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Home / Sentinel Plant Garden

Sentinel Plant Garden

A Global Network of Sentinel Plantings: Recruiting Botanic Gardens and Arboreta to Stop the Spread of Invasive Insects and Pathogens

Botanic gardens all over the world offer a unique opportunity to help detect potential invasive threats to forest health. Like the European traveler to the Amazon with no resistance to malaria, plants in botanic gardens and arboreta all over the world are standing sentinels for potentially invasive pests. Through reciprocal agreements, botanic gardens can provide advance warning for potential pests for every country in their collections.

Nursery stock is well-recognized as a major pathway for the introduction of invasive insects and pathogens to native ecosystems. For many agricultural products, the pests abroad are fairly well-known. However, when it comes to forest pests, plant health regulators in every country are stymied by lack of knowledge about what pests they should be watching for. Furthermore, the growth in volume of international plant trade has greatly diluted the protection that can be achieved by inspection of nursery stock at ports of entry.

The scientific community recognizes that international communication and collaboration offer the best hopes for preventing new pest incursions. Several pest databases on the worldwide web catalog known invasive pests, e.g. DAISIE. But many forest diseases, such as sudden oak death, Dutch elm disease, and dogwood anthracnose were unknown to science prior to their introduction into a new land. How can the potential impact of such pests be identified before they arrive? A network of participating botanic gardens and arboreta, committed to sharing information about pests observed on non-native host plants, will identify these threats and allow nurserymen and pest specialists to develop mitigation programs to stem the tide of alien insect pests and diseases.

The New Zealand expatriate plant pilot program is a good model for demonstrating that systematic observation of native plants overseas is effective. Ten new pests were detected in just 14 overseas site visits. Mealy bugs, scale insects, nematodes and fungal pathogens were the most commonly collected pests (1,2).

How will this network deal with new pest finds?

Gardens with international collections are invited to participate in the Sentinel Plant Network. Staff at these gardens already watch over their collections and examine any ailing plants. However, plant failure is often attributed to poor adaptation to local climate. If unusual problems do occur, the problem needs a professional diagnosis. In the United States, every state has a land-grant institution with a diagnostic laboratory. These labs are willing to help gardens identify the disease or pest, and direct clientele to experts who can provide management strategies. After 9/11 these state labs were integrated into a National Plant Diagnostic Network (NPDN). If the pest is exotic, we will "catch" the next chestnut blight before it gets thoroughly established in the US. NPDN labs have a reporting system with the United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) to deal with new pests that may have arrived with the plant. Counterparts overseas can help mitigate the problem. Or if the problem is endemic to the region of the garden and not known in the country of origin for the host plant, counterparts overseas will be grateful for an early warning that such a pest exists. If hosts are moving in trade, they will take steps to ensure that such exchanges are from clean stock only.

Gardens are networking

Many botanic gardens and arboreta are working to place their collection catalogs on the worldwide web. For example, the PlantSearch database maintained by Botanic Gardens Conservation International currently contains 575,000 records of taxa found in botanic garden collections around the world. Work to grow this database will facilitate locating North American species planted abroad (For example, PlantSearch currently identifies collections of Quercus macrocarpa at botanic gardens in 17 countries around the world). Collections with major holdings are being contacted and asked to participate in a reciprocal agreement to mutual advantage.

Most gardens retain information on the sources of plants in their collection equivalent at least to what would be found on a herbarium specimen label. This means our collection information will be very useful as well as accessible to all. It is vital that we secure cooperation from gardens and National Plant Protection Organizations overseas with collections of North American plants. We hope to promote discussion with potential collaborators, identify obstacles, and find solutions that make joining the network desirable for all concerned.

Three Levels of Network Participation

We envision three levels of garden participation:

Gardens agree to monitor their collections and report pest problems; visitors are informed by signage that the garden is participating in the Sentinel Plant Network, and that they too should report pest problems on nursery stock.

Gardens meet "silver" requirements PLUS help arrange reciprocal agreements with their overseas exchange partners. Gardens offer educational program on invasive species.

Gardens meet "gold" requirements PLUS research records of previous establishment failures; problem plants are replanted and monitored to determine susceptibility to native pests.

How to Join the Network?

E-mail Dr. Kerry Britton


1. Fagan, L., Bithell, S. and Dick, M. (2008). Systems for identifying invasive threats to New Zealand flora by using overseas plantings of New Zealand plants. In: K.J. Fourd, A.I. Popay and S.M. Zydenbos (eds.), Surveillance for biosecurity: pre-border to pest management. New Zealand Plant Protection Society, pp. 51-62.

2. Fagan, L., Bithell, S., Fletcher, F., Cromey, M., Elder, S., Martin, N., Bell, N., Aalders, L., Cousins, K., Barratt, B., Ferguson, C., Kean, J., Phillips, C., McNeil, M., Barron, M., Dick, M., Kay, N., Alcaraz, S. and Kriticos, D. 2008. Evaluating the expatriate plants conpect: Can we predict invasive threats to New Zealand natural ecosystems by focusing our efforts overseas? Better Border Biosecurity (B3) report to governance council, Lincoln, 14 May 2008.