VOA慢速英语--佛罗里达的棕榈树受到疾病的威胁

Florida’s Palm Trees Threatened by Disease

Florida’s famous palm trees are under attack from a disease that completely dries them out within months. And there is no chance for recovery once a tree gets sick.

The cause is an insect about the size of a piece of rice. It spreads the bacterial¹ disease, known as lethal² bronzing, by jumping from plant to plant.

Lethal bronzing has gone from a relatively³ minor⁴ issue on Florida’s Gulf⁵ Coast to a nearly statewide problem in just over 10 years.

Tens of thousands of palm trees have died from the disease. And the rate of its spread is increasing, adding to environmental concerns of Floridians. The state is already struggling to save other plants, its famous citrus trees, from two other diseases.

The tall, wide-leafed sabal palm is Florida’s official state tree. It is especially susceptible⁶ to lethal bronzing.

Farms where the palms are grown, businesses and homeowners are taking a financial hit as they destroy infected trees. Some preventative measures can be taken, but once infected, digging up the tree is the only reasonable solution.

Brian Bahder studies plant diseases spread by insects. He is also a leader in the state’s battle against lethal bronzing.

Bahder told The Associated Press that getting the disease under control is highly important because it could severely⁷ change the local environment. If nothing is done, he said, “I don’t think all the palm trees will die, but the issue we see will get a lot worse before it gets better.”

Experts say lethal bronzing likely came to Florida from Mexico. It also is found in parts of Texas and throughout the Caribbean.

Some worry it will spread to California and Arizona, infecting date palms and damaging that fruit crop. The disease has already heavily damaged coconut⁸ farms in Jamaica, and Brazil is taking preventative measures to avoid invasion.

Lethal bronzing is attacking palm trees right outside Bahder’s office at the University of Florida’s agriculture research station near the city of Fort Lauderdale. Some trees are dying, while others are dead. This gives him a laboratory to test ideas and make presentations, so he is not removing infected trees like many experts advise.

“To understand the disease, I need to watch it spread and see what it is doing,” said Bahder, who is an assistant professor with the university.

Lethal bronzing’s first Florida appearance was near the city of Tampa in 2006. But now it is found from islands off the state’s southern coast to the city of Jacksonville in the north.

The only thing shown to pass the disease is haplaxius crudus, a small winged insect sometimes called the American palm cixiid or treehopper. There are other kinds of treehoppers. But this kind injects the bacteria when they eat liquid from a palm’s leaves. Any palm cixiid that later feeds from the tree will pick up the infection and pass the bacteria to more palms.

Once inside a palm, the bacteria moves to the base of the tree, reproducing again and again until they block its circulatory system. The blockage⁹ makes it impossible for palm tree cells to get the nutrients¹⁰ and sugars they need to survive.

As an infected tree dies, its leaves change from green to a brownish or bronze color within about six months. The disease does not infect humans or animals.

Genetic¹¹ testing shows lethal bronzing likely came from Mexico’s Yucatan area. Bahder believes Hurricane Wilma in 2005 or a storm with a similar path carried infected treehoppers across the Gulf of Mexico to Tampa. Those insects infected area palms, which infected native treehoppers. The disease spread when winds blew infected insects to new areas or they caught rides on vehicles.

To stop the spread, Florida’s agriculture department continuously inspects palm growers and documents those growers found to be free of the disease. If inspectors¹² discover infected trees, the trees are destroyed and the grower’s remaining trees are quarantined for at least six weeks.

Eric Muecke is responsible for Tampa’s forestry¹³ programs. He said the city has had success containing the disease by keeping its palms healthy. Officials have surrounded more susceptible kinds of palms with trees that bacteria-spreading insects do not normally attack.

Brent Gaffney, a Gainesville landscaper, said Bahder’s research is the state’s best hope for containing the disease. But that is only if he gets enough financial support, noted¹⁴ Gaffney. Studies on whether large amounts of antibiotic¹⁵ drugs can save trees shortly after they have been infected are ongoing¹⁶.

After infected trees are removed, nearby palms need preventative antibiotic injections to stop the spread. Each injection costs $50 and loses its effectiveness after three months. Bahder said that makes injections before the disease is present too costly¹⁷ for most homeowners, businesses and local governments.

