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Christian A. Wyenandt, Landon H. Rhodes, Mark A. Bennett and Richard M. Riedel

transplanting and continuing until harvest ( Precheur et al., 1992 ). Even with a good fungicide program, fruit rot caused by anthracnose can be as high as 15% ( Dillard et al., 1997 ; Sherf and MacNab, 1986 ). The disease forecasting system, Tom-Cast, was

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M.H. Maletta, W.P. Cowgill Jr. and S.A. Johnston

A research trial evaluation of fungicides and fungicide combinations in conjunction with weekly or TOM-CAST (an early blight forecast system) spray schedules was conducted in 1998. Fungicide regimens were: Quadris (alternating with Bravo Weatherstik); Bravo Weatherstik; Manzate followed by Bravo Weatherstik; Champ; Champ and Bravo; Nu-Cop; NuCop and Bravo The weekly schedule resulted in 15 fungicide applications; the TOM-CAST schedule required five applications. Foliar disease was rated weekly. Mature fruit were harvested weekly to obtain total and marketable yields. All fungicide treatments reduced foliar disease compared to the untreated control. Quadris alternating with Bravo Weatherstik on a weekly or TOM-CAST schedule provided better disease control than any other material on either schedule. There were no significant differences in disease control among the other materials applied weekly. Disease control achieved with the TOM-CAST schedule was somewhat less than with the weekly schedule for all materials. Quadris/Bravo or Bravo provided the best control and Champ or Nu-Cop alone provided the least control on the TOM-CAST schedule. Total yield was not affected by fungicide or schedule. Marketable yield was reduced by weekly applications of copper fungicides compared to most other treatments. Chemical names used: tetrachloroisophtalonitrile (chlorothalonil); [methyl (E)-2-{2-[6-(2-cyanophenoxy) pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate (asoxystrobin); copper hydroxide; manganese ethylene bisdithiocarbamate and zinc.

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M.H. Maletta, W.P. Cowgill Jr., W. Tietjen, S.A. Johnston and P. Nitzsche

Fourteen different fungicide schedules for early blight control, including eight variations of TOM-CAST, were evaluated at the Snyder Research and Extension Farm, Pittstown, N.J. Weather data was collected with Sensor Instruments Field Monitors. All calendar-based schedules—weekly, biweekly, grower simulation—reduced foliar disease compared to the untreated control. All forecast generated schedules—TOM-CAST variations, FAST and CUFAST—reduced foliar disease compared to the untreated control. Several of the forecast schedules resulted in disease ratings not significantly different from those following calendar based schedules or from each other. The fourteen different schedules required as many as sixteen to as few as four fungicide applications. Disease control schedule did not affect total yield, marketable yield and postharvest losses. Disease control with a TOM-CAST generated schedule based on weather data from an electronic meteorological service was not different from disease control obtained with a TOM-CAST schedule based on ground station weather data. Potential cost savings of as much as $295 per acre resulting from reduced fungicide schedules were estimated. Chemical name used: tetrachloroisophtalonitrile (chlorothalonil).

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M.H. Maletta, W.P. Cowgill Jr., W. Tietjen, S.A. Johnston, T. Manning and P. Nitzsche

Five variations of TOM-CAST and two sources of weather data were used to schedule tomato early blight control for research trials at the Snyder Research and Extension Farm, Pittstown, N.J. TOM-CAST scheduled fungicide applications were initiated at 15, 25, or 35 disease severity values (DSV) and resprayed at 15 or 25 DSV. Weather data for generating the DSVs was obtained on-site with a Sensor Instruments Field Monitor™ or through subscription to the electronic meteorological service SkyBit, Inc. Bravo 720, 3 pints/acre, was used for disease control. Foliar disease, yields, and postharvest decays were evaluated. Daily DSVs, cumulative DSVs, and forecast spray schedule varied with weather data source. Because SkyBit data generated more DSVs during the season than Field Monitor data, the SkyBit-based forecasts called for one or two more sprays than the Field Monitor-based forecasts. However, the number of sprays actually applied was the same, one more or one less for each combination of initiation and respray thresholds. All treatment schedules reduced disease compared to the untreated control. Variation in initiation threshold did not affect disease control. All TOM-CAST schedules respraying at 15 to 20 DSV were as effective as the weekly schedule. All fungicide treatments increased total yields and reduced postharvest decays compared to the untreated control. Most treatments also increased marketable yields. The most efficient, effective Field Monitor-generated TOM-CAST schedule required nine sprays compared to 13 weekly sprays. The comparable SkyBit-generated schedule called for 10 applications. Chemical name used: tetrachloroisophtalonitrile (chlorothalonil).

