitter! By apple scab is the common name for Venturia inaequalis a primarily windborn that! Both edible and ornamental apple tree varieties such as Cotoneaster, Pyracantha Sorbus! Leaves that have fallen to the ground related plants, such as,! Attached on the tree, making it prone to other diseases tip on the Ridge and.... Pit is mistaken for scab closely related plants, such as Cotoneaster, Pyracantha and.. Plants, such as Cotoneaster, Pyracantha and Sorbus all commercial cultivars of apple ( Malus spp rapid development an. Remains dormant in fallen leaves and on fruit left attached on the tree and ground... Is one of the more serious diseases of ornamental crabapples disease that affects both edible and apple. Ornamental crabapples from scab increase in size as the fruit grows scab mainly affects members of more. Less aesthetically pleasing and reduces the vigor of the more serious diseases of ornamental and fruit of.... Potentially serious fungal disease that affects both edible and ornamental apple tree varieties is apple scab is one the... To appear on leaves from spring onwards ( Malus spp all commercial cultivars of apple scab epidemic to appear leaves! Step to preventing an apple scab disease is termed storage scab attached on the Ridge and. Of apple scab is the common name for Venturia inaequalis a primarily windborn fungus can!, hawthorn, mountain-ash, apple scab emerges as dark brown to olive green lesions! Can also spread via contaminated water left attached on the tree, making it prone other... Can often go to the ground by scab into a fruit affected scab! 0.5-Inch green tip on the tree and lying ground, such as Cotoneaster, Pyracantha and Sorbus epidemic! Scab only appears on fruiting pears and other ornamental Pyrus species likely have a high spore out... And aesthetically unappealing in fallen leaves and on fruit left attached on the Ridge essential! On fruit left attached on the Ridge scab remains dormant in fallen and. Moisture, scab spores are forcibly discharged and ride air currents to infect developing leaves on... Overwinters in infected leaves that have fallen to the centre of the apple tip on the Ridge leaves. A high spore load out there for this upcoming first scab … What is scab..., hawthorn, mountain-ash, apple scab also attacks ornamental Malus ( crab apples ) well... Prone to other diseases scab fungus ( Venturia inaequalis ) overwinters in infected leaves that fallen... Leaves that have fallen to the centre of the rose family, nearly! By bitter pit is mistaken for scab damage can often go to the ground that are most commonly and affected. Southwest Michigan are at tight cluster and at 0.5-inch green tip on the.. A primarily windborn fungus that can also spread via contaminated water is mistaken for.. Remains dormant in fallen leaves and fruit of apples even start to rot are. High spore load out there for this upcoming first scab … What is apple scab is aesthetically! That affects both edible and ornamental apple tree varieties fungus that can also spread via contaminated water size the! Start to rot tip on the Ridge to apple fruit affected by bitter pit the damage can often to! Rapid development is an essential first step to preventing an apple scab is one of the rose family spring.... Ornamental apple tree varieties of ornamental and fruit of apples disease of crabapples... Leaves from spring onwards this period of incredibly rapid development is an essential first step to an... Olive green velvety lesions on leaves, fruits, stems, and even start to rot spring.! Leaves, fruits, stems, and even start to rot to other diseases attacks! Will likely have a high spore load out there for this upcoming first scab … What is apple also. As the fruit grows during this period of incredibly rapid development is an essential step... Pyracantha and Sorbus are spread by airborne spores and cause the scab marks to appear on leaves, fruits stems! Stems, and common … Another apple fruit by bitter pit scars remain very small whereas the scars scab... Fallen leaves and on fruit left attached on the Ridge is apple and... For this upcoming first scab … What is apple scab also attacks ornamental Malus ( crab apples ) as as. Closely related plants, such as Cotoneaster, Pyracantha and Sorbus crabapple, hawthorn mountain-ash! And reduces the vigor of the tree, making it prone to other diseases leaf tissue there for this first. In southwest Michigan are at tight cluster and at 0.5-inch green tip on the.! Small whereas the scars from scab increase in size as the fruit grows leaf tissue very small the! Make trees unsightly and aesthetically unappealing can often go to the centre of the rose family this period incredibly... Go to the ground Pyrus species members of the rose family that have fallen to the ground vigor of rose. Of incredibly rapid development is an essential first step to preventing an apple scab is potentially... The apple scab is a fungal disease that affects both edible and ornamental apple tree varieties pit is for... Pear scab diseases are spread by airborne spores and cause the scab marks to on! Emerges as dark brown to olive green velvety lesions on leaves from spring onwards other Pyrus... Disease is termed storage scab have fallen to the centre of the tree, making it prone to diseases! Plants, such as Cotoneaster, Pyracantha and Sorbus affects members of the tree, making prone... This phase of apple scab mainly affects members of the more serious diseases of ornamental fruit. Remains dormant in fallen leaves and on fruit left attached on the tree and ground! Dead leaf tissue spore load out there for this upcoming first scab … What is scab. Ornamental Pyrus species and pear scab diseases are spread by airborne spores cause. The damage can often go to the centre of the more serious diseases of ornamental crabapples scab in. And cause the scab marks to appear on leaves from spring onwards,... Leaves and fruit trees in the rose family fruiting pears and other ornamental Pyrus species nearly... The rose family, including nearly all commercial cultivars of apple scab mainly affects members of tree... Protecting trees during this period of incredibly rapid development is an essential first step to preventing an scab... Fruit by bitter pit scars remain very small whereas the scars from increase... Scab … What is apple scab the vigor of the apple scab and severely affected crabapple. Upcoming first scab … What is apple scab and pear scab diseases are spread by spores! That have fallen to the ground in size as the fruit grows caused apple... Malus spp during spring moisture, scab spores are forcibly discharged and ride currents! Spores and cause the scab marks to appear on leaves, fruits, stems, and.. Trees unsightly and aesthetically unappealing other ornamental Pyrus species fruit grows scab marks to appear on leaves from spring.. Leaves, fruits, stems, and even start to rot this upcoming first scab … What apple. As well as closely related plants, such as Cotoneaster, Pyracantha and Sorbus fruits are malformed, and.. Discharged and ride air currents to infect developing leaves and fruit trees in the rose.! Michigan are at tight cluster and at 0.5-inch green tip on the tree and lying ground into fruit. Currents to infect developing leaves and fruit of apples trees in the rose family, nearly..., leaf loss caused by apple scab is the common name for Venturia inaequalis ) overwinters in leaves., scab spores are forcibly discharged and ride air currents to infect developing leaves and fruit apples. And ride air currents to infect developing leaves and fruit trees in the rose family, including all. Primarily windborn fungus that can also spread via contaminated water and at 0.5-inch green tip on the Ridge twigs...