Bare-Root Vines Timing Nursery Stock & Standards More Info
Eric Stafne, Mississippi State University
This article will answer the following basic questions:
- How do I plant a grape vine?
- What is the best time of year to plant grapes?
- When should I plant grape vines?
- What kind of plant material should I buy?
- Planting Method for Bare-Root Vines
- Nursery Stock and Standards
- Recommended Resources
- Planting Grape Vines
- In This Series
- Grapevine Fertilizer: When And How To Fertilize Grapes
- Fertilizing Grapevines Prior to Planting
- When to Feed Grapevines
- How to Fertilize Grapes
- Care & Harvesting of Grapes
- The Grape Vine
- IN WINTER
- Learn About Grapes
- The Best Fertilizer for Grapes
- A Range of Benefits
- Growing Grapes in Your Backyard
Planting Method for Bare-Root Vines
- Be sure to keep vines moist right up to planting.
- Dig a small hole with a hand-held or tractor-mounted post digger about 6 inches in diameter, 4 inches to 6 inches deep. In soils with high clay content, glazing of the sides of the hole may occur, which can impede root growth. In this situation, break up the glazed areas using a shovel or equivalent tool.
- Immediately prior to planting, trim the roots to fit the hole and cut the top growth back to only two to three buds (above the graft union on grafted vines) on the strongest cane. Remove all other canes.
- Stand the plant in the hole and pack the same soil back into the hole around the plant. If you are using grafted vines, make sure the graft union is above the soil line by approximately 6 inches.
- Install a stake next to the vine to provide stability.
- Water the vine with two or three gallons of water immediately after planting.
- As new shoots begin to grow, watch for signs of pest damage that may inhibit vigorous growth.
- Do not allow weeds to grow near the vine row, and keep the young vines well watered. The amount and frequency of irrigation will vary depending on region and environmental conditions.
Green growing (potted) vines should be acclimated to seasonal weather conditions in a protected area for a few days prior to planting. Do not plant potted vines until after the risk of frost has passed in the spring. Be sure to remove the vine from pots before planting. If you are using grow tubes, install them after planting, lightly covering the base with soil to exclude herbicide sprays. Do not bury them too deep into the soil as root constriction may occur.
In most of the U.S., the best time to plant grape vines is very late winter or early spring, if irrigation is available.
To ensure the highest quality vines and a specific cultivar or rootstock, order vines from a reputable nursery in the summer or early fall prior to planting in spring. If you wait until January or February to order, you could have problems with plant availability and/or quality . For example, you will probably miss out on the best rooted cuttings (often termed #1), and poor quality vines can be too weak to survive. The nursery should ship the vines at or near your desired timeframe around planting.
Once delivered, vines should be planted immediately, if possible, and not stored. Storage of dormant vines leads to desiccation of the roots and buds. This will prohibit the vine from growing optimally and may lead to death.
If vines are received before the site is ready for planting (e.g., soil preparation, irrigation set up or trellis construction has not been completed), unpack the vines and cover them with soil in the shade until planting. This is known as “heeling-in.” Vines will remain healthy in the heel bed for up to four months. Do not store vines in water or a refrigerator for long periods of time. Water the heel bed periodically to keep the roots moist but not wet. Never allow the roots to dry out, as this will lead to poor growth or vine death.
Nursery Stock and Standards
Most grapevines are sold as dormant rooted cuttings and are either grafted or own-rooted. Rooted cuttings are graded by nursery industry standards. Becoming familiar with these standards is important to help you make decisions on plant material and can make the difference between success and failure of a new vineyard. For further information see Quality Guidelines for Grapevine Nursery Stock.
A 2-year-old #1 vine is more vigorous and will transplant with better success and become productive quicker than a #2 vine. A #1 rooted cutting is produced in a phylloxera-free nursery and certified as virus tested. Although certified virus-tested vines are initially more expensive, they are cheaper in the long run as this avoids problems with lower production and poor plant health associated with virus-infected vines. Remember, virus-tested vines from the nursery may not stay that way in the vineyard if efficient vectors are present, and virus-tested vines are not guaranteed to be completely virus free. Virus-infected vines can never be cured. Virus-tested cuttings should be ordered as far in advance as possible (up to one year prior to planting) to ensure availability of planting stock. Vineyard establishment from non-rooted cuttings is a gamble and you should consider success from them as atypical. This method, although less expensive initially, often leads to slower growing vines that do not come into bearing as quickly as purchased vines. You can also inadvertently introduce diseases and viruses into the vineyard by taking cuttings from another vineyard. All new vines should be free of viruses, insects, and disease.
