Vineyard and Winery Information Series:
Vol. 15 No. 2, March - April 2000
Dr. Tony K. Wolf, Viticulture Extension Specialist
II.Climbing Cutworm Alert
III.Update on Grapevine Yellows
IV. VVA/VSHS Meeting Discussions (Part 1)
1999 Commercial Grape Report: According to the Virginia Agricultural Statistics Service (VASS), grape production in Virginia increased by 43% in 1999 over the previous season's crop. Vineyard acreage also increased, from 1,608 in 1998 to 1,963 acres last year. The bearing acreage showed an increase of 11%, totaling 1,434 acres, and pushing average vineyard productivity to about 3.2 tons/acre, a substantial improvement over the 2.0 to 2.5 tons/acre averaged in the previous 10 years. Chardonnay still leads production with 29% of the total bearing acreage, and 39% of all vinifera vines (Table 1). Virginia is currently ranked 10th in the country for grape production (about 7th for wine grape production), with last year's totals increasing to ~ 4,600 tons, up from 3,200 tons in 1998. If you are a commercial grape producer and you did not receive a survey last fall, please contact the VASS office at (804) 771-2493 to be added to the 2000 census.
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Climbing cutworms cause damage in vineyards every spring, although the incidence varies from vineyard to vineyard. A number of growers were caught by surprise last season (1999), and the following is offered as a reminder to the unwary. Climbing cutworms are the larval stage of several moth species. The larvae feed on swollen grapevine buds and can cause significant destruction of buds and recently emerged shoots. Injured buds appear hollowed-out, which is the same appearance of buds damaged by grape flea beetles. Cutworm larvae feed at night and seek shelter in soil and debris during the day. Thus, if you observe damaged buds, and cannot locate the pest, chances are that climbing cutworms are at work. Cutworm larvae are about an inch long. They are smooth, brown or gray, and have stripes running the length of their bodies. A quick search around the base of an affected vine can usually reveal the pest. Some of the most heavily damaged vineyards in 1999 had mulch or weed debris around the base of vines, which offers a refuge for the larvae during the day. Put another way, if your vineyard currently has mulch or other significant vegetative debris under the trellis, BE ESPECIALLY VIGILENT for evidence of cutworm feeding. Feeding begins in the spring when buds begin to enlarge. The extent of damage depends on the cutworm population but also on the duration of the bud-break stage. During cool weather, when the period from bud-swell to bud-break is delayed, damage can be extensive because the larvae have an extended period during which they feed. Conversely, during hot weather, shoots emerge quickly and damage is minimal. Vineyards must be monitored carefully for cutworm feeding in the period around bud-break, and treated with an insecticide if feeding affects more than about 2% of the buds. Note: the 2% level of damage should be adjusted for your specific needs. One of the most damaging aspects of cutworms occurs when they feed on canes that have been laid down on the wire to form cordons. Such canes that are deprived of uniform shoot emergence by cutworm feeding may need to be retrained the following year in order to provide uniform spur placement. On the other hand, older vineyards, that normally crop well, may tolerate 5% or more bud injury without adverse impact on yield or subsequent season spur development. Regardless, you need to walk the vineyard routinely after buds begin to swell to monitor for cutworm activity.
Many of the grape insecticides, such as Sevin, Dipel (Bacillus thuringiensis [B.t.]), and Guthion, are effective against cutworms (and grape flea beetles). Cutworm control can be improved by spraying in the late afternoon or early evening to ensure that fresh residues are present when feeding commences. Read the insecticide label to determine the correct rate of product application.
|Variety||Tons produced||Bearing acres||Non-bearing Acres|
|Other White Vinifera||204.6||240.0||62.1||84.9||42.6||56.2|
|Other Red Vinifera||189.1||212.9||51.2||50.5||58.2||77.2|
|Other White Hybrid||30.2||41.0||23.7||30.3||8.2||9.0|
|Other Red Hybrid||33.1||17.7||23.7||15.1||5.8||5.3|
|Seedless Table (all)||6.9||6.8||4.4||5.0||1.2||0.6|
|Other Red/Black American||34.0||48.8||10.8||18.8||5.7||31.4|
|Other White American||26.8||46.4||12.5||15.3||*||7.2|
* Some figures are not published to avoid disclosure of individual operations.
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Tony Wolf, on leave at the University of Adelaide, South Australia
Grapevine Yellows (GY) is a destructive disease of grapevines. I've discussed this disease in previous VN newsletters and will not provide a comprehensive review here. I do, however, wish to provide an update on our current GY research, and to relate similar research going on here in Australia.
We've recognized the occurrence of GY in Virginia since the late-eighties, where the disease affects mainly Chardonnay and Riesling. I have also seen affected Chardonnay vines in SE Pennsylvania, and there is good reason to suspect its occurrence in parts of Maryland and North Carolina. The only other known occurrence in the US was in the Finger Lakes region of New York State. Grapevine Yellows is also common in western Europe, Israel, and Australia. As with other occurrences, GY in Virginia is caused by phytoplasmas, small bacteria-like organisms that are limited to the phloem or food-conducting tissues of the vine. We now recognize that at least two different phytoplasmas are involved with the disease in Virginia. These phytoplasmas are not currently implicated with other GY diseases in the world; they appear to be unique to our situation in Virginia. The phytoplasmas are transmitted to our cultivated vines by unknown vectors, but presumably these vectors are leafhopper or planthopper insect species. That presumption is based on our knowledge of other yellows diseases, and on what we do know of GY in other countries. We also have evidence that certain indigenous plant species can harbor the phytoplasmas that kill our grapevines. Those species include Vitis riparia, certain Prunus species, and several herbaceous plants including hempbane and goldenrod. Infected Chardonnay and Riesling show typical yellows symptoms, including veinal chlorosis and rolling of leaves, shoot tip and cluster abortion, and lack of periderm maturation on affected shoots. Symptoms are illustrated in a previous newsletter
We have not observed these symptoms on the wild riparia grapevines, lending support to an hypothesis that at least one of the phytoplasmas that affect cultivated grapevines in Virginia co-evolved with the native grape species. The disease becomes apparent when we attempt to grow susceptible varieties/species in this environment; a situation analogous to Pierce's Disease in our Tidewater region. Anecdotally, we have not seen GY symptoms in vines during their first year in the vineyard; it is in their second and subsequent years that the symptoms arise. And, we have seen examples of "edge" effect, where the incidence of GY-affected vines in a vineyard aligns with prevailing wind patterns or proximity to a positive natural reservoir of phytoplasmas (e.g., a V. riparia vine at the vineyard's edge). We have also observed significant "clustering" of affected vines in a given vineyard. Collectively, the above evidence suggests that infection occurs in the vineyard, and that our version of GY is not a nursery-propagated problem.
