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Bacterial Leaf Spot of Pepper

Four field experiments were conducted in 1997 and 1998 to evaluate resistant varieties and fungicide programs applied on preventive and IPM application schedules for managing bacterial leaf spot.  There were spreader rows inoculated with pathogen races 1, 2, and 3 which were the races occurring at the time.  Races 4, 5, and 6 had been identified but were uncommon.  A split plot experimental design was used for the resistant variety evaluation with fungicide as the main plot treatment and variety as the subplot treatment.  This design was used to assess the value of using an integrated management program with fungicides applied to a resistant variety.  The fungicide program was the copper fungicide Kocide 2000 tank mixed with the maneb fungicide Manex, which has since been discontinued and replaced by related mancozeb fungicides.  These are recommended used with copper to increase their activity.

Results.  Genetic control was more effective than chemical control for managing bacterial leaf spot.

Bacterial leaf spot was managed as effectively with applications started after observing symptoms (IPM schedule) as with a preventive schedule.

pepper plants getting sprayed with pesticides in field.
Sprayer equipped with drop nozzles to obtain good spray coverage.
field of peppers with sprinklers running overhead
Sprinklers used to increase favorability of conditions for bacterial leaf spot.
A nontreated pepper plot
Nontreated pepper plants in 1997 fungicide experiment. Defoliation is due to bacterial leaf spot.
A preventively treated pepper plot
Pepper plants in 1997 fungicide experiment that were treated with Kocide + Manex on a weekly, preventive schedule.
an IPM treated pepper plot
Pepper plants in 1997 fungicide experiment that were treated with Kocide + Manex on a weekly, IPM schedule.

 

Publications listed below have more information about research results summarized above, including table with results.  To download report click on publication year, which is year after study was done; all are available at Plant Disease Management Reports website.

  1. McGrath, M. T.  1998.  Comparison of resistant varieties and chemical control for managing bacterial leaf spot of pepper, 1997. Biological and Cultural Tests 13:168.
  2. McGrath, M. T.  1998.  Evaluation of bactericide programs initiated after disease detection for managing bacterial leaf spot of pepper, 1997. Fungicide and Nematicide Tests 53:169.
  3. McGrath, M. T.  1999.  Comparison of resistant varieties and chemical control for managing bacterial leaf spot of pepper, 1998. Biological and Cultural Tests 14:169.
  4. McGrath, M. T.  1999. Evaluation of bactericide programs initiated after disease detection for managing bacterial leaf spot of pepper, 1998. Fungicide and Nematicide Tests 54:167.