Tips on Growing Grapes, University of Minnesota
Planting Grapes, Iowa State University
Growing Grapes, Ohio State University
Ordering Grapevine Cuttings and Plants from Nurseries
Quality Guidelines for Grapevine Nursery Stock
Common Miscommunication Problems between Grape Growers and Nursery Plant Suppliers
Reviewed by Patty Skinkis, Oregon State University
and Keith Striegler, University of Missouri
Planting Grape Vines
Few things are as delicious as homegrown grapes, and the success of your harvest begins right with the planting site and method. For maximum growth and yields later on, give your plants the best foundation possible.
NOTE: This is part 4 in a series of 11 articles. For a complete background on how to grow grape vines, we recommend starting from the beginning.
Before you plant, check your soil pH. This can be done by contacting your local County Extension Office for information about soil testing in your area, or purchase one of our digital meters for quick and accurate results. Ideally, your grapes need a soil pH between 5.5-6.5. Steer clear of soils that are extremely heavy or very poorly drained. Grape vines will grow in a wide range of soil but they must have good drainage.
- Grapes need full sun, 6 to 8 hours a day.
- They grow in rows, to be trained to a trellis and are spaced according to the type of grape. The less vigorous table types and the more vigorous wine varieties should be planted 6-8’ apart. Muscadine grapes should be planted 12-15’ apart.
- All of the table and wine-type grapes are self-fruitful; but when you plant different grape varieties close together, they’re apt to cross-pollinate each other. Under certain environmental conditions, some seedless grapes may produce a few small, edible seeds or seed remnants. It’s believed closeness of seedy grape varieties influences the situation. When pollen from a seedy grapevine pollinates the seedless variety, a seed or seed remnant may develop. Keep this in mind as you choose your planting sites.
- Two Muscadine varieties should be planted to provide pollination. It’s also important to note that non-Muscadine grapes will not pollinate Muscadine grapes.
- Dig a hole big enough to give roots plenty of “elbow room.”
- Plant slightly deeper than the soil line.
- Fill hole about three-quarters full, then soak well with a solution of Stark® Tre-Pep® Fertilizer. (If planting in the fall, wait to fertilize until spring for best results.)
- Finish filling the hole.
- Prune your new vine heavily, leaving only two to three buds on its strongest stem. (As it grows, you’ll keep only the most vigorous sprout to form the main stem.)
- Train to stake during first summer, pinching back all side shoots to two leaves each.
- Shallow cultivation during the early growing months and summer mulching do wonders for your grapevines.
- Your grape vines should live about 20 years with proper maintenance.
- Suggested number of plants for a family of 5: 8-12 (3 vines per person).
In This Series
- Soil Preparation
Care & Maintenance
- Pest & Disease Control
Grapevine Fertilizer: When And How To Fertilize Grapes
Most types of grapes are hardy in USDA growing zones 6-9 and make an attractive, edible addition to the garden with minimal care. To get your grapes off with their best chance for success, it’s advisable to do a soil test. The results of your soil test will tell you if you should be fertilizing your grapevines. If so, read on to find out when to feed grapevines and how to fertilize grapes.
Fertilizing Grapevines Prior to Planting
If you are still in the planning stages with regards to grapevines, now is the time to amend the soil. Use a home testing kit to determine the makeup of your soil. Generally, but dependent upon the grape variety, you want a soil pH of 5.5 to 7.0 for optimal growth. To raise a soil pH, add dolomitic limestone; to lower a pH, amend with sulfur following the manufacturer’s instructions.
- If the results of your test show the soil pH is fine but magnesium is lacking, add 1 pound of Epsom salts for each 100 square feet.
- Should you find your soil is lacking in phosphorus, apply triple phosphate (0-45-0) in the amount of ½ pound, superphosphate (0-20-0) at the rate of ¼ pound or bone meal (1-11-1) in the amount of 2 ¼ pounds (6 ¾ cups) per 100 square feet.
