9:30 a.m. New Products for Disease Control in Carrots Mary Hausbeck, Plant Pathology Dept., MSU

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1 MAPPING YOUR ROUTE TO THE FUTURE Great Lakes Fruit, Vegetable & Farm Market EXPO DeVos Place Convention Center Grand Rapids, MI December 7-9, 2004 Carrot Wednesday morning 9:00 am Where: Gallery Overlook Room F (upper level) Recertification credits: 1 (Private, 1B) CCA Credits: IPM(2) Moderator: Jim Breinling, Mason Co. MSU Extension 9:00 a.m. FQPA Update Barbara Van Til, U.S. EPA Region V 9:30 a.m. New Products for Disease Control in Carrots Mary Hausbeck, Plant Pathology Dept., MSU 9:45 a.m. Why DSV Should Be a Part of a Carrot Grower's Vocabulary? Ryan Bounds, Plant Pathology Dept., MSU Mary Hausbeck, Plant Pathology Dept., MSU 10:00 a.m. 2004: Another Not So Normal Year with Carrot Insects Beth Bishop, Entomology Dept., MSU 10:15 a.m. A Quick Update on Carrot Weed Control Bernard Zandstra, Horticulture Dept., MSU 10:30 a.m. Integration of IPM Methods for Carrot Eco-Lebeling Potential Walter R. Stevenson, Plant Pathology Dept., Univ. of

2 FQPA Update: Potential Impacts to the Carrot Industry Barbara Van Til, Environmental Protection Agency, Region 5 77 W. Jackson Blvd., Chicago, IL Vantil.barbara@epa.gov A brief overview of the Food Quality Protection Act of 1996 and its impacts on pest management in the carrot industry will be provided. Chemicals commonly used by Michigan carrot growers will be discussed, with focus on those with potential impacts to human health and the environment. Integrated Pest Management will be critical to growers success in carrot production as FQPA implementation continues.

3 New Products for Disease Control in Carrots Dr. M.K. Hausbeck ( ; R.S. Bounds (Graduate Student), and B.D. Cortright (Research Assistant) Michigan State University, Department of Plant Pathology Foliar Blight Cercospora and Alternaria blights occur every year in Michigan carrot fields and require management to prevent crop loss. Cercospora blight is caused by the fungus, Cercospora carotae, and is the most important foliar disease of carrots in Michigan. The fungus can attack young foliage, either on the leaves or petioles, causing blight. Alternaria blight is caused by the fungus, Alternaria dauci, and is usually detected later in the season on older foliage. Warm temperatures and long periods of leaf wetness promote disease development. Spores of these fungi are wind-blown to nearby plants or even adjacent fields. Methods to reduce disease pressure include planting disease-free seed, following a 2-year crop rotation, minimizing overhead irrigation during warm weather, and applying fungicides. Methods to effectively schedule fungicide applications according to field scouting and the Tom-Cast disease forecasting system have been developed. New Product Testing Fungicides were evaluated at the MSU Muck Soils Research Farm in 2004 (Table 1). Fontana carrot seeds were planted at a density of 22.8 seeds/ft of row on 21 June in three seed lines per row with rows centered 16 in. apart on three-row raised beds centered 64 in. apart. Treatment plots consisted of one row 20 ft long with 5 ft of unsprayed buffer between plots in the same row. One bed was left unsprayed between treatment plots. Twelve treatments were replicated four times in a randomized complete block design. Fungicides were applied with a CO 2 backpack sprayer equipped with three XR8003 flat fan nozzles spaced 18 in. apart and calibrated to deliver 50 gal/a at a nozzle pressure of 52 psi. Ten weekly applications were made on 6, 13, 20 and 27 August; 3, 10, 17, and 24 September; and 1 and 5 October, except for the 14-day treatment of Bravo Weather Stik 6SC which received five applications on alternate dates. The combined effect of Cercospora and Alternaria blight was assessed from plants in the center 10 ft of the middle row of each plot on 11 October. Carrots in the center 10 ft of the middle row were handharvested, the foliage was removed with a mechanical topper, and root yields were recorded on 11 October. Table 1. Fungicides tested for control of Cercospora and Alternaria blights of carrot, Product Active ingredient(s) Manufacturer Registered Amistar 80WG azoxystrobin Syngenta Yes Bravo Weather Stik 6SC chlorothalonil Syngenta Yes Cabrio 20WG pyraclostrobin BASF Yes Endorse 2.5WP polyoxin D zinc salt Arvesta No Kocide DF copper hydroxide Griffin Yes Pristine 38WG boscalid + pyraclostrobin BASF No Switch 62.5WG cyprodinil + fludioxonil Syngenta Yes