As reviewed elsewhere, GY is ultimately a destructive disease of susceptible varieties. In our experience, affected Chardonnay and Riesling vines are usually killed within 2 to 3 years of initial symptom expression. Currently, our only recommendation for management of the disease is the removal of affected vines from the vineyard as soon as symptoms are obvious and unambiguous. In certain other areas of the world, such as the south of France, GY (specifically Flavescence doree), is managed through application of insecticides to reduce the known vector populations. There, the leafhopper vector is an obligate parasite of grapevines, and has but one generation per year. Thus, timely application of insecticides to the grapevines offers economical control. The situation in Virginia may not be so easily solved: prior to 2000, we had no information on vectors, and we knew that multiple, alternative hosts were potentially involved with the disease. Before headway is made with GY management, we need to identify the vector or vectors of the phytoplasmas. Knowing that, we might begin to construct a management program.
As a first step towards vector identification, we sought and obtained funding from the Virginia Winegrowers Advisory Board in spring, 1999 to conduct weekly surveys of two Chardonnay vineyards for potential vectors. Both vineyards are located in Loudoun County, Virginia, and both have long histories of GY occurrence. Weekly sweeps for leafhoppers and planthoppers were made in both vineyards, and included sweeps of vines as well as sweeps of the ground cover. We also occasionally collected specimens from the vegetation outside the vineyard. We focused on leafhoppers and planthoppers because these insects are recognized for their abilities to transmit phytoplasmas. The bugs were collected, brought back to the lab, catalogued, photographed, described, and then frozen and shipped to a colleague (Dr. James Prince) at Fresno State University in California. Dr. Prince's lab analyzed each insect sample for the presence of phytoplasmas. Typically, each sample contained up to a dozen 'hoppers, usually of multiple species. From more than 150 samples, Dr. Prince found 7 samples, all from late-summer, that tested positive for the presence of phytoplasmas. Positive samples were found in both vineyards. These preliminary results mark a very substantial increase in our understanding of GY in Virginia. Yet, many questions remain and much work lies ahead. First, we plan to repeat the weekly sampling and 'hopper testing in the 2000 season. Ideally, we would hope to find phytoplasma-positive 'hoppers only late in the season. That would suggest that transmission may be occurring at a discrete period of the season. If so, it might be possible to time insect control practices for that time of season. Secondly, we need to determine whether the phytoplasmas detected in the leafhoppers are actually those that cause disease in Virginia grapevines. The techniques used in Dr. Prince's lab have thus far only used methods that allow for a general detection of phytoplasmas, some of which pose no threat to grapevines. The diagnostic techniques that discriminate among specific phytoplasmas exist; it's simply a matter of more time and more effort with the lab work. Third, we need to identify the leafhoppers that were in the positive samples. Although the insects included in each of the 1999 season samples were described, we don't know their identity. Based on the visual appearance of the bugs we collected, we appear to have collected over 30 different species of 'hoppers over the 1999 season! We must work with a leafhopper specialist in the coming year to retro-identify the 1999 specimens, as well as ID the specimens that we will collect in 2000; we must become proficient in recognizing 'hopper species. Fourth, to "prove" that a particular leafhopper or planthopper is capable of vectoring phytoplasmas, we must design and conduct transmission studies using mono-species populations of 'hoppers that have tested positive for phytoplasmas. This all takes time and research funding.
What is the potential outcome of this work? The knowledge of alternative hosts and vectors should allow us to decide whether interdiction of the vectors, as with insecticides, will be feasible. If the vectors are simply casual feeders on our grapevines, then an insecticidal approach may not be feasible--we would have to spray far too frequently with potent, contact insecticides to ensure that no leafhoppers survived in the vineyard. My prediction is that ultimately our management of GY in Virginia will rest with a manifold approach of: 1) avoidance of planting susceptible varieties in known, high-risk sites; 2) reduction of known alternative hosts from in and around the vineyard site; 3) prudent application of appropriate insecticides if vector biology is resolved; and 4) acceptance of a manageable level of vine attrition due to the disease.
Grapevine yellows also occurs here in Australia, and is a substantial problem in the Murray River area of Victoria and South Australia. The phytoplasmas that cause GY here are different from those in Virginia, but some of the same symptoms are produced on vines. The situation here is more complex than what we've found in Virginia. In addition to typical yellows symptoms, a range of other symptoms have also been observed here in association with GY. Those other symptoms include a "restricted spring growth" of shoots, delayed dormancy in the fall, and a condition termed "late season leaf curl". Some feel that the whole range of symptoms is caused by one or more phytoplasmas; others feel that the effects of stress, viruses, or other pathogens are being confused with the specific effects of GY phytoplasmas. While vines are less apt to be killed by GY here, crop yields are significantly (50 to 75%) reduced in affected vineyards. And, given the size of the industry here, the magnitude of the problem, and economic loss, is much greater than that in Virginia. The Australians know that at least two, and probably three different phytoplasmas affect grapevines here. Unknown are alternative hosts, and vectors, although there is some evidence that a leafhoppper (Orosius argentatus) can vector one of the phytoplasmas. There remains uncertainty about whether nurseries can propagate GY-affected wood, but some evidence points to that as one route of disease distribution. In addition to my primary research activities here in South Australia, I've had abundant opportunity to visit with researchers and industry members engaged in answering questions about GY. The expertise and techniques being used here will have direct application to our situation in Virginia.
