Intro
Florida's production of both food and fiber is under serious threat from emerging pathogens new to this state. Many of Florida's most important agricultural and natural resource industries, including citrus, tomato, strawberry and tourism are facing the potential of enormous economic losses. By focusing on problems such as citrus diseases (such as canker, blight and greening), sudden oak death, soybean rust, Pierce's disease of grapes and human pathogens present in vegetables, fruits and seafood we can develop a research capability prepared to prevent and control outbreaks caused by these pathogens. We need the teaching capability to train the next generation of scientists who will keep these pathogens at bay in the future. We also need the capacity to educate Florida's consumers on how to avoid disease from food-borne pathogens; and to inform Florida's growers on steps they can take to avoid economic losses. Florida’s natural and managed landscapes are under threat from pathogens such as sudden oak death which caused massive landscape losses in peer states such as California.
Florida has a wide array of temperate, sub-tropical and tropical ecosystems which render its diverse agriculture particularly vulnerable to new pathogens and which require intensive vigilance by IFAS staff. Recent hurricanes illustrate how wind-borne pathogens can appear or reappear from the Caribbean and Latin America. In addition, tourists and commercial plant imports from around the world have the potential to unwittingly carry pathogens to our state from other countries. All of these factors make Florida more susceptible to these diseases than perhaps any other state in the nation. This situation requires more resources than IFAS can currently provide for research education and outreach.
Plant Pathogens Spotlight
Citrus greening, or Huanglongbing (HLB), is a serious citrus disease because it affects all citrus cultivars and causes rapid tree decline. Discovered in Brazil in 2004, HLB has seriously affected citrus production in a number of countries in Asia, Africa, the Indian subcontinent and the Arabian Peninsula; Psyllids carry HLB to cirus plants (psyllids are small insects that feed on plants). When psyllids are abundant and environmental conditions are favorable, HLB can rapidly destroy existing groves and prevent commercial production of oranges and other citrus cultivars. Mature trees infected may decline and become non-productive, and young trees that become infected never product fruit. In China, the disease was reported to kill young trees in 1 to 2 years. HLB is difficult to manage and continued production of citrus has proven difficult and expensive in areas where it is widespread. Since HLB is transmitted by the psyllid vector which is established in Florida, and weather conditions are apparently suitable for HLB, there is clearly a potential for natural spread now that HLB has been introduced into Florida. Sweet oranges, mandarins and mandarin hybrids (tangelo) are highly susceptible to HLB. Lemons, grapefruit, pummelos and sour oranges are also affected and are rendered non-productive when infected. Mexican limes, trifoliate oranges and some trifoliate orange hybrids are more tolerant and may show only some leaf symptoms. The HLB bacterium also can multiply in Chinese box orange (Severinia buxifolia) and wood apple (Limonia acidissima). Reference.
Prior to 2005, HLB had not been reported in the U.S., Australia or in the Mediterranean Basin. However, this exotic disease has recently been identified in Florida. Current hypotheses for introduction include infected budwood brought into Florida by an importer or private citizen. Inspection of imports and baggage may or may not have caught this introduction, since detection is difficult. However, education of the public may have had an impact, and current programs to deal with this introduced disease include public and industry education and outreach.
Plant Pathogens Frequently Asked Questions
Q. What is a plant pathogen?
A. A plant pathogen is an organism that causes a disease on a plant. Although relatives of some plant pathogens are human or animal pathogens, most plant pathogens only harm plants.
Q. Why are plant pathogens important?
A. Organisms that cause plant diseases reduce our ability to produce food and support the economy. Everything from citrus to grains to ornamental plants are susceptible to plant diseases. Plant diseases cause billions of dollars worth of direct and indirect losses every year (Citrus greening example). Emerging plant pathogens require preparation and planned, scientifically-based response to lessen the impact on our farmers and the economy.
Q. What can we do about plant diseases?
A. Management of plant diseases includes management of overall plant health. Healthy plants are less likely to get diseases, just like healthy humans. You can help reduce the impact of both emerging and endemic plant pathogens by remembering not to transport unhealthy plant parts or products.
Q. What is the difference between an endemic plant pathogen and an emerging one?
A. An endemic pathogen is one that has become established in a new environment and is no longer possible to eradicate. At that point, response switches from keeping it out or eradicating it to managing it through plant health, antimicrobial chemistries and monitoring production. An emerging pathogen is one that has not caused a problem in the new environment because it has not been found there before, or one that has changed to become a problem in a place where it has been known to occur but did not previously have an economic or natural impact.
