Developing tomato varieties resistant to late blight and early blight

abstract

Late blight and early blight result in severe loss of tomato production when environment is favorable to the pathogens and development of either of these diseases. Cornell plant breeders have freshmarket tomato lines with genetic resistance to late blight and strong genetic tolerance to early blight. Lines and hybrids heterozygous or homozygous for the resistances were tested with and without supplementary bio control methods to determine the most effective means to use these resistances to provide optimal control of both diseases under environmental conditions favoring disease development. Hybrids homozygous for both of these resistances were tested under conventional and organic growing conditions, and evaluated for yield and fruit quality. The best lines homozygous for both of these resistances are being released to seed companies, with genetic information and a molecular marker to facilitate transfer to additional cultivars. Growers will be able to use the late blight/early blight resistant varieties to these diseases without use of fungicides, assisting conventional or organic tomato production in all temperate tomato growing regions in the U.S. and worldwide.

submitted by

Mutschler-Chu, Martha Ann | Professor

issue being addressed

Late blight (caused by Phytophthora infestans) results in severe loss of tomato production when environment is favorable to the pathogen and disease development. As a result, late blight is ranked as one of the most important diseases in tomato. Within the US, late blight ranked as the 8th most important tomato disease, based on a weighted average of loss per acre. Early blight is the second most important foliar disease of tomato, and is a major problem for tomato production in temperate growing regions worldwide. Late blight and early blight are currently controlled in tomato by the use of fungicidal sprays; with the timing of these sprays guided by weather conditions. Despite the use of monitoring and controlling chemicals, losses in tomato due to these diseases can be substantial. Furthermore, the use of sprays for control of this disease is increasingly difficult due to changes in pathogen virulence and increased chemical resistance of pathogens.

response

Cornell plant breeders have developed tomato lines with genetic resistance to late blight and strong genetic tolerance to early blight in a background that is well adapted to growing conditions to NY, the Northeast US, and similar temperature growing regions around the world. The resistances were bred into freshmarket tomato lines, with selection for good horticultural type. In cooperation with Thomas Zitter, of the Plant Pathology Department, late blight/early blight resistant lines and hybrids that were homozygous and heterozygous, respectively, for the resistance were tested with and without supplementary bio-control to determine the best strategy for using the resistance. Hybrids homozygous for the resistance were created and tested for horticultural performance under conventional and organic production methods, and were tested in disease pressure fields for level of control possible under conditions favoring disease development. The best of the blight/early blight resistant lines developed at Cornell are currently being released to seed companies, along with information to facilitate transfer of the traits to additional cultivars. The materials are also being used in cooperation with researchers focused on disease control in organic tomato production.

impact assessment

The resistant selections are approaching the state that commercial breeders at seed companies will be able to use them either for hybrid seed production or for further breeding to extend the number of lines and varieties possessing resistance to late blight and early blight. Growers will be able to use these varieties to protect against late blight and early without use of fungicides, or with only the use of mild bio-control agents under particular strong early blight pressure. This will reduce use of fungicides for the control of these important diseases, particularly in years with weather conducive to them. As a result, it will also reduce cost of production, exposure of workers and the environment to fungicides, and reduce the risk of fungicide residue in produce and processed products, benefiting consumers nationwide.

academic priority area

Environmental Sciences | CALS academic priority
Land-Grant Mission | CALS academic priority
New Life Sciences | CALS academic priority

has geographic focus

Maryland | state
Indiana | state
Ohio | state
Missouri | state
Rhode Island | state
West Virginia | state
Washington | state
Virginia | state
Minnesota | state
North Carolina | state
Vermont | state
Maine | state
Michigan | state
South Carolina | state
Wisconsin | state
Delaware | state
Illinois | state
Connecticut | state
Pennsylvania | state
New Jersey | state
Arkansas | state
New York State | state
New Hampshire | state
Tennessee | state

funding source description

USDA Northeast Regional IPM grant
Gift funds from seed companies through the Cornell Vegetable Breeding Institute
Hatch

collaborators

Penn State

key personnel

Thomas Zitter
Majid Foolad
Charles Bornt

mission focus

extension/outreach | project type
research | project type