Spring fever and an urge to get out and putter in the garden are common almost anytime of the year in Hawaii. This year, we also need to consider dengue fever. At least 33 confirmed cases have been reported as of this writing. This means when folks are out sharing nature with mosquitoes, it is important to be protected with repellent and clothing to avoid being bitten. Screened windows, doors and perhaps even mosquito netting over beds might be wise in warm, wet areas where mosquitoes thrive.
We have had dengue outbreaks before and this one may be minor as well, but it takes diligence to clean up areas where mosquitoes breed. Check for standing water in garden pools, containers, water catchment tanks and water holding plants such as bromeliads. Flushing out bromeliads weekly with fresh water or treating with a biological mosquito control such as Bacillus thuringiensis subspecies israelensis will kill mosquito larvae. This mosquito specific biocontrol is available under several brand names at garden shops.
Dengue is just one of many mosquito transmitted diseases with which we should be concerned. There has been a serious epidemic of chikungunya in the South Pacific. West Nile virus is another that may be transmitted to humans from infected birds. We are all getting better educated about the potential hazards of bringing plants and animals into Hawaii without following the proper procedures. Agricultural inspections and quarantines are a way of life when we travel these days, but now we are reminded again that serious human diseases are also lurking, only to be inadvertently introduced into the islands. Of course it is common sense that flu and similar diseases can come with travelers. We experience this each flu season, but dengue fever, yellow fever and perhaps even malaria could become a problem if we are not careful.
Unfortunately, we have the specific mosquito carriers or vectors present. They also require a reservoir where the disease organisms can reside unnoticed. Some research shows that dengue may be harbored by animals other than humans such as monkeys, pigs or rats, although this seems to be rare. I learned this several years ago through a conversation with a Hawaii Department of Health worker. The reason I was concerned is that I became sick with dengue on a Peace Corps trip to Nicaragua. I was so sick that I had to delay coming home for two weeks. If I had felt better, I would have returned to Hawaii immediately, thus inadvertently being potentially infectious. If the right mosquito had found me and then bit someone else, they could have become infected.
Dengue is also called Breakbone Fever, because an infected person feels like every bone in the body is damaged. This condition can last for weeks. It is important to be aware of the potential of this disease and others, since quite a few Hawaii residents are returning from Southeast Asia, the South Pacific and South America this year where dengue is epidemic. Travelers should be aware that if running a fever on return to the islands, it would be a good idea to check in with their physician or urgent care clinic.
Thanks to our isolation and diligent efforts of our Departments of Agriculture and Health, many potential pests or diseases have not found their way here. However, it takes the cooperation of everyone to make sure that we don’t bring in pests that could devastate our economy and overall environment.
Folks returning to Hawaii after a trip sometimes comment with pride about the plant or seeds they got past the inspector. Bringing unchecked plants is foolish and dangerous. For example, the banana skipper became established here in the mid 1970s. No doubt, this butterfly-caterpillar was brought in by someone’s carelessness. The insect is a problem because it feeds on banana leaves. This requires more spraying by the farmer or homeowner. The pest also feeds on cannas, heliconias and bird of paradise. The banana bunchy top virus is another disease that was probably introduced through illegal importation of banana plants.
The thought of accidentally transporting pests into a noninfested area may not excite the average gardener, but beware. Plant pests tend to multiply at an amazing rate. One new female insect brought to our islands can lay hundreds to thousands of eggs. Without natural enemies, these insects could possibly ravage much of our tropical vegetation.
Another example of pest introduction is that of several species of fruit fly. These insects, brought into Hawaii years ago, have spread throughout the islands and caused untold millions of dollars damage to fruit and vegetables. Just a few people illegally bringing in uninspected fruit on their travels may have caused these infestations.
And again, there is lethal yellowing. This is a disease that killed most Florida coconut palms. Luckily, we have not found one case of this disease in Hawaii. Unfortunately, it has reached Mexico and is spreading along the Caribbean coast. Replanting with the resistant dwarf coconut palm and its hybrids have allowed the areas to flourish with palms again.
The Department of Agriculture and the University of Hawaii Plant Pathology people have checked out coconut palms that are dying for one reason or another here. Some damage may caused by herbicides applied too close to the trees. Other palms are affected by bud rot or stem bleeding disease that is often caused by physical damage such as unsanitary pruning equipment or climbing spikes. Some palms have been found to be suffering from lack of fertilizer or water. In fact, we have noticed trees dying in the Kona area where they are not irrigated. This is caused by extended drought in recent years. All these problems are correctable, but if lethal yellowing ever gets into Hawaii, there will be no practical way of stopping destruction of our island’s palms.
