Early Leaf Removal Strategies for Bunch Rot Reduction in Pinot Noir Clones

Progress report for ONC19-061

Project Type: Partnership
Funds awarded in 2019: $39,977.00
Projected End Date: 12/31/2022
Grant Recipient: Ohio State University-Ashtabula ARS
Region: North Central
State: Ohio
Project Coordinator:
Andrew Kirk
Ohio State University-Ashtabula ARS
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Project Information


Pinot noir is currently the highest value wine grape variety in the Eastern US and is among the top cultivated varieties in Ohio (NY Department of Agriculture & Markets 2018, USDA 2017). The variety, however, is known for tight clusters and susceptibility to late-season bunch rot diseases. Recent work has found pre-bloom early leaf removal (ELR) to reduce cluster compactness in tight clustered varieties, while reducing incidence and severity of bunch rot (Acimovic et al. 2017, Hed and Centinari 2018). However, the effects of ELR are variable and highly dependent on variety and localized environmental conditions (Hickey and Wolf 2018). Currently, ELR is considered an experimental practice with little commercial adoption in Ohio.

This proposal seeks to introduce ELR to wine grape producers in Ohio, as well as to further understand the physiological impacts of ELR. One major focus of the research effort will be on validating mechanical leaf removal as a cost-effective means to achieve the benefits of ELR treatments. Additionally, this project will address the diversity of trait expression within the Pinot Noir variety by determining the impacts of ELR on widely planted varietal clones. Importantly, this proposal prioritizes thecreationof extension resources to guide ELR adoption in Ohio.

Project Objectives:
  1. Provide best practice guidance to Ohio vineyards on the implementation of pre-bloom early leaf removal (ELR) as a management strategy for late season bunch rot diseases.
  2. Determine the suitability of mechanization for pre-bloom ELR application in Pinot Noir.
  3. Identify sensitivity differences to ELR application among popular Pinot Noir clones.
  4. Produce cost-benefit analysis of manual and mechanical ELR application methods.


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  • Dr. Maria Smith


Materials and methods:

Ohio State University personnel set up randomized experiments at the Ashtabula Agricultural Research Station, St. Joseph Vineyard, and M Cellars in 2019 and 2020. At the Ashtabula Agricultural Research Station and St. Joseph Vineyard, these trials were designed to test whether different clones of Pinot Noir are more sensitive to the bunch architecture changes associated with Early Leaf Removal. At M Cellars, the trial examined the efficacy of mechanical implementation of Early Leaf Removal, compared to manual application. 

To determine the efficacy of these treatments, OSU personnel collected a wide range of data. At bloom, flower counts were taken for target vines for later determination of the percentage of flowers set to berries. Additional information was collected at this time to support the visual estimation of flowers during bloom. At harvest, fruit chemistry data was collected in addition to berry counts for each target cluster. This will facilitate calculation of percent fruit set, whereas fruit chemistry data will highlight possible changes in fruit quality attributable to the experimental treatment. Yield data at harvest was also collected to assist in the economic analysis associated with implementing the new practice. 

The experiments were conducted successfully in 2019 and 2020. The team is currently analyzing and conducting laboratory work to generate the data for the project deliverables. We expect to be through the remaining lab work by August 2022.

Research results and discussion:

OSU personnel are in the process of collating and analyzing data from the 2019 and 2020 growing season. It is not possible at this time to report conclusively on the results of our work. The project received an additional extension to complete the fruit analyses required to complete deliverables. Our research station has successfully filled multiple positions which will allow us to regain ground after delays in 2020 and 2021.

Participation Summary
3 Farmers participating in research

Educational & Outreach Activities

20 Consultations
15 On-farm demonstrations
2 Online trainings
2 Published press articles, newsletters
4 Webinars / talks / presentations
1 Workshop field days

Participation Summary:

50 Farmers participated
4 Ag professionals participated
Education/outreach description:

Project personnel provided multiple on-farm demonstrations regarding the implementation of Early Leaf Removal. In addition to these efforts, a workshop was held in June 2019. At the Ohio Grape and Wine Conference in February 2020, Early Leaf Removal was a central theme of the technical viticulture sessions, wherein Dr. Maria Smith provided the Ohio Grape Industry with guidance based on our project and the findings of other recent studies. In 2020, Mr. Kirk and Dr. Smith conducted numerous consultations with growers on early leaf removal. Many growers in the grape growing regions of Ohio have adopted this practice. Mr. Kirk presented a summary of this ongoing work at the 2022 Ohio Grape and Wine Conference.

Learning Outcomes

55 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key changes:
  • Awareness of potential for reduction of bunch rot severity

  • Awareness of benefits to fruit quality

Project Outcomes

4 Farmers changed or adopted a practice
1 New working collaboration
Project outcomes:

As of December 2019, numerous local grape growers have adopted early leaf removal as a cultural practice to improve fruit quality, lower incidence of disease, and reduce pesticide application. Based on initial surveying, our belief is that 5 growers have adopted this practice thus far. A workshop on this topic was held in June 2019, which 17 growers attended. 

Success stories:

A grower in Geneva, Ohio mechanized this practice and was able to receive the benefits of early leaf removal in a very cost effective manner. After a severe rain storm in September 2019, his grapes were resilient, possibly in part due to the improvements to skin thickness known to occur after implementation of ELR. A co-operating grower in Madison, Ohio implemented this practice in some, but not all, of his Pinot Noir vineyards. He noticed a marked improvement in the harvest condition of that fruit which had undergone the Early Leaf Removal treatment.

Several large growers in the area have adopted this practice. These growers make up nearly one third of the grape acreage in Ohio. This was encouraging to the project team, as the growers in question had heard about ELR as a practice for many years, but were swayed by the public demonstrations and, importantly, by the commercial growers in the study who adopted the practice and were pleased with results. 


This work is ongoing and analysis relating to the research aims of the project will be possible after a second year of data collection. 

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.