- Lastly, if the soil is low in potassium, add ¾ pound of potassium sulfate or 10 pounds of greensand.
When to Feed Grapevines
Grapes are deep rooted and, as such, require little additional grapevine fertilizer. Unless your soil is extremely poor, err on the side of caution and amend as little as possible. For all soils, fertilize lightly the second year of growth.
How much plant food should I use for grapes? Apply no more than ¼ pound of 10-10-10 fertilizer in a circle around the plant, 4 feet away from each vine. In successive years, apply 1 pound about 8 feet from the base if the plants appear to lack vigor.
Apply plant food for grapes just when the buds begin to emerge in the spring. Fertilizing too late in the season can cause overly extensive growth, which may leave the plants vulnerable to winter injury.
How to Fertilize Grapes
Grapevines, like almost every other plant, need nitrogen, especially in the spring to jump start rapid growth. That said, if you prefer to use manure to feed your vines, apply it in January or February. Apply 5-10 pounds of poultry or rabbit manure, or 5-20 pounds of steer or cow manure per vine.
Other nitrogen-rich grapevine fertilizers (such as urea, ammonium nitrate and ammonium sulfate) should be applied after the vine has blossomed or when grapes are about ¼ inch across. Apply ½ pound of ammonium sulfate, 3/8 pound ammonium nitrate or ¼ pound of urea per vine.
Zinc is also beneficial to grapevines. It aids in many plant functions and a deficiency can lead to stunted shoots and leaves, resulting in a reduced yield. Apply zinc in the spring a week before the vines bloom or when they are in full bloom. Apply a spray with a concentration of 0.1 pounds per gallon to the vines foliage. You may also brush a zinc solution on fresh pruning cuts after you prune your grapes in the early winter.
Decreased shoot growth, chlorosis (yellowing) and summer burn usually mean a potassium deficiency. Apply potassium fertilizer during the spring or early summer when the vines are just beginning to produce grapes. Use 3 pounds of potassium sulfate per vine for mild deficiencies or up to 6 pounds per vine for severe cases.
Care & Harvesting of Grapes
Grapes should be pruned yearly because fruits only form on buds that arise from the previous season’s growth. There are various methods of training grapevines. Your preferences, space limitations, and the variety of grape you are growing will determine your trellis system. Prune vines when they are dormant; in most of the country, that means very early spring, before any green shoots appear. Muscadines in the Deep South can be pruned any time after the first fall frost.
Unless your soil is very poor, grapes, which are very deeply rooted, don’t require much fertilization. Where fertility is low, a soil test will determine whether you should add phosphorus or potassium. For all soils, fertilize lightly the second year. Apply no more than 1/4 pound of 10-10-10 fertilizer in a circle up to 4 feet away from each vine. In following years when the vines are established, apply about a pound up to 8 feet away from the base if growth was slow or foliage color poor the previous season. Apply it only when the buds start to swell in the spring; later fertilizing may cause extensive growth in late summer, making the plant more vulnerable to winter injury.
While grapevines can survive some neglect, they need regular attention to reach maximum yields:
1) Prune carefully. Leaving too much growth causes far more problems than overpruning.
2) Cultivate shallowly around the base of your plant while it’s young to avoid damaging roots near the surface.
3) Fertilize lightly. Unless the soil is particularly poor, grapevines need little feeding. Grape growers encounter a few common problems. For example, if you plant a seedless variety, you may find that your grapes are smaller than those in supermarkets. Grape seeds produce a plant hormone that causes the berries to increase in size. Seedless varieties are missing this hormone and thus produce smaller grapes. If you want larger grapes, keep more buds at pruning and thin out one cluster of every three just before spring bloom. If your grapes are of mature size but fail to ripen on the vine in the (all, the leaves may be shading the grapes, which inhibits ripening. Try pinching foliage-bearing side shoots back to one leaf, which will bring more sunlight and warmth to the clusters.
