Supporting Grape IPM Implementation in Ohio Vineyards Using the Network for Environment and Weather Applications (NEWA)

Final report for ONC18-041

Project Type: Partnership
Funds awarded in 2018: $29,523.00
Projected End Date: 08/28/2019
Grant Recipient: The Ohio State University-Wooster Campus
Region: North Central
State: Ohio
Project Coordinator:
Melanie Ivey
The Ohio State University
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Project Information

Summary:

The Network for Environment and Weather Applications (NEWA) is an on-line tool that uses weather stations and pest forecast models to foster Integrated Pest Management implementation (IPM) and environmental stewardship. Until recently, NEWA was unavailable in Ohio.  Four Ohio growers are committed to utilizing weather stations, connecting to NEWA, and promoting IPM implementation in their region. In this Partnership project the cooperating growers will learn to use NEWA, source weather data using a RainWise weather station, and synthesize pest forecast information into responsible spray decisions. Growers will validate the NEWA forecast models by comparing pest damage between plots managed with and without NEWA. The project will be evaluated through grower feedback, disease incidence and severity assessments, spray and trap data, and yield evaluations. Outreach will target other grape growers in the region who will benefit from NEWA availability in Ohio.  Project results and impacts will be delivered through newsletters, meetings and field days.  Because NEWA is new to Ohio and most grape growers do not integrate weather stations or pest forecast models into their IPM programs, the potential impact of this study is substantial.

Project Objectives:
  1. Validate grape disease and grape berry moth forecasting models in Ohio through
  2. Estimate the economic benefits of using forecasting models to inform decisions and timing of pesticide applications.
  3. Educate collaborating grape growers about NEWA and pest forecast
  4. Inform other Ohio grape growers about the availability of grape pest forecast models via

Cooperators

Click linked name(s) to expand
  • Rachel Kaufman (Researcher)
  • Dr. Elizabeth Long (Researcher)
  • Andrew Kirk (Researcher)

Research

Materials and methods:

Six demonstration plots (50 vines per plot) were set-up during the 2018 growing season in vineyards throughout Ohio.  Four of the plots were in grower vineyards and two were located in research vineyards.  Rainwise weather stations were installed at all six locations and connected to NEWA.  Plots were divided into two sub-plots and diseases and grape berry moth were managed using NEWA in one subplot and a calendar spray program in the other. The NEWA spray guidelines are described in Table 1.  Fungicide applications began one week post bloom and each vineyard was treated with fungicides according to Ohio spray recommendations (Lewis Ivey, 2018).

Table 1.  Spray timing recommendations for NEWA treatments

Target Disease(s) NEW Spray Guidelines
Black rot and Phomopsis Treat black rot and Phomopsis as a disease complex (i.e. one disease).  Apply fungicides when risk level is high.
Powdery mildew Apply fungicides when risk level is high.
Downy mildew Apply fungicide if rain event is predicted in the early morning OR following a likely infection event.

Foliar disease severity (scale of 0-100%) was evaluated one week prior to harvest.  A total of 250 leaves from five of the six locations were collected and initially sorted into two categories- disease symptoms or no disease symptoms.  Leaves with no symptoms were discarded and leaves with symptoms were first rated for total disease severity and then each leaf was rated for black rot, Phomopsis, downy mildew and powdery mildew. Grape berry moth was monitored using traps throughout the season.  Soluble sugars (°Brix), pH, percent titratable acidity (TA), and yield (ton/A) were measured at harvest.  Empirical data from the demonstration plots at The Ohio State University (Wooster and Ashtabula).  If provided, data from the grower participants are reported.  Participant 4 did not provide any data.

Research results and discussion:

Foliar Disease Assessment.  Across all locations (i.e. data for each treatment combined), using the NEWA system to predict the timing of fungicide applications for control of foliar fungal diseases (total disease) was equally effective to applying the sprays using a calendar spray program (p=0.2554; Table 2).  Significant differences were observed within locations (p<.0001) and an interaction between location and spray program was also detected (p<.0001).  A significant interaction between location and spray program was not unexpected given that each location tested the two spray programs on different varieties.

Table 2.  Program, location and program by location effect for total foliar fungal disease severity.

