White Rot and Black Rot Biology and Management
Mike Basedow, Tree Fruit Specialist
Eastern New York Commercial Horticulture
The white rot fungus, Botryosphaeria dothidea, often referred to as "Bot rot" or Botryosphaeria rot, can be a distinct canker on twigs, limbs, and trunks. The fungus produces two types of fruit rot, but leaf infections do not occur. Drought stress and winter injury have been associated with an increase in infection and canker expansion. This is a relatively weak fungal pathogen, and is only problematic when a tree is stressed, such as due to drought, winter injury, insect damage, or fire blight.
The black rot and frogeye leaf spot fungus, Botryosphaeria obtusa, attacks fruit, leaves, and bark of apple trees and other pomaceous plants.
White Rot and Black Rot Biology and Management (pdf; 287KB)

Upcoming Events
New Farm Manager Skills Day - Get the Tools You Need to Grow Your People (Hudson Valley)
March 10, 2026 : New Farm Manager Skills Day - Get the Tools You Need to Grow Your People
Millbrook, NY
Are you moving into a supervisory farm management role this season and want to get off to a good start? Are you an experienced manager who wants to connect with other "people" managers and work on your skills? This one-day workshop is for you!
SPARC WSU Tree Fruit Heat School
March 11, 2026
As part of our multi-state SPARC SCRI project on mitigating orchard heat and cold stress, the WSU Tree Fruit Heat School will focus on understanding and managing heat-related challenges in apple and pear production. The program brings together research-based insights and applied discussions on sunburn physiology and mitigation, red color development in apples and pears, and the impacts of heat on postharvest storage and fruit quality. Each session will include an expert presentation, followed by a panel discussion with panelists from across the US.
Urban Ag Food Safety Webinar
March 11, 2026
Urban and small-scale producers are encouraged to join us for the Urban Ag Food Safety webinar, featuring speakers from Cornell Cooperative Extension and Cornell IPM. We will explore the 'why' behind food safety, providing a basic overview and diving into specific urban ag considerations including water, pest, rodent, and soil health challenges. We will touch on the regulation and marketing landscape, and share resources for learning more. Bring your questions!