Your first planting of grapes may escape insect or disease attacks for a while, but eventually some trouble usually arrives. In humid areas, mildew diseases can be a problem; European grapes are very susceptible to downy mildew, for example. Black rot, caused by a fungus, develops in warm, moist climates of Eastern states. Anthracnose, another fungus disease, flourishes in wet spring weather. Japanese beetles, aphids, and mites are common garden insects that you may find. The grape berry moth is a pest in central and eastern regions. Larvae of the moth feed on buds, blossoms, and berries, tying berries together with silken threads as they feed. Two generations usually occur. Clean up grape leaves in the fall to reduce the number of overwintering pests. The following spring, cultivate around plants to turn up overwintered pupae. The grape phylloxera is a pest common in California, where it attacks roots by sucking juices from them and creating galls, and in the East, where it attacks leaves as well as roots. Galls about the size of peas form on leaf undersides. American varieties are resistant, but other types are not. No chemical controls exist; if you have a severe problem, grow American types or European varieties with resistant American rootstocks.
Grapes do not ripen off the vine, so pick them when they are completely ripe. Use a sharp knife or small pruner to cut the bunches. Bees and wasps may occasionally light on the grapes to feast on some sweet juice, so watch for them.
The Grape Vine
Find the sunniest possible position for your new vine – a south facing site is preferable to catch maximum ripening sun. Vines will thrive in most soils but avoid planting in a frost pocket and choose a well-drained site to avoid water logging the roots. Grape vines will also grow happily in a large container in a sunny spot on the patio or in a greenhouse or unheated conservatory. Ensure the pot has adequate drainage holes and throw some gravel or crocks in the bottom. We recommend using a terracotta, rather than plastic, container and using John Innes No. 3 compost.
Grape vines may be planted at any time of year as long as the ground isn’t frozen. Dig a hole twice the size of the root-ball, spreading the roots gently as you refill the hole to the base of the stem. Press the soil down with the heel of a boot. Young growth will be vigorous but brittle so ensure that adequate support is provided, they are happy to clamber over a trellis or pergola or can be trained along wires secured with sturdy posts.
Allow unrestricted growth for the first summer, and in January prune away everything except for one long shoot growing from the main stem. Bunches of grapes will grow on new shoots from this year-old stalk.
Removing all flowers for the first two years after planting will encourage stronger stem growth. You can then allow three bunches of grapes to grow on three-year-old vines and about five bunches the following year. After this time you can allow the vine to crop freely, simply removing any overcrowded or damaged fruits. In September it’s sensible to begin to remove leaves to allow air to circulate and expose the stems to sunlight. Any awkward, damaged or unproductive stems should be removed during the winter.
Water deeply and regularly in spring (if the weather is dry) and throughout summer whilst the grapes swell and ripen but do not water erratically as this may cause the fruit to split. Container grown plants will require more careful watering and can rapidly parch in hot weather, especially in terracotta pots.
They may also more easily become waterlogged so should stand on pot feet to allow water to drain away. All vines should be watered more sparingly throughout winter.
Grape vines are hungry and will benefit from a regular feed every four weeks throughout the growing season with either blood, fish and bone or liquid seaweed fertiliser. In spring your vine will appreciate a mulch with a layer of woodchips to suppress weeds.
This mulch will be beneficial throughout the summer to keep the soil cool and help it to retain moisture.
During winter the vine will be dormant and leafless and you will see that the top is covered in wax, this is there to protect the graft so should not be removed and it will come away naturally as the vine grows.
The vine may arrive ‘root wrapped.’ We have carefully rolled the root ball in damp moss, wrapped it in plastic to retain the moisture and placed it into an attractive hessian bag. A root wrapped plant should be kept outside or in a cool, sheltered place such as a shed.
Kept indoors they will become confused and begin to bud early, which will damage the young plant. When the final frosts have passed , the moss and plastic wrapping may then be removed before planting.
Vines are hardy but may require some winter protection for the first few years. In heavy snow or particularly severe winter weather even established vines may be damaged but are easily protected with a wrap of hessian or fleece.
COURTESY When planting grapevines, the soil should be amended, and the soil surface should be covered with an organic mulch, such as wood chips.COURTESY Most tulip varieties bloom in four weeks if the temperature is kept constant at 60 F.
Q: I am putting in 30 more wine grapevines. I was thinking of using chat, crushed rock, for mulch rather than wood chips. What do you think?
A: The idea of using rock mulch, rather than wood chips, addresses a controversy among wine grape growers. Some growers of high-quality wine grapes believe that wine grapes must “struggle” to produce a good quality wine grape. They believe the best wine grapes come from poor soils and a limited water supply.
