Plant diseases usually are what we consider in a garden column, but gardeners and other Hawaiian residents need to be wary as well when it comes to carrying human diseases.
Plant diseases usually are what we consider in a garden column, but gardeners and other Hawaiian residents need to be wary as well when it comes to carrying human diseases.
We discovered this in the South Pacific.
Chikungunya is a virus disease about which you don’t want to hear. We just returned from a few weeks in the Society Islands of French Polynesia. Even though we were not informed the disease was epidemic there, we found that thousands of folks had come down with it since October 2014. The disease, carried by mosquitos from one person to another, was running rampant, especially on some islands such as Huahine and Raiatea. According to our state health department, we have had no cases as yet in Hawaii.
Chikungunya starts like a bad case of the flu but quickly leads to severe bone and joint pain that can last for weeks or even months. Folks who have had Dengue or Breakbone fever say the pain was much worse with Chikungunya. Some were unable to stand or walk for several days after high fever.
The young and old are especially susceptible, with several deaths attributed to the virus throughout French Polynesia.
After being bitten by an infected mosquito, it takes four to seven days to show symptoms, so if someone arrives here infected, it would be easy to bring the disease to Hawaii. We have two species of mosquito here capable of transmitting Chikungunya, so it is important to protect yourself from being bitten if traveling in areas where the disease is present.
If you have flu-like symptoms during or shortly after a trip, contact the state health department and your doctor. Most doctors probably would not be prepared to test for Chikungunya unless you inform them of possible exposure to the disease. There is no vaccine or prevention other than avoiding mosquito bites.
Now, back to the garden.
The best disease prevention measure you can take with ornamental plants is to start with healthy or disease-resistant plants.
According to University of Hawaii plant pathologists, once an ornamental plant becomes badly diseased, it is difficult to nurse it back to health. For this reason, every effort should be made to prevent introduction of disease-causing organisms on plant material or in soil.
Plants in poor growth condition usually are more susceptible to disease. Good cultural and sanitation practices will help prevent trouble.
Remove diseased branches or leaves as soon as they appear. Treat pruning wounds with a specially prepared material to stop entrance of wood-decaying organisms.
For treatment of diseased plants, fungicide applications should continue at seven- to 14-day intervals as weather conditions are favorable for the disease. Be sure to follow the manufacturer’s directions on the label.
Best prevention of a disease whether one of plants or humans is keeping it out of Hawaii.
Some folks get unhappy when they find they can’t bring certain plants or seeds into Hawaii; or if they can, they have to go through all kinds of red tape, fumigation or extended quarantines to get the plants through.
A few of these folks figure it is a bother to get permits and go through the proper procedure to bring plants to Hawaii. They smuggle a few plants thinking it won’t make any difference.
This attitude couldn’t be further from the truth or more dangerous. If it weren’t for people bringing in disease and insect-infested plant materials, our islands would not be plagued with such creatures as fruit flies, burrowing nematodes and many other pests that damage food crops as well as ornamentals. Just the fact that we are plagued by fruit flies means the potential export of mangoes and other tropical fruits is nipped in the bud. So, we lose millions of dollars of potential agricultural income just because of some careless person who didn’t think it would hurt to smuggle in some fruit.
Florida has one of the best examples of what happens when folks get careless about clean plant introductions.
An introduced disease called lethal yellowing killed palms by the millions and might be a threat to other areas such as Hawaii. The disease affects coconut palms, Manila palms (Veitchia merillii) and Hawaiian Fan Palm (Pritchardia sp.). The disease attacks and kills more than 40 other species of palms as well.
According to the University of Florida, it has been reported in the Dominican Republic, Bahamas, Cuba other Caribbean Islands, Venezuela, Panama, and West Africa. It was identified in Key West in 1955. It probably was brought to the area by folks bringing in contaminated plants. Between 1955-68, 15,000 trees were lost in Key West alone. In the early 1960s, it appeared on adjacent Stock Island, and in 1970 in Key Largo, 100 miles from Key West. In 1971, it appeared in Torch Key and Coral gables near Miami.
The disease spread into Peninsular Florida. Tremendous economic losses occurred. Millions of palms died and had to be replaced by disease resistant species. Efforts have been made by the Division of Plant Industry there to quarantine the area so the disease will not be spread and, of course, palm seed or plants are not allowed into Hawaii.
The disease is similar to a virus, mycoplasma-like organism that is in the plant. Taking plants from an infected area to an area free of lethal yellowing is extremely dangerous. A leaf hopper, Myndus crudis, is the vector. This insect also is found on St. Augustine lawn grass and easily could be introduced by someone smuggling in grass.
There is no control at present except to avoid transmiting this disease to unaffected areas.
This, again, shows that we should support our state and federal agricultural quarantine laws and agents. Introducing plants illegally could bring a devastating disease such as this to Hawaii.
There are ways to bring in new plants to Hawaii legally. The Hawaii Department of Agriculture and USDA Plant Quarantine Office can give you details plus proper forms to fill out to do this.
By following the law, hundreds of new plant introductions are being made each year. These can enrich our lives without bringing with them unwanted insects and diseases that could bring disaster to our economy.
The Tropical Gardening column is supplied by the University of Hawaii College of Tropical Agriculture and Human Resources. For more information, contact the office near you.