Chemical-Free Vineyards

Progress report for FNE20-952

Project Type: Farmer
Funds awarded in 2020: $14,813.00
Projected End Date: 11/30/2022
Grant Recipient: Villa Milagro Vineyards
Region: Northeast
State: New Jersey
Project Leader:
Steve and Audrey Gambino
Villa Milagro Vineyards
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Project Information


Project overview:

Fungus and weeds in vineyards can cause low crop yield and reduce vine vigor and longevity.  This project evaluates the effectiveness, efficacy and cost savings of two technologies to control fungus and weeds without synthetic chemical: Ozonated Water for fungal control and under-vine mulch alternatives in combination with OMRI certified herbicides for weed control. Both fungal and weed control represent significant expense to East-coast vineyards.

Ozonated water:

The test program will utilize an automated mist system in the canopy supplied by an irrigation system to deliver a steady supply of ozonated water to the test vines. Ozone is a well-established sanitizer used by virtually every major food processor, brewery and winery in the country.  Ozone gas is a very reactive compound (O3) and destroys every microbial cell with which it comes in contact.  While its successful use inside manufacturing facilities is well documented, it has not been used large-scale on crops. Villa Milagro Vineyards experimented with an ozone generator on their spray tank back in 2010.  The missing links were concentration (of ozone on the pathogens), timing and duration of contact.  A sketch of the mist system is found in section "Other Relevant Research Information".

OMRI certified sprays and mulch:

There are several OMRI certified herbicides that are effective.  They are however, cost prohibitive if used at levels needed to produce the same weed control as conventional herbicides.  This project will compare alternative under-vine mulches in conjunction with two OMRI herbicides to determine effective application rates of each for weed control and comparative cost.

Project Objectives:

Our objective is to determine if it is possible, practical and economically viable to eliminate synthetic chemicals used for fungal and weed control in commercial vineyards of the Eastern US.

We intend to design and test a mist spray system within the vines' canopy that can regularly and thoroughly provide ozone to eliminate fungal disease.  We will be able to use our existing drip irrigation system, with appropriate modifications to deliver the ozonated water mist. This project seeks to determine the practicality of the delivery system, its ease of operation, its ability to eliminate synthetic fungicides, its effectiveness in controlling fungal infections and its economic savings so as to be widely adopted.

We intend to test several different mulch types in conjunction with two different OMRI certified herbicides. We will evaluate which combinations effectively control weeds and compare the combined costs of the mulch, its application and upkeep and the herbicide to determine which are within an acceptable range for a commercial vineyard to adopt over synthetic herbicides.

The results of this research would be of considerable interest and economic importance to vineyard owners in New Jersey, New York, Pennsylvania, Maryland and Virginia, which are home to over 2,200 vineyards.


Vineyard owners today are looking for ways to meet consumer demand for more natural products, produced without synthetic inputs.  Reducing synthetic chemical use can greatly reduce grape production costs, improve vineyard worker safety and reduce environmental impacts on soil, water quality and economical balance. 

One of the largest expenses in managing a disease-free vineyard are the chemicals used for fungal and weed control.  This project will seek to prove methods to eliminate or greatly reduce reliance on synthetic chemicals in both these areas of vineyard management.  In addition, we feel that it is possible to simultaneously improve fruit quality - which every grower strives to do.

Fungal control:

While West Coast vineyards, which enjoy dry climates during their growing season, have a comparatively easy time accomplishing the goal of being chemical-free, it has proved elusive, if not deemed outright impossible for Eastern wine growers due to the high year-round humidity which fungal diseases favor.  Three specific fungi, Downy Mildew, Powdery Mildew and Black Rot, if not controlled can destroy a crop at various stages of development, and in the case of Black Rot can weaken and destroy the vine itself.

Chemical expense, and the associated application costs (labor, fuel, tractor use) are significant expenses to commercial vineyards in the East.  Additionally, it is very easy to fall off your spray routine due to bad weather, equipment breakdown and other unexpected events.  Fungal disease can get a foothold the moment a spray program is disrupted, applications are made off-schedule or applications are missed at key disease infection stages .  Certain times during the growing season are more critical, particularly during bloom, when spray consistency is imperative, and any interruption can have dramatically negative impacts on fruit quantity and quality.

