A Meta-analysis of Strawberry Yield Response to Preplant Soil Fumigation with Combinations of Methyl Bromide–chloropicrin and Four Alternative Systems

Abstract

<jats:p>Yield for annual California strawberry (<jats:italic>Fragaria</jats:italic> ×<jats:italic>ananassa</jats:italic> Duch.) production systems in soils treated with combinations of methyl bromide–chloropicrin (MB:CP) were compared with four alternative soil treatment systems using meta-analysis. Studies represent 11 production seasons, and were conducted at three distinct locations in California. Fumigation with mixtures of methyl bromide (MB) and chloropicrin (CP) increased yield significantly compared with any and all alternatives lacking MB. In a combined analysis of 45 studies, fumigation with MB:CP compounds increased yield an average of 94.4% (d<jats:sub>+</jats:sub> = 2.874 ± 0.098) compared with yields for plants in nonfumigated (NF) soils. Further, the effect of MB:CP fumigation increased over the first three strawberry cultivation cycles: MB:CP–fumigated soils provided a 59.2% (d<jats:sub>+</jats:sub> = 2.166 ± 0.146) yield advantage when one cycle of fumigation was omitted, a 100.2% (d<jats:sub>+</jats:sub> = 3.000 ± 0.143) advantage when two cycles were omitted, and a 148.4% (d<jats:sub>+</jats:sub> = 6.201 ± 0.348) yield advantage when three or more cycles of MB:CP were omitted. In a combined analysis that included 34 studies, soil fumigation with MB:CP conferred a 9.6% (d<jats:sub>+</jats:sub> = 0.751 ± 0.087) yield advantage over fumigation with CP alone. Soils treated with MB:CP yielded 6.8% (d<jats:sub>+</jats:sub> = 0.437 ± 0.114) more fruit than those treated with very high rates of CP (336–396 kg·ha<jats:sup>–1</jats:sup>), and 15.4% (d<jats:sub>+</jats:sub> = 1.190 ± 0.134) more than soils treated with commercially realistic rates (168–224 kg·ha<jats:sup>–1</jats:sup>). Similar to the comparison using NF soils, the efficacy of very high rates of CP appeared to diminish over cycles of strawberry cultivation; MB:CP increased yield 2.2% (d<jats:sub>+</jats:sub> = 0.043 ± 0.162) in the first CP production cycle, 10.6% (d<jats:sub>+</jats:sub> = 0.588 ± 0.174) and 13.7% (d<jats:sub>+</jats:sub> = 2.054 ± 0.401) in the following two cycles. Combinations of dichloropropene (DP) and CP were no more effective than were lower rates of CP alone, and MB:CP conferred a 14.4% (d<jats:sub>+</jats:sub> = 0.962 ± 0.162) yield advantage over mixtures of DP:CP. Mixtures of MB:CP increased yield 29.8% (d<jats:sub>+</jats:sub> = 3.199 ± 0.287) compared with metam sodium (MS). The standardized effect was similar when comparing MB:CP combinations with either MS or NF soils, suggesting little effect of MS on the yield response. Chemical names used: trichloronitromethane (chloropicrin); 1,3-dichloropropene (dichloropropene); sodium <jats:italic>N</jats:italic>-methyldithiocarbamate (metam sodium).</jats:p>

Relative Performance of Strawberry Genotypes over Four Cycles of Cultivation on Fumigated and Nonfumigated Soils

“…Reports published during the past 50 years have documented the benefits of preplant soil fumigation with a mixture of methyl bromide and chloropicrin for annual (Wilhelm et al, 1974;Wilhelm and Paulus, 1980) and perennial strawberry (Fragaria ×ananassa) production systems (Hancock et al, 2000). Recent research syntheses have shown that yield differences between plants cultivated in fumigated and nonfumigated soils increase over cycles of strawberry cultivation (Shaw and Larson, 1999). The increasing benefits of soil fumigation over time resulted from deterioration of soil environments with repeated cropping of strawberry in the absence of fumigation, rather than from accrued benefits of repeat fumigation.…”

Meta-Analysis and Other Approaches for Synthesizing Structured and Unstructured Data in Plant Pathology

“…It was also in the late 1990s that the first meta-analysis on a plant pathology topic, the effect of preplant fumigation with methyl bromide (MeBr) versus chemical MeBr alternatives on the yield of strawberry in California, appeared in the literature (117). Interestingly, this topic was revisited in one of the most recently published plant pathology meta-analyses in late 2013 (14); a comparison of these two research syntheses thus can shed light on scientific advances in this active and important area of research over more than a decade.…”

“…The selection process yielded a total of 45 studies (entries) in the 1999 paper and 136 entries (of which 68 were from strawberry in California) in the 2013 paper. The results of the 1999 analysis (117) showed that MeBr + chloropicrin significantly and consistently increased yield compared with chloropicrin alone (by 9.6%), 1,3-dichloropropene + chloropicrin (14.4%), metam sodium (29.8%), and the nonfumigated check (94.4%), leading to the conclusion that there was no technically viable alternative for standard MeBr preplant fumigation in strawberry production in California. In contrast, the 2013 analysis (14) showed that several of these same alternative treatments were statistically equivalent to MeBr, most notably a 1,3-dichloropropene + chloropicrin 65:35 mixture at standard rate.…”

Enhancing Tuber Calcium Concentration May Reduce Incidence of Blackspot Bruise Injury in Potatoes

“…For the analysis of variance Tables (4-7), a widely accepted statistical method ''metaanalysis'' (Cochrane and Cox, 1957) was used that combined replications from identical experiments grown in the same field in different years; the total number of replications of the experiment was 20 replications per treatment per cultivar. Examples of the use of this type of analysis combining identical plant experiments from different years or laboratories is available in several references (Morgan et al, 2003;Shaw and Larson, 1999). Starter fertilizer (6N-24P-24K) pretreated with Admire was applied at a rate of 560 kgÁha -1 .…”