As a footnote to this article, we pack our gear and head home from South Australia in a bit more than 2 weeks. The past 4 months has been a unique and extremely rewarding experience. In addition to South Australia, I've been able to visit New South Wales, Queensland, Victoria, and Tasmania. It's difficult to say what I'll most miss here: the friends, the vast open spaces, the mallee scrub, the sounds, the clear blue skies, the wines the list is long. See you in Virginia.
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The annual meeting of the Virginia Vineyards Association and VA State Horticultural Society was held in Williamsburg in January. Viticultural presentations were transcribed and a portion of those talks is presented here. Additional transcripts will appear in the May-June Viticulture Notes.
Doug Fabbioli, Tarara Winery, Leesburg, VA
There is a lot of information being presented today. "What fits with you, what works best, and what is most comfortable for you" has a lot to do with your decisions on varieties, trellising, irrigation, etc. I am going to go through a few things that we've done at Tarara. I started there about two and a half years ago. The emphasis needed to be in the vineyard, and it's starting to come around. The answers, solutions, cost-effectiveness that we found may or may not work for you. It's up to you to decide.
Improved economic practices really equal three things. Improved quantity, improved quality, and decreased costs. How can I improve my quality, but still keep my costs down? I'll go through a few things that we do. The first thing is to balance our vines. Chambourcin has a downward growth habit, so instead of fighting with tapeners, we decided to train them to a high cordon, and let them grow downward, similar to GDC.
When we go through and prune, we use three-step pruning. We have an older vineyard that needs some attention. It's not where I want it, and it is going to take a few years to get it where I want it. The first step is getting rid of extended spurs where there are shorter replacements. We are taking care of those spurs before the finish pruners come through and have the opportunity to leave that long spur. We are taking it out of position. We'll also replace any dead wood and non-productive cordons with new canes to bring down and develop new cordons. Step two is taking a gas powered hedge trimmer and going though at the four bud point and cutting canes. My boss likes efficient toys like this. Someone is behind pulling all of those canes away. Step three is to finish prune. We have about fifty acres with 4 or 5 full-time people who are not necessarily in the vineyard all of the time. When it comes to March 1st, the other half of the business takes my labor, which is digging trees, so I need to have the majority of pruning done by March 1. We start as soon as the leaves drop. By doing this second step, I believe it's quicker, and also, these guys don't like to be out there on a 20 degree day pruning and fine tuning. But when they go through there with a hedge trimmer, they are just cutting and pulling. They are able to move their bodies, keep their blood flowing, and actually feel like they got something done each day, not just freezing to death.
We are running a lot of wire in the vineyard. Some of it is for irrigation, a nd a lot of it is for the canopy. First, we put some wire up about six inches above the cordon, and we are also moving a lot of our vines to Smart-Dyson, so we are putting a wire about a foot below the cordon. We have a carrier and hitch it to a three-point hitch and hole digger, and it just runs by free run. We walk out to the end of the row, and pull the wire down to the end, pull the wire taut, at the tractor end, cut it, and move the tractor to the next row. It works very well because you are working at the speed of a person, and if it gets caught on something, you aren't going to rip out a post or break your tractor or wire because you are pulling it out. It only takes one person walking the wire. One thing we do with our removable catch wires is use galvanized roofing nails with the wide head instead of the expensive pieces. We put the nails in at an angle, and they hold the wire very well. We have wood posts throughout the vineyard, and it has helped us a lot. We aren't trying to pound things two or three times. They hold up very well, they don't break.
We came into a problem this year, we planted some Viognier and Pinot gris in '93, and they haven't been tended to well. They were irrigated, but not pruned. We finally started to spend a lot of time on them, getting them up. When we did a count to see where we were at, there were about 25% missing vines. My initial thought was to buy replacement vines and spread them throughout the vineyard and fill in the holes. My boss said, why are we going to buy Pinot gris and Viognier when we are running out of Merlot in the tasting room all of the time? I slept on it and came back and said, okay boss, you gave me a good idea. We decided to transplant these young vines. We took a section of the vineyard where the two sections of Viognier and Pinot gris met, and we separated them out from there. We pulled out the Pinot gris from one side, planting it in one area. We pulled out Viognier from the other area and planted intermittently in the Viognier section. This opened up a whole area of about 3 _ acres for us to plant Merlot in. The wire is in, the irrigation is in, and there are even holes there for us to put the grapes in, when Spring comes around. Will it work? I don't know. We just came up with this a couple of months ago, and I ran it by Tony Wolf and Jeanette Smith. I'll show you basically what we did. We came in with a little New Holland and used it as a power spade. We speared the soil under the vine, started to lift the earth up, and then pulled the vine out by hand. We got a vine with no soil, and we accepted the fact that we were bare-rooting these vines. We pruned them very hard before starting, but we also left the position of our spurs. We didn't try to cut back on our cordon at that point. We just cut the spurs back to one or zero buds. I wasn't too worried about getting fruit, but I would really love to keep that cordon length. Then we went ahead and took the same piece of equipment and dug a hole for the vines. Here we are putting them in at six-foot spacing, digging the hole first, cleaning it up with a shovel, then we dropped the vines in and put the soil back around the vine. At this point, we watered them in, because this was done in late-October. So far it has worked pretty well. We'll find out what pushes in this spring. Overall, I felt comfortable with how many roots were retained. There were some areas where we cut some roots, and are not going to get some vines. We tried to comb through as we went, rather than trying to plant something you know wasn't going to grow.
