Report to the Republic of Palau: 2008 update on Invasive Plant ...

Because <strong>of</strong> <strong>the</strong> size and serious nature <strong>of</strong> this infestation, a thorough ground survey should be
conducted <strong>to</strong> determine <strong>the</strong> extent <strong>of</strong> <strong>the</strong> problem and <strong>to</strong> develop a strategy for control and
<strong>the</strong> prevention <strong>of</strong> spread country-wide. The biological evaluation by <strong>the</strong> USFS in 2006
recommended mapping, moni<strong>to</strong>ring and an integrated control program. The thrips Leothrips
urichi is well stabled in <strong>the</strong> Nekken area and effective in controlling Clidemia in open areas
but largely ineffective in shady forested habitats. In Hawaii, <strong>the</strong> pathogen Colle<strong>to</strong>trichum
gleosporoides f. sp. clidemiae has defoliated extensive areas under cool, windy and moist
wea<strong>the</strong>r conditions .
• A single Datura metel (jimson weed) plant was found on Ngerchu (Carp) Island and it is
infrequently seen on o<strong>the</strong>r islands. Examples <strong>of</strong> this weedy plant should be eliminated when
<strong>the</strong>y are found.
• A recent introduction, Episcia reptans (flame violet), is being planted extensively at <strong>the</strong>
<strong>Palau</strong> Pacific Resort. An example was also seen on Koror. This attractive plant is likely <strong>to</strong>
be cultivated widely as a garden plant. It appears <strong>to</strong> spread aggressively in low-light
conditions, posing a threat <strong>of</strong> escape from cultivation. A risk assessment should be
performed on this species <strong>to</strong> determine fur<strong>the</strong>r management action. A decision on fur<strong>the</strong>r
action is needed soon; o<strong>the</strong>rwise, given its attractive nature, this plant will soon be planted all
over <strong>Palau</strong>.
• Falcataria moluccana (ukall ra ngebard, Moluccca albizia) may not be as invasive in <strong>Palau</strong>
as elsewhere in <strong>the</strong> Pacific. In fact, some <strong>of</strong> <strong>the</strong> older trees are now dying and, if <strong>the</strong>y are not
being replaced, <strong>the</strong> species may actually be decreasing in abundance. Never<strong>the</strong>less, given its
invasive nature elsewhere and <strong>the</strong> difficulty and expense <strong>of</strong> controlling trees once <strong>the</strong>y
become large, <strong>the</strong> extent <strong>of</strong> <strong>the</strong> infestation should be mapped and its reproduction and spread
should be evaluated <strong>to</strong> confirm whe<strong>the</strong>r or not it is a threat. If a small plane is available it
may be possible <strong>to</strong> conduct an aerial survey, given <strong>the</strong> distinctive appearance <strong>of</strong> <strong>the</strong> crown <strong>of</strong>
this species. In <strong>the</strong> meantime, it would be prudent <strong>to</strong> not plant it more widely and <strong>to</strong>
eliminate isolated trees where feasible. <strong>Palau</strong> should request technical assistance from <strong>the</strong>
US Forest Service for evaluation, and if control is desired, request technical assistance from
<strong>the</strong> National Park <strong>of</strong> American Samoa through <strong>the</strong> PILN. The wood <strong>of</strong> <strong>the</strong>se trees is
extremely brittle and, if near homes or o<strong>the</strong>r habitation, pr<strong>of</strong>essional arborists are needed <strong>to</strong>
fell <strong>the</strong>se trees.
• Hyptis pectinata (mint weed) has <strong>the</strong> potential <strong>to</strong> become a problem in <strong>Palau</strong>, as it has several
o<strong>the</strong>r places in <strong>the</strong> Pacific. It is primarily an agricultural pest and a weed <strong>of</strong> disturbed areas.
Only a few specimens were seen on Babeldaob in 2002 and it was reported present on
Angaur (Fosberg et al., 1979) but not seen. A survey should be conducted <strong>to</strong> determine <strong>the</strong>
extent <strong>of</strong> this species and, if feasible, it should be eradicated before it spreads more widely.
Because it is primarily <strong>of</strong> agricultural concern, perhaps <strong>the</strong> Natural Resources Conservation
Service could provide assistance.
• Eradication <strong>of</strong> Imperata cylindrica should be pursued <strong>to</strong> completion.
• The biological control agents for Lantana camara (lantana) should be moni<strong>to</strong>red <strong>to</strong> make
sure <strong>the</strong>y are present. If not, or if new ones are available, <strong>the</strong>y may need <strong>to</strong> be introduced.
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