Management of Fusarium Wilt of Cucurbits with Vetch Cover Cropping and Grafted Transplants

Project Overview

OW12-034
Project Type: Professional + Producer
Funds awarded in 2012: $49,158.00
Projected End Date: 12/31/2014
Region: Western
State: Oregon
Principal Investigator:
Dr. ALEXANDRA STONE
Oregon State University

Annual Reports

Commodities

  • Fruits: melons
  • Vegetables: cucurbits

Practices

  • Crop Production: crop rotation, cover crops
  • Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research, participatory research, workshop
  • Farm Business Management: whole farm planning, budgets/cost and returns
  • Pest Management: biological control, genetic resistance, integrated pest management
  • Soil Management: green manures

    Abstract:

    Cucurbit production for confectionary seed, processing, and fresh market in western Oregon has become less profitable due to a soilborne disease. Fresh market farm fields of cucumbers, melons, and winter squash, as well as fields of Golden Delicious squash grown for confectionary seed, were scouted by project staff for diseases and disorders. 

    Opportunities to sell vegetables throughout the winter have expanded because of the growth of winter sales opportunities through wholesale and retail markets and CSAs. However, many farmers have not been able to meet this increasing market demand due to losses from storage rots.

    The objectives of this project were to:

    1) Scout for, diagnose, and identify the host range of soilborne cucurbit diseases occurring on farms in the Willamette Valley.

    2) Scout for and diagnose storage diseases of cucurbit crops and determine the impact of harvest date and gypsum applications on crop quality and storage rot incidence.

    3) Engage farmers in learning how to reduce cucurbit losses to soilborne diseases and storage rots.

    4) Disseminate project results to a wider audience of farmers and agricultural professionals.

    5) Evaluate impact of project activities on farmer knowledge and intentions.

    Several seasons of field scouting revealed that cucumbers, as well as varieties of all three winter squash species (Cucurbita pepo, C. moschata, and C. maxima), are affected by this soilborne disease. In addition, the potential yield loss in a crop with high disease incidence and severity has been shown to be 75% or greater across all of those cucurbit types.

    Fusarium spp. and Plectosphaerella cucumerinum were cultured from diseased crowns, roots, and vascular tissues of diseased plants in 2013, but not all could be identified to species using cultural methods. A new graduate student isolated 1,400 fungal isolates from winter squash and cucumber plants collected from a wide variety of field locations in 2014; she will complete identification and then evaluate them for their pathogenicity on cucurbits in 2015. 

    Storage squash of diverse winter squash cultivars were diagnosed with Fusarium fruit rots (Fusarium spp), black rot (Phoma cucurbitacearum), gray mold (Botrytis cinerea), and white mold (Sclerotinia sclerotiorum). An early harvest date either improved or had no effect on fruit quality through December 2014. In addition, there was no apparent impact of gypsum applications on fruit rot incidence as of that date.

    Farmers have received diagnoses of critical diseases impacting profitability of fresh market and processing cucurbit crops. In the last year of the project, farmers will participate in workshops in which they will learn about the host range and potential yield losses associated with the soilborne disease and about strategies to avoid storage rots. Information on the diagnosis and management of all diseases will be disseminated through articles published to oregonvegetables.com (such as Winter Squash Storage Rots and their Management (see outeach section). In winter 2014-15, an online survey will be sent to all farmers who sent in samples, allowed field scouting or participated in winter meetings to determine how their knowledge of cucurbit field and storage diseases/problems and their future management intentions had changed as the result of their participation in the project. Management of these diseases will increase crop quality and farm profitability, and extend the winter squash marketing season into mid-winter.

    Introduction

    Cucurbit production for confectionary seed, processing, and fresh market in western Oregon has become less profitable due to a soilborne disease that is now being diagnosed. A farm growing wholesale fresh market slicing cucumbers came to OSU for help with this crop, as their cucumber plants wilted and died before the end of the production season and yields were declining dramatically. The problem in cucumbers was originally diagnosed (by a diagnostic lab) as Fusarium wilt. During the first year of this project it became clear that the cause of the problem was not Fusarium wilt of cucumbers. Instead, it is a disease of the root and crown (and possibly vascular system), and it affects not just cucumbers but other cucurbits, including winter squash varieties of Cucurbita pepo, C. moschata, and C. maxima. The Willamette Valley produces confectionary pumpkin seed from approximately 5,000 acres of the winter squash cultivar ‘Golden Delicious’ which is susceptible to this disease.

    Fresh market winter squash sales currently end for many farmers in December. However, as the opportunities to sell vegetables throughout the winter has expanded (because of the growth of winter sales opportunities through wholesale and retail markets and CSAs), farmers have been trying to sell squash later into the winter. For many farmers, this has not been successful due to losses from storage rots. Most farmers do not have adequate storage facilities for winter squash, nor are they aware of the available research-based information on how to grow, harvest, and store squash to maintain its quality later into the winter. As the result of this need, the project expanded its scope to address the diagnosis and management of storage rots. The project identified currently available information on the production, harvest, and storage of more typical winter squash varieties (acorn, delicata, kabocha, and butternut) to improve storage duration and quality and began the process of ground-truthing that information under Willamette Valley conditions.

    Project objectives:

    Objective 1) Scout for, diagnose, and identify the host range of soilborne cucurbit diseases occurring on farms in the Willamette Valley.

    Objective 2) Scout for and diagnose storage diseases of cucurbit crops occurring on farms in the Willamette Valley and determine the impact of harvest date and gypsum applications on crop quality and storage rot incidence.

    Objective 3) Engage farmers in learning how to reduce cucurbit losses to soilborne diseases and storage rots.

    Objective 4) Disseminate project results to a wider audience of farmers and agricultural professionals.

    Objective 5) Evaluate impact of project activities on farmer knowledge and intentions.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.