Our proposal would test the effectiveness of in-canopy misting spray nozzles to regularly and thoroughly deliver ozonated water to the vines' foliage and fruit.  By not relying on time-consuming spraying, the risk of missing a spray could be eliminated.  The ozone generator would be connected to our existing irrigation system and an array of mist nozzles would be permanently embedded in the vine canopy.  This method would eliminate the need for tractor use to spray, and the associated costs of maintenance and fuel, the required labor, and of course, no fungicides.  Eventually the application could be automated.

Weed control:

Today, not a day goes by when we don't read something about the negative human and environmental impacts of the most widely-used vineyard herbicide, glyphosate.  Nonetheless, farmers continue to use it because of its cost-effectiveness and systemic mode of action.  But even these benefits may be diminished as some weeds are starting to show resistance to it.  There are and have been several OMRI listed herbicides on the market for a number of years, however  in order to be as effective as glyphosate their cost is roughly 20 to 30 times more, thus they have not become widely used.

With traditional fungicides and herbicides there is what's called an REI, REntry Interval, to be observed by workers.  Even the mildest chemicals require a 12 hour REI and some as high as 72 hours, meaning that the vineyard is unsafe to enter for that time frame.  If this rule is violated, unsafe labor conditions are created.  In addition to the worker safety issue, REI reduces the number of hours that workers can be in the vineyard.  OMRI listed herbicides have an REI of Zero, making them both worker-safe and cost-effective as workers may return to work immediately.

Our project would evaluate various under-vine mulches combined with OMRI herbicides.  Some mulches are more permanent than others, and their costs vary, which is why several will be evaluated.  While mulch will never be 100% effective, we feel that if it can significantly suppress weed growth, then the application of an OMRI listed herbicide, in lower concentrations at expanded intervals may be able to control weeds, thus bringing the costs in line with that of conventional herbicides and allowing more vineyards to eliminate synthetic herbicide use.


Click linked name(s) to expand
  • Dr. Jaqueline Ricotta, PhD


Materials and methods:

This project seeks to determine the effectiveness of mist application of ozone to control three fungal diseases that are the bane of vineyard operations: Powdery Mildew (Uncinula necator), Downy Mildew (Plasmopara viticola) and Black Rot (Guignardia bidwelli).  While there are several other fungal diseases common to vineyards, these are the "Big Three" and if we can succeed with these, we will know it can control the others.  Powdery and Downy affect any green tissue, interfering with photosynthesis if on leaves, and rotting fruit in severe cases.   Black Rot infects the foliage and the fruit, turning the berries into dried out mummies which house spores that can be released the following year.  Vineyard managers are trained to spot early symptoms of Powdery and Downy, so only in extreme cases would it get to the fruit.  Black Rot is more insidious.  You don't know you have it until it is too late to eradicate.  It has a 10 to 14 day incubation period during which there are no visible symptoms.

One important note comparing ozone to conventional fungal sprays.   Ozone is an eradicant, conventional sprays are preventive.  This is relevant to the design of the canopy mist system.  One of the problems with conventional sprays is that you are spraying for a target not yet seen or known.  But once the fungus takes hold, it's increasingly hard to remove it. Vineyard managers tend to "over apply" their conventional synthetic chemicals just to be safe, as nobody wants to risk getting an infection.

By contrast, ozone has no residual effect, but can knock out any infection with which it comes in contact.  One of the reasons our prior attempt to spray with ozone failed was that it was impossible to be in the vineyard spraying often enough to prevent disease.  Our project design will eliminate the problem of having to drive the tractor frequently enough to keep diseases down, by virtue of installing mist spray heads throughout the test vines' canopy.  Our protocol will determine the duration of misting required for control.

