Apple (Malu ×domestica) replant disease (ARD) is a soil-borne disease syndrome of complex etiology that occurs worldwide when establishing new orchards in old fruit-growing sites. Methyl bromide (MB) has been an effective soil fumigant to control ARD, but safer alternatives to MB are needed. We evaluated soil microbial communities, tree growth, and fruit yield for three pre-plant soil treatments (compost amendment, soil treatment with a broad-spectrum fumigant, and untreated controls), and five clonal rootstocks (M7, M26, CG6210, CG30, and G16), in an apple replant site at Ithaca, N.Y. Molecular fingerprinting (PCR-DGGE) techniques were used to study soil microbial community composition of root-zone soil of the different soil treatments and rootstocks. Tree caliper, shoot growth, and yield were measured annually from 2002–04. Among the five rootstocks we compared, trees on CG6210 had the most growth and yield, while trees on M26 had the least growth and yield. Soil treatments altered soil microbial communities during the year after pre-plant treatments, and each treatment was associated with distinct microbial groups in hierarchical cluster analyses. However, those differences among fungal and bacterial communities diminished during the second year after planting, and soil fungal communities equilibrated faster than bacterial communities. Pre-plant soil treatments altered bulk-soil microbial community composition, but those shifts in soil microbial communities had no obvious correlation with tree performance. Rootstock genotypes were the dominant factor in tree performance after 3 years of observations, and different rootstocks were associated with characteristic bacterial, pseudomonad, fungal, and oomycetes communities in root-zone soil.
Shengrui Yao, Ian A. Merwin, and Janice E. Thies
Elio Jovicich, John J. VanSickle, Daniel J. Cantliffe, and Peter J. Stoffella
The uninterrupted supply of high quality colored peppers to the U.S. is mainly from imports of greenhouse-grown fruits. Average year-round wholesale market price of these imports was $4.80/kg when U.S. field-grown fruit price was $1.60/kg for colored and $0.91/kg for green. High market prices and a suitable environment for growing colored peppers in inexpensive protected structures led to construction of 25 ha of greenhouses currently growing peppers in Florida. Greater demand for specialty vegetable crops, loss of methyl bromide, and an increase in urban sprawl and price of arable land may result in growers considering greenhouses to produce high value peppers. We estimated the profitability of a greenhouse enterprise with a budget analysis and calculated the returns to capital and management. We assumed use of current technology applied in commercial greenhouse crops in Florida, and in experimental crops at the Univ. of Florida. Revenues per square meter were estimated from current yields and historical fruit price data. Plants were grown in perlite in a high-roof polyethylene-covered greenhouse (0.78 ha) located in north central Florida. Transplanting occurred in August and fruits were harvested from November to May for a yield of 13 kg·m-2 with a total cost of production of $41.09 and an estimated return of $17.89. The return on investment was 17%. Only yields greater than 7.8 kg·m-2 generated positive returns using the average wholesale fruit price during the season ($5.29/kg). For this price, a range of possible yields (5–17 kg·m-2) led to returns ranging from $–9.52 to $30.84, respectively. The estimates indicated that production of greenhouse-grown peppers could represent a viable production alternative for Florida vegetable growers.
Mario Orozco-Santos, Javier Farías-Larios, Jaime Molina-Ochoa, and José Gerardo López-Aguirre
Melon wilt (MW) is one of the main diseases affecting the cucurbitaceous crops in the Pacific Central region of Mexico. The use of resistant varieties is the most effective strategy to reduce the damage caused by MW; however, variety performance depends on the fungal race occurring in the field. The use of fungicides, such as benzimidazols and methyl bromide, is a common practice, but there are contamination concerns, and a search is on for alternatives to diminish the negative effects on the agro-ecosystem. The aim was to determine the effect of the application of soil amendments and mulching on the incidence of MW, and on melon yield. Soil amendments incorporated were: rice straw (3 t·ha-1); compost 1, prepared with chicken and bovine manure, and banana and orange wastes (5.7 t·ha-1); compost 2, prepared with bovine and horse manure, coconut wastes and grasses (8 t·ha-1), vermicompost (3 t·ha-1), and a control. All treatments were established using transparent mulching during 21 days. The number of MW propagules in amended soils were similar at 5, 10, and 20 cm deep, but the percentage of diseased plants was higher (4.5%) in the control, which could be caused by the incidence of other fungi propagules, perhaps antagonistic, that contributed in diminishing the MW when compared with the control. The fruit weights and fruit sizes were not different between treatments on small (21–30 sizes), medium (15–18 sizes), and large (9–12 sizes), but total fruit numbers were 1.15-, 1.07-, 0.99-, and 1.09-fold higher when compared with the control. The application of soil amendments affected the antagonistic fungal populations even when it did not affect the cantaloupe yield. We suggest that soil amendments will improve soil fertility and increase melon yields, and studies are currently running.
