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Joseph L. Smilanick

Postharvest Pathogens and Disease Management . 2005. P. Narayanasamy. John Wiley, Somerset, NJ. 578 pages. $135.00. Hardcover. ISBN: 978-0-471-74303-3 Postharvest diseases are responsible for the spoilage of durable and fresh perishable

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Dermot P. Coyne, Eladio Arnaud Santana, James Beaver, James R. Steadman, Graciela Godoy Lutz, Douglas Maxwell and Lisa Sutton

Bean golden mosaic (BGM), rust (RU), web blight (WB), and common blight (CB) are major constraints affecting bean yields in the Dominican Republic (DR). The objectives of the USAID DR supported project were to educate graduate students, improve research facilities and equipment, institutionalize the project, and develop a comprehensive bean disease management program. The project trained 25 researchers. A national center for bean improvement (CIAS) was established. Facilities for plant pathology, germplasm storage, and screenhouses were built and equipment and vehicles were acquired. The high-yielding rust-resistant red mottled bean variety `PC-50' was introduced and grown on about 60% of the hectarage. However, BGM became a serious problem with the increase of the white fly population (vector of BGMV) due to increased vegetable production. Under severe BGM, yields were low in plantings made after 15 Dec. The combination of the use of `PC-50', along with a fallow period with delayed planting until early November, reduced the populations of white fly, BGM, RU, and CB and led to a dramatic yield increase of beans and to self sufficiency in beans in the DR. PC-50 became damaged by a new RU race and a resistant line PC-21-SMA (UPR) was released. New bean lines with resistance to BGM, WB, RU, and CBB are being tested for release.

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Ji Heun Hong, Douglas J. Mills, C. Benjamin Coffman, James D. Anderson, Mary J. Camp and Kenneth C. Gross

Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill., cv. Sunbeam) fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at 5 °C under a modified atmosphere. In this study, we used the fourth uniform slice from the stem end and analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, molds, yeasts and occurrence of water-soaked areas. With both NF and Tom-Cast fungicide treatments, slices from tomato fruit grown with hairy vetch mulch showed greater firmness than those from tomato fruit grown with black polyethylene mulch after 12 d of storage. Ethylene production of slices from tomato fruit grown using hairy vetch mulch under Tom-Cast was about 1.5- and 5-fold higher than that of slices from tomato fruit grown under the WF and NF fungicide treatments after 12 d, respectively. Within each fungicide treatment, slices from tomato fruit grown using hairy vetch mulch showed less chilling injury (water-soaked areas) than those from tomatoes grown using black polyethylene mulch. The percentage of water-soaked areas for slices from tomato fruit grown using black polyethylene mulch under NF was over 7-fold that of slices from tomato fruit grown using hairy vetch under Tom-Cast. These results suggest that, under our conditions, fruit from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch.

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Jacqueline Joshua and Margaret T. Mmbaga

Fungal pathogens impose major constraints on agricultural production globally ( Collinge et al., 2010 ). Disease management strategies have relied heavily on conventional chemical fungicides. Persistent challenges associated with the use of

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M. Chérif, J.G. Menzies, D.L. Ehret, C. Bogdanoff and R.R. Bélanger

Two experiments were conducted in separate locations, one at Université Laval in eastern Canada (Québec) and one at the Agassiz Research Station in western Canada (British Columbia), in an attempt to determine the effectiveness of soluble silicon (Si) against cucumber root disease caused by Pythium aphanidermatum Edson. Long English cucumber (Cucumis sativus L. cv. Corona) plants were grown either in a standard nutrient solution or in nutrient solutions supplemented with 1.7 mm (100 ppm) Si and inoculated or not with the pathogen. Supplying the solutions with 1.7 mm Si significantly reduced mortality and disease symptoms attributed to infection by P. aphanidermatum. Grown in presence of Si, plants infected with P. aphanidermatum showed a significant increase in yield, marketable fruit, and plant dry weight compared to Si-nonamended and infected plants. These beneficial effects were observed under both experimental conditions. The fruit yield of noninoculated plants was not affected by the presence of Si in the Agassiz experiment. However, Si-amended control plants were more productive in the experiment conducted at Laval, apparently because of contamination problems, which indicates that Si beneficial effects are most likely related to disease management.

