Emerging Threats
Thousand Cankers Disease of Walnut
Thousand cankers disease (TCD) is a caused by a combination of a fungus (Geosmithia morbida) and the walnut twig beetle (Pityophthorus juglandis). The walnut twig beetles carries fungal spores, and when they tunnel through the outer bark into the tree the fungus is transmitted during gallery construction. This has also been found if the beetle “tastes” the tree and does not produce a gallery. The fungus kills an area under the bark and the areas of dead tissue are called cankers. When the walnut twig beetles are abundant, numerous cankers can form and coalesce to girdle twigs and branches, restricting movement of water and nutrients. Black walnut (Juglans nigra), the most valuable native species to the state, is the most susceptible of the Juglans species to this disease.
Asian Longhorned Beetle
Asian Longhorned Beetle (ALB) feeds on a wide variety of hardwood tree species that are native or planted in Kansas. It kills trees by creating large tunnels as larvae causing branches or stems to break and eventually lead to tree death. Because this beetle is not native to North America, it has no known natural enemies, and our trees have low resistance to this pest. It has not been detected in Kansas. It has been stated that if the ALB were to become established in the US, it could become one of the most destructive and costly pests ever to industry, urban neighborhoods, and natural forests.
Spongy Moth
In 1869, the European spongy moth was introduced to North America by Professor E.L. Trouvelot in an attempt to breed a hardy silkworm. Some insects escaped and were soon established in a vacant lot next to his home in Medford, Mass. Since then, it has been infested the northeast, resulting in massive defoliation of shade, fruit, and ornamental trees as well as hardwood forests. Caterpillars devour the leaves of many hardwood tree species and shrubs that can turn a usually lush summer scene into one of winter. Estimates up to 13 million acres of trees have been defoliated in one season, damaging local ecosystems and killing trees after repeated attacks.
Asian Spongy Moth is a native of Asia and was first detected in Washington in 1991. Ongoing and completed eradication of various sites in the U.S. have so far prevented the establishment of this generalist feeder. This moth is much more destructive if it became established and spread east because of its broad host range and the females are active fliers due to their larger wingspan.
Sudden Oak Death
In June 2019, the causal agent of Sudden Oak Death (SOD), Phytophthora ramorum, was detected in rhododendrons originating from Park Hill Plants nursery in Oklahoma, and plants from that nursery were shipped to 60 Walmart stores across Kansas and one Home Depot store in Pittsburg, Kansas.
Sudden Oak Death (SOD) is caused by Phytophthora ramorum, a water mold pathogen. The pathogen is also the cause of the Ramorum Leaf Blight, Ramorum Dieback and Phytophthora Canker Diseases. SOD was first detected in the San Francisco Bay Area in the mid-1990s. It was first recognized as killing trees in Oregon forests in in 2001. The SOD pathogen is considered especially dangerous because it affects a wide variety of trees, shrubs and plants and there is no known cure. The pathogen has killed millions of tanoak and coast live oak trees along the central CA coast into Southern OR and is a concern because it also infects rhododendron, camellia and other common horticultural nursery plants.