4 Cercospora blight was the primary disease in this trial and was detected during the first week of August. Few Alternaria blight symptoms developed on mature foliage in late September. Leaving plots untreated resulted in severe petiole (> 50 lesions/plant) and leaf (68%) blight (Table 2). When compared to the incidence of petiole blight of untreated plots, applications of Cabrio 20WG (8 and 12 oz/a), Amistar 80WG (3 and 5 oz/a), or Pristine 38WG reduced petiole disease when applied in alternation with Bravo Weather Stik 6SC or when Bravo Weather Stick 6SC was applied weekly (1.5 and 1 pt/a). All fungicide programs, except Switch 62.5WG, reduced the severity of petiole blight and improved petiole health compared to the untreated. No significant improvement in disease control or yield occurred when higher rates of Cabrio 20WG or Amistar 80WG were used. Applications of Switch 62.5WG did not differ from the untreated control for all parameters measured. Cabrio 20WG (8 and 12 oz) alternated with Bravo Weather Stik 6SC resulted in a significantly higher yields than the Switch 62.5WG treatment and the untreated. No phytotoxicity was observed from any treatment. Table 2. Results of new product testing for control of Cercospora and Alternaria blights of carrot. Petiole blight Treatment and rate/a (application sequence z ) Incidence (%) y Severity x Petiole health w Leaf blight (%) v Yield per 10- ft row (lb) Untreated e u 5.0 c 7.5 d 68.2 d 14.7 c Bravo Weather Stik 6SC 1.5 pt (1-10) abcd 1.5 ab 1.8 ab 5.5 abc 24.6 ab Bravo Weather Stik 6SC 1.5 pt (1,3,5,7,9) de 2.5 b 3.3 bc 13.8 c 25.1 ab Bravo Weather Stik 6SC 1 pt (1-10) abc 1.8 ab 2.0 abc 4.2 ab 25.0 ab Cabrio 20WG 8 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) ab 1.0 a 1.3 a 2.8 a 26.1 a Cabrio 20WG 12 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) a 1.5 ab 2.0 abc 6.2 abc 27.3 a Amistar 80WG 3 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) abc 1.0 a 1.8 ab 3.6 a 24.4 ab Amistar 80WG 5 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) abc 1.0 a 1.5 a 3.6 a 25.0 ab Endorse 2.5WP 2.2 lb (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) bcde 1.8 ab 1.8 ab 4.7 abc 23.2 ab Kocide DF 1.5 lb (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) cde 2.3 ab 3.5 c 12.5 bc 25.8 ab Pristine 38WG 10.5 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) abc 1.0 a 2.3 abc 5.1 abc 23.9 ab Switch 62.5WG 11 oz (1-10) e 4.5 c 6.3 d 55.6 d 18.7 bc z Application sequence: 1 = 6 Aug; 2 = 13 Aug; 3 = 20 Aug; 4 = 27 Aug; 5 = 3 Sep; 6 = 10 Sep; 7 = 17 Sep; 8 = 24 Sep; 9 = 1 Oct; 10 = 5 Oct. y Percentage of plants from 10 ft of the center row with at least one petiole lesion. x Petiole blight severity rated on a 1 to 5 scale; where 1 = 0 petiole lesions per plant, 2 = 1-10, 3 = 11-21, 4 = 21-50, and 5 = > 50. w Petiole health rated on a 1 to 10 scale; where 1 = healthy and vigorous to 10 = necrotic or dead. v Evaluated using a leaf blight assessment key representing the percentage of disease foliage. u Means within a column followed by the same letter are not significantly different according to Tukey s Studentized Range Test (P=0.05).

