Progress 10/01/02 to 09/30/05
Outputs
Maile Alyxia oliviformis harvested in the Cook Islands, woven into garlands, and dipped in Dimethoate and DeltaGuard II one day after harvest, were air-shipped to Hawaii. Garlands were randomly assigned to 1 of 5 treatment groups (5 reps per group), and immersed in hot water (49C) for 3, 5, 7 or 10 min. The control group was soaked in ambient water for 15 min. After treatment, all garlands were stored at 46C. At four days after treatment (DAT), the garlands were evaluated for thermal damage daily. On a scale of 1 to 5, each garland was rated based on the percentage of damaged leaves (1 = 0%, 2 = 25%, 3 = 50%, 4 = 75%, 5 = 100% damage). Thermal damage appeared as brown, water-soaked leaves with higher translucency than undamaged leaves. Creases on the leaves were darkened by water soaking into the damaged tissue. On 5 and 6 DAT, the thermal-damaged leaves dried to a lighter brown and were more desiccated than undamaged leaves. Leaf drop was minimal for all treatments and
included green as well as browned leaves. From 5 DAT, garlands treated for 7 and 10 min were noticeably browner and desiccated as compared to the control. Burrowing nematode Radopholus similis numbers were reduced to less than 1.0 per g of infested roots in potted anthuriums drenched with hot water at either 49 or 50C for 5 to 20 min. The random persistence of nematodes in 1 or 2 plants irrespective of treatment poses a major challenge for quarantine purposes. Since precautions were taken to minimize passive contamination, reinfestation may be from R. similis migrating from untreated stem tissue. Plant growth (lower dry weights of tops and roots) were negatively impacted by the hot water treatments, especially among bare-rooted-dipped plants; however, most anthurium cultivars evaluated appeared to be tolerant to heat, with no noticeable thinning or yellowing of foliage. Anthurium propagative stems (gobo) hot air-treated at 50C for 15 or 30 min had up to 85% shoot eruption 4 weeks
after treatment (WAT), compared to 52% for untreated gobo. At 8 WAT, the heat-treated gobo had more leaf, shoot, and root development compared to untreated gobo. Two varieties of potted bromeliads, three species of potted palms (Caryota spp., Chamaedorea elegans, Rhapis excelsa), and four varieties of Dracaena (D compacta, D marginata 'Tricolor', D. warneckii, D. massangeana) were treated in a hot water shower at 45C for 6 min, 49C for 6 min, or 49C for 12 min. All plant species treated at the lower temperature (45C) displayed no thermal damage. Most plants treated at 49C for 6 or 12 min. displayed some bleached spots on the foliage and flower bracts 1 WAT, which gradually turned browned 4 WAT. Young shoots emerged damaged at 5 WAT; however, by 6 WAT, no further damage was observed. All four Dracaena spp. exhibited browning near the growing point and on new leaves at 1 WAT, and while they began recovering by 6 WAT all were aesthetically unmarketable.
Impacts
Heat treatments at temperatures and durations required for quarantine disinfestation continue to be proven safe on a variety of plant material, including cut maile garlands (hot water 49C for 3 or 5 min) , palms (hot water 45C for 6 min), Dracaena spp. (hot water 45C for 6 min), anthurium gobo (hot air 50C for 15 or 30 min), and bromeliads (hot water 45C for 6 min), with very little or no thermal damage. Modifications to the hot water drench system or protocol are needed to ensure adequate treatment of stem tissue as well as roots for complete elimination of R. similis in infested plants.
Publications
- Hara, A.H. 2005. Disinfestation treatments for cut flowers and potted ornamentals. pp. 21-24. In K.W. Leonhardt and P. Nakao (eds.) Proceedings for the 2004 Hawaii Floriculture Conference, Kahului, HI, University of Hawaii at Manoa, CTAHR Proceedings P-04/05.
- Tsang, M.M.C., Hara, A.H. and Sipes, B.S. 2004. Efficacy of hot water drenches of Anthurium andraeanum plants against the burrowing nematode Radopholus similis and plant thermotolerance. Annals of Applied Biology. 145:309-316.
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Progress 10/01/03 to 09/30/04
Outputs
Potted parlor palm, Chamaedorea elegans, rhapis palm, Rhapis excelsa, fishtail palm, Caryota mitis, and Dracaena spp. (Warnecki, Massangeana, Tricolor, and Compacta cultivars) all grown in 20% peat moss and 80% black cinder, and bromeliads (100% peat moss, Marjan and Fiesta cultivars) were subjected to hot water shower treatments at 45 C for 6 min, 49 C for 6 min, or 49 C for 12 min. All treatments were followed by drenching with ambient temperature water for a duration equal to half the treatment time. All species and cultivars tested tolerated treatment at 45 C for 6 min with no thermal damage. Fishtail and rhapis palms also withstood 49 C treatments with minor damage to their growing points that became evident 4 wk after treatment, only after the young leaves emerged. All four Dracaena cultivars tolerated 49 C for 6 min at treatment, but not 49 C 12 min; growing tips were damaged and took approximately 3 wk after treatment to recover when leaves fell off and new,
undamaged growth emerged. Parlor palms and bromeliads were sensitive to both 49 C treatments, with discolored foliage (bleached at first, turning brown at 2 wk, and blackening of parlor palms at 3 wk) and damage to young, emerging shoots at 5 wk after treatment. Bromeliads began to recover 6 wk after treatment.