Open access

Katherine Bennett, Mary Vargo, Guido Schnabel and James E. Faust

Two application methods of calcium (Ca), fertigation and spray, were investigated regarding their effects on Botrytis blight on petunia (Petunia ×hybrida) flowers. Plants were grown for 6 weeks with three nutrient solutions consisting of 0, 100, or 200 mg·L−1 Ca and weekly calcium chloride (CaCl2) sprays of 0, 750, or 1500 mg·L−1 Ca for a total of nine treatment combinations. Flowers were harvested, inoculated with Botrytis spores, placed in humidity chambers, and evaluated for Botrytis blight severity. Disease severity decreased by 57% and 70% when flowers were treated with Ca spray applications of 750 and 1500 mg·L−1 Ca, respectively; however, no change in disease severity occurred across the Ca fertigation applications. Ca concentration in the flower petal tissue increased with the Ca spray applications: the flower petal Ca concentration increased from 0.26% to 0.65% of tissue dry mass (DM) as the Ca spray application rate increased from 0 to 1500 mg·L−1. However, no change was observed across the Ca fertigation treatments. Leaf tissue Ca concentration increased from 2.1% to 3.2% DM as the fertigation solution increased from 0 to 200 mg·L−1 Ca, whereas spray application had no significant effects of leaf tissue Ca concentration. The results demonstrate that spray application is a more effective technique than fertigation application to provide higher Ca tissue concentrations in flowers, and that the Ca concentration in flower petal tissue is an important consideration when evaluating tissue susceptibility to Botrytis blight. Because of the high rate of fungicide resistance to Botrytis cinerea found in commercial greenhouses, spray applications of CaCl2 are an important disease management tool for commercial growers.

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Julian Mendel, Christina Burns, Beatrice Kallifatidis, Edward Evans, Jonathan Crane, Kenneth G. Furton and DeEtta Mills

trained on the scent of the laurel wilt pathogen as an early detection tool of presymptomatic trees and as an additional tool for overall disease management. The potential for successfully treating presymptomatic, R. lauricola –infected trees with

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Rohini Deshpande, D. P. Coyne, K. G. Hubbard, J. R. Steadman, E. P. Kerr and Anne M. Parkhurst

The microclimate of Great Northern (GN) dry bean lines with diverse plant architecture was investigated in terms of white mold (WM) incidence and yield. A split-plot design was used with protected (3 weekly sprays of benomyl 0.9 KG HA-1 after flowering) and unprotected treatments as main-plots and GN lines as sub-plots in a WM nursery (1990, 1991). Canopy density, erectness, leaf area index, and plant characteristics were measured. `Starlight' (upright) and `Tara' (prostrate) were selected for detailed microclimate studies. An infrared thermometer, humidity sensor, and a thermistor were placed within the canopy at the advent of flowering. Leaf wetness and its duration were estimated by the leaf temperature in combination with air temperature and dewpoint temperature. `Starlight' showed later and shorter duration of leaf wetness, lower humidity, and WM and higher yield than `Tara'. Severe WM and reduced yields occurred also on all other susceptible entries with dense prostrate plant habits in the unprotected plots. Fractal analysis was done on the images of the canopy to quantify the light interception within the canopy.

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Gary E. Vallad and Bielinski M. Santos

report card Fla. Sci. 69 100 116 Jeger, M.J. 2004 Analysis of disease progress as a basis for evaluating disease management practices Annu. Rev. Phytopathol. 42 61 82 Jones, J.B. 1991 Bacterial spot 27 Jones J.B. Jones J.P. Stall R.E. Zitter T