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  • Author or Editor: Koon-Hui Wang x
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Radopholus similis distribution in Anthurium plant tissue was determined in a greenhouse experiment. Two thousand mixed life stages of R. similis per plant were inoculated onto Anthurium cultivars `Alii' and `Midori'. Nine months later, nematodes per gram of tissue were determined from stem sections (0-3, 3-6, and above 6 cm from the base), the lowest leaf petiole, and root tissue. R. similis occurred in all stem sections, leaf petioles, and roots in both `Alii' and `Midori'. Nematode distribution differed between the two cultivars. `Midori' had higher numbers of nematode in the roots whereas `Alii' had higher numbers of nematode in the stem sections and first leaf petiole. Anthurium apical stem cuttings could be contaminated with R. similis and may not be a nematode-free propagation material.

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The application of locally available invasive algae biomass as a fertilizer for crop production in Hawaii is being investigated as a substitute for imported chemical fertilizers. Three closely related greenhouse trials were conducted to determine if the algae served as a source of potassium (K) on growth, yield, and K mineral nutrition in pak choi (Brassica rapa, Chinensis group). In the first trial, three algal species (Gracilaria salicornia, Kappaphycus alvarezii, and Eucheuma denticulatum) were applied at five rates of K, each to evaluate their effects on growth and K nutrition of pak choi plants. The pak choi was direct seeded into 0.0027-m3 pots containing peatmoss-based growth media. In trial 2, pak choi was grown in peat media at six rates of K provided by algae (E. denticulatum) or by potassium nitrate (KNO3). In trial 3, the six rates of K were provided through algae (K. alvarezii), KNO3, and potassium chloride (KCl) and were compared for growth and K nutrition. Results from the first greenhouse trial showed no significant differences among the three algal species in yield or tissue K content of pak choi. However, plant yield and tissue K concentration were increased with application rates. The maximum yield and tissue K were observed when K was provided within the range of 250–300 kg·ha−1. Similarly, in Expts. 2 and 3, there were no significant differences between commercial K fertilizers and algal K species for yield. Only K rates were significant for yields and tissue K concentrations. It was concluded that K in the invasive algae was similarly available as K in commercial synthetic fertilizers for pak choi growth in terms of yield and tissue K content under our experimental conditions.

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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.

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