February 11, 2013 | Andrea Watts

It is expected that crops and, in turn, revenue may be lost to pests, but through the use of integrated pest management and farmscaping, the crop damage caused by native pests can mitigated. However, when exotic, or invasive, species enter a farm’s ecosystem, traditional IPM practices designed to work with native prey and predators, may prove unsuccessful in stemming the damage these new intruders cause.

Invasive species are organisms – plants, insects, mollusks, or pathogens – that cause economic or environmental damage when introduced into a new landscape. The annual damage in the U.S. from invasive species is in the billions of dollar and their removal and or containment has been a major focus for federal and state agencies’ for years.

Clinton Campbell, Washington State & Alaska Operations Support Officer for the USDA Animal and Plant Health Inspection Service’s (APHIS) Plant Protection and Quarantine (PPQ) unit, and Brad White, Pest Program Manager for the Washington State Department of Agriculture, both agree that land farmed sustainably is just as vulnerable to invasive species damage as conventionally farmed land. Invasive species “completely upset [and] short circuit the system,” of established integrated pest management practices, White says.

Though invasive species can become established in any region throughout the United States, “climate and local conditions have a bearing on getting [a pest] established,” Campbell says. Florida, Texas, and California are examples where a warm climate combined with multiple entry points makes these regions more vulnerable to invasive species’ introduction. And where there is an urban-rural interface, there is also a greater likelihood of discovering an invasive species because of a greater volume of import traffic, a robust transportation system, and a susceptible environment.

Controlling Invasive Species

There are several methods used to eliminate invasive species: biological control, chemical control, regulatory control, and physical control, and it’s the “nature of the pest” that determines the method of removal, Campbell says. Biological control uses the known natural enemies (predators or parasites) of the invasive species to contain or eliminate them from the landscape, while physical control is modifying the environment to remove the pest’s habitat, such as removing trees when they are infested with Asian Long-Horned Beetles. Regulatory control, such as quarantines, helps contain pests and integrates well with other control methods. But it is the use of chemical controls that will likely cause farmers to be concerned if their fields are certified as sustainable. For example, the Brown Mamorated Stink Bug, a pest that was first identified in Pennsylvania in 1998 and has recently been found in Oregon and Washington states, is resistant to most organic approaches so pesticides have to be used, White explains.

To complicate matters further as they relates to new invasive species, White says we have “no idea what’s coming down due to climate change,” which could make some regions more vulnerable to an exotic establishment than they were previously. Additionally, no early indicators exist to determine whether an exotic pest will become invasive; it is variable, White says. While sometimes it is known in advance that a plant or animal may be a “bad actor,” for other species it could take years.

One species that concerns White and Campbell is the vineyard snail, a native of Europe. This dry land snail has created destruction in Australia’s small grain crops industry, because it clogs equipment and destroys crop. “Just about anything that moves has the potential to move a pest,” Campbell says, and with the snail being found in the port of Tacoma, White is concerned that the real possibility exists for it to reach eastern Washington, Washington state’s breadbasket.

In each state, APHIS and state personnel conduct organized surveys on farms to identify if there are undetected invasive species. A few years ago, a survey of Idaho potato farms found the Pale Cyst Nematode, a pest that affects potatoes. Fortunately, because this pest was identified early, it was quarantined and eliminated before it was able to proliferate further.

Prevention and Preparation

So what can farmers do to prevent invasive species from becoming established on their farmland? If farmers are interested in participating in an APHIS survey, Campbell suggests joining an organization or commission that is responsible for overseeing the agricultural commodity. APHIS contacts agricultural industry organizations to establish pest detection partnerships and to recruit participants.

“Be aware of where source material [seeds, plant cuttings, etc.] is coming from,” White recommends. If an agricultural commodity has a certification program, it is likely that the source material sold to farmers has been inspected to ensure it is free of contaminants.

While Campbell says, “farmers have a good idea … of the risks involved with invasive species,” it is a good practice to stay current on the latest invasive species in the state. There are many federal, state, and local resources available that provide information on identification and removal methods. For example, in Washington state, the Invasive Species Council serves as a resource for policy makers and the public on invasive species, and the WSDA also has information available on its website.

But, the most important resource for preventing the establishment of invasive species is the farmers themselves. An “excellent resource [for finding a new invasive species] is the landowner,” White says, because they will likely recognize an unfamiliar pest or plant. Campbell cites the practice of famers walking their fields and having familiarity with their land as a valuable tool; “Vigilance, in the various forms it takes, is a good thing to do.”