Cause Calcium deficiency causes this abiotic disease associated with growth conditions, particularly soil moisture. Sudden flooding after a long dry period frequently induces black heart. The disease does not appear in crops grown at a continuously low or uniform moisture level. Soil aeration is important, particularly when soil moisture rapidly increases to saturation. Crops growing under excessive nitrogen levels are more susceptible to blackheart following a sudden increase in soil moisture, as the rate of growth exceeds the rate of calcium uptake from the soil.
Symptoms Many symptoms appear in young leaflets still within the plants' crowns. Tissue turns black, and necrosis advances rapidly until it involves the entire heart. Soft rot bacteria often follow, resulting in a slimy decay. First evidence may be chlorosis of the early-matured leaves followed by the blackened heart.
- Maintain uniform soil moisture and moderate levels of available nitrogen.
- When conditions favor blackheart, immediately apply a spray of calcium nitrate or calcium chloride at 5 to 10 lb/100 gal in a volume of 100 to 150 gal/A. Use sufficient spray pressure to penetrate outer leaves and reach the heart. Do not wait until symptoms appear; that may be too late to correct the problem.
Reference Foster, A.C. 1934. Black heart disease of celery. Plant Disease Reporter 18:177-185.