Relative Performance of Strawberry Genotypes on Fumigated and Nonfumigated Soils

Abstract

<jats:p>Performance characteristics for 12 strawberry genotypes (<jats:italic>Fragaria ×ananassa</jats:italic> Duch.) from the Univ. of California, Davis, strawberry improvement program were evaluated in annual hill culture, with and without preplant soil fumigation using a mixture of 67 methyl bromide:33 chloropicrin (trichloronitromethane) (wt/wt, 392 kg·ha<jats:sup>-1</jats:sup>). Plants were established at two locations; one trial followed several cycles of strawberry plantation, whereas the other had not been cropped with strawberries for 20 years. Plant mortality was &lt;3% and did not differ between soil treatments; thus, the main effects of fumigation treatment in these experiments were due to sublethal effects of soil organisms. Plants grown in nonfumigated soil produced 51% and 57% of the fruit yield of plants grown in fumigated soil for soils with and without a recent history of strawberry cultivation, respectively. Nonfumigated treatments also had reduced fruit weight and uniformly lower vegetative vigor during the early phases of plantation establishment. Significant genotype x fumigation interactions were not detected for any of the growth or performance traits at either location. Further, the proportion of variance attributable to interactions was at most 25% of that due to variation among genotypes, even for this highly selected population. Genotypic correlations for traits evaluated in different fumigation treatments ranged from 0.80 to 1.00; thus, selection in either soil environment is expected to affect largely the same sets of genes. These results demonstrate that strawberry productivity is substantially increased by fumigation, even in the absence of lethal pathogens or a discernible replant problem. More importantly, there appears to be little opportunity for developing cultivars specifically adapted to sublethal effects of nonfumigated soils.</jats:p>

Strawberry Cultivars and Mycorrhizal Inoculants Evaluated in California Organic Production Fields

“…Currently, many high-yielding commercially available cultivars are adapted to the central coast climate (24). These cultivars were evaluated and selected for yield and fruit quality in chemically intensive conventional systems (15). These systems include annual soil fumigation with a mixture of methyl bromide and chloropicrin as well as regular applications of insecticides and fungicides (17).…”

Relative Performance of Strawberry Cultivars from California and other North American Sources in Fumigated and Nonfumigated Soils

“…Mortality was <1% for plants established in fumigated and nonfumigated soils, and no visual symptoms of lethal pathogens were observed. As for previous trials conducted at this location, the main effects of fumigation treatment in these experiments must be due to sublethal effects of soil organisms (Larson and Shaw, 1995a;Yuen et al, 1991).…”

“…Recent efforts to improve strawberry performance in nonfumigated soils through genetics and breeding have emphasized the need for reducing plant mortality due to lethal pathogens and obtaining enhanced tolerance to the sublethal or competitive effects of soil organisms (Fort et al, 1996;Galletta et al, 1989;Larson and Shaw, 1995a;Yuen et al, 1991). Investigations of genetic alternatives to preplant soil fumigation within the Univ.…”

“…consequences of sublethal soil organisms (Fort et al, 1996;Larson and Shaw, 1995a). Because these nonspecific causes can reduce productivity by 50% or more, sublethal soil organisms will remain an obstacle to strawberry management on nonfumigated soils even if cultivars with sufficient resistance to lethal pathogens are developed.…”

United States Department of Agriculture—Agricultural Research Service research on alternatives to methyl bromide: pre‐plant and post‐harvest

“…Although choice of variety is very important for success, the performance of commercially available cultivars had never been compared in organic fields. High yielding cultivars were evaluated and selected for their yield and fruit quality in conventional production practices 47. Organic growers rely on cultivars designed for use in MBC‐fumigated soils, although cultivars perform differently in fumigated and non‐fumigated conventional fields 48.…”