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Nursery & Forest
Volume 60 Number 1 Date 04/23/2015 VIRUSES OF ORNAMENTALS - Recent greenhouse inspections conducted in Adams, Chippewa, Eau Claire, Kewaunee and Outagamie counties found an assortment of virus-infected plants. Viruses of ornamental plants are highly transmissible through routine greenhouse operations and have become increasingly prevalent in the nursery trade. Viral diseases detected this month include hosta virus X on hosta 'August Moon' and 'Sum & Substance', tobacco rattle virus on bleeding heart 'Alba' and 'Pink', and a potyvirus on bearded iris 'Immortality'. Another virus new to Wisconsin, tomato chlorotic dwarf viroid, was diagnosed on petunia 'Peppy Lavender' and on a supertunia hybrid. There are no controls for plant viruses. Once a plant is infected, it must be removed from sale and destroyed. NR 40 INVASIVE SPECIES RULE - Many aquatic and terrestrial plants commonly used in the nursery industry will be listed as prohibited or restricted once revisions to the DNR's Chapter NR 40 Invasive Species Rule take effect this season. The addition of 49 new prohibited plant species, 32 new restricted plants, and two species that will be listed as both prohibited and restricted has been proposed. The rule revision provides a three-year phase-out period for herbaceous species on the restricted list, and a five-year phase-out period for restricted trees and shrubs. Plants on the prohibited list will not have a phase-out option. Nursery operators and brokers are advised to review the proposed revisions and know the invasive plants regulated under Chapter NR40: http://dnr.wi.gov/topic/Invasives/classification.html . LILY LEAF BEETLE - Overwintered beetles were observed on lily foliage at a residence in Marathon County on April 19, confirming the winter survival of this newly-introduced exotic invader. Detected for the first time in Wisconsin last June, lily leaf beetle (LLB) has been reported from at least 17 separate sites, all in the Kronenwetter, Mosinee and Rothschild areas of Marathon County. Currently the LLB population appears to be limited to Marathon County, thus control or eradication may still be possible with diligence of local communities. Gardeners, nursery growers and residents are encouraged to closely inspect lily plants for the bright red beetles and their larvae and report any finds to the DATCP Nursery Program at datcpnursery@wisconsin.gov. Recommended controls include manually picking the adults and larvae from plants or applying an insecticide labeled for use on ornamental plants and available at garden centers and hardware stores. More than one application may be required to effectively control LLB. -- Ellen Hermanson, DATCP Nursery Inspector EMERALD ASH BORER- The treatment window for soil-applied systemic insecticides used to protect ash trees from EAB extends from mid-April to mid-May. Application during this period allows 4-8 weeks for the material to be transported throughout the tree's vascular system prior to the onset of EAB adult and larval feeding. By contrast, trunk injection and basal bark spray products are applied later, during the period after bloom and leaf expansion but before eggs have hatched, generally from mid-May to mid-June. Emerald ash borer treatments must be made annually or every two to three years depending on the product used and local EAB pressure, and are only recommended for healthy, high-value ash trees within 15 miles of a known infestation. Owners of trees larger than 20 inches in diameter at breast height (DBH) are advised to consult a certified arborist or tree care specialist to have their ash professionally treated with a product that can provide full protection of mature trees from EAB. -- Renee Pinski, DATCP Forest Entomologist 
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