Effect

Num DF

Den DF

F Value

Pr > F

Program

1

1083

1.29

0.2554

Location

4

1136

338.14

<.0001

Program*Location

4

1108

6.51

<.0001

Overall, foliar disease pressure was low at four of the five locations that provided data (Table 3).  Of the five locations, and in both treatment plots, participating vineyard 3 had the most disease and the Wooster research vineyard had the least amount of disease (p<0.0001).  This is interesting because these two vineyards are less than 6 miles apart, emphasizing the importance of local environmental conditions on disease development.  At participating vineyards 3, total disease severity was high in both treatment plots due almost exclusively to downy mildew (Figure 1).  At the Wooster vineyard there was no downy mildew or powdery mildew and the diseases that were observed (black rot and Phomopsis) were negligible.  Participating vineyards 1 and 2 and the Ashtabula vineyard are clustered together near Lake Erie and among the four diseases evaluated were most impacted by downy and/or powdery mildew.

At all of the locations except Ashtabula, using the NEWA system to predict the timing of fungicide applications for control of foliar fungal diseases  was equally effective to applying the sprays using a calendar spray program (Table 3).  At Ashtabula, disease severity was higher in the plots treated using the NEWA system to predict the timing of fungicide applications than those treated based on a calendar spray program.  Powdery mildew severity was higher in the plots using NEWA (5.3%) compared to using a calendar spray program (1.3%) (Figure 1).

At the Wooster location three less fungicide applications were applied to the plots treated using the NEWA forecasting system compared to those treated using a calendar spray program and disease control was equally effective in these plots.  One less fungicide application was applied to the plots in Ashtabula sprayed using the powdery mildew, black rot and Phomopsis risk assessment compared to the calendar program.  Participating vineyards 1 and 2 each applied one more spray to the plots treated based on the downy mildew model in NEWA compared to those treated using a calendar spray program.  

Table 3.  Total foliar fungal disease severity at each demonstration location.

Location/Participant (Variety) Spray Program Percent Foliar Disease Severitya
Wooster (Catawba) Calendar

1.6 e

NEWA

1.2 e

Ashtabula (Pinot Gris) Calendar

11.7 b

NEWA

12.9 c

Participant 1 (Concord) Calendar

9.7 d

NEWA

7.5 cd

Participant 2 (Chardonnay) Calendar

12.8 b

NEWA

15.3 b

Participant 3 (Vidal Blanc) Calendar

47.8 a

NEWA

49.7 a

P value  

<.0001

aSeverity is on a scale of 0-100% leaf area affected and represents the mean of only those leaves with symptoms.  Values followed by the same letter are not significantly different.

 SARE Figure 1 Rev 06082020

Grape Berry Moth (GBM) Assessment.  At the two research locations and participating vineyards 1 and 2, GBM was not detected in the traps and no insecticides were applied.

Grape Maturity Indices. Soluble sugars (°Brix), pH, and percent titratable acidity (TA) of berries did not differ based on the spray program (Table 4).  

Table 4.  Comparison of grape maturity indices between grapes harvested from the two research locations  and two grower locations from plots sprayed using a calendar spray program or sprayed based on disease forecasting or risk assessment through NEWA.

Location Variety Spray Program °Brix pH TA (%)
Ashtabula Pinot Gris Calendar 20.0 3.5 0.48
    NEWA 19.6 3.4 0.48
Wooster Catawba Calendar 17.2 2.9 1.11
    NEWA 16.0 2.9 1.23
Participant 1  Concord Calendar 18.0 3.3 0.69
    NEWA 17.4 3.3 0.73
Participant 2 Chardonnay Calendar 21.3 3.4 0.68
    NEWA 21.4 3.4 0.70

Marketable Yield. Overall, total marketable yield was an average of 25% less in the NEWA treated research plots compared to the plots sprayed using a calendar spray program (Table 5). At participating vineyard 2, yield was ~16% less in the NEWA treated research plots compared to the plots sprayed using a calendar spray program.  On average for the three locations that reported yield, 22% less fruit was harvested from the NEWA treated research plots compared to the plots sprayed using a calendar spray program.

Table 5.  Total marketable yield (ton/A) harvested from Catawba (Wooster), Pinot Gris (Ashtabula), Concord (Participant 1) and Chardonnay (Participant 2) vines sprayed using a calendar spray program or sprayed based on disease forecasting or risk assessment through NEWA.  Yield was calculated based on 1089 vines per acre. 

