These immigrants aren't wanted in the U.S.

In a Nov. 29 commentary published by the California Farm Bureau Foundation, ornamental growers Norm Groot of Monrovia Growers and Janet Kister of Sunlet Nursery shared their concerns about the potential devastation caused by imported pests. The two growers cited the devastating impact that Phytophthora ramorum has had on hundreds of California nurseries and garden centers during the past three years.

{sidebar id=40}

Making a beeline for the U.S.

California is not alone in dealing with imports of new pests. Florida, because of its climate and location, is a magnet for immigrant insects and disease pathogens. Florida’s Division of Plant Industry reports the state is literally under siege from new exotic pests. It reports that almost every month, a new exotic arthropod is detected in the state.

Between 1986 and 2000, 150 species of insects, mites and spiders became established in Florida. These immigrant species have come from all over the world with the majority coming from the Neotropical region or from Asia. Of the major insect orders represented, the most have been Homoptera species, followed by Coleoptera.

Last October, Florida Agriculture Commissioner Charles Bronson announced the successful results of a biological control program that had been implemented in more than 30 counties to control pink hibiscus mealybug. This Asian native was first discovered in the state in 2002. Although most infestations have been found on hibiscus, this mealybug attacks more than 200 plant species.

Because of the pest’s widespread distribution, Florida officials determined eradication was unfeasible. Therefore, a biological control program was implemented that includes two parasitic wasps reared in facilities in Florida, California and Puerto Rico. Since 2002, more than 2 million parasites have been released. Another control is a Cryptolaemus lady beetle that was already established in Florida.

Control of the mealybug looks promising. As of last October in Broward and Miami-Dade counties, the average decline in the mealybug adult female population had been over 97 percent at study sites.

About the same time that Florida was announcing the results of its biological control program, Louisiana Department of Agriculture and Forestry confirmed infestations of pink hibiscus mealybug at three residential locations for the first time in that state. Louisiana officials worked with USDA to release the same parasitic wasps that had been effective in Florida.

Need to be vigilant

Groot and Kister report that USDA’s Animal and Plant Health Inspection Service inspection stations handle 1.5 billion plant units annually, which accounts for 75 percent of propagated material brought into the United States. The growers said only 2 percent of propagated material brought through Miami ports and airports is inspected. Regardless of how vigilant government officials are at finding unwanted pests, with such a small amount of plant material inspected, chances are an undesirable immigrant is going to escape detection.

Consequently, growers need to be diligent in inspecting plant material from offshore producers. All ornamental growers who use offshore material have to be concerned about any changes considered to federal regulations that impact plant imports. Just ask any of the growers who have had their businesses affected by Phytophthora ramorum, Ralstonia solancearum race 3 biovar 2, Q-biotype whitefly, chili thrips (Scirtothrips dorsalis) and chrysanthemum white rust.

{sidebar id=1}

To learn more about new pests and invasives, attend Society of American Florists’ 23rd Annual Conference on Pest and Disease Management for Ornamentals, Feb. 22-24 in Portland, Ore. For more: (800) 336-4743; www.safnow.org.

- David Kuack