Skip to content Skip to navigation
UMass Collegiate M The University of Massachusetts Amherst
  • Visit
  • Apply
  • Give
  • Search UMass.edu
Center for Agriculture, Food, and the Environment
UMass Extension Vegetable Program
  • Vegetable Home
  • About
    • About the Vegetable Program
    • Faculty & Staff
    • Funding
    • Request a visit
    • Request a Crop & Pest Management Planning Meeting
    • Contact us
  • Publications
    • Vegetable Notes
    • New England Vegetable Management Guide
    • Northeast Vegetable and Strawberry Pest Identification Guide
    • Cucurbit Disease Scouting & Management Guide
    • Sweet Corn IPM Scouting Guide & Record Keeping Book
    • Nutrient Management Guide for New England Vegetable Production
  • Fact Sheets
  • Special Topics
    • Brassica Pest Collaborative
    • Heating Greenhouses with Locally Grown Corn
    • Winter Production and Storage
  • Resources
    • Food Safety for Farmers
    • Nutrient Management
    • Scouting Resources
    • Research Reports
    • Recursos en Español (Spanish-Language Resources)
    • Useful Links
  • Services
    • Disease Diagnostics
    • Soil and Plant Nutrient Testing
    • UMass Extension Bookstore
    • Hot Water Seed Treatment
    • Mentor Farm Program
    • Scouting Program
  • News & Events
    • Upcoming Events
    • News
    • Past Events
  • Make a Gift

Solanaceous, Early Blight

Image
Alternaria leaf spot on tomato. Photo: Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org
Image
Alternaria lesions on tomato fruit. Photo: R. L. Wick

Alternaria solani

Early blight caused by the fungus Alternaria solani occurs wherever potatoes and tomatoes are grown. Uncontrolled, the disease may cause serious defoliation, resulting in decreased yield and quality.

Identification:

Early blight occurs on the foliage, stem, and fruit of tomato. It first appears as small brown to black lesions on older foliage. The tissue surrounding the initial lesion may become yellow, and when lesions are numerous entire leaves may become chlorotic. As the lesions enlarge, they often develop concentric rings giving them a ‘bull’s eye’ or ‘target-spot’ appearance. In the late summer when conditions are favorable for disease development, lesions can become numerous and plants defoliated, reducing both fruit quantity and quality. Fruit can become infected either in the green or ripe stage through the stem attachment. Lesions can become quite large, involve the whole fruit, and have characteristic concentric rings. Infected fruit often drop and losses of 30-50% of immature fruit may occur. Foliar symptoms on potato are quite similar, though defoliation rarely results. Tuber lesions are dark, sunken, and circular often bordered by a purple to gray raised tissue. The underlying flesh is dry, leathery, and brown. Lesions can increase in size during storage and tubers become shriveled.

Septoria leaf spot usually appears on lower leaves after the first fruit develops. Lesions are small, circular, with dark brown to purple borders and tan to gray centers. Black pycnidia  (fruiting bodies) within lesions are visible with a hand lens. If many leaf lesions develop on a leaf, it may turn yellow, then brown, and wither. Fruit infection is rare.

Life Cycle:

A. solani survives between crops on infected plant debris, soil, other solanaceous host weeds and can be carried on tomato seed and infected tubers. The fungus enters the leaves directly or through wounds. Primary infection can occur on older foliage early in the season, but most secondary spread occurs as the plants age. Actively growing, young tissue and vigorous plants with adequate nitrogen generally do not express symptoms. Infection is favored by mild, rainy weather.

S. lycopersici overwinters in infected crop or solanaceous weed hosts debris. The pathogen can also survive on stakes and cages and be carried in seed. Once introduced, conidia are spread by splashing water, workers and equipment working when foliage is wet, and insects.

Cultural Controls & Prevention:

  • Use resistant or tolerant cultivars.
  • Start with disease-free seed, transplants, and seed tubers.
  • Control susceptible weeds (ie horsenettle) and eliminate volunteer plants and cull piles.
  • Plow under plant debris after harvest.
  • Fertilize properly and keep plants growing vigorously.
  • Rotate out of tomatoes for two years.
  • Careful attention to the timing of irrigation (avoid late afternoon or evening) and proper plant spacing to reduce the amount of time during which the plants remain wet can reduce disease spread.
  • Stake plants to improve air circulation and reduce the contact of the plant with soil.
  • Avoid working the plants when they are wet.
  • Spray regularly with fungicides. Spray applications should be scheduled by spore trapping or forecasting systems (TOM-CAST) to be most effective. Early season applications often fail to control secondary spread of the disease.

Chemical Controls & Pesticides:

For Current information on disease recommendations ins specific crops including information on chemical control & pesticide management, please visit the New England Vegetable Management Guide website.

Crops that are affected by this disease:

  • Potato
  • Tomato, Field
  • Tomato, Greenhouse
Last Updated: January 14, 2013

The Center for Agriculture, Food and the Environment and UMass Extension are equal opportunity providers and employers, United States Department of Agriculture cooperating. Contact your local Extension office for information on disability accommodations. Contact the State Center Director’s Office if you have concerns related to discrimination, 413-545-4800 or see ag.umass.edu/civil-rights-information.

Ways to Connect

  • Ask a question
  • Request a Visit
  • Request a Crop & Pest Management Planning Session
  • Submit a Sample
  • Become a Mentor Farm
  • Join the NEVBGA
  • Make a Donation

Connect with us on Social Media

extension vegetable program facebook page  extension vegetable program instagram   extension vegetable program youtube channel

Center for Agriculture, Food, and the Environment

 

Stockbridge Hall,
80 Campus Center Way
University of Massachusetts Amherst
Amherst, MA 01003-9246
Phone: (413) 545-4800
Fax: (413) 545-6555
ag [at] cns [dot] umass [dot] edu (ag[at]cns[dot]umass[dot]edu)

 

Civil Rights and Non-Discrimination Information

College of Natural Sciences

Login for faculty and staff

CAFE Units

Mass. Agricultural Experiment Station

UMass Extension

UMass Research and Education Center Farms

UMass Cranberry Station

Water Resources Research Center

Interest Areas

Agriculture

Commercial Horticulture

Energy

Environmental Conservation

Food Science

Nutrition

Water

Youth Development & 4-H

Services

Pesticide Education

Plant Diagnostics Laboratory

Soil and Plant Nutrient Testing Laboratory

Hot Water Seed Treatment

Water Testing / Environmental Analysis Laboratory

Projects

Conservation Assessment Prioritization System (CAPS)

Extension Risk Management/Crop Insurance Education

Mass. Envirothon

Mass. Herp Atlas

Mass. Keystone

MassWoods

North American Aquatic Connectivity Collaborative

RiverSmart

UMass Design Center in Springfield

Resources

Extension Sales Portal

Agriculture & Commercial Horticulture Resources

Community & Economic Vitality

Disaster Preparedness

Food Safety

Home Lawn & Garden

Integrated Pest Management (IPM)

Land Conservation Tools

Pollinators

Tick testing

Resources for Faculty and Staff

Extension Programs

4-H Youth Development

Agriculture

Crops, Dairy, Livestock and Equine

Fruit

Greenhouse Crops and Floriculture

Landscape, Nursery and Urban Forestry

Pesticide Education

Turf

Vegetable

Clean Energy

Climate Change

Food Science

Nutrition Education

Value-Added Food

Seal of The University of Massachusetts Amherst - 1863
©2025 University of Massachusetts Amherst · Site Policies · Accessibility