Mechanical blossom thinning effects on Gala and Honeycrisp apples

Project Overview

ONE15-242
Project Type: Partnership
Funds awarded in 2015: $9,541.00
Projected End Date: 12/31/2016
Region: Northeast
State: New York
Project Leader:
Mario Miranda Sazo
CCE Lake Ontario Fruit Program

Annual Reports

Commodities

  • Fruits: apples, general tree fruits

Practices

  • Crop Production: application rate management
  • Education and Training: on-farm/ranch research
  • Pest Management: physical control
  • Production Systems: general crop production
  • Sustainable Communities: sustainability measures

    Proposal abstract:

    Crop load management is the most important yet difficult management strategy that determines the annual profitability of apple orchards. The economic impacts of achieving the proper crop load each year are large – often $5,000-$10,000/acre. Carbaryl, which is a carbamate insecticide, has been an essential component of chemical thinning programs for more than 40 years. However, there is concern that Carbaryl will be removed from the market by regulatory action in the US. If Carbaryl were removed from the market, growers in the Northeastern US would not achieve adequate thinning. At Cornell we continue to research chemical thinning alternatives without Carbaryl, but there is significant interest in economical and safe nonchemical thinning strategies.  

    Our goal is to provide data of the impacts of mechanical blossom thinning (MBT) on yield, return bloom, fire blight, and an economic analysis of the potential value of this technology to improve profitability and sustainability. NY is noticeably behind other regions around the world in terms of MBT research or grower adoption. Its use has not gained a foothold due to our concern that MBT can spread fire blight on apples.

    We propose to conduct on-farm MBT research with cooperator Jason Woodworth who recently acquired a string thinner machine. He will host on-farm meetings to introduce the new technology to his peers and discuss its advantages and disadvantages at Extension meetings. Cooperator will be asked to evaluate the usefulness and relevance of this project to his business through exit interview and/or questionnaire.

    Project objectives from proposal:

    Proposed solution

    In NY State, we have had the concern that mechanical string thinning can spread fire blight in a high density apple orchard. However, we believe that there are still opportunities to further reduce fruit thinning costs and improve profitability and sustainability of high density apple production by studying and incorporating the safe use of mechanical blossom thinning with a string thinner. There has been limited testing and adoption of mechanical thinning practices in high density apple orchards in the Northeastern US.

    We will conduct two on-farm trials with grower Jason Woodworth who recently acquired a mechanical string thinner at his farm located in Waterport, NY. This project will use his new string thinner and a tractor to collect on-farm data on the efficiency of mechanical blossom thinning by: (1) determining the proper thinning severity, (2) the optimal application timing for Honeycrisp and Gala, (3) quantifying the potential spreading of fire blight, (4) supplementing the mechanical thinning with other chemical treatment, and (5) measuring return bloom, potential yields, and fruit size distribution.

    Project methods

    In May 2015, we will conduct two string thinner studies on mature ‘Gala’ and ‘Honeycrisp’ apple trees on B.9 rootstock at 2X11 ft. spacing. The ‘Gala’ and ‘Honeycrisp’ trees are 6 and 8 years old, respectively. Both are trained to a Super Spindle apple system at Lamont Fruit Farm Inc., Waterport, New York. The shape of the canopy is a narrow tree wall. The string thinner (Darwin machine) will consist of a tractor –mounted frame with a 10 ft. tall vertical spindle in the center of the frame. Attached to the spindle will be 54 steel plates securing a total of 216 plastic cords each measuring 2 ft. in length. Speed of the clockwise rotating spindle will be adjusted with a hydraulic motor. The string thinner spindle will be operated at 220 or 240 rpm, and the mechanical thinner will be driven through the orchard rows at 5 miles/hour. All treatments will be applied at 70-80% bloom stage for the king flower and balloon stage for the laterals on May 2014. 

