Progress 10/01/02 to 09/30/06
Outputs
Injections of phosethyl-Al into trees of all ages from those with 30 cm of trunk from soil surface to the base of fronds and up were effective in controlling bud rot. While annual injections were the norm, the interval between treatments can be as much as three years without loss of treated plants. Infections by secondary fungi at the injection site, a sometimes serious problem in windward locations, were controlled by applying the material during dry periods and strict sanitation of the injection site and of application equipment. Although annual compost applications around trees appeared to be beneficial protection from infection and death were not totally eliminated. After three years Royal, Manila, Alexander and Fiji Fan palms were not killed by Phytophthora katsurae in a bud rot endemic area of Haiku, Maui. These species could be replacements for coconut in some landscape applications. However, the coconut palm is so identified with the tropical effect that Hawaii
visitor destinations seek to project and that visitors expect these species are not fully acceptable to the landscape industry as replacements for the coconut palm. Also the Alexander palm is considered an invasive species in Hawaii. Since trees in non-endemic bud rot areas can survive with the fruit infection phase for years, a systematic planting of replacement coconuts palms and fungicide injections is the usual recommendation for highly managed landscapes such as hotel and condominium grounds and golf courses in these areas.
Impacts
Since acquiring nuts for planting from the resistant material has not been possible, host resistance is not a viable solution to this problem in Hawaii. Fan and Alexander palms could replace coconuts as ornamental palms in Hawaii. Compost applications will probably be a supporting treatment to systemic fungicides for control of bud rot in the near term.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
No further progress has been made on collection of nuts from remnants of the original Wishard germplasm collection in Puako or a secondary planting at the National Tropical Botanical Gardens Kahanu Gardens. Fiji Fan Palm and Alexander Palm continue to be the best performing palms in the eight palm species trial planted in 2002. Preliminary tests of composts for control of bud rot were beneficial for overall growth of mature trees but were not large enough to demonstrate efficacy. These tests will be expanded during the current year with the number of fruit per tree infected used as the measure of efficacy instead of tree death.
Impacts
Since acquiring nuts for planting from the resistant material has not been possible, host resistance is not a viable solution to this problem in Hawaii. Fan and Alexander palms could replace coconuts as ornamental palms in Hawaii. Compost applications will probably be a supporting treatment to systemic fungicides for control of bud rot in the near term.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
Further records of the Wishard coconut collection in the Mary Wishard Memorial Coconut Grove at the Kahanu Gardens, National Tropical Botanical Gardens were uncovered and a better inventory of the collection conducted in mid 2004. The plants were installed in late 1976. While there is still some question as to the original number of accessions planted, it appears to be 34. The surviving plants can be assigned to 13 of those accessions with a high degree of certainty. An additional 6 accessions can be identified where all individuals have succumbed. There are six accessions which suffered 50% or less mortality over the 28 years they have been in place. Of these, the varieties Ivory and Rotuma survived at 83 and 78% respectively. The other four had survival rates of 50 to 67%. It is, therefore, encouraging to think that some resistance to bud rot exists in the collection. Unfortunately, we have not yet been able to collect any viable seed from the surviving trees to
plant out at our Haiku site to date. In an effort to gather seed for planting, the original grove in Puako was visited and contacts made with current owners of the now subdivided property. Many of the trees have died or been removed and almost all are being trimmed to remove fruit and fronds for safety reasons. A few of the owners indicated a willingness to suspend trimming of trees away from trafficked areas to allow collection of mature fruit. In the endemic bud rot area of Haiku, Maui the eight palm species planted in mid 2002 continue to do well.
Impacts
Alternative palm species to replace coconut in P. katsurae endemic areas are available. It appears promising that some host resistance to P. katsurae is present in the Wishard coconut collection. Developing this resistance will enable the coconut to continue as a prominent palm in bud rot endemic areas of Hawaii.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
Late in 2003 an examination of the coconut collection derived from selfed fruit from the Wuchard collection planted about 25 years ago at the Kahanu Gardens of the National Tropical Botanical Gardens, Hana, Maui, Hawaii was conducted. The Wuchard collection is probably the largest germplasm pool in Hawaii and contains a broad range of varieties from throughout the Pacific from the early to the mid 20th century. The accessions at Kahanu have not been well documented. Through out the years maps and planting records have been lost. Approximately 20% of the plants survive. None of the surviving trees were obviously infected with P. katsurae. However, almost every fruit which had fallen displayed classical symptoms of P. katsurae infection. Thus none of the surviving trees based on fallen fruit observations has high resistance to P. katsurae. While most of the original tall type trees were too tall to examine fruit still on the tree, two individuals which appeared to be
dwarf atoll drinking types had fruit still on the tree which were healthy. Mature fruit of these trees and others trees which appear healthy will be planted out at a less disease conducive site in Haiku, Maui as they become available to see if any accessions have at least some resistance to the pathogen. The Kahanu Garden site is a particularly poor one for growing coconuts. It is in an area of very high rainfall at the bottom of a valley with a high water table. The area appears to be underlain by pahoehoe which helps maintain the high water table. In the endemic bud rot area of Haiku, Maui eight palm species were planted in mid 2002. Royal palms have done poorly. While Fiji fan palm and Alexander palm have done fairly well. The other palms have not taken off but are growing at a slower pace. Of the Royal palms which succumbed none were killed by P. katsurae. Monitoring of test plants in commercial landscapes injected with potassium phosphite have been surviving at a much better rate
than near by non-treated plants. However, injection site infections with secondary fungi is a problem at some test sites.
Impacts
A few alternative palm species to replace coconut in P. katsurae endemic areas will become available. The presence or absence of genetic resistance in the most diverse collection of coconut germplasm in Hawaii will be documented.
Publications
- No publications reported this period
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