5 Nozzle and Spray Pressure Comparison A second study was conducted at the MSU Muck Soils Research Farm to examine nozzle types, spray pressure, and reduced fungicide rates. A higher spray pressure (100 psi) was used when applying fungicides at reduced rates. Fungicides were applied with a CO 2 backpack sprayer equipped with either three XR8002 flat fan nozzles or three 8002 twin-flat fan nozzles spaced 18 in. apart and calibrated to deliver 30 gal/a at 50 or 100 psi. Nine applications were made on 6, 13, 20, and 31 August; 7, 14, 22, and 29 September; and 5 October. Table 3. Effects of nozzle type, spray pressure, and fungicide rate on Cercospora blight of carrot. Treatment and rate/a, applied at 7-day intervals Nozzle type Spray pressure (psi) Foliar Petiole infection (%) z Severity y Infection (%) Plant health x Yield (lb/10 ft) Untreated b w 4.5 b 98.9 d 5.3 b 17.9 Bravo Weather Stik 6SC 0.75 pt... flat fan a 2.0 a 75.6 bcd 2.0 a 23.5 Bravo Weather Stik 6SC 1.5 pt... flat fan a 2.0 a 49.8 ab 1.3 a 23.0 Bravo Weather Stik 6SC 0.75 pt... twin fan a 1.9 a 80.3 cd 1.5 a 23.4 Bravo Weather Stik 6SC 1.5 pt... twin fan a 1.9 a 60.3 abc 1.8 a 25.4 Bravo Weather Stik 6SC 0.75 pt alternate Cabrio 20WG 0.38 lb... flat fan a 1.9 a 41.7 ab 1.0 a 23.0 Bravo Weather Stik 6SC 1.5 pt alternate Cabrio 20WG 0.5 lb... flat fan a 1.8 a 40.8 a 1.0 a 26.5 Bravo Weather Stik 6SC 0.75 pt alternate Cabrio 20WG 0.38 lb... twin fan a 2.0 a 58.7 abc 1.0 a 26.4 Bravo Weather Stik 6SC 1.5 pt alternate Cabrio 20WG 0.5 lb... twin fan a 2.0 a 40.7 a 1.3 a 20.9 Cabrio 20WG 0.5 lb alternate Kocide DF 1.5 lb. flat fan a 1.9 a 30.7 a 1.3 a 21.1 Cabrio 20WG 0.5 lb alternate Kocide DF 1.5 lb. twin fan a 1.8 a 31.8 a 1.0 a 23.2 z Based on a visual estimation of the percentage of foliage infected. y Severity of petiole infection based on visual estimation utilizing a 1 to 5 scale (1=no lesions, 5=>50 lesions per petiole). x Overall plant health rated on a 1 to 10 scale, where 1=no sign of foliar infection, 10=complete defoliation. w Column means with a common letter or with no letter are not significant different, Fisher LSD, P=0.05. Cercospora incidence was first noted at the beginning of August and progressed to moderate levels by the end of September. At the time of harvest, all treatments (regardless of rate, nozzle type, and spray pressure) had significantly better ratings of foliar infection, petiole severity, and plant health than the untreated (Table 3). There was no significant difference among the treatments for these same ratings and values were similar. Significant differences among the treatments were noted for petiole infection. All treatments, except the reduced rates of Bravo Weather Stik 6SC (0.75 pt) applied every seven days at 100 psi, had significantly fewer infected petioles than the untreated. Spraying Cabrio 20WG (0.5 lb) in

6 alternation with Kocide DF (1.5 lb) at 100 psi, either with flat or twin-flat fan nozzles, resulted in the fewest infected petioles. There was no significant difference in control when using a reduced rate of Bravo Weather Stik 6SC (0.75 pt) alternated with Cabrio 20WG (0.38 lb) and increasing the pressure with both nozzle types. Though not significant, there was an increase of infected petioles (20 to 25.8%) when reducing the rate of Bravo Weather Stik and increasing pressure for either nozzle type. Plots were hand harvested, keeping carrot loss to a minimum, and no significant differences in yield were noted for among the treatments.

