EVALUATION OF CARROT CULTIVARS AND BREEDING SELECTIONS TO IDENTIFY RESISTANCE TO FOLIAR BLIGHTS,

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1 CARROT (Daucus carota subsp. sativus) Alternaria Leaf Blight; Alternaria dauci Cercospora Leaf Blight; Cercospora carotae R. V. James and W. R. Stevenson Department of Plant Pathology University of Wisconsin-Madison Madison, WI EVALUATION OF CARROT CULTIVARS AND BREEDING SELECTIONS TO IDENTIFY RESISTANCE TO FOLIAR BLIGHTS, 1998: A trial was established at a commercial muck farm near Portage, WI on May 18 to evaluate fifty carrot cultivars and breeding s for reaction to Alternaria and Cercospora leaf blights. Seeds were planted at approximately 24 seeds per foot (slicing type) or 10 seeds per foot (dicing type) using a cone seeder. The soil type was Adrian Muck with ph of 5.3 Each plot consisted of two 12-foot-long rows planted 1 foot apart in the center portion of a raised bed which was 54 inches wide. A randomized complete block design with three replications was used. To minimize interplot interference and provide a uniform source of inoculum throughout the trial, a row of Lucky B, susceptible to both blights, was planted on each side of each test plot. Test plots were separated within the bed by 3 foot open buffer spaces. Fertilizer consisted of preplant application of 240 lb/a of lb/a of Boron. Asana XL (5.8 fl oz./a) was applied to the foliage June 17 for insect control and weeds were controlled with application of Fusilade DX (12 fl oz./a on June 6; 8 fl oz./a on July 20) and Linex 50 DF, 1.1 lb/a + Sencor 75 DF, 1.8 oz/a on June 21. Fungicide was inadvertently applied once at the beginning of the season when the adjacent commercial field was treated (Terranil 90 DF, 1.4 lb/a, July 7) but no additional fungicide was applied during the rest of the season. Disease severity was rated August 3, August18, September 3, September 21 and September 30 using the Horsfall- Barratt system. A five-foot-long section of row was hand dug from each plot on October 1 and the yield was graded into five size classes (based on diameter) and culls. The size classes were then grouped appropriately to conform to standards for dicing or slicing carrot contracts. values were calculated for each cultivar and breeding based on typical processing contracts. Rainfall measured at the nearest recording weather station (Hancock, WI) was May (18-31) - 0.7", June - 6.4", July - 2.5", August - 6.5" and September 2.3" for a total of 18.4". Alternaria and Cercospora leaf blights were slow to develop in this trial, with low disease severity recorded through the August 18 rating. Disease development accelerated in late August and September with the susceptible standard, Lucky B, exhibiting 55% foliage infection in the final rating (September 30) and a number of test lines showing higher percent foliage infection. A number of lines exhibited significantly lower levels of disease at this rating. Lines with a final disease rating significantly lower than the susceptible check include: (7241A), (W2-HC4), , Apache, Blaze, Carson, Cheyenne, Coral II, CXC 2589, Enterprise, Fullback, Halfback, Indiana, Newport, Prospector, PSR , XPH18031 and Xph95W94. Lines with area under the disease progress curve (AUDPC) significantly lower than the susceptible check include: (7241A), (W2-HC4), (5280B), , , Apache, Blaze, Bolero, Canada, Carson, Cheyenne, Coral II, Danvers 126, Enterprise, Fullback, Halfback, Indiana, Newport, Prospector, PSR , XPH18029, XPH18031, XPH18085 and Xph95W94. The ten lines with the highest total yield value (graded for slicing) were: Bolero, Blaze, Carson, Eagle, Heritage, Napa, Prospector, Protégé, Rogers 1851A and Scarlet Nantes. The ten lines with the highest total yield value (graded for dicing) were: CXC 2589, , Canada, Carson, Cascade, Danvers 126, Early Gold, Fullback, Halfback and XPH18031 (Table 4). Lines which exhibited relatively low levels of disease (as measured by final disease or AUDPC) and good yield value include: Apache, Blaze, Bolero, Canada, Carson, Coral II, CXC 2587, Danvers 126, Enterprise, Fullback, Halfback, Prospector, PSR , XPH18029, XPH18031 and XPH Three of the industry standards included in the trial -- Bolero and Prospector (slicer standards) and Danvers 126 (dicer standard) are included in this group and a number of other lines also show promise with good yield, calculated crop values exceeding $1,000 per acre, and low disease development. This indicates that progress is being made

