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)
Apples
Apricots
Asparagus
Beets
Blueberries
Broccoli
Brussels Sprouts
Cabbage
Carrots
Cauliflower
Cherries
Cucumbers
Dry Beans
Eggplant
Ethnic Vegetables
Garlic
Grapes
Horseradish
Kohlrabi
Leeks
Lettuce / Leafy Greens
Melons
Nectarines
Onions
Parsnips
Peaches
Pears
Peas
Peppers
Plums
Potatoes
Pumpkins / Gourds
Radishes
Raspberries / Blackberries
Rhubarb
Rutabaga
Snap Beans
Squash - Summer
Squash- Winter
Strawberries
Sweet Corn
Sweet Potatoes
Tomatoes
Turnips
Upcoming Events
2026 Champlain Valley Summer Orchard Field Tour
July 15, 2026 : 2026 Champlain Valley Summer Orchard Field Tour
Keeseville, NY
Join the ENYCHP and Cornell scientists on July 15 for our annual Champlain Valley Summer Orchard Meeting! This year we will be meeting at Hart Apple Farm to learn about the varieties they are growing in one of their newer plantings, hear updates from faculty and extension agents on their current research projects, and view a few of Mike's local thinning projects firsthand.
DEC credits in categories 22, 1A, and 10 will be available. Refreshments will be provided.
Free to attend, however we do ask that you register ahead so we know how many people to expect. Rain date is July 16.
2026 Hudson Valley Berry Field Day
July 15, 2026 : 2026 Hudson Valley Berry Field Day
Kinderhook, NY
Join specialists Heather Kase, Scott Cosseboom, Nathaniel Westrick, and Anna Wallis for updates and a review of berry phenology and pest management. Presentations will be given on berry horticultural and pest management considerations for strawberries, blueberries, brambles, and minor fruit crops. Light refreshment & snacks will be provided. Registration is encouraged but there is no fee for attendance. 1.00 DEC credit will be available in categories 10, 1a, and 22