Videos
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Gardening in the Zone: Growing Christmas Trees ISU Extension forester Paul Wray talks about how to grow Christmas trees in Iowa in this 2004 Gardening in the Zone segment. |
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Gardening in the Zone: Starting Seeds Indoors Richard Jauron discusses how to start your garden seeds indoors to get a jump start on your garden. |
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Gardening in the Zone: Lilacs Dr. Cindy Haynes, horticulture specialist with Iowa State University Extension and Outreach, discusses the varieties of lilac bushes and how to properly prune them. |
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Gardening in the Zone: Overwintering Geraniums Richard Jauron, ISU Horticulture Specialist, discusses the different ways you can overwinter your geraniums. |
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Rhizosphaera Needle Cast Rhizosphaera needle cast is the most common disease on spruce trees that is received in the Plant and Insect Diagnostic Clinic. Rhizosphaera needle cast is caused by fungal pathogens within the genus Rhizosphaera. This genus also infects several conifer species including; fir, cedar, spruce, and pine |
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Oak Wilt Oak wilt is a serious disease that can infect many oak species. It is caused by the fungus, Ceratocystis fagacearum. Red oaks are very susceptible to the oak wilt fungus and can die within 4-6 weeks. White and bur oaks are susceptible, but the symptoms develop slowly. Trees can be infected by the fungus through root grafts or by beetle vectors that carry spores to newly wounded trees. When a tree is infected it tree tries to protect itself by producing gummy material called tyloses which can clog the water conducting vessels. Water is prevented from moving to the canopy and leaves begin to wilt. Leaves of infected oaks can wilt, turn brown at the edges, and fall off. The outermost ring of sapwood sometimes turns brown and appears as streaks when the bark is peeled; or as a ring when the branch is cut in cross-section. Because oak wilt is often confused with other disorders, positive identification requires recovery of the causal fungus from the tree. |