Impacts
Hot water shower treatment at 45 C for 6 min did not adversely affect any species or cultivars of potted ornamentals evaluated. Fishtail and rhapis palms also withstood 6 and 12 min treatments at 49 C with no thermal damage. Four Dracaena cultivars tolerated 6 min at 49 C. Heat treatments continue to prove to be a practical, nonchemical alternative to chemical quarantine treatments on a variety of valuable potted tropical ornamental plants.
Publications
- Arcinas, A.C., Sipes, B.S., Hara, A.H. and Tsang, M.M.C. 2003. Hot water drench treatments for the control of Radopholus similis in rhapis and fishtail palms. HortScience. 39(3):578-579.
- Hara, A.H., Burnham Larish, L.L. and Tsang, M.M.C. 2003. Potential for hot-air disinfestation of protea flowers. VI International Protea Research Symposium Acta. Hort. 602:61-65.
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Progress 10/01/02 to 09/30/03
Outputs
Efficacy of hot-water drenching treatments were evaluated for disinfesting roots of potted anthurium, Anthurium andreanum, of the burrowing nematodes, Radopholus similis. A continuous drenching of the roots and media in pots with 50 C water for 5 to 20 min eliminated or reduced the nematode populations to <1/g dry root. A low number of survivors persisted in the roots and/or stems of a few plants after heat treatments. Non-treatment of the shoots and possible migration of live nematodes from stem to root tissues are probable causes of the survivors. Plant tolerance to hot-water treatment varied between cultivars with most cultivars tested showing good tolerance to hot-water drenching. All heat-treated plants suffered some phytotoxic heat damage as measured by the dry weight of the plants when compared to untreated plants at the conclusion of the study. However, visual inspection of the plants showed little difference between treated and untreated plants in the heat
tolerant cultivars. Heat conditioning prior to hot water drenching did appear to induce thermotolerance in the plants when compared to unconditioned anthuriums. Efficacy of a hot water dip (50 C) for different durations on coqui frog, Eleutherodactylus coqui, egg mortality was investigated as a means of controlling coqui frogs in potted plants and nurseries. No hatching of immersed eggs is predicted after 4 min 38.4 seconds and 1 min 54.5 seconds in 43 and 45 C water, respectively. A combination hot water system was fabricated to provide for both hot water dip for propagative cuttings and hot water drenches for potted plants. A 300-gallon hot water dip system previously designed by Tsang and Hara for cut flowers and foliage was modified to provide hot water for the drenching system, allowing for one source of hot water for both the dip and drench treatment. The hot water dip will be used to disinfest commercial quantities of top cuttings of quarantine pests, including snails, foliar
mealybugs and the banana moth, Opogona sacchari. The prototype hot water drenching system initially outfitted to treat up to 4 one-gallon size potted plants has been scaled-up to simultaneously handle up to 20 three-gallon size potted plants. Output data collected from the prototype drench system was used to calculate flow rates, filtering and instrumentation requirements for designing the commercial-sized system. A skate-wheel conveyor system was incorporated in the design to allow continuous batch treatment of potted plants (3 gal) for large export shipments (about 700 plants) via 40 ft ocean freight containers. The combination hot water dip and drench system was built to meet the demands of Japan and California nematode certification requirements, two of the world's most rigorous quarantine security systems.
Impacts
There are no safe, effective chemical alternatives against nematodes since the elimination of such nematicides as Nemacur because of their toxicity to humans and the environment. Our project is investigating heat treatments against burrowing nematodes for which there is zero tolerance by quarantine officials in plants leaving Hawaii. By allowing 50 C hot water to run through a potted rhapis palm for 16 minutes, burrowing nematode populations were reduced by 99.6% when compared to no treatment, with little effect on the quality of the palm. Hot water treatments are a practical alternative to chemical control of many root-infesting pests of quarantine significance. While potted palms were used in our trials, hot water treatment can be considered for any potted plants that are susceptible to plant parasitic nematodes and can benefit the entire potted ornamental industry.
Publications
- Tsang, M.C., Hara, A.H. and Sipes, B.S. 2003. Hot-water treatments of potted palms to control burrowing nematode, Radpholus similis. Crop Protection. 22:589-593.
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Progress 10/01/01 to 09/30/02
Outputs
No progress to report. This project was initiated on October 1, 2002.
Impacts
(N/A)
Publications
- No publications reported this period
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