Protocol Design:

We plan to use the ozone system on two different grape varieties, one Vinifera and one Hybrid, on a portion of each type, leaving the rest of those varieties as the control. The vinifera will be Cabernet Sauvignon, (54 vines in each of 2 adjacent rows) and the hybrid will be Frontenac (16 vines in each of  3 adjacent rows).  Our control vines will be the remainder of our 10 acre vineyard (which includes the remaining Cab Sav. & Frontenac) in which we will follow our established and effective conventional spray program.

How we will measure the effectiveness of the ozone mist:

Daily scouting reports with photos will be used along with counts of infected leaves in each test section to determine the level of control.  With the exception of Black Rot, Powdery and Downy mildews have a very clear and visible presentation.  In a conventionally sprayed vineyard, when done properly, there should be almost no evidence of either.  Thus, if the ozone test fails, the contrast will be clear, and counts of infected leaves will document the statistical differences.  If ozone works, the test rows will appear similar to the conventionally sprayed control rows.  Black Rot is not immediately visible, but 10 - 14 days later the symptoms are clear to the naked eye, thus the same comparison will be utilized.  (photos of these three fungal diseases are found in the following section) 

The misting heads will be attached to the trellis wires in the test rows. (see drawing in the following section)

Weed control:

We will test 4 types of mulch combined with 2 different OMRI herbicides (8 different combinations) and compare to conventional synthetic herbicides.  The test will be conducted with two rows each of the four different mulches (gravel, chopped straw, landscape fabric, wood chips/sawdust), (8 rows total).  One row of each mulch type will be tested with test herbicide 1 and the other two with test herbicide 2.  The remaining vineyard rows will be sprayed with our current selection of herbicides; Prowl, a pre-emergent for grasses, Chateau, a pre-emergent for broadleaf weeds, and Cheetah, a burn-down herbicide.

Of primary concern are broadleaf weeds which can harbor soil pathogens harmful to the vines.  Both test OMRI herbicides excel at knocking down these types of weeds.  Secondary concern are grasses.  Because of their ryhzome nature, they are harder to control with contact herbicides, thus the popularity of systemics such as glyphosate.  Our test rows will be tilled immediately before adding mulches, but not our control rows.  This is because the weeds in our control rows are already under control, and tilling would actually aid in the establishment of weeds in the fresh and exposed soil.

How will we measure the effectiveness of each mulch/spray combination?

Our test is not about eradication, as there will always be some weeds or grass under the vine and a vineyard can tolerate that.  It is a matter of management not annihilation.  Our true test is to determine if we can achieve the same level of weed control with a test mulch/OMRI herbicide as is achieved with our current mix of herbicides.  We will MEASURE the amount and frequency of our test sprays to calculate the cost.  We will count the number of broadleaf weeds per under-vine-foot in both the test and control strips to compare the effectiveness.  The other measurement will be the amount of OMRI herbicide used over the course of the season to maintain the same level of weed control as a conventional program.  We can then compare the costs of each mulch/OMRI herbicide combination to the costs of a conventional herbicide spray program to determine whether our model could be considered cost-effective.

Research results and discussion:

We began work promptly in February 2020.

Mulches were applied.

Organic herbicides were applied one time.

In Mid-March the COVID pandemic forced us to close our tasting room.  It also closed the Embassy in Mexico, and as a result our annual H2A workers were not able to return here.

Our severely limited manpower was pressed into service taking care of our vines, pruning, shoot positioning, spraying etc.

By late July we had not kept up with the organic herbicide work, had not installed the ozone mist system, at this point our workers had finally returned from Mexico, and the vineyard was way behind.  It took us till late August to get it where it needed to be.

I contacted Grant Program Coordinator Candice Huber to discuss what we could do.

She informed us we could pick it up in 2021.  

Being closed for 3 months and with our restaurant sales outlets still closed, we are still scrambling to stay afloat.

It is our hope that things stabilize quickly in 2021, that our workers are allowed to return from Mexico on schedule by mid-March, and we can pick up where we left off last year.

Participation Summary
1 Farmer participating in research
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.