We kicked in a new method for harvesting in '98, not really new, but for this area and our size, it's relatively new. We went ahead and picked into the half-ton bins. The idea behind it is that you are processing fruit on a large scale, you aren't dealing with 25-lb baskets, you don't have to lay them out ahead of time, and you don't have to follow behind and pick them up. The half-ton bins have their advantages and disadvantages. As we are making high end Chardonnay, and we are going to whole-cluster press, we go ahead and spend the money to pick into the little baskets, you get better cooling over night, and if it needs sorting, you can do that. We lay out a six-foot table, go through the fruit on the top of the basket, pick through what we can, flip it over into another basket, and pick out the bottom, stack it back on and get ready to put it into the press. If you are dealing with grapes you are going to crush right away, a lot of the time our reds, instead of leaving them over night in the cold box, I'll go ahead and crush them, turn on the jackets, and treat them with cold that way. Especially on the cooler days, when you are getting out there and your grapes are 50°F anyway, get it done, don't stack that fruit and wait until tomorrow, get it in the fermenter and start the process. You do have these tradeoffs along the way, and you have to decide what you think is going to work better as far as quality and quantity. What's going to work for you? One of the keys is to know your costs. Know what it costs to leaf pull a row. If you have a 5-acre vineyard maybe you don't want to buy that leaf puller, maybe you should hook up with the high school kids down the road. I'm at the point where I have a good staff, and that makes a big difference for us. A five-year plan is critical. Know what you want to market, what you want to sell, what kind of wine you are going to be making if you are going to be a winery, and who you're going to be selling your grapes to in the future.
In the winery it really helps us to have a second label. We talked earlier about what kind of wines you want to make when your dealing with those $7-10 bottles of wine and it's a house blend. A lot of stuff can land in that. I don't want to give away Bob's secrets, but he has some lead way whether that Black Dog has Cabernet franc in it or some other variety. When you're working as a winery and you're making wine, you are working with some top end Viognier. You want to make it the best, but you got a barrel that doesn't fit in. What are you going to do with it? Take that barrel and put it into the lower end, and that's ok. That is going to step up that lower end and make that Viognier that much better. How does that work for quantity and quality? Well, you are making 25 less cases, but you are able to ask $2 or $3 more dollars a bottle, because that wine is at a higher level. It's nice to have outlets like that. Small wineries don't necessarily have outlets like that. As much as I love making premium wines, the wines in this area that sell are sweet and pink, or red, or fruit flavored. This is where we get a variety of wine makers and a variety of growers. To be able to cover each end a little bit is going to help you in the pocket book.
Make your quality cuts early. With all due respect to Shep Rouse (Rockbridge Vineyards) I stopped making a Pinot noir, because I couldn't make a good one, and I got really frustrated with it. So I turned my Pinot into a blush wine, and it's working out. For me to take all of that energy and effort into making the best Pinot that I could, and coming out with an ok Pinot, I was expending all of that energy that I could be putting in to some Bordeaux varieties and make a better wine. You know, if you've got a wine that's not of caliber, don't put it in the new barrels. Make that choice early on, and put it in stainless. The sooner you make those cuts, the better off you're going to be.
I had some people in the tasting room that were interested in working in the cellar, and that worked out really well. If they know something about what's going on in the cellar, they are going to be that much better when they are working behind the bar. They are going to be able to tell customers about what they did, and how those wines are made. I do the same thing with the vineyard staff. At the end of the day after picking, if I still have tanks and presses to clean, I'll move those guys from working by the box to working hourly to pick up a little extra money and help us get out of there at a decent hour. We have a unique situation because my boss believes it is important to keep good people, and I really commend him for that because I have got some of the best staff that I think anyone could wish for. The key to good labor is to treat them like that, you don't want to bend over backwards and give them the world, but one thing that we do is to go out in the vineyard to find solutions to problems. I ask them what is working and what isn't, and maybe I have some good ideas, but I get some better ideas from the staff who is actually doing the job, whether it is the guy pulling leaves, or his supervisor. This does two things, more often than not, it's going to give you the right response, but second of all, it's going to make them go up two notches in spirit and growth, because you are interested in them. These aren't people that you are bringing in for three weeks in the spring and two weeks in the fall for picking. We have our people work year-round. They go from the vineyard to picking blackberries in the summer, to digging trees in the fall. Since they live on the property, we hire their wives in the summer to leaf pull and shoot position. This works really well. The resource of ideas in the vineyard is amazing.
Jim Law, Linden Vineyards, Linden, VA
We are a varied industry, and I am going to continue from where Doug left off, and talk about what works for us. In this industry, we are looking at two different types of people, grape growers and wine growers. At Linden, we consider ourselves wine growers. So what is the difference? Grape growers see the final product as grapes. Wine growers see the final product as wine. There is a big difference, and there is no right or wrong here. There are just different ways of looking at it. A grape grower looks at maximizing production and the economics, and it is their job to get as much tonnage as they can for as little as they can. That is what farming is all about. A winegrower operates at a different level, which doesn't make any sense at all, really. It's really on blind faith that what you do in the vineyard is done because it makes a better wine. We work on that premise. At Linden, we are now four different wine growers with four different properties, Linden being the major one. We are all employees or staff of Linden Vineyards, the grapes all come to Linden Vineyards, they are made into wine at Linden Vineyards, and each vineyard has it's own vineyard designation. This is something new that we have implemented over the past few years. It gives a basis for the vineyardist to do the best job that they can.
