Evaluation of the insect resistance of interspecific squash hybrids

Project Overview

Project Type: Farmer
Funds awarded in 2011: $4,022.00
Projected End Date: 12/31/2013
Region: Northeast
State: Connecticut
Project Leader:
Bryan Connolly
Green Dragon Farm

Annual Reports


  • Vegetables: cucurbits


  • Crop Production: application rate management
  • Pest Management: genetic resistance

    Proposal summary:

    This project will evaluate the insect resistance of hybrid hubbard/kabocha (maxima) x butternut squashes. Maxima squashes are known for their excellent table and ornamental qualities but they are extremely susceptible to both striped cucumber beetle and squash vine borer. Conversely, butternut squashes have good table quality and low ornamental value but excellent insect resistance. We would like to evaluate the little known Japanese maxima x butternut hybrid squash ‘Tetsukabuto’ and compare it to the parental species. Additionally, we will create new hybrids attempting to capture the table and ornamental qualities of maxima types and combine them with the insect resistance of the butternut squashes.

    Project objectives from proposal:

    Year one:

    We will plant the butternut C. moschata types ‘Waltham Butternut’ and ‘Kikuza’, with the hybrid ‘Tetsukabuto’, and two maxima types ‘Blue Hubbard’ and ‘Burgess Buttercup’. The insect resistance of the pure C. maxima and “Waltham Butternut” C. moschata types are known and serve as controls. This will be done in a randomized block design with three replication of 5 hills of each variety, see attached year one field diagram. Between hill spacing will be 3ft, between row distance will be 6 ft. Each hill will have 3 individual squash plants, for a total of 45 plants of each variety and 225 squash plants for the entire experiment. Plants will be direct seed in late May. Striped cucumber beetle numbers and seedling survivorship will be monitored once a week through June. For July and August squash vine borer presence and adult plant survivorship will be tracked weekly. In October squash fruit number per repetition, block, and variety will be totaled. Data will be analyzed using the statistics package in Excel or in SAS. Squash will be cooked and evaluated for culinary qualities in late fall to mid winter.

    In addition to the survival and insect resistance experiment we will conduct cross-pollinations to produce new hybrid plants, 3 hills of ‘Gold Nugget’ (bush vine pink fruited C. maxima), “Bush Buttercup” (bush vine green fruited C. maxima), “Blue Ballet” (semi bush blue fruited C. maxima), and “Lakota” (striped green and orange C. maxima) will be planted. These maxima squash will all be pollinated by ‘Kikuza’ C. moschata. This pollen parent was chosen because it is a flat tan C. moschata, previous crosses we have done with ‘Waltham Butternut’ and maxima types has resulted in odd pear shaped fruits, see attached photo, that we did not think would be appealing to customers. In our experience this interspecific hybrid sets the most seed when maxima is used as the mother parent and the cross is done before 5 a.m. the day of flowering.

    Ten flowers of each maxima variety named above will be pollinated with three male ‘Kikuza’ flowers each. The day before blooming the flowers blush orange, see attached photo, indicating they will open the next morning, that evening masking tape will be placed around the tip of the flower prevent opening and therefore stopping uncontrolled pollinations, both male and female flowers are taped. At about 4:30 a.m. males flowers of ‘Kikuza’ will be picked and brought to the female maxima flowers, the petals of the males will be peeled off, the female flower is then opened and the pollen place on the stigma of the female flower, the male flower is discarded and petals of the female taped again to prevent any other pollen from reaching the stigma. The cross-pollinated female flowers are marked with flagging tape and the pollen parent is written with a permanent marker on the flagging, see attached photos.

    For more details on squash pollination see Connolly, B. 2005. The Wisdom of Plant Heritage, Organic Seed Production and Saving. Northeast Organic Farming Association Interstate Council publication.

    Year two:

    The seeds resulting from the above C. maxima x C. moschata pollinations will be added to the block design. Three blocks of five repetitions of ‘Gold Nugget’ x ‘Kikuza’, ‘Bush Buttercup’ x ‘Kikuza’, ‘Blue Ballet’ x ‘Kikuza’, ‘Lakota’ x ‘Kikuza’, ‘Waltham Butternut’, ‘Kikuza’, ‘Tetsukabuto’, ‘Burgess Buttercup’, and ‘Blue Hubbard’ will be planted with three plants per hill, totalling 45 plants per variety or hybrid equaling 405 plants for the complete experiment. Planting, data collection, and analysis will follow the methods of year one.

    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.