A new problem of macadamia trees (Macadamia integrifolia Maiden and Betche) in Hawaii is characterized by slight leaf chlorosis, followed by rapid leaf browning, and tree death. Ambrosia beetle [Xyleborus affinis Eichhoff and X. perforans Wollastan (Coleoptera: Scolytidae)] infestations and fungal fruiting bodies were present on trees that subsequently exhibited the decline pattern. `Ikaika' was the most susceptible cultivar, and tree death occurred 8.3 ± 2.6Sd months after beetle infestations were detected.
David H. Oil, Gary Ueunten, Alan Yamaguchi, Mike A. Nagao, Arnold H. Hara and Wayne T. Nishijima
A.C. Arcinas, B.S. Sipes, A.H. Hara and M.M.C. Tsang
Exporters of potted nursery stock face strict quarantine regulations against the burrowing nematode, Radopholus similis. Currently, there are no treatments approved by quarantine authorities to disinfest plants of R. similis. Interceptions of the nematode lead to significant economic loss and curtailment of trade, therefore hot-water drench treatments were investigated for quarantine utility. Drenches with 50 °C water were applied for 10 to 16 minutes to two economically important palm species, rhapis (Rhapis excelsa) and fishtail (Caryota mitis). Plants were inoculated with 5,000 mixed life stages of R. similis and allowed to establish for 14 weeks before drench treatments. In rhapis, a moderately good host to R. similis, a 16-minute hot water drench had high efficacy, achieving 99.6% mortality. In fishtail, a poor host, all treatments longer than 10 minutes at 50 °C eliminated R. similis from the plants. Probit regression estimates of the LT99, were 16.9 and 10.3 minutes respectively. However χ2 goodness-of-fit tests were significant (χ2 = 21.136, df = 3, p < 0.0001) for rhapis. Since most observed values were between the 95% fiducial limits, this suggests that the large χ2 value was caused by variability in response or insufficient repetitions rather than an inappropriate model. A χ2 statistic could not be computed for fishtail because poor host status led to variances that were nearly equal to zero. The high efficacy of hot water drenches for the control of R. similis is approaching the Probit 9 standard of 99.9968% mortality required for approval as a quarantine treatment.
Arnold H. Hara, Trent Y. Hata, Victoria L. Tenbrink, Benjamin K.S. Hu and Mike A. Nagao
Postharvest treatments significantly reduced or eradicated pests on various tropical cut flowers and foliage. Immersion in water at 49° C for 10 minutes killed armored scales on bird of paradise leaves, Strelitzia reginae Banks, as well as aphids and mealybugs on red ginger, Alpinia purpurata (Vieill.) K. Schum. Vapor heat treatment for 2 hours at 45.2° C provided quarantine security against armored scales on bird of paradise leaves. A 5 minute dip in fluvalinate combined with insecticidal soap eliminated aphids and significantly reduced mealybugs on red ginger. A 3 minute dip in fluvalinate, a 3 minute dip in chlorpyrifos, or a 3 hour fog with avermectin-B significantly reduced thrips on orchids, Dendrobium spp., without injury to the flowers. No postharvest treatment was both effective and nonphytotoxic on all commodities.
Trent Y. Hata, Arnold H. Hara, Mike A. Nagao and Benjamin K.S. Hu
Frangipani (Plumeria hybrid `Donald Angus') cuttings immersed in hot water (49C for 10 min) followed by 0.8% indole-3-butyric acid (IBA) basal treatment (hot water + IBA) had greater root length and weight compared to the nontreated control, hot water, or IBA treatment alone. Greater percentage of rooting and number of roots per cutting were observed for hot-water-treated + IBA-treated cuttings compared to the non-treated control and hot-water treatment alone. In a second study, Dracaena fragrans (L.) Ker-Gawl. `Massangeana', D. deremensis Engl. `Warneckii', D. deremensis Engl. `Janet Craig', D. marginata Lam., and cape jasmine (Gardenia jasminoides Ellis) cuttings displayed results similar to those observed with Plumeria cuttings. In addition to enhancing rooting, hot water + IBA also stimulated the number of shoots per cutting on anthurium (Anthurium andraeanum Andre `Marian Seefurth'), croton [Codiaeum variegatum (L.) Blume var. pictum (Lodd.) Mull. Arg.], D. marginata, D. fragrans, Plumeria, and ti (Cordyline terminalis `Ti') cuttings.