I would like to talk about what we do to do the best job that we can in the vineyard. Pruning is not really a way of crop control for us, because we don't feel that pruning alone can do that. Pruning is a way of getting uniformity within the canopy, and to make sure that we don't have too much growth within one area, and to get growth to spread out. Uniformity is probably the most important thing we look for within the vineyard. We want to make sure that shoots are all the same length, that they are all positioned equidistant from each other, that they are all growing in the same direction, and that they all have about the same number of leaves. We feel that that is absolutely critical. We shoot thin according to the vineyard. We have found that with different varieties we need to shoot thin very differently. For example, we shoot thin Seyval very vigorously, whereas we hardly thin Riesling at all. The other varieties will be thinned according to the specific variety and the age of the vines, as well as according to the specific block. I have four acres of Chardonnay, but I have six distinct blocks. Those four acres are one block, but they are on different soil types, different vine ages, and they are on different training systems. I have a fifteen year old vineyard that was originally on a T bar system, but we have changed it over. We didn't change it over uniformly, because the block was on two different soil types. So we went to the vertical system on a thinner soil, and we went to a Lyre system on the richer soil. That has worked out fairly well. But even within the rows we have different vigor, so we manage each vine individually. Some vines have a lot more shoots than others depending on where they are within that row. One of the things that I think anyone who has grown grapes has been frustrated by is the amount of time and labor spent shoot positioning and tying. It is something that drives me crazy every summer. We use the Max tapeners still, and I have found that they are still the best tool for tying. After fifteen years, we cleaned out the shed and got all of the broken tapeners cleaned out. I thought we had about a dozen broken tapeners, well, we had 45 broken ones. So we trashed those, and I see tapeners as usable for one season. I buy them all new each year, and they usually last for that season. It's a lot of money, time and labor. But I also have been focusing on what is important for us. I am a true believer in what happens in the vineyard is much more important than what happens in the winery. I did a little bit of calculating recently. First of all, we use mostly oak barrels. I love making wine in barrels. There is just something about barrels that give an integration and a texture to wine that you can't get in any other container. But, I don't like the flavor of oak, so we are using more and more older barrels. In fact, I haven't bought any new barrels in a couple of years. If I was to continue to buy new barrels, I figured what the cost of the barrels would be per ton. That is how I am trying to think, not the cost per bottle, but translating the cost of the winery into the vineyard. If fact, to put a ton of grapes into new French oak costs $1500, and that's just the cost of the oak. Well, if I can take that $1500 and put it into the vineyard in terms of more labor and better vineyard management, to me, I'll have a much better wine than if I spent that $1500 going into French oak. In fact, I implemented this three years ago, and I have seen drastic increases in the concentration and quality of the wine without the oak flavor, because to me it was interfering with the flavor of the fruit.
There are two important factors that I have found go into the vineyard. The first is sunlight, and the second is yield. Where does the sun hit the fruit, how much sun hits the fruit, where does it hit the leaves? As each year goes on, I'm finding the more sun the better. Canopy management is major, especially shoot positioning and tying. Leaf pulling is another thing. We first started about 12 years ago, and the results were dramatic. I am at the point now where I am pulling two times a season. We pull right after shatter, about 10-14 days after bloom. I am hesitant to pull a lot of leaves, because those are healthy leaves and they are contributing back to the vine. So we do a light leaf pulling in order to get some of the sunlight into the canopies to get those berries used to the sun. I wait until later in the season when those leaves start to yellow, and you can tell they aren't very productive, but they are blocking sun and also preventing air circulation. Then we go through a second time and pull those leaves. At that time, I pull a lot, it's scary at first, but I am amazed at the difference in flavor. That is what we are looking at, not so much rot, even though rot is important, but the flavor difference between a pulled cluster and an unpulled cluster is amazing. You can taste the difference in the grapes and you can certainly taste the difference in the wine. Hedging is done on a demand basis. Every block is different, and the age of vines is enormous. Young vines need a lot more hedging than older, mature vines. According to rain fall, some years we need to hedge a lot more than others. Finally, I want to get into yields, and green harvesting is something that we have implemented more and more over the past few years. We drop a lot of fruit. We do this for a number of reasons. First of all, it's crop control. I feel that although sunlight will dictate what kind of flavors you'll get, as well as the quality of flavors, yield will determine the concentration of those flavors. I am an advocate of the higher the yields, the less the concentration of flavors you'll have in the wine. For a green harvest, we usually do it in July, before veraison for the whites. We drop fruit according to the vine capacity. Varieties like Seyval and Sauvignon blanc are left with more fruit than we would for the same aged vines of Chardonnay. We want more concentration in Chardonnay than a lighter style wine such as Sauvignon blanc. We do it on a shoot by shoot basis. Short shoots that have less than twelve leaves are stripped of all fruit. We'll leave the fruit on longer shoots depending on cluster size. One thing I have found especially with the tight cluster varieties is the longer I wait to thin, the less rot I have. If I do it earlier, the vine will make up for it by having larger berries. If I do it later, the berry size stays smaller, and the clusters stay looser. This works especially well with Seyval. With reds, we always do a green harvest during veraison, when the clusters are turning red, and we do it at about 70% veraison. We drop fruit that has more green to it and also fruit on shorter shoots. I have found that the variety this makes a huge difference on is Cabernet franc. We have gone from a vegetative aroma to a much more pure berry aroma with the Cabernet franc, because we have eliminated uneven ripening. The final issue is contracting. I have changed my contracts recently. Back in the early 1980's I was really pushing a lot for giving brix bonuses, because I felt that brix was an indication of quality. This year, I am not going to do that, because I don't feel that brix is an indication of quality. I feel that if a grower does all of these things, it doesn't matter. I have found that in some years we are having lower brix, but we have gotten tremendous quality. I don't feel that brix is an indication of quality, so why should I reward or disadvantage growers according to brix.
One last thing, my staff and growers are tasting constantly. We taste every week, except during harvest when we don't have enough time. We taste different vineyard blocks and different treatments. We are constantly running experiments, but to us, the ultimate question is how does it taste. That is something I encourage any grower/winery relationship to do.
Dr. Michael Ellis, Ohio State University
"Phomopsis cane and leaf spot, and late-summer fruit rots"
First of all, hello. I think this is the third or fourth time I've been here, and it's nice to be back. It's a real thrill to see how things are going. I enjoyed the discussion that just occurred, and one thing that kept popping up was the emphasis on quality grapes, regardless of what we do. Without quality grapes, we aren't going to have anything to work with in terms of a wine industry. We face a lot of the same problems in Ohio that you do in Virginia. Certainly we have very intense disease pressure. I know that your emphasis here is primarily on vinifera, but when you look at the disease complex we have to deal with on a year to year basis in Ohio, it's identical. So a lot of what I've done with the Ohio growers applies here, especially when you get into southern Ohio. When Tony called me up, he asked me to come over and share with you some of our results on Phomopsis research we've been doing over the last couple of years, and that's what I'd like to do this afternoon. I would like to emphasize to you that I am here for you. I am here on your dime, and if I can help anybody, or if there's any questions of any type, or even later on, if you want to give me a call, I'd be happy to talk with you about anything I've covered. My talk today is primarily on phomopsis, but I'll also talk about other late-season fruit rots.
