MONDAY, OCTOBER 14, 2024. BY STEPHANIE BOLTON, PhD, LODI WINEGRAPE COMMISSION.
This Fall, the Lodi Winegrape Commission is hosting special VIRUS TESTING DAYS to provide growers, vineyard managers, pest control advisors and consultants assistance with the daunting task of testing a vineyard for economically important viruses. The more we study grapevine viruses the more we realize how complicated virus sampling and testing can be.
As stated in a recent Harvard article about alcohol and health by Kenneth Mukamal and Eric Rimm, there is a need to “treat the subject with the nuance it requires.” The grapevine virus disaster in California is no different.
These VIRUS TESTING DAYS take some of the complication out of the equation and streamline testing so that it is more efficient and economical. First, the laboratories that are invited to participate have been verified as having a high level of accuracy for the viruses of concern. Second, seasoned virus experts and laboratory personnel will be onsite to offer support around which viruses to test for, how to use composite sampling to reduce costs, where to sample in the vineyard and more. Third, we’ll offer bulk discount pricing and free shipping of samples. Fourth, testing supplies will be available free of charge. Finally, we’ve simplified the virus testing panels which are offered.
In short, the Lodi Winegrape Commission is reducing many of the hurdles to virus testing that were outlined in our 2020 book, What Every Winegrower Should Know: Viruses, and are repeated further below in the excerpt.
LODI VIRUS TESTING DAYS are a drop-in type of event. Come in the morning if you need help creating a cost-efficient sampling plan or arrive later in the day with your samples already collected and labeled if you only want to take advantage of the discount pricing and free sample delivery. Come at any time with your questions about mealybugs and virus vectors, viruses, the Tree Assistance Program, rogueing or vineyard removal (including burning and Air District incentives). In addition to a laboratory, I will be present at each VIRUS TESTING DAY and we will also have various special guests.
The overall objective for these VIRUS TESTING DAYS is to encourage and support virus testing in our vineyards, so that we have the knowledge we need to best care for the health of our grapevines, our financial investments and our region. Knowing the virus status of your vineyard really does matter to you and your neighbors.
LODI VIRUS TESTING DAYS
Dates, Labs & Special Guests:
Wednesday, October 23, 2024 – Wonderful Laboratories (entire day) and Lodi Winegrape Commission special guest, the USDA Tree Assistance Program (9:00am – 12:00pm)
Thursday, November 7, 2024 – Agri-Analysis, Dr. James Stamp and Lodi Winegrape Commission special guest, Canine Detection Services
Wednesday, November 20, 2024 – AL&L Crop Solutions and special guest TBD
Venue: Lodi Winegrape Commission, 2545 West Turner Road, Lodi CA 95242
Time: 8:00am – 2:00pm
Who Should Attend: Anyone considering a vineyard removal in the next few years or trying to gather the virus-status of their vineyard to make more informed financial decisions.
Description: To help growers reduce the cost of virus testing and potential vineyard removal, Dr. Stephanie Bolton organized LODI VIRUS TESTING DAYS with verified laboratories. We’ve simplified the process and are offering support to determine which viruses to test for based on your individual needs, sampling support, free sample shipping, testing supplies and a group discount on testing fees. Drop in to talk through your questions about viruses, mealybugs, sudden vine collapse and vineyard removal, including the Tree Assistance Program and Ag Burning Alternative Incentives.
RSVP: To the Lodi Winegrape Commission by phone 209.367.4727 or email stephanie@lodiwine.com.
Below is an updated excerpt of the Virus Testing Chapter from our “red virus book”:
WHY TEST FOR VIRUSES?
1. Knowledge is money-saving power when it comes to viruses – once you know what you’re dealing with, you can make decisions that may save you lots of money over time.
2. Visual symptoms and ripening delays provide clues that a grapevine is infected with a virus, but they cannot be relied upon alone for detection in California. Testing by a trusted laboratory is crucial for an accurate diagnosis if you think you may have a virus infection.
3. Not all viruses affect a vineyard in the same way – for example, leafroll virus, red blotch virus, fanleaf virus, and vitiviruses (or co-infections of these viruses) each have their own management strategies, mostly due to the way they can spread to healthy vines. It’s important for the grower to understand which, if any, viruses they may be dealing with.
4. If your vines are infected with viruses, they are sources of inoculum which could infect healthy vines in your vineyard, in your neighbor’s vineyard, and in other vineyards across your region.
5. If only some of your vines or a portion of your vineyard is infected, you can act now to reduce the spread.
6. If you have leafroll virus in your vineyard, there can be a carryover infection into the next vineyard planting on the same ground – something you will want to know in order to determine what to plant in that ground next.
