For years, strawberry ( Fragaria × ananassa L.) runner plant nurseries have relied on methyl bromide (MB) or mixtures of MB and chloropicrin (Pic) fumigation of soil to produce healthy transplants ( Ajwa et al., 2003 ; Kabir et al., 2005
Eva García-Méndez, David García-Sinovas, Maximo Becerril, Antońeta De Cal, Paloma Melgarejo, Anselmo Martínez-Treceño, Steven A. Fennimore, Carmen Soria, Juan J. Medina and Jóse M. López-Aranda
Steven A. Fennimore, Milton J. Haar, Rachael E. Goodhue and Christopher Q. Winterbottom
.2 billion, accounting for 79% of the total U.S. gross sales ( National Agricultural Statistics Service, 2007 ). California nurseries produce more than a billion strawberry runner plants annually with a total value of ≈$60 million ( California Strawberry
Kirk D. Larson and Douglas V. Shaw
Three preplant soil fumigation treatments were applied on 5 Apr. 1993 to a nursery site that had not been planted previously to strawberries (Fragaria ×ananassa Duch.): 1) a mixture of 67 methyl bromide: 33 chloropicrin (CP) (by weight, 392 kg·ha–1) (MBCP); 2) 140 kg CP/ha; and 3) nonfumigation (NF). On 26 Apr., cold-stored `Chandler' and `Selva' strawberry plants of registered stock were established in each treatment. Soil and root/crown disease symptoms were absent in all treatments during the course of the study. In October, runner plants were machine-harvested and graded to commercial standards. The cultivars produced a similar number of runners per mother plant. Fumigation with MBCP, CP, and NF resulted in 18.56, 15.75, and 7.89 runners per mother plant, respectively. For `Selva', runner root and crown dry weights were similar for the MBCP and CP treatments, but NF resulted in significant reductions compared to the other two treatments. For `Chandler', fumigation with CP resulted in reduced root dry weight, and NF resulted in reduced crown and root dry weights compared to fumigation with MBCP. The results demonstrate the marked decreases in strawberry runner production and runner size that can occur in the absence of preplant soil fumigation, even on new strawberry ground. Also, small, but significant, reductions in runner production and runner size may occur with CP applied at a rate of 140 kg·ha–1 compared to standard fumigation with MBCP. Chemical name used: trichloronitromethane (chloropicrin).
Zahangir Kabir, Steven A. Fennimore, John M. Duniway, Frank N. Martin, Gregory T. Browne, Christopher Q. Winterbottom, Husein A. Ajwa, Becky B. Westerdahl, Rachael E. Goodhue and Milton J. Haar
1 Department of Plant Sciences. 2 To whom reprint requests should be addressed; email firstname.lastname@example.org . 3 Department of Plant Pathology. 4 Formerly of the California Strawberry Commission, Watsonville. 5 Department of Nematology. 6
Stan C. Hokanson, Fumiomi Takeda, John M. Enns and Brent L. Black
1 Assistant professor. Previously, research geneticist in the Fruit Laboratory. 2 Research horticulturist. 3 Horticulturist. 4 Plant physiologist. We gratefully acknowledge Kate Salazar for micropropagation of strawberry plants used in the
Douglas V. Shaw, Thomas R. Gordon, Kirk D. Larson and Sharon C. Kirkpatrick
Mother plants from strawberry (Fragaria ×ananassa Duch.) genotypes susceptible to and resistant to verticillium (Verticillium dahliae Kleb.) were inoculated with this pathogen in a high elevation nursery. The infection rate for mother plants was 77.3% ± 7.5% and 80.7% ± 5.4% for resistant and susceptible genotypes, respectively. Conversely, the percentage of runner plants identified as infected by postharvest petiole assay that were produced by these inoculated mother plants differed significantly (P < 0.01) between sets of genotypes, 25.1% ± 3.7% and 59.8% ± 5.3% for resistant and susceptible genotypes, respectively. The percentage of runner plants from inoculated mothers that eventually collapsed in the fruit production field was larger than the percentage identified as infected by petiole assay for susceptible genotypes (68.9% ± 4.1%), and substantially less than the pre-plant infected fraction for resistant genotypes (3.5% ± 1.4%). Yield for runner plants from inoculated mothers was reduced by 73% to 75% for susceptible genotypes, and by 7% to 15% for resistant genotypes. The percentage of runner plants identified as infected in the nursery was correlated with the percentage of plants that collapsed in the fruiting field (r = 0.91, P < 0.01) and with yield in infested plots (r = -0.79, P < 0.01). Most of the effect of this disease was expressed as plant collapse, but the presence of yield reductions larger than the rate of plant collapse demonstrated substantial sub-lethal effects as well.