Our research objectives are to determine the time of susceptibility of grape berries and rachis tissues to infection by phomopsis. I'll explain as I go through this, why I think this is important. But we have learned a lot about this disease and hopefully I'll be able to share some of that with you. Another objective is to determine the temperature and leaf wetness duration required for infection by phomopsis. We hope to develop a disease predictor model more or less like the Mills table (apple scab) or the black rot table for phomopsis cane and leaf spot.
Cane and leaf spot damage to the leaves and cluster stems can result in poor quality fruit. We have had two excessively wet years recently, and we have seen some tremendous damage due to phomopsis cane and leaf spot. It can weaken canes, which makes them more susceptible to winter injury and wind breakage. When you look at the leaf symptoms of phomopsis, it's not very exciting, you see these little white spots, these chlorotic spots. If you see this kind of damage in your fields, you've got a serious problem. This is where we see most of the damage occurring, on the first two-three nodes of the shoot, and also on the rachis. Our current fungicide recommendations are aimed at the early season and are directed primarily to control cane infections. The phomopsis fungus overwinters on infected canes. Spores from infected canes represent the primary inoculum for infections in the spring. To reiterate, that's the cane and leaf spot phase that can cause some serious problems. In Ohio, throughout the Northeast, and in Michigan, the fruit rot phase has also become a problem. That's one reason we have initiated our research to primarily look at fruit rot. It can cause direct losses of fruit, resulting in the greatest economic loss in Ohio two years in a row. We have had some vineyards lose up to 30% of the fruit. So this thing can get quite serious, and again, these were in the real wet years. Our current understanding of phomopsis fruit infections comes from work done on Concords in New York State. Berry infections on Concord grapes occur primarily during bloom or shortly after, with little or no berry infection occurring later in the growing season. That's really the whole key to the work I'll be presenting here. Our knowledge prior to these investigations showed that really no berry infection occurred after bloom. Early season infections remain latent in green fruit, until fruit begins to ripen near harvest. As the fruit starts to ripen, the fungus becomes active, and causes the fruit to rot.
So, based on what we knew before, most of the infections occur right during bloom, on the very young fruit, and on a very susceptible rachis. We understand that most of the infection occurs very early. There's a thing we call latent infections, and I think it's probably pretty common in some of the summer rots, but in phomopsis, it's a phenomenon. The fungus actually moves in, and this probably applies to botrytis as well, fungus actually moves into the fruit, and you've got this fruit hanging out there and it looks beautiful. Now, the infection has occurred early, but you got the fruit hanging out there, and it looks great. And all of a sudden, as the fruit starts to mature, sugars go up, we are always busy watching what changes take place, and that latent fungus becomes active. That is called a latent infection, and it's very common in plant pathology, strawberry botrytis fruit rot, is a latent infection and the more we look at a lot of diseases, the more we see that. When is the fungus moving in? That's what we focused on primarily with our research. We initiated experiments to study when grape berry and rachis tissues become infected with phomopsis.
We used intact clusters on potted vines that were inoculated at various stages of development to determine the time of berry and rachis susceptibility. This procedure seems kind of straight forward, but you know it's pretty tough to develop clusters on vines in the greenhouse, and you need to get enough to where you can do a lot of studies. I really like this technique, because I think it will help us with some other diseases as well. By growing the vines up the previous year, this is a two year process, and getting fruit buds on them, you can train the one shoot and get very nice clusters for work in greenhouse or growth chambers, and that's what we need for some of these studies. We take these clusters and inoculate them with various growth stages. I don't know if people here are familiar with the Eichorn-Lorenz growth stages, but they are various stages of development that you can use to describe vine growth. Just to give you an idea, we made inoculations very early, at E-L stage 12, basically pre-bloom, and up to E-L stage17, about 50% flowering. Young fruit set, stage 27, small berries, bunch size, according to the previous literature, by the time we got to this stage, we should be resistant. When we get to this stage, I think we probably do have some good resistance to some of the other diseases. We come up to pea size berries, beginning of berry touch, and beginning of ripening. So we actually inoculated at all of these various stages in order to determine whether the rachis and berry tissues were susceptible at each of those stages. Inoculations were done, spraying with the fungus, we put them in the moist chamber and we put them in the greenhouse. This is a moist chamber with the inoculated plants. But these are the types of symptoms that we would get from inoculating with phomopsis. You can see the rachis damage. Generally, you won't see symptoms, you'll see rachis symptoms show up pretty early, but we do get latent infections. No matter when you inoculate you don't see fruit rots show up until the berries start to ripen. This is one of the clusters (Seyval) that has been inoculated, you can see as the berries start to ripen, we get fruit rot.
Our results showed that, contrary to what we had thought, berries and rachis are susceptible to phomopsis infection throughout the growing season. Susceptibility actually increases throughout the season. I think that one thing that really saves us, with this disease, is that a lot of the inoculum in a real wet spring, is deposited and gotten rid of before these highly susceptible periods occur. We took these studies into the field, this happens to be on Catawba. We're probably going to do some on Seyval, for validation work, but I had a nice Catawba vineyard established that we could use. We actually went in at all of these different growth stages, tagged these clusters, and inoculated. The reason we used this vineyard is because I had this overhead mist system, so I could induce these wetness periods to increase the chances of having a good infection. We saw about the same results. I would like to emphasize here that again, this is a control, so these are not inoculated. We had a level of almost 23% of natural fruit infection out in that vineyard. This was following those two years where we had pretty bad disease. This is a lot more prominent than we had previously thought. We see the same type of results in the field for rachis and berry infection.