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Joseph. M. Kemble, Goeff W. Zehnder, W. Robert Goodman, Mahefatiana Andrianifahanana, Ellen M. Bauske, Edward J. Sikora and John F. Murphy

The Alabama Tomato Integrated Pest Management (IPM) Program was demonstrated during two growing seasons in southeastern Alabama. The program consisted of a twice-a-week insect/disease scouting service combined with a weather-timed spray program (TOM-CAST). On average, growers made four fewer insecticide applications and three to four fewer fungicide applications when following the IPM program compared to their conventional, calendar-based program. There was no apparent reduction in yield when following the IPM program. An economic analysis indicated that growers following the IPM program saved an average of $54.36/acre ($134.32/ha).

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W.P. Cowgill Jr., M.H. Maletta, T. Manning, W.H. Tietjen, S.A. Johnston and P.J. Nitzsche

Research trials, conducted from 1991 to 1998, evaluated early blight forecasting systems for use in fresh-market tomato (Lycopersicon esculentum) production in northern New Jersey. Initial trials focused on determining which of three forecast systems—NJ-FAST, CU-FAST, TOM-CAST—would optimize fungicide use. The TOM-CAST system generated fungicide application schedules that reduced foliar disease rating compared to the untreated check and, in 1 year, controlled diseases as well as a weekly schedule with 3 rather than 14 applications. TOM-CAST was easier to use than NJ-FAST or CU-FAST because it required fewer weather data inputs and simpler forecast calculations. Subsequent trials evaluated and defined thresholds for using TOM-CAST in northern New Jersey and evaluated the efficacy of several fungicides with TOM-CAST. Of the six TOM-CAST modifications evaluated, TOM-CAST beginning fungicide applications at 25 cumulative dew severity values (dew SV) and reapplying fungicide at 15 or 25 cumulative dew SV reduced disease rating as much as a weekly schedule in 1995 and 1996 and with fewer applications. After 5 years of trials, decision thresholds for using TOM-CAST in northern New Jersey were chosen and this new version of the forecast system designated NJ-TOM-CAST. It was verified in 1997 and 1998 and shown to generate fungicide application schedules that reduced foliar disease rating compared to the untreated check in both years and as much as the weekly schedule in one year. From 1995 through 1998, the conservative TOM-CAST schedules, TOM-CAST 25-15 or NJ-TOM-CAST, required on average 6 fungicide applications per year compared to weekly schedules that required on average 15 applications per year. In 1996, marketable yield was increased with TOM-CAST scheduled treatment compared to the untreated check and was the same as or greater than yield with weekly treatment. In the other 3 years, fungicide applications, whether applied on a calendar-based or TOM-CAST-based schedule, did not increase marketable yields compared to the untreated check. Fungicides shown to be effective when used with NJ-TOM-CAST schedules included both low cost and new chemistry materials. Copper fungicides, some of which are allowed in organic crop production, did not consistently control fungal diseases when applied on the NJ-TOM-CAST schedule. Applying fungicides on the NJ-TOM-CAST schedule instead of calendar-based schedules did not increase bacterial disease severity. Powdery mildew damage was more severe with NJ-TOM-CAST-scheduled applications than weekly applications in 1 year, affirming the importance of disease monitoring in the field when using NJ-TOM-CAST. By 2000, through a cooperative effort of Rutgers Cooperative Extension and SkyBit, Inc. (Boalsburg, Pa.), a commercial weather service, NJ-TOM-CAST was available to northern New Jersey tomato growers by subscription.

