Diagnosis and Management of a New Disease of Cucurbits in Oregon

2015 Annual Report for SW15-021

Project Type: Research and Education
Funds awarded in 2015: $145,291.00
Projected End Date: 12/31/2017
Region: Western
State: Oregon
Principal Investigator:
Oregon State University

Diagnosis and Management of a New Disease of Cucurbits in Oregon


Winter squash is grown in the Willamette Valley of Oregon for fresh market sales and as a processing crop for pie filling and confectionary seed. However, a soilborne disease is reducing yield and quality of both fresh market and processing squash. The overarching goal of this project is to increase the economically viable production of winter squash and confectionary seed. This project will work towards that goal by diagnosing squash wilt and root and crown rot, identifying resistant/tolerant varieties, and evaluating the efficacy of crop rotation and available pesticides.

This project will engage project and other farmers throughout the course of the project. Field trials will be conducted on participating farm fields. Field tours will be conducted each fall. Project findings will be presented at the N. Willamette Hort Society Vegetable and Organic Days, the Oregon Processed Vegetable Annual Meeting, and the OSU Small Farms Conference. Farmers and buyers will interact with whole and cut squash at interactive conference booths each winter.


Objectives/Performance Targets

Objectives/Performance Targets

Objective 1) Engage project farmers in project development, delivery, evaluation, and outreach

Year 1. Discuss project plans with project farmers.

Years 1-2: Project farmers host field trials and participate in outreach events (presentations, conference booths)

Year 2: Farmers and collaborators discuss and evaluate project for final report (February 2017)

Results: Farmers are engaged in project development, delivery, evaluation, and outreach.

Objective 2) Identify causal agents of squash wilt and root and crown rot

Years 1 and 2: Isolate fungi from diseased plants. Evaluate pathogenicity of isolates on Golden Delicious in greenhouse and field trials. 

Results: Causal agents of squash wilt and root/crown rot are identified.

Objective 3: Identify squash cultivars with resistance or tolerance to squash root and crown rot/wilt, as well as good yield and long shelf life

Years 1-2?. Variety trials will be conducted on farms with known history of wilt and crown/root rot to Identify tolerant and resistant varieties. Varieities will be evaluated for disease susceptibility, yield, and storability.

Results: Resistant and tolerant varieties are identified and their potential yield and storability described.

Objective 4: Evaluate the efficacy of crop rotation

Years 1-2: Squash crops planted to fields of varied squash cropping histories will be scouted for root and crown rot and vascular discoloration and those data related to field cropping history.

Results: Efficacy of rotation and required rotation length are described.

Objective 5: Evaluate the efficacy of available pesticides and their interactions with herbicides

Years 1-2: Fungicide and herbicide field trials will be conducted in Golden Delicious fields of known soilborne disease history.

Results: Efficacy of pesticides and any interactions with herbicides are described.


Objective 1: 

  • Presentation on diagnosis and host range of soilborne disease complex of cucurbits. Vegetable Farm Field Day. September 10, 2015. 50 attendees.
  • Overview of the winter squash project. Fresh Market Winter Squash Field tour. Sept 15 2015. 25 attendees.
  • Winter squash booth. Variety Showcase. Portland, OR. September 28. 2015. 130 attendees.

Objective 2: 

  • Cultural/molecular diagnosis of 4 putative causal agents
    • Fusarium oxysporum f. sp. melonis
    • Fusarium oxysporum f. sp. cucumerinum
    • Plectosphaerella cucumerina
    • Fusarium solani 

Objective 3: 

  • Three replicated host range trials conducted (8 cucurbitaceae species/25 varieties; 1 OSU research station trial, 2 on-farm trials). Zucchini and cucumber are least susceptible; maximas are most susceptible.
  • Three kabocha/buttercup trials conducted (16 varieties; 1 OSU research station trial, 2 on-farm trials). Tetsukabuto (C. maxima/C. moschata hybrid typically used as a rootstock for grafting onto melons for planting into soils infested with soilborne pathogens) is resistant/tolerant to this soilborne disease complex, high yielding, long storing in barn conditions, completely resistant to storage rots, and has excellent sensory quality in December -February (mid-winter).

Impacts and Contributions/Outcomes

Several farmers intend to grow Tetsukabuto for mid-winter sales.  

A large Pacific Northwest produce distributor is evaluating Tetsukabuto as a new disease resistant long-storing winter squash that can be locally grown and stored for mid-winter sales.  

Farmers are learning about this soilborne disease complex, its impact on yield, and how to scout for it.


Kenneth Johnson

Oregon State University
2082 Cordley Hall
Dept of Botany and Plant Pathology
Corvallis, OR 97331
Office Phone: 5417375249
David Brown

Mustard Seed Farm
7300 McKay Rd NE
St Paul, OR 97137
Office Phone: 5036337333
Website: www.mustardseedorganic.com/
John Eveland

Gathering Together Farm
25159 Grange Hall Rd
Philomath, OR 97370
Office Phone: 5419294270
Website: gatheringtogetherfarm.com
Edward Peachey

Associate Professor
Oregon State University
4017 ALS
Dept of Horticulture
Corvallis, OR 97331
Office Phone: 5417373152
Jeff Falen

Persephone Farm
30291 Bates Lane
Lebanon, OR 97355
Office Phone: 5414515640
Website: persephonefarmoregon.com
Greg Ropp

Autumn Seed
5995 NE Highway 20
Corvallis, OR 97330
Office Phone: 5417588234
Website: autumnseed.com