7. Ignoring virus infections for even one year can cost the grower a lot of money due to the fast rate of spread (especially with leafroll virus).
8. Testing new plants before propagation reduces the possibility of planting vines carrying a virus infection.
9. It’s crucial to know the virus status of any wood before you plan to top-work a vineyard or provide wood for bench-grafting.
BEFORE YOU TEST FOR VIRUSES
Learn the basic symptoms and means of spread for the main economically important viruses – these will help you know which viruses to test for.
If you are testing because you see red leaves in your red grape variety vineyard, eliminate other causes which are cheaper to deal with first. Grapevine leaves are not normally supposed to turn red in the fall for most varieties. Exceptions include: Petite Sirah, Malbec, Carignan, Carmenere, Ruby’s Red, Alicante, Teroldego, and possibly others – these may naturally turn red or reddish. Although beautiful in color, grapevine leaves naturally turn yellow, orange, and brown. When leaves turn red it is an indication of a problem – usually physical injury of the vine, a nutrient deficiency, or a grapevine virus disease.
NOTE: Vines with viruses may or may not express symptoms such as red leaves. Also, white varieties and rootstocks do not show the red leaf virus symptom.
WHICH VIRUSES SHOULD YOU TEST FOR?
The main economic viruses of concern in California commercial vineyards at the moment are: leafroll 3 virus, red blotch virus, fanleaf virus, leafroll 2 virus, leafroll 1 virus and the vitiviruses GVA and GVB.
If you think your vineyard has experienced mealybugs now or in the past, or if your vines are experiencing or are at risk for the sudden vine collapse, we recommend testing for leafroll 2 and leafroll 3 plus GVA and GVB.
HOW TO TEST FOR VIRUSES: A STEP-BY-STEP PRACTICAL GUIDE
STEP ONE. DECIDE UPON YOUR REASON FOR TESTING.
Decide why you are testing, since this reason will dictate your sampling plan.
• Do you think your entire vineyard may be infected?
• Is it a new or old planting?
• Are you trying to find new infected vines to remove (rogue) before the virus spreads?
• Are you trying to determine what percentage of the vineyard block is infected?
• Are you experiencing patches of dying vines as in the sudden vine collapse?
• Are you worried that a neighboring vineyard’s mealybugs and viruses are spreading into your vineyard?
• Do you have a ripening problem?
• Do you have mealybugs and want to know if your vines have been exposed to leafroll virus and/or vitiviruses?
• Do you have a red grape variety vineyard and are seeing red leaves in the Fall?
• Are you testing for the Tree Assistance Program or to get a disease exemption letter for open-air ag burning?
• Are you sampling dormant canes (both rootstock and scion) at the nursery before placing your final order?
STEP TWO. PICK A LAB.
Choose a laboratory that meets your needs for testing, turnaround time, customer service, sample delivery and budget. Review lab websites and call potential labs to make sure they are a good fit for your needs. Ask around for recommendations. Discuss your reason for testing with the lab.
STEP THREE. WRITE UP A SAMPLING PLAN.
Along with your chosen laboratory, develop a sampling plan based on the reason(s) for testing and your budget. This written sampling plan should include:
• How many total vines will be sampled
• Exactly which vines are to be sampled (vineyard block, row # and vine # OR symptomatic vines plus random healthy vines to use as a baseline comparison)
• How/if you will be compositing the samples
• Which vine parts are getting sampled (petioles, canes, etc.) and where on the vine is ideal to sample (near the trunk, etc.)
• How many pieces per vine need to be collected (for example, one cane from each side of the vine) and any specifics on size (thickness of canes at least the size of a pencil, etc.)
• How the vines will be marked and recorded
• Where the laboratory wants the samples delivered or shipped (confirm an address – some of the lab websites and Sample Submission Forms have confusing information)
• How the lab prefers the samples delivered or shipped (within 1 day of collection, a preferred shipping carrier, etc.)
• The total number of samples to be submitted
• Which virus(es) you want to test for
NOTE: Every sampling plan should include testing healthy vines as a baseline comparison, with the exception of testing for a government agency or disease exemption. Think about it: If you only test symptomatic vines (those with red leaves, for example) you may miss a much larger infection occurrence as many vines may not show symptoms.
STEP FOUR. COLLECT SAMPLES.
PRO TIP: Collecting samples is much easier with two people – one person to clip the canes, and another person with good handwriting to record the information and keep the samples organized.