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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. `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. Slices were analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, fungi, yeasts, and chilling injury. With both NF and Tom-Cast fungicide treatments, slices from tomatoes grown with hairy vetch (Vicia villosa Roth) mulch were firmer than those from tomatoes grown with black polyethylene mulch after 12 days storage. Ethylene production of slices from fruit grown using hairy vetch mulch under Tom-Cast was ≈1.5- and 5-fold higher than that of slices from WF and NF fungicide treatments after 12 days, respectively. The percentage of water-soaked areas (chilling injury) for slices from tomatoes grown using black polyethylene mulch under NF was over 7-fold that of slices from tomatoes grown using hairy vetch under Tom-Cast. When stored at 20 °C, slices from light-red tomatoes grown with black polyethylene or hairy vetch mulches both showed a rapid increase in electrolyte leakage beginning 6 hours after slicing. However, slices from tomatoes grown using the hairy vetch mulch tended to have lower electrolyte leakage than those grown with black polyethylene mulch. These results suggest that tomatoes from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch. Also, use of the disease forecasting model Tom-Cast, which can result in lower fungicide application than is currently used commercially, resulted in high quality fruit for fresh-cut processing.

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M.H. Maletta, W.P. Cowgill Jr., W. Tietjen, P. Nitzsche and S.A. Johnston

Since 1990, FAST - Pennsylvania State University, CUFAST - Cornell University. and TOM-CAST - Ridgetown College, Ontario, three systems for forecasting early blight, have been field tested at The Snyder Research and Extension Farm in northwestern New Jersey for their potential use in fresh market tomato production in that area of the state. In 1993, the number of fungicide applications for tomato early blight control required by the three forecast systems was less than the number required following a weekly schedule. FAST and CUFAST scheduled applications of chlorothalonil, 1.5 lb per acre, reduced disease severity, hut TOM-CAST scheduled applications did not reduce disease severiety compared to the untreated control. Culture did not affect disease control results hut did affect disease incidence and post-harvest losses. Total and marketable yields were not affected by fungicide application schedule. Potential cost savings of $270 or $465 per acre, resulting from reduced numbers of fungicide applications following CUFAST or FAST. were estimated. Chemical name used: tetrachloroisophtalonitrile (chlorothalonil).

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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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M.H. Maletta, W.P. Cowgill Jr., T. Manning, W. Tietjen, S.A. Johnston and P. Nitzsche

Weather information has many applications in crop production practices, including disease forecasting. A variety of weather instruments are available for on-farm use, but associated costs and need for regular calibration and maintenance can limit actual use, especially by smaller growers. Subscription to an electronic meteorological service may be a viable alternative to on-site weather stations. In 1997 and 1998, hourly temperature, relative humidity and leaf wetness were monitored at six sites in a 400-m2 area of New Jersey with Field Monitor™ data loggers (Sensor Instruments, Inc.) and by subscription to SkyBit, Inc., an electronic meteorological service. There was close correspondence in temperature data from the two sources at all sites, the average seasonal difference ranging from 0 to 2 °F. Relative humidity data was variable between the two sources, the greatest variation occurring at low and high humidity, the ranges at which relative humidity sensors had been shown to be least accurate. Leaf wetness estimates from the two sources agreed at least two-thirds of the time. Data differences related to source were attributed to both systematic and random error. The usefulness of electronic weather data in crop production depends on how sensitive the particular weather-dependent applications (e.g., predictive disease and insect models) are to variation in the input data. The TOM-CAST early blight forecaster for tomatoes was not particularly sensitive to differences between SkyBit and Field Monitor leaf wetness estimates.