Pear corky spot

Pear corky spot is a physiological disorder primarily affecting pear trees, characterized by the development of localized necrotic spots on the fruit skin and underlying tissue. Unlike fungal or bacterial diseases, it is non-infectious, arising from internal cellular metabolic disturbances during the growth cycle.

The fundamental cause of this disorder is a localized calcium deficiency within the fruit. Because calcium moves slowly through the plant's vascular system, competing demands from actively growing shoots often deprive the developing fruit of this essential nutrient, leading to the collapse of cells beneath the surface.

Initial symptoms appear as small, slightly sunken, dark green or brown spots on the fruit skin as it approaches maturity. As the condition progresses, the tissue underneath these spots becomes dry, brown, and corky in texture. In severe cases, the fruit becomes severely deformed and bumpy, making it unmarketable.

Environmental and cultural factors significantly influence the severity of the disorder. High temperatures, irregular irrigation, and excessive vegetative growth caused by over-fertilization with nitrogen exacerbate the condition. Orchards planted on sandy or acidic soils with low calcium availability are particularly prone to outbreaks.

Prevention and management strategies focus on balancing tree nutrition and irrigation. Key measures include:

• Applying calcium-based foliar sprays throughout the growing season.
• Maintaining uniform soil moisture levels via consistent irrigation.
• Limiting heavy pruning to reduce vegetative competition for calcium.
• Performing annual soil tests to adjust calcium and pH levels as needed.