2 toward development and acceptance of cultivars that could grow and yield well without application of fungicide or with significantly reduced fungicide application. Data collected by Steve Keil, Agrilink Foods Vegetable Co., provide additional valuable information on root quality. Those cultivars and breeding lines having minimal root defects and greatest root length combined with being top performers in other categories such as disease resistance, yield and value of yield would appear to have the greatest potential for Wisconsin production.

3 Table 1. Processing type and source of seed for cultivars and breeding lines used in this trial. # Cultivar or line Source Use Type Dice Slice Mini Slicer Standards 1 Bolero 1 Vilmorin 2 Prospector 1 Peto 3 PY-60 1 Peter-Edward Dicer Standards 4 Danvers 126 Rogers 5 Gold King Rogers Test Lines 6 Apache 1 Sun 7 Blaze 1 Rogers 8 Canada Bejo 9 Carson 1 Bejo 10 Cascade Bejo 11 Cheyenne 1 Sun 12 Coral II 1 Seeds Garden City 13 Eagle 1 Sun 14 Early Gold 1 Peto 15 Enterprise 1 Peto 16 Falcon 1 Sun 17 Fullback 1 Rogers/ Novartis 18 Halfback Novartis 19 Heritage 1 Asgrow 20 Idaho Bejo 21 Indiana 1 Bejo 22 Lucky B Chrisseed 23 Napa 1 Bejo # Cultivar or line Source Use Type Dice Slice Mini 24 Newport 1 Bejo 25 Oranza 1 Bejo 26 Protégé 1 Asgrow 27 PY-60 Improved 1 Rispens 28 Scarlet Nantes 1 various (3475M) USDA/Simon (7241A USDA/Simon (W2-HC4) USDA/Simon (5280B) USDA/Simon (WAY247B) Goldman W279B) Goldman (W280B) Goldman Chriseed Chriseed Chriseed 39 CXC Chriseed 40 HMX 4302 Harris-Moran 41 HMX 4303 Harris-Moran 42 PSR Peto 43 Rogers 1851A 1 Rogers 44 Xph87W341 Crookham 45 Xph95W94 Crookham 46 XPH18029 Asgrow 47 XPH18031 Asgrow 48 XPH3910 Asgrow 49 XPH18085 Asgrow 50 XPH18032 Asgrow 1. Requested by WI Carrot Growers Association Cooperative to be included in this trial 2. Inbred line from UW Department of Horticulture carrot and onion breeding program 3. Line from USDA carrot breeding program, UW Department of Horticulture Table 2. Severity of leaf blight on carrot cultivars and breeding s. Percent foliage infection 1 Relative Cultivar or breeding 8/3 8/18 9/3 9/21 AUDPC 2 Slicer Standards 1 Bolero Prospector PY Dicer Standards 4 Danvers Gold King Test Lines 6 Apache Blaze Canada Carson Cascade