7 Why DSV Should be a Part of a Carrot Grower s Vocabulary Ryan S. Bounds (Graduate Student) and Dr. Mary K. Hausbeck ( ; hausbec1@msu.edu), Michigan State University, Department of Plant Pathology Introduction. Disease forecasters can play an important role in Integrated Pest Management (IPM) systems for vegetable crops by alerting growers when weather conditions are favorable for disease development. The Tom-Cast disease forecasting system was originally designed to manage diseases of tomato and has since been adopted by the Michigan asparagus and carrot industries for disease management. Since 1997, researchers at MSU have tested the Tom-Cast system for controlling Alternaria and Cercospora blights of carrots, both in commercial production fields and at the Muck Soils Research Farm. The purpose of this presentation is to provide a brief summary of recent Tom-Cast research and to re-emphasize the benefits of using Tom-Cast to prompt sprays for managing carrot foliar blights. Tom-Cast. Tom-Cast uses the hours of leaf wetness for each 24-hour period (11:00 AM to 11:00 AM) and the average temperature during the wetness periods to calculate a disease severity value (DSV) (Table 1). DSVs range from 0 to 4, corresponding to environmental conditions unfavorable to highly favorable for disease development. Daily DSVs are summed and accumulate, and when a threshold value of 15 DSVs is reached, a fungicide spray is applied and the DSV total is reset to zero. Table 1. Leaf wetness duration and temperatures used to calculate DSVs for Tom-Cast. Leaf wetness periods (hours) required to produce daily Disease Severity Mean temperature Values (DSVs) of: C F (source: Madden et al Phytopathology 68: ) Weather Monitoring Equipment. Leaf wetness and temperature were monitored with sensors manufactured by Spectrum Technologies, Inc. The sensors (Figure 1) are relatively inexpensive yet reliable for obtaining the weather information used by Tom-Cast. A computer equipped with the Specware software program must be used to launch (activate) the sensor. Under the options tab of the Specware program, set the wetness threshold to 0 and select save parameters. This ensures the sensor will detect leaf wetness whenever moisture is present on the leaf wetness grid. Further details on use of the Specware program can be obtained from Forecasting with Tom-Cast and Spectrum Weather Equipment Figure 1. A leaf wetness and temperature sensor is oriented at a 45 angle facing north and located in the upper 75% of the carrot canopy.

8 ( Publications.htm) or by contacting your local extension agent. Does the system work? Yes, applying fungicides when prompted by Tom-Cast results in similar disease control and often requires fewer applications when compared with calendar-based (7- or 10-day) spray schedules. In 2001 and 2002, Bravo Ultrex (1.4 lb/a) was applied every 7 days or according to three disease forecasting systems. Five to seven fewer sprays were prompted by Tom-Cast 15 DSV when compared to the weekly schedule (Figure 2). Tom-Cast 15 DSV was the only disease forecaster to limit foliar blights to low levels comparable to the weekly fungicide program sprays sprays 2002 Petiole health Untreated 7-day Cercospora predictor Alternaria predictor Tom-Cast 15 DSV Untreated 7-day Cercospora predictor Alternaria predictor Tom-Cast 15 DSV Figure 2. Petiole health ( 1 = healthy, vigorous; 10 = weak, dead) of Cellobunch carrots treated with Bravo Ultrex 82.5WDG (1.4 lb/a) in 2001 and In a separate 2-year study (2001 and 2002), fungicide sprays were initiated either prior to disease or when disease symptoms developed at a trace, 5%, or 10% level and reapplied every 10 days or according to Tom-Cast using a 15, 20, or 25 DSV threshold. Tom-Cast 15 DSV prompted 1 to 3 fewer sprays than the 10-day schedule and limited blights to low levels. A total of 4 sprays were saved by initiating fungicide spray when a trace amount of disease developed on the foliage and reapplied according to Tom-Cast 15 DSV when compared to the 10-day schedule initially applied prior to disease development (Table 2). Table 2. Cost of fungicide programs when Bravo Ultrex 82.5WDG (1.4 lb/a) alternated with Quadris 2.08F (6.2 fl oz/a) was applied in 2001 and Application interval Disease present when sprays begun # Sprays Cost/A # Sprays Cost/A 10-day none 9 $102 9 $92 Tom-Cast 15 DSV none 8 $92 6 $63 Tom-Cast 15 DSV trace (scouting) 5 $56 5 $50 Tom-Cast and scouting savings: $46/A $42/A A 2003 study identified that the use of strobilurin fungicides (Amistar/Quadris, Cabrio, or Pristine) should be included in the fungicide program when Tom-Cast 15 DSV was used to prompt sprays to protect a blight-susceptible variety. These fungicides must be used in alternation with protectant fungicides (Bravo or Kocide) to prevent fungicide resistance from developing. On blight susceptible Fontana carrots, a strobilurin fungicide was necessary when using Tom-Cast 15 DSV to reduce disease to levels comparable to the weekly treatment. Tom-Cast prompted 50% fewer sprays than the 7-day treatment in this study.