The bottom line is that berry and rachis infection from phomopsis, particularly in Seyval, Catawba, and Chambourcin grapevines, can occur throughout the growing season, with an apparent increase in susceptibility from bloom through berry touch. In order to obtain more effective control of berry and rachis infections, we may need to improve the timing for control of phomopsis, not only during bloom, and shortly after bloom, but also at later stages of berry development. I think we do a good job of controlling this, just because we have a very intensive spray program for the rest of our disease complex. I do want to make some practical comments on control. We don't have a lot of fungicides that are currently registered. Out of all the chemistry we currently have, mancozeb and captan are the two best fungicides available for phomopsis control. Strobilurins (e.g., Abound) are registered for phomopsis control, but they aren't that effective. Ferbam and Zyram really aren't that effective either. Benlate is very effective for phomopsis, but it is a pretty expensive spray. The sterol inhibitors (e.g., Nova) are very ineffective against phomopsis. As a matter of fact, we sprayed Nova in the field trials to prevent black rot, so it wouldn't effect our phomopsis trials. Mancozeb has always been the backbone of the early season spray program on wine grapes in Ohio.
Botrytis and summer rots: Tony also wanted me to talk about summer rots, and I have a feeling that the late summer rots we experience in Southern Ohio are not very different from what you experience here in Virginia. Of course, our main threat is botrytis. Make sure that when you see some rots, and the berries start to deteriorate, you involve your pathologist, to make sure it is phomopsis, or Botrytis, and not bitter rot. Botrytis bunch rot is probably, in terms of fruit rots, the cause of a lot of fungicide sprays. I just wanted to give a quick fungicide update, and I am sure those of you who are producers are already aware of these newer products. Vangard was introduced two years ago, and these are new fungicides that are very effective for botrytis bunch rot control. Elevate was registered last year. I think it is very opportune. It's very important that we are getting some of this new fungicide chemistry. I just want to make a couple of comments on resistance. I'll tell you these new fungicides couldn't have come at a better time. I'll go over a few more things tomorrow, when I get into the strobilurins. Vangard has a use rate of 10 oz. per acre used alone, or 5 to 10 oz. per acre when it is used in a tank mix. No more than 20 oz/acre can be used a season, and believe me, as expensive as it is, you're not going to want to use it more than 2 times. I don't overlook or ignore the costs of these chemicals. There is a seven-day PHI for Vangard. Elevate was registered in 1999 and we don't really have any experience with it yet. The use rate is one pound/per acre, and no more than three pounds a season can be sprayed. It has a 0-day PHI. So, when we look at what we have for botrytis materials currently, the most active are Rovral, Vangard, Rovral+Vangard (1/2 rates), and Elevate. One thing we are going to face with all of these fungicides is resistance. If you've been using Rovral two or three times a season for several years, it's still effective, but it's probably not as effective as when you first started using that chemical. Benlate is pretty much gone. I still know a lot of growers that use it for botrytis, and that's probably because it's one of the cheapest things they can get their hands on. I mentioned the combination of Rovral and Vangard, with half rates of each, and we have seen some good results from New York. Elevate is not as effective as Vangard. It's important that we have it though in order to rotate materials. Wayne Wilcox, my good friend and counterpart at New York, Geneva Station conducted fungicide trials that indicated Abound had at least fair activity against botrytis bunch rot. Now that's interesting. This slide summarizes a trial done in 1998, a very wet year. Vangard at 10 oz had 90% control, at 5 oz it only had 67% control. So, if you cut the rate, you cut the effectiveness. Vangard at a half rate plus a pound of Rovral had 97% control. That looks good, and it may be something for you to consider. The cost is there, but actually when you make that combination, it's not much more expensive than Vangard at 10 oz. Rovral, with two sprays at a pound and a half, with the last two sprays at two pounds, had really good control. Rovral is a good material, but look at Abound. We have 68% control using Abound, and that's not too bad. If we can use Abound in a comprehensive disease management program, aimed primarily at other diseases, and pick up some botrytis activity, that's even better. Fungicide timing for sprays for botrytis on grapes: Folks, I don't think we have this down nearly as well as we should. We make recommendations based on previous research, but people in NY, and myself, have concluded that we don't have the timings down as we should. First of all, the first sprays, recommended on the label, and basically if you want the Cadillac spray for a Cadillac crop bringing in 5,000 a ton, with tight clusters and a botrytis problem, you spray all four of these sprays. But when you look at the cost of this, and I don't know a grower that doesn't, it's not a possibility. Generally, it's mid to 90% bloom period. When you look at botrytis and bloom, botrytis is very important as far as bloom infection and latent infection on strawberries and other crops. In theory, this bloom spray should be very important, but most growers don't make a bloom spray. I would like to point out that Wayne Wilcox has a Ph.D. student and they are going to be taking a look at this, and I am hopeful that they generate some information that is going to help us. The next spray, would be prior to bunch closing. Then, the beginning of ripening (veraison), and then two weeks later, or prior to harvest, as needed. If you have a late ripening variety, like Riesling, you're taking a long time between veraison and harvest. These are the sprays in Ohio, we recommend coming in right before veraison, and then playing it by ear. If you get real wet weather and start to see rot, you come in with a second spray. Very few growers spray more than twice. But if you are talking about some of the vinifera varieties, it may be more important. These are the sprays, I really don't have a more solid recommendation other than what we currently have, but again, the Cadillac spray program would be to spray all of these. I would say that the strobilurins are going to be very important for the period of immediate pre-bloom to immediate post bloom, for a couple of reasons. First, we are going to lose the sterol inhibitors completely if we don't get some new chemistry. So, if we can have some Abound in there around bloom, taking care of the rest of your disease complex, and picking up some added benefits against botrytis, it makes good sense to me, and it's not adding anything to the cost of the spray program.
Fungicide resistance development: All of these materials are very prone to fungicide resistance development. They have a very narrow spectrum of activity, and unfortunately, most of the new chemistry we see coming out does. If you spray Vangard every time, you're going to have resistance, and the same with Rovral: if you spray 4 times a season, you increase your chances of resistance.