4 Percent foliage infection 1 Relative Cultivar or breeding 8/3 8/18 9/3 9/21 AUDPC 2 11 Cheyenne Coral II CXC Eagle Early Gold Enterprise Falcon Fullback Halfback Heritage HMX HMX Idaho Indiana Lucky B Napa Newport Oranza Protégé PSR PY-60 Improved Rogers 1851A Scarlet Nantes XPH XPH XPH XPH XPH Xph87W Xph95W (3475M) (7241A (W2-HC4) (5280B) (WAY247B) W279B) (W280B) Pr > F 3... <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 LSD Severity of leaf blight symptoms was rated on a Horsfall-Barratt scale of 0 (no infection) to 11 (all foliage dead). No attempt was made to evaluate symptoms of Alternaria and Cercospora blights separately. Ratings were converted to percent foliage infection. 2 Relative area under the disease progress curve. Data for each date were plotted on a graph and the area under the line was calculated for each treatment providing a measure of the relative severity of disease throughout the season. A disease rating of 100% foliage infection for the entire season would produce a value of 1.0. All relative AUDPC values are expressed as the proportion of this value. Either decreased disease severity or later disease development will contribute to lower relative areas under the disease progress curve. 3 Analysis of variance was performed on data, and Fisher's protected least significant difference (LSD) was calculated. NS = not significant at the P = 0.05 level.

5 Table 3., size distribution and gross value for carrot cultivars and breeding s. Cultivar or Breeding Selection (Ton/ A) 1 < ¾ Percentage of yield for carrot Graded as Slicers 2 Graded as Dicers 2 diameter (inches) Percentage of Gross Percentage of Price/ of Price/ ¾ - 1 ¼ - 1 5/8 - % ¾ - > Discards 2 > 2 cards Ton 1 ¼ - Dis- Ton 1 ¼ 1 5/8 2 > 2 culls 1 5/8 1 5/8 Gross of # of carrots with aster yellows symptoms Slicer Standards Bolero Prospector PY Dicer Standards Danvers Gold King Test Lines Apache Blaze Canada Carson Cascade Cheyenne Coral II CXC Eagle Early Gold Enterprise Falcon Fullback Halfback Heritage HMX HMX Idaho Indiana Lucky B Napa Newport Oranza Protégé PSR PY-60 Improved Rogers 1851A

6 Cultivar or Breeding Selection (Ton/ A) 1 < ¾ Percentage of yield for carrot Graded as Slicers 2 Graded as Dicers 2 diameter (inches) Percentage of Gross Percentage of Price/ of Price/ ¾ - 1 ¼ - 1 5/8 - % ¾ - > Discards 2 > 2 cards Ton 1 ¼ - Dis- Ton 1 ¼ 1 5/8 2 > 2 culls 1 5/8 1 5/8 Gross of # of carrots with aster yellows symptoms Scarlet Nantes XPH XPH XPH XPH XPH Xph87W Xph95W (3475M) (7241A (W2-HC4) (5280B) (WAY247B) W279B) (W280B) Pr > F 3... <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 < LSD NS 1 A 5-foot section of row was hand dug in each plot and yield was converted to tons/a. Hand digging is likely to result in a higher apparent yield as fewer carrots are lost than when mechanically dug. Carrots were graded into five size classes or culls (misshapen or rotted). The size classes were then grouped appropriately to conform to standards for dicing or slicing carrots. --- indicates extremely poor stand. No yield data were taken for these entries in trial. 2 s are calculated based on typical 1998 processing contracts for uncrowned carrots. Dicing carrot contract: Minimum size accepted is 1 1/4 inch; discard class includes culls and carrots below the minimum diameter. Dicing base price per ton is: >90% of crop over 2 diameter - $51.70; 81-90% > 2 - $51.30; 71-80% > 2 - $50.10; 61-70% > 2 - $48.00; 51-60% > 2 - $45.90; < 51% > 2 - $ Slicing carrot contract: Minimum size accepted is 3/4 inch diameter; discard class includes culls and carrots below the minimum diameter. Slicing base price per ton is: < 10% over 1 5/8 diameter - $54.70; 10-19% > 1 5/8 - $53.90; 20-29% > 1 5/8 - $52.40; 30-39% > 1 5/8 - $49.40; 40-49% > 1 5/8 - $46.45; >49% > 1 5/8 - $ Prices listed in the table include a $4.75 per ton variety premium, added to the base price, for : Apache, Blaze, Cheyenne, Enterprise, Indiana and Napa. 3 Analysis of variance was performed on data, and Fisher s protected least significant difference (LSD) was calculated. NS = not significant at the P = 0.05 level.