I’m Pete Musto.

And I’m Anna Matteo.

Words in This Story

citrus – n. a juicy fruit, such as an orange, grapefruit, or lemon, that has a thick skin and that comes from a tree or shrub¹⁸ that grows in warm areas

leafed – adj. having a specified¹⁹ kind or number of the flat and typically green parts of a plant that grow from a stem or twig²⁰

susceptible – adj. easily affected²¹, influenced, or harmed by something

winged – adj. having parts on one’s body that are used for flying or gliding²²

circulatory – n. of or relating to the movement of blood or other fluids through the body

quarantine(d) – v. to keep a person, plant, or animal away from others to prevent a disease from spreading

landscaper – n. a person whose job is to make changes to improve the appearance of an area of land

antibiotic – n. a drug that is used to kill harmful bacteria and to cure infections

1 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

2 lethal   

adj.致死的；毁灭性的

参考例句：

• A hammer can be a lethal weapon.铁锤可以是致命的武器。
• She took a lethal amount of poison and died.她服了致命剂量的毒药死了。

3 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

4 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

5 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

6 susceptible   

adj.过敏的，敏感的；易动感情的，易受感动的

参考例句：

• Children are more susceptible than adults.孩子比成人易受感动。
• We are all susceptible to advertising.我们都易受广告的影响。

7 severely   

adv.严格地；严厉地；非常恶劣地

参考例句：

• He was severely criticized and removed from his post.他受到了严厉的批评并且被撤了职。
• He is severely put down for his careless work.他因工作上的粗心大意而受到了严厉的批评。

8 coconut   

n.椰子

参考例句：

• The husk of this coconut is particularly strong.椰子的外壳很明显非常坚固。
• The falling coconut gave him a terrific bang on the head.那只掉下的椰子砰地击中他的脑袋。

9 blockage   

n.障碍物；封锁

参考例句：

• The logical treatment is to remove this blockage.合理的治疗方法就是清除堵塞物。
• If the blockage worked,they could retreat with dignity.如果封锁发生作用，他们可以体面地撤退。

10 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

11 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

12 inspectors   

n.检查员( inspector的名词复数 )；（英国公共汽车或火车上的）查票员；（警察）巡官；检阅官

参考例句：

• They got into the school in the guise of inspectors. 他们假装成视察员进了学校。 来自《简明英汉词典》
• Inspectors checked that there was adequate ventilation. 检查员已检查过，通风良好。 来自《简明英汉词典》

13 forestry   

n.森林学；林业

参考例句：

• At present, the Chinese forestry is being at a significant transforming period. 当前, 我国的林业正处于一个重大的转折时期。
• Anhua is one of the key forestry counties in Hunan province. 安化县是湖南省重点林区县之一。

14 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

15 antibiotic   

adj.抗菌的；n.抗生素

参考例句：

• The doctor said that I should take some antibiotic.医生说我应该服些用抗生素。
• Antibiotic can be used against infection.抗菌素可以用来防止感染。

16 ongoing   

adj.进行中的，前进的

参考例句：

• The problem is ongoing.这个问题尚未解决。
• The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。

17 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

18 shrub   

n.灌木，灌木丛

参考例句：

• There is a small evergreen shrub on the hillside.山腰上有一小块常绿灌木丛。
• Moving a shrub is best done in early spring.移植灌木最好是在初春的时候。

19 specified   

adj.特定的

参考例句：

• The architect specified oak for the wood trim. 那位建筑师指定用橡木做木饰条。
• It is generated by some specified means. 这是由某些未加说明的方法产生的。

20 twig   

n.小树枝，嫩枝；v.理解

参考例句：

• He heard the sharp crack of a twig.他听到树枝清脆的断裂声。
• The sharp sound of a twig snapping scared the badger away.细枝突然折断的刺耳声把獾惊跑了。

21 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

22 gliding   

v. 滑翔 adj. 滑动的

参考例句：

• Swans went gliding past. 天鹅滑行而过。
• The weather forecast has put a question mark against the chance of doing any gliding tomorrow. 天气预报对明天是否能举行滑翔表示怀疑。