Canopy management: Tony has done some good work here, and it's been done all over the world. If you have a tight-clustered variety, and a botrytis problem, you need to open that canopy. Leaf removal is paramount. Leaf removal won't take care of all of your problems, but it will certainly help. Cultural practices will make a fungicide program better. Some interesting research in NY is being conducted on the effects of early season diffuse or non-visible berry infections by powdery mildew. When you look at certain berries, you can't see the mycelium covering the berry. Effects of diffuse or non-visible powdery mildew infections on berries are not yet clear; however, they may affect the development of other diseases such as Botrytis bunch rot and sour rot.
Bitter Rot, Ripe Rot, and Macrophoma Rot: There has not been a lot of research on these complexes, but if you have a serious problem with one of these, someone really needs to take a close look at the strobilurins because they have a very broad spectrum of activity. Some applications of Abound, Sovran, or Flint in the late-season may be helpful.
Question: You pointed out that Benlate has some efficacy on phomopsis and some efficacy on powdery mildew. Would you put a Benlate spray on early in a section where you have seen hot spots by phomopsis in the previous year?
Answer: Primarily, because of cost, I would say no. I think if you do a good job with Mancozeb, and if you have good coverage at that time of year, you are going to do a decent job against phomopsis. Benlate is out for powdery mildew in my book; you are just wasting your money. It's interesting because this emphasizes the significance of fungicide resistance development. When Benlate was first introduced, it was unbelievable. It controlled powdery mildew like Bayleton did when it was first introduced. But we used it so extensively that powdery mildew has developed resistance to it.
Question: I had a beautiful crop of Pinot in 1997, but I did get some powdery mildew infection, and I stopped it. I thought I was over the hump, but you could see scarring on the grapes. We had two back to back days of heavy rain a week before I had planned to harvest. I sprayed with Rovral with a pistol, and I only got the outside of the clusters. The back side of every cluster had ripe rot. I was convinced that it was the scarring that allowed the Botrytis in.
Answer: I am sure ripe rot is a serious problem down here. But when you spray Rovral for ripe rot, you are wasting your money. Ripe rot causes the cluster to begin fermenting. It is not the same as botrytis. There has been a lot of money wasted, spraying Rovral on ripe rot. I am interested in that association, and it may be something we should take a closer look at in the future. But ripe rot is a terrible thing when it shows up, and all you can do is pick as fast as you can. That is why I was excited to see that there is an association between the powdery mildew and scarring. We can really put more emphasis on powdery mildew control early in the growing season.
Question: Have you ever measured the effectiveness of dormant sprays?
Answer: Dormant sprays in theory are great, and yes, I have been interested in those for powdery mildew. Powdery mildew overwinters on the bark surface almost exclusively. There was some work done in NY that showed if you used lime sulfur, you could see some positive results. But the rates were 300 gallons of water an acre and 30 gallons of lime sulfur per acre. I can't recommend it until there is more research. The only time I recommend lime sulfur is for anthracnose control.
Question: Are you wasting your money on late-season botrytis control?
Answer: At times I really wonder, especially if you have a tight-clustered variety that is breaking inside. I am not going to stand up here and say no, it's not worthwhile to spray, but I have serious doubts of what the spray is going to do for you in terms of having a beautiful crop. I think the emphasis should be during veraison. If you should see it show, I might spray one more time, but I can't guarantee that the later spray will help. I think that there are some other rots, like sour rot, that are showing up that these sprays don't control. I have been concerned with these late season sprays to control botrytis. But I am not going to say don't use them until I have some concrete data.
*These talks are only a portion of the Williamsburg Meeting transcripts. The balance of the talks will appear in the May-June Viticulture Notes. Thanks to Alison Hectus for tediously transcribing talks.
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Virginia Cooperative Extension Vineyard Meetings:
12 April 2000
Madison, VA, Quaker Run Farm, Tom and Debbie Flynn
Speaker: Dr. Jeffrey Derr, Weed Specialist, Weed Control Strategies and Products
Directions from Madison: Take Rt. 231N to Banco, VA. In Banco, take a left on Rt. 670 to Criglersville, VA. Just beyond Criglersville take a left on Rt. 649 and bear right on Rt. 672. Go approx. 2.5 miles and the farm is on the right.
24 May 2000
Sperryville, VA, Sharp Rock Vineyard, David and Marilyn Armor
Speaker: Dr. Tony Wolf, Viticulturist, Current Situation Topics and Management Strategies
Directions: From Sperryville, take Rt 231S 8 miles to Rt. 601, take a right on Rt. 601 and go approximately 1 mile to the farm on the right. From Madison, take Rt. 231N for 12 miles, and turn left on Rt. 601 and follow above directions.
14 June 2000
Gordonsville, VA, Horton Vineyard, Dennis and Sharon Horton
Speaker: Dr. Doug Pfeiffer, Entomologist, Insect Problems and Controls
Directions: From Ruckersville, take Rt. 33 east approximately 8 miles, the winery is on the left.
These are informal meetings from 11:00 am 12:45 pm. A tour of the vineyard will be followed by a lunch discussion with the noted speaker. Refreshments will be provided, please bring a bag lunch. Questions can be directed to:
Kenner Love, Rappahannock County Extension Agent
(540) 675-3619, firstname.lastname@example.org
Brad Jarvis, Madison County Extension Agent
(540) 948-6881, email@example.com
"Viticulture Notes" is a bi-monthly newsletter issued by Dr. Tony K. Wolf, Viticulture Extension Specialist with Virginia Tech's Alson H. Smith, Agricultural Research and Extension Center in Winchester, Virginia. If you would like to receive "Viticulture Notes" as well as Dr. Bruce Zoecklein's "Vinter's Corner" by mail, contact Dr. Wolf at:
Dr. Tony K. Wolf
AHS Agricultural Research and Extension Center
595 Laurel Grove Road
Winchester, VA 22602
or e-mail: firstname.lastname@example.org
Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension, Virginia Tech, and Virginia State University do not endorse these products and do not intend discrimination against other products that also may be suitable.
Visit Virginia Cooperative Extension.
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