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1.9 Case study: Integrated management of Alternaria blight in carrots Introduction Efficacy of sole control measures Integrated of control measures Concluding.

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Presentation on theme: "1.9 Case study: Integrated management of Alternaria blight in carrots Introduction Efficacy of sole control measures Integrated of control measures Concluding."— Presentation transcript:

1 1.9 Case study: Integrated management of Alternaria blight in carrots Introduction Efficacy of sole control measures Integrated of control measures Concluding remarks

2 Alternaria dauci in carrots

3 Carrot field infected with Alternaria dauci

4 Carrot combine

5 Chemical management of A. dauci Sprinkler irrigation 123456789 Air spraying Ground spraying Time (days)

6 Fungicide treated plot Untreated control plot

7 For management of A. dauci up to 4 sprays are applied each week and up to 40 sprays are applied in a growing season !!!

8 Objective of the research To develop an integrated management strategy that will: 1. Reduce the number of sprays applied in a growing season; 2. Prevent disease development and yield losses

9 Management of A. dauci Chemical fungicides (protectant, systemic) Cultural measures (spatial organization of planting, sanitation, irrigation type) Genetic (cultivar resistance) Sole application of measures Chemical and drip irrigation Cultivar resistance and chemical control Integration of measures

10 Temporal and spatial dissemination of spores

11 Distance from source field (m) 0100200300400500600700 0 10 20 30 40 Y=34.6-0 11X+0.0001X 2 -4E-08X 3 R 2 =0.97 Disease severity (%) Spatial influence of an infected field on neighboring fields Wind direction Infected source field Neighboring affected field

12 Spatial organization of plantings Wind direction 1234 5674

13 Effect of sanitation: burring of infected debris after harvest in the soil Before after

14 Optimization of chemical control 60708090100110 0 20 40 60 80 100 Disease severity (%) Untreated Bravo, Score Time (days after planting) Efficacy of various fungicides

15 Why the systemic mobility of the fungicide is not an advantage? Development of A. dauci on carrot leaves

16 Why the systemic mobility of the fungicide is not an advantage? Protectant fungicide Systemic fungicide

17 Optimization of chemical control Optimal timing for spraying initiation Control efficacy (%) -20-10010 20 40 60 80 100 0 Time from disease onset and spraying initiation (days) Tebuconazole mancozeb Disease onset

18 Optimization of chemical control 8090100110120 100 0 20 40 60 80 Time from planting (days) Disease severity (%) Untreated 8 sprays First 4 Last 4 Date of praying (DAP): Initiation Termination First 4 sprays Last 4 sprays 8 sprays 29 77 29 65 119 119 Treatment Disease onset Optimal timing for spraying initiation

19 Optimization of chemical control Optimal timing for spraying termination Disease severity (%) -14 Control -42 -29 -21 60 80 100 20 100 20 40 0 Time before harvest (days) Last spray (days before harvest)

20 Genotype resistance Disease severity (%) Time from planting (days) 60708090100110 20 40 60 80 100 0 cultivars 20 40 60 80 100 0 60708090100110 Disease severity (%) Time from planting (days) Genotype resistance + fungicides

21 Type of the irrigation system 3/99/915/921/927/9 6 8 10 12 Hour of foliage dryness Overhead irrigation

22 Integration of drip irrigation and application of fungicides Disease severity (%) Time from planting (days) 20 40 60 80 100 0 Overhead Drip 5060708040 + fungicide

23 Effects of drip irrigation on the epidemic and on fungicide efficacy Drip pathogen environment host Shorter wetness duration 70%

24 Effects of drip irrigation on the epidemic and on fungicide efficacy Drip pathogen environment host Lower weathering of fungicide from the foliage 30%

25 Time Disease severity (logit) Contribution of sanitation and spatial organization of planting

26 Time Disease severity (logit) Contribution of cultivar resistance, drip irrigation protectant fungicides

27 Time Disease severity (logit) Contribution of systemic fungicides

28 Time Disease severity (logit) Integration of control measures +Drip irrig. +systemic fung. Resistant cv. +spatial organization

29 Concluding remarks The major means for suppression of Alternaria blight in carrots is chemical application of fungicides. Up to 40 sprays are currently applied in a growing season. Use of resistant cultivars, drip irrigation, burying infected debris after harvest and re-organization of planting in space, each may contribute to disease suppression. Integration of several control measures enable to reduce the number of sprays, without increasing the risk for disease outbreaks.


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