Jul 19, 2011

Heat wave may be conducive to black streak development in celery

The most recent weather forecast for Michigan predicts temperatures ranging from 90 to 97°F for the next six to seven days. Based on studies conducted from 2006 to 2010 and observations from many Michigan celery growers, black streak development in 2005, 2006, 2007 and 2010 occurred when hot weather with temperatures above 90°F persisted for a couple of days during the rapid growth phase of celery. Depending on weather conditions after crop establishment in the field, celery normally reaches its rapid growth phase in four to seven weeks after transplanting. At that stage, transplants are well established, have good root systems, new leaves are formed, and the entire plant undergoes a rapid biomass accumulation.

Crops/plantings at risk

All crops currently well established in the field could be at risk. However, based on previous experience, the most vulnerable crop is celery transplanted between May 29 and June 26, 2011. Dutchess has so far been the most susceptible cultivar and many growers avoided planting it during the period of high risk. However, given the magnitude of the hot temperatures and the length of the heat wave, other cultivars may show the disorder at harvest.

Management options

Currently, there is no management strategy that has shown efficacy on this disorder. Work conducted in 2010 shows that over application of boron could increase the problem. Therefore, growers should avoid applying boron during this time period. Overhead irrigation during hot days could help cool the crop. While this strategy has not been tested scientifically, it is strongly recommend to growers. This may be a good opportunity to test the impact of overhead irrigation on the incidence of the disorder. Growers should pay special attention to the crop transplanted between May 29 and June 26, 2011.

Our team will be monitoring the disorder and would appreciate any comments from growers. Contact us at 517-896-8988 or email Mathieu Ngouajio.

By Mathieu Ngouajio, Michigan State University Extension