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concentrations within the chambers reached 200 ± 5 ppb, the ozone-generating system was turned off and the ozone depletion rate (time to <5 ppb) for each chamber was recorded at approximate 5- to 6-min intervals. This depletion rate was used as an indicator that

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environmental impacts, including ozone depletion, smog, acidification, eutrophication, carcinogenic or non-carcinogenic human toxicity, respiratory effects, ecotoxicity, and fossil fuel depletion [ U.S. Environmental Protection Agency (USEPA), 2008 ]. These are

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, chlorine gas, ozone, and copper require strategic implementation to work effectively. For example, although copper is an essential element for plant growth, an excessive amount is toxic and requires careful monitoring ( Zheng et al., 2004 ). The costs and

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ozone-depleting effects ( Hoffmann et al., 2020 ). Since then, several chemical fumigants have appeared on the market to replace methyl bromide, such as benzamide, sodium methylamine, and 1,3-dichloropropene ( Yan et al., 2017 ). Metham sodium, a type of

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effective soil disinfestation in horticultural crop production ( Butler et al., 2014 ). With the phase-out of methyl bromide, as part of the Montreal Protocol to reduce ozone depletion, research has focused on developing alternative chemical and biological

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intensity, diversity, and high capital costs inherent in this cropping system have led to a reliance on MB fumigation for preplant control of a broad range of soilborne pathogens, weeds, and nematodes. MB was classified as a Class I stratospheric ozone-depleting

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Methylbromide is the standard fumigant used for tomato production in Florida. Since it been classified as a category 1 ozone depleter and is to be phased out by 1 Jan 2001 replacement methods of fumigation must be found. Several materials in 1993 were compared to methylbromide in production of `Colonial' tomatoes. These included metham sodium (applied through drip at 3 rates and applied to soil at 935 l·ha-1 and tilled in), dazomet (applied at 2 rates and tilled in), 1,3 dichloropropene + chloropicrin and untreated check. None of the treatments were as effective as methylbromide in reducing root galling by root knot nematodes. Total yields were not affected by treatments even though root system of untreated plants was severely galled. Modifications are to be made for 1994 season and materials added to trial.

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With the phase-out of methyl bromide because of its impact on ozone depletion and the shift to a more protected culture system in organic vegetable production, grafting practice has gained greater attention in the United States because it may be considered a viable disease control method in organic vegetable production. However, there is a lack of information on the economic feasibility of using grafting in organic tomato (Solanum lycopersicum) production in a protected culture system such as a high-tunnel system. Using 2-year on-station trial data collected in Citra, FL, we examined the effect of using grafting on the economic returns of organic tomato production in high tunnels. Our analysis suggests that grafting tends to increase the marketable yield of organic tomato production in high tunnels. However, the enhanced yield does not necessarily increase the net return, depending on market conditions and the relative performance of grafted transplants. In addition, our results indicate that the net return of grafted production is highly sensitive to the tomato selling price. Obtaining a price premium is essential for increasing the profitability of grafted organic tomato production in high tunnels.

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Methyl bromide (MeBr) is an important and effective soil fumigant commonly used to control weeds and soilborne pests. Because MeBr has been implicated as a contributor to the depletion of stratospheric ozone, it is scheduled for phaseout by 2005. This study examined nonchemical and chemical practices as alternatives to MeBr. Off-season flooding followed by a series of soil preplant chemical treatments [MeBr with 33% Pic; 1,3-D mixed with 17% (C-17) and 35% (C-35) Pic combined with Peb; and metam-Na combined with 1,3-D and Peb were evaluated on spring tomato (Lycopersicon esculentum Mill.) and eggplant (Solanum melongena) production in northern Florida. Pest control and tomato and eggplant yields were not significantly different between the flooded and non-flooded control plots. The most effective alternatives to MeBr were 1,3-D and Pic mixtures (C-17 and C-35) combined with Peb. Tomato and eggplant yields for these chemicals were statistically equivalent to that of MeBr. Tomato, but not eggplant, yield and nematode control were poor with metam-Na combined with 1,3-D and Peb in comparison to the other fumigant combinations. Chemical names used: 1,3-dichloropropene (1,3-D); trichloronitromethane [chloropicrin (Pic)]; S-propyl butyl(ethyl)thiocarbamate [pebulate (Peb)]; sodium N-methyldithiocarbamate (metam-sodium (metam-Na)].

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