Scab is caused by a fungus that infects both leaves and fruit. First, choose a resistant cultivar when planting a new crabapple tree. She is a food and travel writer who also specializes in gaming, satellites, RV repair, gardening, finances and electronics. Many diseases commonly occur on apple (Malus domestica) and flowering crabapple trees (Malus species), which can reduce flowering and the quality of the fruit in South Carolina. Some native species may be more resilient to this disease as compared to others, however once infected on the leaves it can spread to the fruit as well as lead to leaf defoliation. Prevention & Treatment: Remove all infection sources, such as blighted twigs and cankers, before growth starts in the spring. They are particularly devastating in South Carolina and can result in 100-percent crop loss. and mountain ash (Sorbus spp.). It’s most common in areas with a large number of red cedars and/or junipers nearby (many grow wild in our region). Join our mailing list to receive the latest updates from HGIC. These two diseases caused by the fungi Schizothyrium pomi and Gloeodes pomigena, respectively, infect the surface of the fruit and are mainly cosmetic problems. Remove the galls from juniper branches during dormancy. Heavily infected leaves drop from the tree. Flyspeck (small dots) and sooty blotch on apple fruit.Clemson University – USDA Cooperative Extension Slide Series, www.ipmimages.org. If the flowering crab tree in your garden or home landscape is losing its leaves prematurely, it may be infected with a harmful fungal disease such as apple scab or cedar apple rust. Most of the diseases can be avoided, prevented or maintained. Apple scab is a disease caused by the fungus, Venturia inaequalis, which spreads by airborne spores and survives the winter on fallen leaves. of the leaves turned brown and the tree looked terrible. Growing crabapple trees in the home landscape is much easier if you choose disease- and insect-resistant varieties. Control the powdery mildew disease by providing ample sunlight and proper spacing to your tree when planting. In the home garden, planting disease resistant apple varieties, such as ‘Liberty’ and ‘Freedom’, is strongly recommended. The fungus, Physalospora obtusa (Botryosphaeia obtusa), causes black rot. Crabapple: copper fungicides are also used to treat crabapple trees. ), pear (Pyrus communis) and Cotoneaster (Cotoneaster spp. ‘Freedom’ – Fruit is predominately red, with bright red stripes on a yellow background. Rake and remove leaves to reduce early spring infection sources. Follow all directions, precautions and restrictions that are listed. Cause: Junipers serve as host plants for the fungus where it grows as a gall on the branches. The dots are slightly elevated and occur in groups of six to 50. Fungicides for crabapple trees are captan, mancozeb or thiophanate-methyl. In general, they are subject to the same diseases and insects that affect commercial apple varieties. The disease develops rapidly in early spring during rainy weather when temperatures are above 60 °F and the tree is in bloom. This disease comes off looking very ornamental or in other words like it will only harm some leaves. Heavily infected leaves turn yellow and fall from the tree. The fungal spores often infect the trees through open wounds in the bark made by borers, or by injury from lawn mowers and other yard maintenance equipment. ).The apple scab fungus has several host-specific strains that can cause disease on one type of plant but not any other. More information is available in HGIC 1007, Crabapple, and HGIC 1350, Apple. If disease is severe enough to warrant chemical control on apple trees, use streptomycin during bloom when temperatures are above 60 °F and rain is possible (wait 50 days to harvest). Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status and is an equal opportunity employer. This disease comes off looking very ornamental or in other words like it will only harm some leaves. Fruits could get darkened corky spots, if the disease is not controlled. Fruit may turn russet-colored and develop poorly. Pruning cuts should be made 12 to 18 inches below any sign of infected tissue. Table 1. Diane Dilov-Schultheis has been writing professionally since 2000. Nancy Doubrava, Former HGIC Horticulture Information Specialist, Clemson UniversityR.W. The disease also can occur on raspberry (Rubus spp. They can be susceptible to a range of pests such as the woolly aphid, diseases and disorders, but in most cases action can be taken to prevent or control the problem. If caught early enough, then the fruit can be treated with a sulphur spray. Make 2 more applications at 3 day intervals during bloom. Elimination of cedars and junipers within a mile of ), crabapple (Malus spp. Avoid planting trees in wet areas or near downspouts. It can be a severe problem wherever these two are grown together, and most ornamental crabapples and apples are susceptible. See: Apple (Malus spp. After a few weeks the spots enlarge and have alternating zones of black and brown. The disease in apples is called Speck rot and Sphaeropsis rot, respectively. Though products are available at gardening stores for homeowners, many gardeners are not inclined to use pesticide applications for home fruit production. Cedar apple rust gall on cedar.Karen Russ, ©2007 HGIC, Clemson Extension, Cedar apple rust gall on cedar in spring, after rain.Joseph O’Brien, USDA Forest Service, www.ipmimages.org. Spring fungicide applications – For trees that are highly susceptible to the apple scab fungus, annual fungicide treatments are the best option. Learn which plants thrive in your Hardiness Zone with our new interactive map! Crabapple diseases are so common many tree owners feel obliged to spray their crabapples with fungicides several times a year just to keep them looking good. Crabapple varieties can vary greatly in their susceptibility to apple scab (Venturai inaequalis). I wouldn’t want the cost of those sprayings, either! The apple scab strain that affects apples and crabapples is the same, which also means that an infected crabapple tree can spread the disease to a nearby apple tree, and vice versa. If disease is severe enough to warrant chemical control, choose one of the following fungicides for use on apples: thiophanate-methyl, a copper fungicide, captan or sulfur. Leaves with many leaf spots turn yellow and fall off early. Pest & Disease Control for Apple Trees. Realize that resistance is relative, and a “resistant” cultivar can still become diseased under some conditions—but it will have fewer disease problems than a … Crabapple trees come in all sizes, shapes and blossom colors. Crabapple Diseases and Pests . Flesh is cream colored, firm, juicy. Apply all chemicals according to directions on the label. Do not overwater or overfertilize your tree and plant it in a location with sufficient soil conditions--not compacted soil or alkaline-rich soil. The bacteria overwinters on or under infected bark and in the early spring begins to ooze out. COVID-19 Extension Updates and Resources ... More Information », Factsheet | HGIC 2000 | Reviewed: Dec 12, 2018 | Print | Download (PDF). Additionally, if fire blight is expected to be severe on apples in the upcoming season, a copper fungicide spray (copper sulfate or copper ammonium complex) can be made during dormancy – just before buds open. The fungicide for use on crabapple trees is mancozeb (do not spray after bloom) or myclobutanil. Plan the perfect garden with our interactive tool →, Superior Crabapple Trees for the Landscape, Landscape America: Flowering Crabapple Tree. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. The fungus cannot be transferred from apple tree to apple tree, or from juniper to juniper. All Rights Reserved. Prevention & Treatment: Maintain good air circulation by pruning, to keep trees from becoming too dense. 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