When we plant non-native species in our gardens and yards, these plants have tremendous potential to cause unexpected harm. Here's a story about a big one that affects us all.
From the New York Times, May 9, 2013
"Florida’s citrus industry is grappling with the most serious threat in its history: a bacterial disease with no cure that has infected all 32 of the state’s citrus-growing counties.
"Although the disease, citrus greening, was first spotted in Florida in 2005, this year’s losses from it are by far the most extensive. While the bacteria, which causes fruit to turn bitter and drop from the trees when still unripe, affects all citrus fruits, it has been most devastating to oranges, the largest crop.
"The disease, which can lie dormant for two to five years, is spread by an insect no larger than the head of a pin, the Asian citrus psyllid. It snacks on citrus trees, depositing bacteria that gradually starves trees of nutrients. Psyllids fly from tree to tree, leaving a trail of infection."
Here’s more about the Asian citrus psyllid, from UC Davis:
"Asian citrus psyllid is an insect found in tropical and subtropical Asia, Afghanistan, Saudi Arabia, Reunion, Mauritius, parts of South and Central America, Mexico, and the Caribbean. In the United States, Asian citrus psyllid was first found in Palm Beach County, Florida, in June 1998 in backyard plantings of Orange Jasmine (Murraya paniculata), a popular ornamental shrub with fragrant flowers (also known as Orange Jessamine). By 2001, it had spread to 31 counties in Florida, with much of the spread due to movement of infested nursery plants (see footnote 1). In the spring of 2001, Asian citrus psyllid was accidentally introduced into the Rio Grande Valley of Texas on potted nursery stock (orange jasmine) from Florida (see footnote 2)."
The NYTimes article goes on to say:
“Before this year, the losses and increased costs of fighting the disease had already taken a toll on Florida’s citrus industry, which has been in decline for 15 years. In a 2012 report, University of Florida agricultural analysts concluded that between 2006 and 2012, citrus greening cost Florida’s economy $4.5 billion and 8,000 jobs.
“Concerted efforts by growers and millions of dollars spent on research to fight the disease have so far failed, growers and scientists said. The situation was worsened this season by an unusual weather pattern, including a dry winter, growers said."
We are discovering more and more about how non-native species can often be the source, vector or primary habitat for non-native insects that can turn out to be extremely destructive to our natural and agricultural landscapes. When we garden and landscape, we individual citizens should try to minimize our accidental role in these calamities.
How? We should start being careful about casually assuming we can have anything we want in our landscapes, that our aesthetic wishes take precedence over a healthy environment. We should be careful about where we buy plants, and let suppliers know that these things matter to us as consumers. If at all possible, we should never buy plants from big box stores, only from local nurseries.
Even better would be to buy only locally grown plants that have not been transported from distant lands, and to garden only with plants native to our own region, to eliminate at least one group of potentially harmful things: the un-noticed insects that frequently come along with non-natives.
To learn more about the vast subject of gardening with native plants, I invite you to explore the blog, Native Plants and Wildlife Gardens.
1. Halbert, S. E., C. L. Niblett, K. L. Manjunath, R. F. Lee, and L. G. Brown. 2002. Establishment of two new vectors of citrus pathogens in Florida. Proceedings of the International Society of Citriculture 9th Congress. Alexandria, VA: ASHS Press. 1016–1017.
2. French, J. V., C. J. Kahlke, and J. V. da Graca. 2001. First record of the Asian citrus psylla, Diaphorina citri Kuwayama (Homoptera: Psyllidae) in Texas. Subtropical Plant Science 53:14–15.
“Sue, I have valued your guidance tremendously this year. You have a sharp mind and a gentle hand—a wonderful combination in a teacher!”