American Nurseryman Magazine - Horticulture Magazine and Horticulture Books - Plant Health - April, 2011 - DEPARTMENTS

American Nurseryman Magazine - Horticulture Magazine and Horticulture Books - April, 2011

DEPARTMENTS

Plant Health

Briefs

Thrips management plan

A new, comprehensive program designed to help manage thrips - including western flower thrips and chilli thrips - was released in February, and it offers ornamental growers four options tailored to specific infestation scenarios.

  • Program A, Aggressive Treatment Program, is to be implemented when plants are virus hosts and thrips are present; plants are ready to be shipped and thrips populations are present in high enough numbers to reduce crop marketability; or plants have thrips populations that need to be managed but the plants are not virus hosts.
  • Program B, Maintenance Treatment Program - not using biological control agents, is intended for situations where plants are virus hosts but they have no thrips; or plants are not virus hosts but have low thrips populations.
  • Program C, Maintenance Treatment Program - using biological control agents, is to be used in the case that plants are virus hosts but no thrips are present; or plants are not viral hosts but have low thrips populations.
  • Program D, Maintenance Treatment Program - prior to introducing biological control agents, is employed when plants are virus hosts but thrips are not present; or plants are not viral hosts but have low thrips populations.

Action plans are offered for each program, and a table of potential foliar-applied insecticide choices - including name brands, active ingredients and registered use sites (greenhouse, lath house, indoors, nursery and shade house) - is provided for quick and easy reference.

The project was partially funded by the American Floral Endowment, Floriculture & Nursery Research Initiative (comprising the USDA-ARS, Society of American Florists, American Nursery & Landscape Association) and the IR-4 Project.

Information can be found online at the site of the Invasive Arthropod Working Group, part of the University of Florida's Institute of Food and Agricultural Sciences, Mid-Florida Research and Education Center (address below), where you can download a pdf copy of the thrips management program for ornamental horticulture: http://mrec.ifas.ufl.edu/lso/.

Minnesota implements thousand cankers quarantine

The Minnesota Department of Agriculture moved in February to protect the state's 6 million eastern black walnut trees when it issued a temporary exterior quarantine restricting the import of walnut trees and certain related products into Minnesota from areas known to be infested with Thousand Cankers Disease (TCD). To date, TCD has been confirmed in Arizona, California, Colorado, Idaho, New Mexico, Oregon, Tennessee, Washington and Utah, and it appears to have the potential to spread rapidly to other locations.

The disease is caused by a fungus carried by the walnut twig beetle, which tunnels beneath the bark of walnut trees, thus introducing the fungus and creating small cankers. Cankers spread and grow together as the tree is infested by more beetles; this restricts circulation and ultimately kills the host tree.

The list of walnut products covered by Minnesota's quarantine includes live walnut trees, walnut logs, walnut lumber, walnut firewood, walnut nursery stock, wood chips and mulch made from walnut wood, walnut branches and roots, and packaging materials made from walnut wood. The quarantine does not apply to walnut nuts, nutmeat, walnut hulls, finished products made from walnut wood without bark, or processed lumber that is 100 percent bark-free, and kiln-dried with square edges.

The state is seeking public comment on the temporary quarantine prior to replacing it with a formal quarantine. More information about TCD and the quarantine can be found on MDA's website at www.mda.state.mn.us.

Laurel wilt hits Miami-Dade county

Laurel wilt disease has been positively identified on three swamp bay trees in south Miami-Dade County, Florida, according to the Florida Department of Agriculture and Consumer Services. The disease is caused by a fungus - Raffaelea lauricola - vectored by the redbay ambrosia beetle (Xyleborus glabratus), whose presence had been confirmed last year. Host plants include redbay, swamp bay, avocado, sassafras, pondspice, pondberry and others in the Lauraceae (which may include California bay laurel or Oregon myrtle). Residents have been instructed to use local firewood only and not to transport host trees, unless purchased from a registered nursery. More information on laurel wilt disease can be found at www.freshfromflorida.com/pi/enpp/pathology/laurel_wilt_disease .


SUZANNE KLICK

Stink bug on the move

First the East Coast, then the West - and now points in between. The brown marmorated stink bug (Halyomorpha halys) appears to be set on conquering the U.S., with reports of the nuisance confirmed in more than half of the country. The Iowa State University Extension Plant and Insect Diagnostic Clinic (ISU-PIDC) and the Iowa Department of Agriculture and Land Stewardship confirmed that a single specimen was positively identified in Cedar Rapids - the first confirmation of the pest in the state - although the beast was dead on arrival. According to the organizations, "It is not known if this find indicates an established population or an isolated individual as [brown marmorated stink bug] travels readily in shipping containers and with people."