9 Another Not-So-Normal Year for Carrot Insects Beth A. Bishop Department of Entomology, Michigan State University Aster leafhoppers are the most important insect pest of carrots in Michigan and throughout most of the Great Lakes region. Aster leafhoppers impact carrots by transmitting the disease, aster yellows. Aster yellows can kill young carrot plants and, in older plants, causes abnormal foliage growth and roots that are excessively hairy and bitter tasting. Aster leafhoppers are the only known vector of aster yellows. Leafhoppers acquire the disease by feeding on infected foliage. After an incubation period of several weeks, leafhoppers are able to infect new plants through their feeding. Once it has acquired aster yellows, a leafhopper remains infected throughout its life. The risk of aster yellows disease depends on the number of INFECTED aster leafhoppers in the area, which is a function of the total number of leafhoppers and the proportion infected (infectivity rate). Although a few aster leafhoppers in the Great Lakes region in the spring may come from overwintered eggs, most are migrants from southern states. Some of these migrants enter the area already infected with aster yellows. Both the proportion of leafhoppers infected and the number of migrants varies from year to year. Thus the risk of aster yellows early in the season varies. Offspring of the original migrant leafhoppers become infected with aster yellows by feeding on infected plants. Therefore, the persistence and spread of aster yellows during the rest of the growing season depends on the population density of aster leafhoppers and how many of their food sources are infected with the disease. Since 2001 we have assessed the relative risk of aster yellows throughout the growing season by testing the infectivity level of aster leafhoppers. Analysis of the data shows variability from year to year and location to location in the proportion of aster leafhoppers infected with aster yellows. However, in most years a general pattern emerges. The infectivity level of aster leafhoppers early in the season (June) varies from about 1% to 5%. The rate stays fairly constant until about mid-july when it usually drops to 0% for a short while, before rising to a much higher level (from 10% to 30%) (Figure 1). This is consistent with the scenario of a low percentage of migrant aster leafhoppers carrying aster yellows and spreading the disease to local plants. Subsequent generations acquire the disease depending on the prevalence of infected plants and aster leafhopper population growth, both of which vary, depending on a number of environmental and biological factors. The year 2004 was very different. Testing in mid to late June revealed a fairly low proportion of aster leafhoppers infected with aster yellows (0 to 2%, depending on location). After this date the infectivity rate dropped to 0% for most populations and remained at this level throughout the season. The proportion of carrots infected was correspondingly low, although fields exposed to migrant populations early in the season did have a small proportion of plants showing aster yellows symptoms (10 to 15% of roots with symptoms). It is clear that, although we understand many of the environmental and biological factors that affect aster leafhoppers and aster yellows, there are other factors at work that we do not yet understand. Figure 1. Proportion of aster leafhoppers collected from a carrot field in Oceana County, Michigan infected with aster yellows (PCR testing) throughout the 2001 through 2003 growing season.