7 Table 4. Ranking of cultivars and breeding s according to several criteria. % foliage infection significantly below that observed for the susceptible check, Lucky B (ranked by % foliage infection) Cultivar or breeding % foliage infection AUDP C (Ton/A) of As As Slicers Dicers 9 Carson Blaze (W2-HC4) Cheyenne Xph95W CXC Fullback Indiana (7241A) Newport Coral II Halfback Apache Enterprise XPH PSR Prospector AUDPC significantly below that calculated for the susceptible check, Lucky B (ranked by AUDPC) Cultivar or breeding % foliage infection AUDP C (Ton/A) of As As Slicers Dicers 9 Carson (W2-HC4) Cheyenne Blaze (7241A Xph95W Fullback Indiana XPH Newport Enterprise Coral II Apache Halfback Prospector XPH XPH Canada Danvers Bolero PSR (5280B) "Top 20", ranked by total value of yield - as slicing carrots Cultivar or breeding % foliage infection AUDP C of As As Slicers Dicers 1 Bolero Eagle Napa Scarlet Nantes Protégé Rogers 1851A Heritage Blaze Carson Prospector Apache Canada Idaho CXC Cascade Lucky B Halfback PY-60 Impr Enterprise HMX "Top 20", ranked by total value of yield - as dicing carrots Cultivar or breeding % foliage infection AUDP C (Ton/A) of As As Slicers Dicers 39 CXC Canada Early Gold Carson Cascade Danvers Halfback Fullback XPH XPH XPH Xph87W Coral II XPH XPH PSR Bolero Gold King

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9 Table 5. Summary Table - "Top performers" for at least one criterion (entries are listed in alphabetical order). "Boxed" numbers indicate: Foliage infection (final rating, ), significantly lower than susceptible check (Lucky Slicer - value of yield - top 20 in value B) Dicer - value of yield - top 20 in value AUDPC - significantly lower than susceptible check (Lucky B) Cultivar or breeding % Foliage Infection AU DPC (Ton / A) 1 of Slicer of Dicer 6 Apache Blaze Bolero Canada Carson Cascade Cheyenne Coral II CXC Danvers Eagle Early Gold Enterprise Fullback Gold King Halfback Heritage HMX Cultivar or breeding % Foliage Infection AU DPC (Ton / A) 1 of Slicer of Dicer 20 Idaho Indiana Lucky B Napa Newport Prospector Protégé PSR PY-60 Imp Rogers 1851A Scarlet Nantes XPH XPH XPH XPH XPH Xph87 W Xph95 W Cultivar or breeding % Foliage Infection AU DPC (Ton / A) 1 of Slicer of Dicer (7241A) (W2-31 HC4) (5280B) Slicer standards (for comparison) 1 Bolero Prospector PY Dicer standards (for comparison) 4 Danvers Gold King Table 6. Carrot length, count and quality observations (Data from S. Keil, Agrilink Foods Vegetable Co.) # of Root length (in) Count Defects reps Range Range Forks Cracks Rot Aster Yellows Curve/twist Cultivar or harvested (over all Aver- (over all Aver- Breeding Line reps) age reps) age all reps) age all reps) age all reps) age all reps) age all reps) age Apache Blaze Bolero Canada Carson Cascade Cheyenne Coral II CXC

10 # of Root length (in) Count Defects reps Range Range Forks Cracks Rot Aster Yellows Curve/twist Cultivar or harvested (over all Aver- (over all Aver- Breeding Line reps) age reps) age all reps) age all reps) age all reps) age all reps) age all reps) age Danvers Eagle Early Gold Enterprise Falcon Fullback Gold King Halfback Heritage HMX HMX Idaho Indiana Lucky B Napa Newport Oranza Prospector Protégé PSR PY PY 60 Improved Scarlet Nantes XPH XPH XPH XPH 87W XPH 95W XPH XPH A (W2-HC4) (5280-B) W (W879B) (W280B) W