Kirk D. Larson and Douglas V. Shaw
Strawberry (Fragaria ×ananassa L.) runner plant production during a 4-year period was compared on nursery soils treated with methyl bromide (MB) and chloropicrin (CP) mixtures (MB:CP) and three alternative soil treatments: CP, mixtures of 1,3-dichloropropene (Telone®) and CP (DP:CP), and no fumigation (NF). The effect of soil treatment on runner plant production for a single nursery propagation cycle was determined in all 4 years. In 2 years, runner production in a final propagation cycle was also determined as a function of soil treatment in previous cycles. A single propagation cycle in NF soil decreased runner production relative to all other treatments. Treatments with CP at rates of 140 to 191 kg·ha–1 generally decreased runner production significantly (P ≤ 0.05) in comparison with treatment with MB:CP; use of CP at rates ≥303 kg·ha–1 resulted in statistically equivalent runner production. In one trial, use of two DP:CP formulations (516 kg·ha–1 of a 7:3 DP:CP mixture, and 448 kg·ha–1 of a 3:7 DP:CP mixture) significantly reduced and did not affect runner production, respectively, relative to the use of MB:CP. Use of MB:CP in the previous propagation cycle also increased runner productivity in comparison with NF. Runner productivity of planting stock produced with 314 kg·ha–1 of CP did not differ statistically from that of stock produced with MB:CP, but productivity of planting stock on soil treated with 157 kg·ha–1 of CP was intermediate between that on NF and MB:CP-treated soil. Planting stock grown on nontreated soil in two previous propagation cycles produced 25% fewer runner plants than did similar stock grown on MB:CP-treated soil. Productivity of planting stock produced with CP at rates of 280 to 314 kg·ha–1 in two previous propagation cycles did not differ statistically from that of stock produced with MB:CP. Results of meta-analyses indicated that fumigation with MB:CP was more effective in increasing runner production than was CP or NF, regardless of the propagation cycle or rate of application. For mixtures of 1,3-dichloropropene and CP, nursery productivity was maximized by using at least 280 kg·ha–1 of CP.
Douglas V. Shaw, Thomas R. Gordon and Kirk D. Larson
1 Pomology Dept. 2 Plant Pathology Dept. We wish to thank Lassen Canyon Nursery for their generous assistance in conducting the nursery phases of this research.
Thomas R. Gordon, Sharon C. Kirkpatrick, Douglas V. Shaw and Kirk D. Larson
1 Plant Pathology Dept. 2 Pomology Dept. We gratefully acknowledge Lassen Canyon Nursery for providing the land and labor needed to conduct the experiments on which this study is based, and research assistance from B. Aegerter, J. Beales, P
D. Kirschbaum, D.J. Cantliffe, C.K. Chandler and R.L. Darnell
The present research was undertaken to examine carbohydrate composition and distribution patterns and induction of flowering and runner formation in attached and detached strawberry plants grown under varying temperature conditions. There was an interaction between attached mother and daughter plants. Daughter plants affected flowering in mother plants, and mother plants influenced vegetative growth in daughter plants. Attachment and high temperature decreased root soluble carbohydrate concentration and promoted runner formation in both mother and daughter attached plants, suggesting that changes in carbohydrate concentration in the roots may be correlated with changes in vegetative growth. According to the results of this research, high temperatures are likely to enhance vegetative growth, whereas lower temperatures are likely to enhance the floral response. Differential temperature regimes applied to the mother/daughter plant experimental system could be an alternative to photoperiod treatments as a tool to study the correlation between environmental conditions and changes in vegetative and reproductive growth in strawberry.