10 25% 20% 15% Proportion of ALH infected with AY---Oceana Co % 5% 0% 5-Jun 20-Jun 5-Jul 20-Jul 4-Aug 19-Aug 3-Sep

11 Carrot Weed Control for 2005 Bernard Zandstra Michigan State University East Lansing, MI Carrot weed control trials were conducted on sand and muck soil during On sand the following preemergence herbicides did not cause yield reduction: Lorox 0.5 lb active ingredient per acre (1 lb product), Command 0.5 lb (1.3 pt), Dual Magnum 1.7 lb (1.8 pt), Prowl 2 lb (2.4 qt), and Caparol 1 lb (1 qt). The following postemergence treatments did not cause yield reduction: Lorox 0.5 lb (1 lb), Goal (8 fl oz), Chateau lb (2 oz), and Caparol 1 lb (1 qt). All of these treatments gave good weed control on sand. The well-timed rains helped incorporate the preemergence herbicides, making them very effective. The moderate temperatures and regular rains caused the carrots to grow well and overcome any stunting caused by the herbicides. On muck soil, all of the preemergence treatments had yield reduction as a result of weed pressure. We were unable to keep the plot clean as a result of excess rain during the growing season. The best treatments were Lorox 1 lb ai (2 lb product), Prowl 2 lb (2.4 qt), and Caparol 1 lb (1 qt). In the postemergence trial, the following treatments had no reduction in yield: Lorox 0.25 lb (0.5 lb) plus Poast 0.19 lb (1 pt) plus COC, Lorox 0.5 lb (1 lb) plus Poast 1 pt plus COC, Sencor 0.25 lb (0.33 lb), and Sencor 0.5 (0.67 lb). Treatments with only slight yield reduction were: Goal (8 fl oz) and Caparol 1 lb (1 qt). Several treatments had lower yields, but the reduced yields appeared to be the result of increased weed pressure. None of the treatments appeared to cause excess carrot foliar injury. The Goal and Chateau treatments caused some foliar burn, but the carrots soon outgrew the injury. Dual Magnum was labeled for carrot this year. It is a third party label held by the Michigan Vegetable Council. Dual Magnum may be used only on soils with more than 20% organic matter (OM). Make one application of pints after seeding. There is a 64-day preharvest interval. Dual Magnum controls annual grasses and suppresses yellow nutsedge for about 4 weeks. It is very active against eastern black nightshade and redroot pigweed. It tends to be a little weak on common lambsquarters.

12 Integration of IPM Methods for Carrot Eco-Labeling Potential Walter R. Stevenson University of Wisconsin, Department of Plant Pathology Tel. No The integration of multiple practices in the production of vegetable crops is an important factor in managing pest problems at economic levels with reduced risk inputs. IPM techniques include crop rotation, cultivars with reduced susceptibility to pest problems, knowledge of pest levels to time treatment, weather information to predict pest outbreaks and reduced-risk pesticides that help to avoid potential adverse impacts on the environment, the applicator and the consumer. The vegetable industry has adopted a wide range of IPM practices over the years that are making a significant impact in how crops are grown. As we evaluate the IPM practices used by growers, we observe a range in the adoption of specific practices that are used by some growers, but would likely benefit the entire vegetable industry. Some of the early adopters of these practices are clearly benefiting from the seasonal use of some elements of IPM while other growers continue to use older, more established production methods. Nationally and internationally there is increasing emphasis on reducing pesticide inputs. We see this in the growing trend of organic production and sales of a wide range of commodities. We also see a transitional area termed eco-production where there is emphasis on reducing pesticide inputs and wherever there are few or ineffective alternatives to pesticide use, substituting reduced-risk pesticides for older, more toxic materials. The Wisconsin Healthy Grown program is a key example of how collaborative efforts between growers (Wisconsin Potato and Vegetable Growers Association), an environmentally friendly focus group (World Wildlife Fund) and university research and extension (UW- Madison) can collaborate in production and sales of an economically important commodity (fresh market potatoes). As the Healthy Grown program moves forward, we are observing a shift towards the increased adoption of IPM practices and a significant reduction in the toxicity of the pesticides and pesticide programs used by growers. In the long term, this trend benefits the entire potato industry. The adoption of eco-production practices has obvious applications for crops other than potato. In the Midwest, we feel significant gains can be achieved with carrot producers and processors. The carrot crop has a significant research base that we have accumulated and useful pest management information that is readily being adopted by the both growers and processing industries. During the summer of 2003 we worked closely with a processor, three Wisconsin carrot growers and pest management consultants in developing and implementing a multifaceted approach to production of these crops. During 2004, this work was continued as we worked intensively with two carrot growers, processors and pest consultants and incorporated several new cultivars they felt were promising to their production and processing needs. The approach we took was to compare two crop management programs 1) standard production programs currently used by progressive growers that already incorporate several elements of pest management ( Current WI Program ) and 2) the Wisconsin Next Step Program that integrates multiple pest management tools and further potentially reduces dependence on pesticide use. Details of the carrot disease management protocols used for each cropping program are listed in Table 1 and 2.