MATERIALS NEEDED:
• gallon Ziploc bags
• a cooler (depending on the time of year, you may or may not need a cold pack too – if using a cold pack or ice, throw a towel or some newspaper on top of the cold pack or ice because you aren’t supposed to let the plant material freeze)
• a Sharpie
• the lab’s Sample Submission Form (downloaded and printed from their website)
• a clipboard with pen and paper
• pruning shears/clippers
• something to carry the Ziploc bags with samples (a tote bag or a 5-gallon bucket works well)
• something to mark the vines you are sampling
• if planning on shipping the samples overnight, you need a cold mailer such as a Styrofoam cooler with ice packs large enough to hold all of your samples and a box that the cooler can fit in
Before starting the sample collection, fill out the lab’s Sample Submission Form as much as you can.
Label a set of Ziploc bags with a Sharpie. Vine pieces will go directly into these labeled bags as you collect them, placing one sample into one Ziploc bag. You will need to give each sample/Ziploc bag a code which will match what you *legibly* write on the Sample Submission Form. We recommend a letter to indicate the vineyard block, a row number, and a vine number like this:
It’s also good practice to write your last name on the bottom right of each Ziploc bag.
Whomever collects the samples will need to understand how to use your labeling code. If your rows are not numbered already, be specific about where the samplers need to start counting the rows (for example, start on the northwest corner with Row #1 and count up as you move south). With vines, be specific as to how they should count the vine number (for example, count west to east with any missing vines as a number). Give the samplers a map of the vineyard (you can print a satellite image of your vineyard from Google if you do not have a map of your own).
We recommend sampling woody canes close to the trunk, as there is less risk for contamination (versus petioles). You can use one pair of clippers without sanitizing them in between vines and you do not need to wear gloves. The cane pieces should be about 8 inches long and will fit nicely inside gallon Ziploc bags. An easy way to remember the size of a cane needed is that you want it to be at least as thick as a pencil and about the length of your elbow to your wrist. When you place canes in the bag, do your best not to let the cut ends of the canes touch the outside of the bag or your hands.
Mark the vines which you are sampling with paint on the bottom half of the trunk, flagging tape or a zip tie on the dripline. Make a note of how you mark them in your records.
It’s a good idea to take photos of some of the vines being sampled for your records (at least one possibly infected vine and one healthy looking vine). PRO TIP: If you turn on the location recording on your smartphone and take a close up picture of the vine, the approximate GPS position of the vine will be stored with the photo.
Once all samples are collected, finish filling out the lab’s Sample Submission Form and make a copy for your records. Add in any special instructions, such as composite sampling. If you have any questions, it’s best to call the laboratory for assistance.
Prepare your shipping materials or plan to deliver the samples in a cooler to the laboratory. If shipping, overnight the samples in a cold mailer such as a Styrofoam cooler with ice packs. Keep in mind that the last overnight pick-up may be as early as 3pm for some shipping stores. Enclose the Sample Submission Form with the samples such that it won’t get wet from any cold pack condensation.
Deliver or ship your samples to the lab as soon as possible (within 2-3 days). Samples degrade in a few days and need to be refrigerated until they are received by the lab. You may refrigerate the samples for 1-2 days before shipping, but it is recommended to submit the samples on the day of collection.
HOW TO REDUCE TESTING COSTS
SET-UP FEE. There is a set-up fee associated with virus testing, so submitting more samples at one time is usually cheaper than submitting the same number of total samples multiple times.
COMPOSITE SAMPLING. Composite sampling will save most growers money. Some labs allow you to composite up to 10 cane pieces into one sample for testing, allowing the testing of 5 vines (at 2 canes per vine) in one sample. If you want to composite samples to save money but also want to know which individual vines are positive, some labs will test a composite first and then only if there is a positive, will go back and test the samples individually (this needs to be part of the sampling plan discussed with the lab as each vine’s wood needs to be labeled separately and delivered in its own Ziploc bag). Your lab will be able to instruct you on the composite method that will work best for you. Make sure that you write any special composite instructions on the Sample Submission Form.
SPOT TESTING of SYMPTOMATIC VINES. If you have a large, red grape variety vineyard (50+ acres) and there are many vines showing virus symptoms, but only a small percentage (<10%) appears infected, it may be worthwhile to spot test symptomatic vines. In this case, the point of testing would be to train your eye (or the eyes of a few employees) to be able to detect a virus infection in this particular vineyard so that you could mark the vines for removal that winter. Remember to test several random healthy-looking vines too. You will not want to composite vines in this instance, but rather test individual vines. Be sure to take photos and mark the vines carefully to use for training purposes. Once you have dialed in what a virus-infected vine looks like for that vineyard at that time, you can have a crew mark all symptomatic vines for removal.
