Winter Squash Evaluation and Improvement for Downy Mildew Resistance and Fruit Quality

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2016: $14,862.00
Projected End Date: 12/31/2017
Region: Southern
State: Virginia
Principal Investigator:
Edmund Frost
Common Wealth Seed Growers / Twin Oaks Seed Farm


  • Vegetables: cucurbits


  • Production Systems: general crop production


    During the 2016 growing season Common Wealth Seed Growers conducted winter squash research that included a variety trial of 23 seedstocks; three selection projects ('Seminole Pumpkin,' 'Chinese Tropical Pumpkin' and 'Cuban Neck Pumpkin’); and a breeding trial with F5 seeds from a cross of 'Seminole Pumpkin' and 'Waltham Butternut.'

    Winter Squash Variety Trial, August 2016

    Common Wealth Seed Growers is a Virginia seed company started in 2014 to promote regional seed system development through research, education, seed production, plant breeding and selection. 


    The goal of this project is to identify and develop high quality Cucurbita moschata (winter squash and tropical pumpkin) varieties that thrive under low-input, organic management in Virginia’s hot and humid conditions, especially in terms of resistance to downy mildew.

    In a previous SARE-funded winter squash trialing project from 2014 (see SARE Award Number FS13-273, 'Identifying and Marketing Quality Open-Pollinated and Organic Cucurbit Seedstocks for Virginia'), Edmund Frost identified several winter squash seedstocks from the Southeast US, and several tropical pumpkin seedstocks with good downy mildew resistance. These seedstocks, however tended to have problems that included large size, large seed cavity size, poor marketability, poor eating quality, and splitting. The northern winter squash varieties entered in the trial performed poorly for downy mildew resistance.

    Based on this trial, and based on conversations with winter squash producers at agriculture conferences and tradeshows throughout the Southeast and mid-Atlantic regions in 2014 and 2015, Common Wealth Seed Growers identified a need for better adapted, downy mildew-resistant, high quality winter squash varieties.

    Project objectives:

    We approached the need for downy mildew-resistant and regionally adapted winter squash from two angles:

    -Selection projects aimed at improving the existing varieties 'Seminole Pumpkin,' 'Chinese Tropical Pumpkin,' and 'Cuban Neck Pumpkin;' as well as a breeding trial using F5 seeds from a cross of 'Seminole Pumpkin' and 'Waltham Butternut.’ Goals included recording data on DM resistance, yield and eating quality, and identifying and saving seed from individual plants that stood out.

    -A winter squash variety trial of 23 seedstocks. Goals included recording data on DM resistance, yield and eating quality; comparing the seedstocks used in the above selection projects to several commercial butternut varieties; documenting the progress in ongoing selection work with the Seminole-Waltham cross by trialing seedstocks from different generations of the cross; and evaluating new tropical pumpkin seedstocks to identify standout varieties or material useful for future breeding work.

    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.