6 Quick Tips: Managing invasives

Widespread movement of plant material around the world has resulted in a rapidly growing list of new arthropod pests, diseases, and weeds in the United States. This has led to increased shipping restrictions and quarantine regulations, costing the greenhouse and nursery industry billions of dollars. Here are some tips to help you keep track of emerging invasive species and quickly manage any new pests found in your own operation. Implementing these practices will ensure that you don’t inadvertently spread a new pest and contribute to the potential development of an industry wide problem.

Quick Tip 1
Establish a regularly scheduled, comprehensive monitoring program.

Regular scouting for early detection of pests and diseases is always an essential practice but is especially critical when there is risk of establishment of invasive species. In California, quarantine-compliance agreements for certain pests, such as light brown apple moth, require documentation of monitoring and in-house inspections. Sampling methods used in your monitoring plan should be appropriate to the target pests and the crop — you may have to follow sampling procedures that are specified in quarantine protocols if you are dealing with quarantined pests. In addition to crops inside the greenhouse, you should inspect plants outside of the greenhouse — outdoor crops, landscapes, native plants, vegetative buffers, hedgerows, windbreaks, weeds, etc., can all serve as a source of pest infestations. Monitoring should also include areas adjacent to neighboring agricultural fields.
 

Be sure to carefully inspect incoming plant material as soon as possible before bringing them into the greenhouse because many invasive pests arrive in shipments of plant material. Ideally, isolate incoming plants in a separate quarantine area and inspect them for several weeks before introducing into the production greenhouse. It is especially critical that you inspect plant material prior to shipment to ensure that life stages of pests do not move to other areas along with the shipment.

In addition to the scout, train all employees who handle plant material to recognize crop pests, especially new invasive species. Even the best scout cannot see everywhere, and trained employees can assist the scout by looking for pests and disease symptoms as they irrigate, pot, prune, harvest, grade, etc. A system can be developed that facilitates communication of the problems these employees see in the course of day-to-day activities to the scout or other appropriate personnel, so that this information can also be used in making pest management decisions. To alert employees about potential invasive pests and keep them on the lookout, place pictorial posters with identification and other relevant information about the pests in grading and shipping areas and break rooms.

Quick Tip 2:
Seek help at the first sign of an unidentified pest.

If an unusual pest shows up in your facility, it is critical that you get it identified immediately. Although concerns about potential regulatory issues may lead to hesitancy in seeking help, an unresolved pest infestation can lead to major problems in the future if not immediately addressed. A quick response time limits the spread and potential damage from the pest. Growers should immediately contact their extension agent or university expert who can assist with identification and management of new pests using a variety of resources such as the National Plant Diagnostic Network.

Quick Tip 3:
Implement good sanitation and preventive control practices.

Keep the areas immediately surrounding the exterior of the greenhouse free of weeds and other plants that could harbor pests. Monitor plants outside the greenhouse and remove them if they attract and harbor pests. Steam or chemically treat soil and other media used for growing plants to ensure that they are free of disease organisms and weed seeds. Greenhouse vents may need to be screened to exclude pests, especially if there is a high risk of infestation of a quarantine pest. Implement strategies to reduce the likelihood of pest entrance through greenhouse doors, such as an airlock entrance room.

Quick Tip 4:
Implement a resistance management program.

Light brown apple moth is an invasive, leaf-rolling moth from Australia that causes significant crop damage. It was first found in the continental United States in Alameda County, Calif., in 2007 and has since spread to many other counties. It feeds on 250 plant species in more than 50 families, which includes many greenhouse plants.

Sometimes invasive pests are new pesticide-resistant strains of an existing pest species, such as the Q-biotype of Bemisia tabaci. To avoid pesticide resistance, implement a resistance-management program centered on rotating pesticides with the same mode of action. If there is only one chemical that is effective against a pest and other available products are only marginally effective, a good strategy to follow is to use the marginally effective materials when pest pressure is less severe and reserve the effective material for more critical situations.

Quick Tip 5:
Work with others to prevent the spread of invasives.

The key to managing invasives is the development of eradication efforts shortly after the initial infestation. Quick and effective eradication efforts require collaboration between universities, industry, and regulatory agencies. A good model for this is the Q-biotype whitefly where a collaborative system was developed that helps growers identify and manage this pest. Growers are advised to work proactively with local industry associations to build teams that can respond collaboratively to new pest issues. This will help to ensure that a mechanism is in place for timely eradication if a new agricultural pest is found in your area.

Quick Tip 6:
Keep updated on emerging invasive species in your area.

New invasive species are constantly emerging, so ongoing training from university cooperative extension personnel and industry professional groups is essential for the scout and all employees that manage the IPM program or work with plants. Regularly consult publications and website information from cooperative extension, universities, agricultural agencies, professional associations, pest exclusion regulators, and invasive pest task forces for the latest updates on relevant invasive species.
 

Julie Newman is an environmental horticulture advisor at the University of California Cooperative Extension.

Have a question? You can write Julie at jpnewman@ucdavis.edu.