Search Results
Feeding preference of melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae) was evaluated on 21 Dendrobium cultivars and the bamboo orchid Arundina graminifolia (D. Don) Hochr. Pigmented flowers resembling the morphotype phalaenopsis from Phalaenanthe sections were preferred over nonpigmented phalaenopsis, Phalaenanthe × Ceratobium hybrids, and bamboo orchids. This study suggests the separation of susceptible cultivars from preferred cultivars as a pest management strategy for melon thrips control.
Vapor heat treatments to disinfest tropical cut flowers and foliage were evaluated using a commercial facility. Efficacy was determined for specific durations against representative Hawaiian quarantine pests on their plant hosts. Nymphs and adults of aphids, soft and armored scales, mealybugs, and thrips were killed after 1 hour at 46.6C, and both life stages of aphids and armored scales along with mealybug nymphs after 2 hours at 45.2C. Injury to several varieties of Hawaiian floral commodities (Araceae, Musaceae, Zingiberaceae, Heliconiaceae, Orchidaceae, Marantaceae, Lycopodiaceae, Agavaceae, Proteaceae) during these treatments was determined. Large heliconias, most red ginger, bird-of-paradise flowers and leaves, and most foliage were not damaged; anthuriums, pincushion protea, and orchid flowers and foliage were very sensitive to vapor heat. Treatment modification was needed to reduce plant injury to these commodities without losing efficacy. The number of shelf-life days of the treated plant material was estimated from the visual ratings.
Abstract
A study of anthurium farms in Hilo, Pahoa, and Kurtistown, Hawaii was conducted to assess types of unmarketable anthurium (Anthurium andraeanum André cv. Ozaki) flowers. Of the 5000 flowers harvested from test plots on each farm during 1 year, total flowers rejected were 32%, 31%, and 26% at the three farms, respectively. At all farms, mechanical injury was the most common type of reason for rejection of flowers, followed by curved petiole; rejections due to insects, mites, and diseases were minimal. The incidence of sunburn, phytotoxicity, thrips, and mites differed among seasons at Hilo and/or Kurtistown.
Abstract
Dimethoate 4EC, fenpropathrin 2.4EC, fluvalinate 2F, oxamyl 2L, chlor-pyrifos 4EC, malathion 5EC, diazinon 4EC, and oxydemeton-methyl 2EC insecticides significantly reduced injury of anthurium (Anthurium andraeanum Lind. & Andre cv. Ozaki) flowers by the orchid thrips, Chaetanaphothrips orchidii (Moulton). Injury was characterized by white streaks and/or scarrings occurring primarily on the abaxial surface only or on both adaxial and abaxial surfaces of the spathe. Injury on the adaxial surface occurred only at 0.15% of all thrips-injured spathes observed during the study period. Thrips injury on anthurium flowers in control plots during Aug. 1984 to Sept. 1985 decreased to 3% during Feb. and Mar. 1985, and increased to 90% during Sept. 1985. Chemical names used: O,O-dimethyl S-[2-(methylamino)-2-oxoeth-yl]phosphorodithoate (dimethoate); (Rs)-α-cyano-3-phenoxybenzyl 2,2,3,3-tetramethyl cyclopropanecarboxylate (fenpropathrin); N-[2-chloro-4-(trifluoromethyl)phenyl]-DL-valine (±)-cyano(3-phenoxyphenyl)methyl ester (fluvalinate); S-{2-(ethyl suffinyl)ethyl}O,O-dimethylphosphorothioate (oxydemeton-methyl); methyl 2-dimethylamino)-N-[[(methylamino)carbonyl]oxy]-2-oxoethanimidothioate (oxamyl); O,O-diethyl 0-[6-methyl-α-(1-methylethyl)-4-pyrimidinyl] phosphorothioate (diazinon); O,O-diethyl O-(3,5,6-trichloro-2-pyridyl)-phosphorothioate (chlorpyrifos); and diethyl [(dimethoxyphos-phinothiovl)thio] butanedioate (malathion).
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.
Phytotoxicity from hydrogen cyanide (HCN) fumigation was measured in several varieties of Hawaiian cut flowers and foliage (Zingiberaceae, Heliconia, Orchidaceae, Marantaceae, Lycopodiaceae, Agavaceae, Proteaceae) as a potential disinfestation treatment. Concentrations tested were 2500, 3700, 4600, and 5500 ppm HCN for 30 min. All foliage and most heliconia were undamaged at fumigation levels of 5500 ppm HCN; most protea and `Midori' anthuriums were uninjured at 4600 pm HCN; red and pink ginger were uninjured at 3700 ppm HCN; and all pincushion protea showed phytotoxicity to HCN. Red ginger was quickly damaged when exposed to sunlight immediately after treatment at 2500 ppm HCN. No injury was observed in simulated shipment tests of red ginger and `Ozaki' anthuriums fumigated at 2500 ppm HCN. Wet, red ginger flowers longer than 6 cm were damaged at 2500 ppm HCN, whereas shorter flowers were uninjured. Wet `Ozaki' anthuriums showed phytotoxicity only at 4600 ppm HCN. Wet, treated lycopodium and bamboo orchid foliage was not injured. The number of marketable days and shelf life of the treated plant material were estimated from the visual ratings.
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.
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.
Burrowing nematode (Radopholus similis) causes severe stunting and yield reduction in anthurium (Anthurium andraeanum) cut flower production. Two field trials were conducted at commercial grower farms to test the efficacy of fluopyram or fluopyram + trifloxystrobin for managing burrowing nematodes. Nematode population densities in roots and cinder media were evaluated during the trial in addition to cut flower yield and canopy cover. In the first trial, the nematode population in roots was reduced by 57% after two applications of fluopyram 3 months apart. As plant health improved, the increasing anthurium root weight supported higher nematode populations. After 14 months, fluopyram-treated plots had 43% more green canopy cover and a 53% increase in flower production compared with the untreated control plots. At a second location, population densities of burrowing nematode were reduced in roots after one application of fluopyram + trifloxystrobin and remained low with quarterly applications. Nematode populations were initially reduced in fluopyram-treated plots followed by a resurgence as demonstrated in the other trial. Ten months after the initial treatment, flower yield was greater in fluopyram + trifloxystrobin-treated plots with more large and extra-large flowers produced. Canopy cover was 45% and 22% greater with fluopyram + trifloxystrobin and fluopyram applications, respectively. Fluopyram shows potential for management of burrowing nematodes in anthurium by improving plant vigor and cut flower production.