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David W. Wolfe, Daniel T. Topoleski, Norman A. Gundersheim, and Betsy A. Ingall

A 3-year field study conducted on an Eel silt loam soil (Aquic Udifluvent) compared cabbage (Brussica oleracea L. capitata group), cucumber (Cucumis sativus L.), snap bean (Phaseolus vulgaris L.), and sweet corn (Zea mays L.) for their growth and yield response to an artificially compacted soil layer beginning at about the 10-cm depth. Slower growing cabbage seedlings in compacted plots were more subject to flea beetle damage than the uncompacted controls. Prolonged flooding after heavy rainfall events in compacted areas had a more adverse effect on cabbage and snap bean than on cucumber or sweet corn. Sweet corn showed almost no growth reduction in one of the three years (1993) when relatively high fertilizer rates were applied and leaf nitrogen deficiencies in compacted plots were prevented. Maturity of cabbage, snap bean, and cucumber was delayed, and the average reduction in total marketable yield in (direct-seeded) compacted plots was 73%, 49%, 41%, and 34% for cabbage, snap bean, cucumber and sweet corn, respectively. Yield reduction in transplanted cabbage (evaluated in 1993 only) was 29%. In a controlled environment greenhouse experiment using the same soil type and similar compaction treatment as the field study, compaction caused a reduction in total biomass production of 30% and 14% in snap bean and cabbage, respectively, while cucumber and sweet corn showed no significant response. The growth reductions of snap bean and cabbage in the greenhouse could not be attributed to compaction effects on soil water status, leaf turgor, nutrient deficiency, or net CO, assimilation rate of individual leaves. Root growth of sweet corn was least restricted by the compacted soil layer. The contrast between our field and greenhouse results indicates that the magnitude of yield response to compaction in the field was often associated with species sensitivity to secondary effects of compaction, such as prolonged flooding after rainfall events, reduced nutrient availability or uptake, and prolonged or more severe pest pressure.

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Jesse Wimer, Debra Inglis, and Carol Miles

reduced verticillium wilt severity of grafted watermelon plants at a naturally infested field site with a relatively high V. dahliae soil density. While these results appear promising, growers in Washington are unlikely to adopt grafting as a

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Job Teixeira de Oliveira, Rubens Alves de Oliveira, Domingos Sarvio Magalhães Valente, Isabela da Silva Ribeiro, and Paulo Eduardo Teodoro

in increased soil density and soil RP ( Cortez et al., 2018 ). In an attempt to develop techniques of indirect measurement of soil attributes, apparent soil EC has been highlighted. One of its usefulness in agriculture stems from the fact that soil

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Sahar Dabirian, Debra Inglis, and Carol A. Miles

increased to 4 cfu/g at Eltopia, 5 cfu/g at Othello, and 55 cfu/g at Mount Vernon. In contrast, V. dahiae soil density under clear mulch after harvest was similar to the level at planting at each location (<1, 3, and 27 cfu/g, respectively). Fig. 1. Soil

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Andrew P. Nyczepir, Alexis K. Nagel, and Guido Schnabel

The expression of gastrodianin antifungal protein (GAFP) in a form of its VNF isoform increases tolerance to Phytophthora root rot (Phytophthora cinnamomi) and the root-knot nematode (Meloidogyne incognita) in transgenic plum lines. However, nothing is known about the potential of the GAFP lectin to confer disease resistance to the ring nematode, Mesocriconema xenoplax, in plum. Three transgenic plum lines (4I, 4J, and 5D) expressing gafp-1 under the control of CaMV 35S promoter sequence were evaluated for their response to M. xenoplax in the greenhouse. All plum lines were rated as hosts of M. xenoplax. Among the individual plum lines tested, the number of M. xenoplax per gram of dry roots was lowest in the rhizosphere of transgenic line 5D, intermediate in that of the nontransformed control line, and greatest in line 4J. The results of this study indicate that the comparisons of the final soil densities (Pf) of adult and juvenile M. xenoplax expressed as nematodes per gram of dry roots provide a better measure of the nematode carrying capacity by the tested lines than Pf values referred to as number of M. xenoplax/100 cm3 soil.

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Judy A. Thies, Don W. Dickson, and Richard L. Fery

spring test ( Fig. 2 ). Minimum soil temperatures were 25 °C or greater for 46 of 79 d during the spring test. Maximum temperatures were greater than 30 °C on 57 d during the test. Soil density of M. incognita J2 before fumigation with methyl bromide

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Andrew P. Nyczepir and Bruce W. Wood

-fumigated plots, indicating that the nematode had reinfested and begun to reproduce in the nematicide-treated plots. These results confirmed the prolonged (28 months) beneficial effect of the fumigant nematicide in suppressing the nematode soil densities and the

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Shaun R. Broderick and Williams B. Evans

biosolids applied, 20 tons/acre, did cause phytotoxicity particularly at the early growth stage. Repeated applications of biosolids to soils would likely increase organic matter in the soils, improve soil structure, decrease soil density, and improve water

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Monica Ozores-Hampton

structure, increase soil organic matter (SOM) and fertility, retain moisture, prevent leaching of nutrients, decrease soil density, suppress weeds, increase population of beneficial insects, control erosion, manage plant-parasitic nematodes, increase soil

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Jin-wei Zhang, Yi-xue Liu, Jin-ping Yu, Wei Zhang, Ya-qiong Xie, and Ning-ning Ge

, hydrolyzable nitrogen, rapidly available phosphorus, rapidly available potassium, and organic matter) and soil physical properties (clay content and soil density) for the 0- to 25-cm soil layer were analyzed by the Tianjin Institute of Resource and