    The specific treatments for ‘Gala’ are: (1) Control apple trees that will receive the grower standard chemical thinning program (bloom + PF + 12 mm + 18 mm sprays) and without the use of the string thinner, (2) Apple trees thinned with the string thinner at 220 rpm and 5 mph, (3) Apple trees thinned with the string thinner at 240 rpm and 5 mph, (4) Apple trees thinned with the string thinner at 220 rpm and 5 mph, followed by Maxcel @75ppm sprayed at the 8-10mm fruitlet stage on June 2014, (5) Apple trees thinned with the string thinner at 240 rpm and 5 mph, followed by Maxcel @75ppm sprayed at the 8-10mm fruitlet stage on June 2014.

    The specific treatments for “Honeycrisp/B.9” are: (1) Control apple trees that will receive the grower standard chemical thinning program (bloom + PF + 12 mm + 18 mm sprays) and without the use of the string thinner, (2) Apple trees thinned with the string thinner at 220 rpm and 5 mph, (3) Apple trees thinned with the string thinner at 240 rpm and 5 mph, (4) Apple trees thinned with the string thinner at 220 rpm and 5 mph, followed by Maxcel @50ppm sprayed at the 8-10mm fruitlet stage on June 2014, (5) Apple trees thinned with the string thinner at 240 rpm and 5 mph, followed by Maxcel @50ppm sprayed at the 8-10mm fruitlet stage on June 2014.

    The two field experiments will be designed as randomized complete blocks with five replications consisting of 50 trees per plot. Before string thinning treatments are applied, the initial number of blossom clusters per flagged data tree will be recorded and trunk cross-sectional area will be recorded. Immediately after treatment, blossom clusters will be counted on the data trees. One extra data tree per plot will be used to quantify the potential damage to the bark, shoots, leaves, and buds, and for assessing fire blight. In July 2014, ten trees will be selected within the center of each plot to ensure consistent treatment, uniformity, and will be used to quantify the final number of fruitlets and the diameters of 10 fruitlets per tree. In September 2015, whole tree fruit counts and fruit weight of three data trees per plot will be collected at harvest one time for Gala and two times for Honeycrisp. In October 2015, fruit size distribution of two data tree per plot will be determined with an electronic sorter at the NY State Agricultural Research Station in Geneva.

     

    Project timetable

    May-June 2015: Miranda Sazo will coordinate the two mechanical blossom thinning projects with grower Jason Woodworth.

    Main field tasks for Gala and Honeycrisp sites: (1) Plots will be flagged, (2) Initial number of blossom clusters will be recorded before string thinning treatments are applied, (3) string thinning treatments and chemical thinning sprays will be applied by grower cooperator, (4) number of blossom clusters will be recorded after string thinning treatments are applied, and (5) the removal of entire blossom clusters, the potential damage to the trees and the spreading of fire blight will be evaluated.

    July 2015: Fruit counts and fruit diameter measurements will be conducted @ July 15.

    September 2015: Measure whole fruit counts and fruit weight for each cultivar.

    October 2015: Fruit size distribution evaluation at the NY State Agricultural Research Station in Geneva.

     

    Project outreach

    We will deliver to apple growers our findings on both the horticultural results of mechanical blossom thinning and the economic impacts of this technique. This will include: one field demonstration of mechanical blossom thinning on Gala and Honeycrisp at Lamont Fruit Farm in May 2015. The grower collaborator will host an on-farm meeting to introduce the new technology to his peers and discuss its advantages and disadvantages.

    In August 2015 we will conduct a stop during the Lake Ontario Summer Tour to explain the on-going project with grower Jason Woodworth. Our fruit region has a summer tour that attracts over 250 attendees from many fruit growing regions in the US and Canada. The results will be presented by the project team at the 2016 winter fruit schools and 2016 Empire State EXPO which are attended by over 350 growers in the region. The project will be featured in our Cornell Cooperative Extension, “LOF Fruit Notes Newsletter”. Results will be published in the NY Fruit Quarterly magazine circulated to over 1000 fruit producers in the Northeast.

    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.