There are many old sayings, old adages and old wives’ tales in the British Isles that have weathered the test of time and ultimately hold true. One man’s meat is another man’s poison is a good example.
We are now driving a rented car through Northern Scotland where legends abound and we have noted large stands of rhododendron, especially rhododendron ponticum. This popular group of plants that includes azalea and tropical vireyas was introduced to the isles centuries ago. They became popular in many gardens because they were well adapted and beautiful. Some species however, were so happy that they escaped and became established in overgrazed pastures.
By then the original forests of England and Scotland had long been altered by man and grazing animals. These rhododendrons were perfectly adapted to the vacuum created because the animals would not feed on them. Now these beautiful shrubs have become small trees in many areas but have become pests shading grasses and other plants the local folks prefer.
Back home in Hawaii, we find ourselves facing the same situation with many introduced plants and animals. Before there were laws against importing anything we wanted, some introductions became a problem. Now, thanks to our isolation and diligent efforts of our Department of Agriculture, many potential pests 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.
One example is a disease that wipes out coconut palms. When I was in West Africa, I saw thousands of palms dead and dying. This disease looked much like lethal yellowing disease that struck in Florida and the Caribbean. How did it get to Africa? Where did it come from? With our planet so interconnected as it is today, it is easy to spread diseases and insects from one place to another.
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 insect 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 now threatening our Big Island banana industry is another that was introduced through illegal importation of banana plants.
The thought of accidently transporting pests into a non-infested area may not excite the average gardener, but be wary, 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 in damages to tropical fruit and vegetables. It will cost millions to rid ourselves of these pests. 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 has claimed the lives of most Florida coconut palms as well as scores of other susceptible species. Luckily we have not found one case of this disease in Hawaii. Unfortunately, it has reached Mexico and is spreading along the Caribbean coast. It would not be surprising to soon see it in Central and South America.
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 be due to 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 nutrients or water. In fact, we have noticed trees dying in the Kona area where they are not irrigated. This is due to our extended dry periods and restrictions on water use. All these problems are correctable, but if lethal yellowing ever gets to Hawaii, there is no practical way of stopping destruction of our island’s palms.
When lethal yellowing hit the mainland of Florida, it was discovered that other palms are also susceptible to the disease in varying degrees. According to the University of Florida Lethal Yellowing Research Station in Fort Lauderdale, dozens of other palms are susceptible like the Manila palm, fishtail palm, our endemic loulu palm and many others.
Who would want to be the cause of bringing something like this to Hawaii? You are probably thinking, “Oh, no, not me, I know if a plant is healthy or not.” Most growers do recognize the telltale signs of insect activity like wilting, chewed leaves, or blasted flowers. But plant pests do not always leave signs of their presence. Plants may be contaminated by microscopic cysts or larvae, or insect eggs.
Anyone who wishes to transport plant materials to Hawaii or from one island to another island should first consult the Hawaii Department of Agriculture. These officials will brief gardening enthusiasts on any applicable quarantines and aid them in complying with quarantine regulations. Don’t be a party to the destruction of our islands’ native forests, agriculture or the plants in your own yard. Besides, now there is a stiff fine and even jail sentence for offenders.