NOTE: If leafroll 3 virus is discovered it may be worthwhile at this time to do a second virus-testing pass, checking the vines adjacent to the infected vines within the row for leafroll 3 virus. Then you would be able to get a more accurate estimate of the percent infection across the vineyard and you could decide whether or not to remove the vines adjacent to the symptomatic vines.
GET TESTED WITH A FRIEND OR TWO. It’s much easier (and more comforting?) to get tested for anything scary with a friend. Plus, you can help each other figure out how to do it all, sample together (it takes two people), and ship together. You’ll pay one set-up fee if you use the same lab and one Sample Submission Form. I bet the lab will even bill each of you individually if you ask and indicate that request on the Sample Submission Form – just like splitting the bill at a restaurant.
THE FUTURE OF VIRUS TESTING
Testing for grapevine viruses is a constantly changing business – as new viruses and new strains of existing viruses are discovered, laboratory tests must also evolve. Communication between scientists, laboratories, and growers is vital. With sample preparation and virus detection techniques improving over time, hopefully our industry will see the cost of testing reduced in the future. However, we do not recommend waiting to test your vineyard since virus spread can happen quite rapidly and accurate methods are available now.
WHAT IF YOU HAVE VIRUSES?
• Sorry, that sucks. Welcome to the club – there are a LOT of members all over California.
• If any of your vines are positive for a grapevine virus, you can decide on a management strategy suitable for that particular virus or virus combination. Right now and in the foreseeable future, there is no cure for a vine infected with a grapevine virus.
• Learn more about any viruses which show a positive test result. Check out lodigrowers.com/ education/viruses/ for information and videos on leafroll and red blotch viruses.
Prof. Gerhard Pietersen of South Africa – our leafroll virus expert – provided excellent practical advice and hope in his presentation during our 2019 Mealybug & Virus Outreach Meeting, which is available to watch on lodigrowers.com.
• Determine whether the virus(es) are having a negative impact on your profitability, now or in the future.
– Are you meeting your desired sugar, yield and quality parameters in those areas of your vineyard which are infected?
– In practice, some vines have a stronger immune system and less overall stress, and they can produce quality grapes despite a minor virus infection. These vines are generally ancient vines on their own rootstocks with very low yields. More commonly, vines have a weaker immune system and high overall stress, and they struggle to produce quality grapes when infected with a virus.
• Try to determine the percent of your vineyard which is infected. Knowing how much of a vineyard is infected with which virus(es) can help you decide whether it makes more economic sense to remove infected vines or to start planning to remove the entire vineyard.
• When it comes to leafroll, red blotch and vitiviruses, removing the virus inoculum (by removing or rogueing the entire grapevine) is the most efficient strategy for helping to protect other healthy vines from infection. It is best to remove a grapevine in the winter after a period of rain so you can remove as many roots as possible. For leafroll and vitiviruses, it’s also best to treat the grapevine with a systemic material targeting the vine mealybug before removal (remembering to allow for enough time for the material to be effective). If mealybugs are present in that area, a re-infection from leafroll virus and/or vitivirus particles in the leftover root remnants may occur in replants.
• The USDA Farm Service Agency’s Tree Assistance Program (or TAP) has approved red blotch and leafroll virus as natural disasters eligible for financial assistance. Contact your local FSA office or read the article called “Pulling Out a Vineyard? Read This First.”
If all of this seems overwhelming, that’s because it is. But it is also really important, which is why we are offering help. If after reading these tips and talking with a laboratory you need more help – we are here. Lodi growers can call or email Dr. Stephanie Bolton at the Lodi Winegrape Commission: 209.367.4727 or stephanie@lodiwine.com.
The Virus Testing Chapter of What Every Winegrower Should Know: Viruses was written by Stephanie Bolton and thoughtfully reviewed by Matt Frank, Tia Russell, Dr. Marc Fuchs, Prof. Gerhard Pietersen, and Dr. Neil McRoberts.
Have something interesting to say? Consider writing a guest blog article!
To subscribe to the Coffee Shop Blog, send an email to stephanie@lodiwine.com with the subject “blog subscribe.”
To join the Lodi Growers email list, send an email to stephanie@lodiwine.com with the subject “grower email subscribe.”
To receive Lodi Grower news and event promotions by mail, send your contact information to stephanie@lodiwine.com or call 209.367.4727.
For more information on the wines of Lodi, visit the Lodi Winegrape Commission’s consumer website, lodiwine.com.
For more information on the LODI RULES Sustainable Winegrowing Program, visit lodigrowers.com/standards or lodirules.org.