Spray Program

Marketable Yield (ton/A)

  Wooster (Catawba)  Ashtabula (Pinot Gris) Participant 1 (Concord) Participant 2 (Chardonnay)
Calendar 5.9 5.7 3.2
NEWA 4.3 4.4 2.7

Participant Feedback and Perceptions.   Two of the participating growers agreed to present their perceptions of using NEWA and disease forecasting to manage fungal foliar diseases of grape at the 2019 Ohio Wine and Grape Conference.  Both participants indicated that they liked having access to realtime weather via the weather stations and would continue to use the weather stations to support their disease management decision making.  Both participants indicated that the downy mildew risk assessment tool on the NEWA platform was not easy to understand or particularly useful.  The research team provided support for using the assessment tool (via handouts and face-to-face meetings) but they felt that just using the rain data was sufficient (i.e. hold off on spraying until rain was predicted.)  While the growers found the powdery mildew/black rot/Phomopsis risk assessment tool useful they also indicated that the risk levels to apply a spray corresponded almost exactly with the calendar spray program timings. Participatory grower 2 continues to use both the weather station and disease risk assessment models through NEWA.  In 2020, they have reported that they have skipped one fungicide application that would normally be applied if a calendar spray program was being used.  The grower reported that “Without the weather station and NEWA -as imperfect as it is- I would have had a spray in between.”

Conclusions.  The goal of this project was to establish the NEWA pest and disease forecasting and risk assessment system as a beneficial IPM tool for Ohio grape growers.  We determined that using the NEWA pest and disease forecasting and risk assessment system was comparable to a calendar spray program for managing foliar fungal diseases when disease pressure was low. In Ohio, 10-14 fungicide applications are made during the growing season with an average cost of $700 to 800/acre/application depending on the fungicides used (fungicide cost only).  At two locations, fewer fungicide applications were made using the disease risk assessments through NEWA.  At participating vineyards 1 and 2, one additional fungicide spray was applied based on the risk level determined through NEWA.  While there were no differences in fruit quality between berries produced from grapes that were sprayed using the NEWA pest and disease forecasting and risk assessment system or those sprayed with a calendar spray program yield was lower in the plots that were sprayed using the NEWA pest and disease forecasting.  In 2018, the average price per ton for native, hybrid, and vinifera grapes was $773, $1165, and $2235, respectively (Smith, 2018).  In this study yield reduction ranged from 0.5 to 1.6 tons, which represents a loss of ~$1237 for the Catawba planting, $2906 for the Pinot Gris planting and $1118 for the Chardonnay (Participating vineyard 2). Additional replicated trials to make broader inferences on the effectiveness and economic feasibility of the NEWA pest and disease forecasting and risk assessment system are needed.  However, the potential for establishing this system as a beneficial IPM tool for Ohio grape growers if high, especially if it is used in combination with other IPM disease and insect pest management strategies.

References:

Smith, M.  2018.  2018 Ohio Wine Grape Production and Pricing Index.  The Ohio State University, Columbus OH.  https://ohiograpeweb.cfaes.ohio-state.edu/sites/grapeweb/files/imce/pdf_factsheets/2018%20grape%20pricing%20index_Final.pdf

Participation Summary
4 Farmers participating in research

Educational & Outreach Activities

25 Consultations
4 On-farm demonstrations
3 Webinars / talks / presentations
1 Workshop field days
1 2019 Ohio Wine and Grape Conference, Dublin, OH

Participation Summary

60 Farmers
5 Ag professionals participated
Education/outreach description:

Consultations: At least three on-site visits were made to assist growers with installing the weather stations, selecting plots, and assessing disease, insect and yield.  In addition, one-one phone calls during the season were held to troubleshoot problems either with the NEWA system or plots.

Workshop / field days: Grape Field Day, July 19 2018, Kingsville, OH.  Attendees (65) were provided a tour of the demonstration plot at the Ashtabula Agricultural Research Station and introduced to the project and the utilities of NEWA.

Webinars, talks and presentations: Two video conferences were held with the participating growers were held. The first call was to review the logistics of the project, provide resources to the growers and explain the on-line system that we would use to exchange information and data.  During the second call growers were provided with instructional support for using the NEWA web interface and provided an overview on the diseases and insect pests that the project was focusing on.

Conferences: Ohio Wine and Grape Conference, February 16 2019, Dublin, OH.  Attendees (73) listened to a panel consisting of two of the participatory growers and two of the project coordinators (Kirk and Lewi Ivey) speak about their experiences with using NEWA and disease forecasting and risk assessments as an IPM tool for managing grape diseases and insect pests. A 20 minute presentation was given by project coordinator Lewi Ivey that summarized the data from the Wooster and Ashtabula research plots.

