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An important aspect of organic farming is to minimize the detrimental impact of human intervention to the surrounding environment by adopting a natural protocol in system management. Traditionally, organic farming has focused on the elimination of synthetic fertilizers and pesticides and a reliance on biological cycles that contribute to improving soil health in terms of fertility and pest management. Organic production systems are ecologically and economically sustainable when practices designed to build soil organic matter, fertility, and structure also mitigate soil erosion and nutrient runoff. We found no research conducted under traditional organic farming conditions, comparing bareground monoculture systems to systems incorporating the use of living mulches. We will be focusing on living mulch studies conducted under conventional methodology that can be extrapolated to beneficial uses in an organic system. This article discusses how organic farmers can use living mulches to reduce erosion, runoff, and leaching and also demonstrate the potential of living mulch systems as comprehensive integrated pest management plans that allow for an overall reduction in pesticide applications. The pesticide reducing potential of the living mulch system is examined to gain insight on application within organic agriculture.

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An experiment to determine the response of four potted anthurium cultivars to sequential preemergence herbicide applications was conducted at a commercial nursery located in Mt. View on the Island of Hawaii. The four cultivars tested were: Lady Ann, Sundial, Tropic Fire, and Nicoya. Herbicides were applied at two rates, the anticipated labeled use rate (1X) and two times the anticipated labeled use rate (2X). The herbicides evaluated in this experiment were diuron, isoxaben, sulfentrazone and oryzalin. Herbicide applications were directed to the base of plants to avoid direct contact with leaves and flowers. Applications were made at 64-, 69-, 70-, and 98-day intervals for a total of 5 sprays. At 71 days after the last spray application, each plant was collected to determine the number of flowers and dry weight accumulation of leaves, shoots and roots. There was a significant interaction between the chemical treatments and the cultivar for leaf dry weight accumulation. Sulfentrazone 1X and 2X significantly reduced the dry weight in all four cultivars compared to the untreated controls. Leaf weights for the isoxaben (1X) treatments were not significantly reduced for all cultivars. However, `Lady Anne' was significantly reduced at the 2X rate of isoxaben. Leaf weights for diuron and oryzalin at both 1X and 2X treatments were not significantly different from the untreated control. Only sulfentrazone reduced shoot dry weight and flower number. Diuron was the only herbicide that did not reduced root dry weight.

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Two long-term field experiments were conducted from 1998 to 2000 to compare the yields of marketable eggplant in a buffelgrass living mulch system to a conventional monoculture bare ground system. The initial experiment compared the yields in the conventional treatment to living mulch treatments, that were chemically suppressed at three levels of sethoxydim applied at 0.1, 0.2, and 0.3 kg·ha-1 a.i. Regression analysis did not reveal a significant linear response of eggplant yield to increasing levels of sethoxydim. The average cumulative yield of the three living mulch treatments, 130 days after transplant (DAT), was 4,296 kg·ha-1 compared to 2,079 kg·ha-1 for the conventional treatment. The higher yield in the living mulch treatments was due to a mite infestation that was much more pronounced in conventional plots. In the follow-up experiment, three different living mulch management (mechanical suppression, chemical suppression, and untreated) treatments were compared to a conventional monoculture bare ground treatment. There was no mite infestation affecting this experiment and cumulative yields of marketable fruit at 159 DAT were 5,362, 4,521, 4,155, and 2,535 kg·ha-1 for conventional bare ground, mechanical suppression, chemical suppression and untreated living mulch treatments, respectively. Orthogonal comparisons showed that the yields from the conventional treatments were not significantly different from the suppressed living mulch treatments. However, the eggplant yields from the unmanaged living mulch treatments were significantly reduced in comparison to the conventional and also the suppressed living mulch treatments.

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Two experiment were conducted in 1999 and 2000 to determine the response of orchid cultivars, grown as potted plants, to postemergence herbicides. In a film covered commercial nursery in Pahoa, four orchid cultivars were exposed to five sequential herbicide applications. The cultivars used were: Emma White (Dendrobium), Wildcat Blood Ruby, Volcano Queen (both Oncidiums), and SuFun Beauty (Vanda). The herbicides evaluated in this experiment were diuron and clopyralid applied at the anticipated (1×), 2×, and 4× use rate. Spray applications were made directly to crop foliage using a spray to wet application. The first application was applied on 11 Nov. 1999 with sequential applications made at 20-, 208-, 73-, and 69-day intervals for a total of five sprays. Orchid dry weight accumulation was not significantly reduced and all cultivars responded in a similar way. “Emma White” was the only cultivar to express abnormal growth to clopyralid in the form of J-shaped flower spikes and deformed flowers. The other three cultivars did not show any noticeable injury in response to any of the spray applications. A follow up experiment was conducted on the dry leeward coast of Oahu in a commercial saran house. Diuron was the only herbicide evaluated at one and four times the anticipated labeled use rate. The first application was made on 27 Apr. 2000 with sequential applications made at 50-, 21-, 70-, and 66-day intervals for a total of five sprays. The orchids selected for this experiment included nine Dendrobiums and one Vanda. Treatments were made directly to plant foliage using a spray to wet application. Whole plant dry weight accumulation of the 10 cultivars responded in a similar way and no herbicide treatment reduced dry weight accumulation in comparison to untreated plants.

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Abstract

Red kidney bean (Phaseolus vulgaris L.) plants were grown continuously under 35-40%, 70-75%, or 95-100% relative humidity in growth chambers. There were no significant differences in fresh or dry weight of plants after 20 or 26 days’ growth in the chambers. Water consumption was significantly lowered by the highest humidity, and the dry weight produced per unit of water consumed was significantly greater in those plants grown at 95-100% relative humidity. After 47 days at the stated humidity levels, no significant differences were found in fresh or dry weight of the fruits. The only significant difference in seed dry weight was between the lowest and the medium humidity. The yield in the low humidity was 60% of that in the medium humidity. Thus, there are no significant reductions in either growth or yield of bean plants by continuous growth at near saturation relative humidity.

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