13 Data collected over two very different production years in terms of weather and pest pressure suggest that carrot growers can reduce fungicide inputs (20-50%) and total active ingredient significantly, without sacrificing disease control, root harvestability or total yield. Performance of weather-based treatments was comparable to grower standard treatments as measured by disease severity, control efficacy and yield samples collected. On cultivars Heritage, Enterprise, Fontana and Canterbury, a 15 Disease Severity Value (DSV) weather-based treatment provided superior or equivalent disease control and comparable yields to the standard programs with 1-2 fewer fungicide applications. Similarly, forecasting treatments on cultivars Canada, Carson, Sirocco and Bolero (with modest levels of foliar disease resistance) provided the same control as the standard program with a 20 DSV interval and 2-3 fewer fungicide applications. Continued grower and industry-wide education regarding these IPM tactics and reduced-risk techniques is expected to improve strategy implementation, production sustainability, food quality and environmental health. Table 1. Field Activity Plan For Evaluation Of IPM Practices On Carrots During 2003 IPM Practice Category Next Step Program Current Grower Program Cultivar Selection Bolero, Enterprise, Sirocco, Carson Heritage, Fontana or Danvers Fungicide Program primarily for management of Alternaria leaf blight and Cercospora leaf blight Scout weekly from emergence Sprays begin at 1% disease Use TomCast Program spray interval at 20 DSV, compare with 15 DSV Alternate chlorothalonil and strobilurin chemistry beginning with chlorothalonil Scout weekly from emergence Sprays begin when plants reach about 6 in height calendar approach Spray weekly with fungicide Spray program consists of chlorothalonil each spray Table 2. Field Activity Plan For Evaluation Of IPM Practices On Carrots During 2004 IPM Practice Category Next Step Program Current Grower Program Cultivar Selection Heritage, Enterprise, Canterbury, Heritage, Fontana or Danvers Canada, Carson and Bolero Fungicide Program primarily for management of Alternaria leaf blight and Cercospora leaf blight Scout weekly from emergence Sprays begin at 1% disease Use TomCast Program spray interval at 15 DSV for cv s Heritage, Enterprise, Canterbury, and 20 DSV for Canada, Carson and Bolero Alternate chlorothalonil and strobilurin chemistry beginning with chlorothalonil Scout weekly from emergence Sprays begin when plants reach about 6 in height calendar approach Spray weekly with fungicide Spray program consists of chlorothalonil each spray The adoption of improved IPM strategies by carrot producers has the potential to significantly reduce disease management inputs while maintaining disease control efficacy, yield and root quality. We have observed similar results in small research trials and large replicated trials on commercial farms during the past two years in Wisconsin. The results of these trials show that by selecting cultivars with improved disease resistance, using treatment thresholds (1% foliage infection) combined with the TomCast Program (DSV totals) for scheduling fungicide sprays and substituting newer reduced risk fungicides for older chemistries, it is possible to substantially reduce the total ai of fungicide application, the pesticide toxicity score associated with the season-long disease management program and overall disease management costs. Since growers have directly participated in these large trials, they have firsthand experience with the use of the TomCast program and the decision-making process involved in pyramiding multiple IPM tools in their fields and the eco-production of this important vegetable crop.