Learning Outcomes

4 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

4 Farmers changed or adopted a practice
1 Grant received that built upon this project
1 New working collaboration
Project outcomes:

The goal of this project was to establish the NEWA insect pest and disease forecasting and risk assessment system as a beneficial IPM tool for Ohio grape growers. Disease forecasts are predictions of infection periods that are based on the biology and epidemiology of the pathogen, host factors (i.e. growth stage, resistance) and environmental conditions.  They are used as a tool to aid in the timing of fungicides, which can reduce production costs through more efficient use of the fungicide.  Similarly, early warning systems and forecasts based on insect pest biology and phenology and environmental conditions can be used to optimize the timing of insecticides.  Disease and insect pest forecasting can also reduce pesticide exposure to the environment (i.e. soil, water and non-target species), operators and consumers.  Ultimately forecasting systems should maximize crop yields and economic returns while reducing negative impacts on the environment.

In Ohio, 10-14 fungicide applications are made during the growing season at an average cost of $700 to 800/acre/application depending on the fungicides used (fungicide cost only).  Fungicides are typically sprayed based on a 7-14 day spray schedule depending on the phenological stage of the vines.  From bud burst until 10-12 inch shoot growth fungicides are applied weekly to protect new growth from infections.  During the critical period for fruit infections, pre-bloom to 3-4 weeks post-bloom or pea-size, fungicides must be applied every 7-10 days to protect the fruit.  After the fruit reach pea-size they are resistant to new infections and emphasis is put on protecting the foliage, rachis and vines from infections.  During the growth stages prior and after the critical period for fruit infections disease forecasting models can be used to predict infection periods and optimize the timing of fungicide applications. 

In this project we compared the number of fungicide applications, foliar disease severity, yield and fruit quality in six demonstration plots that used a calendar spray schedule or grape fungal disease forecasting to apply fungicides.  We determined that using the fungal disease forecasting through NEWA was comparable to a calendar spray program for managing foliar fungal diseases (powdery mildew, black rot, Phomopsis and downy mildew) when disease pressure was low to moderate.   At two of the demonstration vineyards, two fewer fungicide applications were made using the disease risk assessments through NEWA, representing a cost savings of $1400 to $1600/acre.  However, one additional fungicide application was made at each of two other demonstration vineyards, increasing the cost of fungicides by $700 to 800/acre.  The number of sprays applied were not provided for the two remaining demonstration plots.  In 2018, the average price per ton for native, hybrid, and vinifera grapes was $773, $1165, and $2235, respectively (Smith, 2018).  We observed a yield reduction that ranged from 0.5 to 1.6 tons in the three vineyards that reported yield data.  Based on cultivar losses for these three vineyards were ~$1237 (Catawba), $2906 (Pinot Gris) and $1118 (Chardonnay).  Considering both fungicide costs and yield, average estimated net losses and/or gains for the Catawba, Pinot Gris and Chardonnay demonstration plots were +$363, -$943, and -$1118 respectively.  Although yield differences were observed, fruit quality between berries produced from grapes that were sprayed using the NEWA pest disease forecasting and risk assessment system or those sprayed with a calendar spray program yield were the same.

Grape berry moth (GBM) is the most important insect pest of grape in Ohio.  The larva of GBM bore into the grapes and feed on developing berries.  In this project we planned to use the GBR risk assessment model available through NEWA to guide the timing of insecticide applications.  However, GBM was not detected and thus no insecticides targeted for GBM were applied.

While additional replicated trials will be necessary for widespread adoption of the NEWA pest and disease forecasting and risk assessment system by Ohio grape producers, the potential for establishing this system as a beneficial IPM tool in the future is promising, especially if it is used in combination with other IPM disease and insect pest management strategies.

Recommendations:

Overall all but one of the grower participants embraced using an on-site weather system to assist them with their disease management decision making.  In addition, two of the growers continue to use the weather stations in combination with the disease forecasting models for grape.  Since the start of this project six other grape growers have inquired about installing a weather station and two of these growers purchased weather stations.  Based on the economic data collected from this project it will be difficult to convince growers in Ohio to adopt the forecasting models.  However, I think that in combination with intelligent sprayer technology, which lowers the cost of fungicides by 3 fold or more and improves fungicide coverage, and through additional replicated research using the models, we can meet our goal of establishing the NEWA insect pest and disease forecasting and risk assessment system as a beneficial IPM tool for Ohio grape growers.

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.