Shann Tanner, Christina Wells, and Gregory Reighard
The effectiveness of soil solarization as an alternative to methyl bromide (MBr) fumigation in replanted peach orchards was investigated at the Musser Fruit Research Farm near Clemson, S.C. A split plot experimental design was used, with soil treatment as the whole-plot factor and rootstock as the sub-plot factor. In Spring 2002, preexisting trees were removed from the study site, and six orchard rows were cultivated and subsoiled. In June, two rows were covered with clear polyethylene sheeting and solarized for the remainder of the summer. In November, two additional rows were treated with MBr (474.3 kg·ha-1), while the two remaining control rows received no soil sterilization treatment. In Jan. 2003, 36 `Redglobe' peach trees budded on Guardian™ or Lovell rootstock were transplanted to the site, and one minirhizotron was installed beneath each tree. Minirhizotron observations were made every 14–21 days from Feb. through Oct. 2003, and stem caliper measurements were taken on four dates during this interval. Trees grew significantly larger in the MBr and solarized rows than in the control rows (P< 0.1; Tukey's hsd), but there were no differences in stem caliper growth between MBr and solarization-treated trees. Reduced aboveground growth in control trees may have been related to greater carbon expenditure belowground: in the absence of soil sterilization, fine root median life spans were reduced by 27–28 days (P< 0.0001; proportional hazards regression) and rates of root production and mortality were significantly higher (P< 0.1; repeated measures ANOVA). Solarization and MBr fumigation appeared to provide similar benefits in reducing root turnover and improving aboveground growth at this site.
Judy A. Thies, Jennifer J. Ariss, Richard L. Hassell, Sharon Buckner, and Amnon Levi
: Where do we need more research? 1999 Annual Research Conference on Methyl Bromide. Alternatives and emissions reductions. Paper #55. 3 Jan. 2015. < www.mbao.org/mbrpro99.html > Memmott, F.D. Hassell, R.L. 2010 Watermelon ( Citrullus lanatus ) grafting
Stephen R. King, Angela R. Davis, Wenge Liu, and Amnon Levi
; Paplomatas et al., 2002 ; Tsror and Nachmias, 1995 ). Bacterial wilt of tomato caused by Ralstonia solanacearum (Smith) Yabuuchi et al. can be a devastating disease that has few control alternatives. Methyl bromide has not proven effective for control of
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.
Leonor F.S. Leandro, Lisa M. Ferguson, Frank J. Louws, and Gina E. Fernandez
alternative farming systems compared with large-acreage operations. Growers are currently faced with the serious challenge of implementing alternatives to soil fumigation with methyl bromide ( Wilhelm and Paulus, 1980 ; Yuen et al., 1991 ), banned in 2005
James P. Gilreath and Bielinski M. Santos
runner plant nurseries with methyl bromide alternative fumigants HortScience 43 1495 1500 Gilreath, J.P. Santos, B.M. 2004 Manejo de Cyperus rotundus con alternativas al bromuro de metilo en tomate de mesa Manejo Integrado de Plagas y Agroecología 71 54
Judy A. Thies and Amnon Levi
of 15% to 20% for watermelon in Georgia and Florida ( Lynch and Carpenter, 1999 ). The removal of methyl bromide from the U.S. market has raised great interest in developing an alternative approach for managing root-knot nematodes in vegetable crops