Strategies to mitigate losses due to black streaks in celery

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

In 2005 and 2006, celery growers suffered severe economic losses due to a physiological disorder known as “black streaks.” The internal disorder makes the entire crop unmarketable. With celery being one of the most intensive and high value crops (about $7,800/A in 2009 for the Michigan industry), growers could be severely affected because of the high production costs. ‘Dutchess’ has so far been the most affected cultivar.


Celery plants with this defect look perfectly healthy in the field; however, when cut, some petioles show “black streaks” in the lower half or throughout the entire length of the petiole. Symptoms are generally more pronounced in larger plants than in smaller ones.


The problem is a physiological disorder (not caused by a pathogen). Studies conducted in 2006 showed that the symptoms can be triggered under field conditions by high temperatures. The number of petioles with “black streaks” symptoms increased as temperature in our experiment was raised. The cultivar ‘Greenbay’ exhibited high levels of tolerance to the disorder. Studies conducted in the greenhouse highly suggested that boron deficiency could be implicated in the occurrence of “black streaks” in celery. Also, it is likely that the combination of a mild boron deficiency and high temperature during the rapid plant development phase could promote the disorder. Unfortunately, the weather has been relatively cool over the last two summers and our field studies conducted with boron did not provide definitive conclusions.

Tips for avoiding losses in 2010

In the past (2005 and 2006), “black streaks” occurred on celery plants that were in their exponential growth phase (active growth) during the month of July. Both 2005 and 2006 weather data indicate that during that time air temperatures exceeded 90oF for a couple of days.

With a zero tolerance for this problem, growers should be particularly careful in programming and scheduling their crop. Our current suggestions, based on the 2005 and 2006 experience and follow up trials are as follow:

  1. Minimize the acreage of highly susceptible varieties for planting between May 25 and June 15 because the rapid growth phase of the crop may coincide with the hottest part of the season.
  2. During that window of time use a tolerant cultivar like ‘Greenbay.’
  3. Make sure boron supply to the crop is adequate, especially under hot weather, when the crop is growing very fast and make foliar applications if needed.
  4. Contact our team if you observe symptoms of the disorder for sampling and analysis. Email: Phone 517-355-5191 x 1410

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