The hot desert, with nighttime temperatures around 90 F or hotter during harvest time, is thought to produce a poor quality wine grape. It is believed that nighttime temperatures should be cooler than this during harvest. Few people believe that a good quality wine grape can come from this type of environment.
Some of these same producers believe that soils for wine grapes should not be full of nutrients. Adding compost or soil amendments that improve the soil, they believe, produces a grape without intense flavor typical to the variety, a poorer quality grape.
The verdict is still out, but I believe that wine grapes struggle enough in our climate and soils without additional stress from poor soils and a lack of water. I have seen wine grapes grown in backyards in our climate without soil amendments. The soils around the home, in these cases, was “fill dirt” specified by the contractor. In most cases, these did poorly.
I have seen wine grapes grown in our climate in native soil, with no organic surface mulch such as wood chips. These did much better. I might point out that in cases like these the soil was a good agricultural desert soil, not “fill dirt.”
I have concerns about growing wine grapes in home landscapes if the home is surrounded with fill dirt. I believe this soil should be amended at the time of planting, and the soil surface should be covered with an organic mulch, such as wood chips. I am concerned that applying rock mulch, like chat, to its surface will lead to future problems for wine grapes and many other landscape plants sensitive to poor soils and not intended for our climate.
Q: When should I put tulip bulbs in the fridge so that they bloom on Easter or a few days earlier. Can you please help me? I want a nice table centerpiece.
A: Getting tulips to bloom precisely at Easter is difficult for a homeowner because they frequently do not have enough information about the tulip or a precision growing environment.
Commercial growers using greenhouses get plants to bloom precisely on a specific date by selecting known varieties and growing them at precise temperatures. Some plants, such as mums and Christmas cactus, require controlling the length of darkness or the application of growth regulating chemicals at specific times.
Tulips are a little easier. Most tulip varieties bloom in four weeks if the temperature is kept constant at 60 F. Plants grow faster or slower depending on temperatures. Plants grow faster in warm weather and slower in colder temperatures. If tulips are grown 10 degrees warmer, 70 F, subtract a week. If grown 10 degrees cooler, 50 F, add a week.
A few varieties might take five to six weeks to bloom at 60 F. For precision blooming, it’s best to know the variety of tulip being grown and how many weeks it takes to bloom.
Some flowering plants require cold temperatures to bloom. We oftentimes have enough outside cold temperatures for tulips during winters in the Las Vegas Valley if they are planted on the north side of a building and in the shade. But it depends on the variety.
To vernalize tulips (subjecting the bulbs to cold temperatures so they produce flowers) the bulbs are placed in a refrigerator 12 to 14 weeks. They will grow a little bit, slowly, at this temperature. Some varieties of tulip require fewer than 12 to 14 weeks. Some tulip bulbs are available pre-chilled.
Here is how I would do yours. Stick the bulbs in the refrigerator, upright, in slightly moist potting soil for 14 weeks. At the end of 14 weeks, put them at room temperature five weeks before you want them to bloom.
If they are growing too fast, grow them colder; put them outside in the shade on the north side of the house to slow them down. When they are back on track, bring them back indoors. Water them when needed, but don’t keep the bulb wet.
The bulb can’t be dry, either. It can lose roots that way. Use a soil moisture meter to judge when to add water. Fertilize lightly once a month with a water-soluble fertilizer during warm temperatures.
Q: Have you done any experiments with gamma rays and X-rays applied to seeds attempting to mutate them into something different? I’m totally curious if this is at all done or just a neat idea.
A: Giving seeds some sort of radiation to mutate them into something better is a little bit like taking a Hyundai and smashing it into a brick wall hoping to get a Mercedes. This kind of research was tried by scientists not that long ago without much success. The mutations were all over the place.
Manipulation of a plant is focused on its DNA, or genes. When radiation is given to seeds, we do not know which part of the DNA, if any, is changed until they are grown. Just like the Hyundai example, the results can be highly variable.
Genetic engineering, on the other hand, is precise. If genetic engineering is successful, scientists must precisely understand the genetic information inside the plant.
Specifically, they must know exactly which gene controls which plant function. Genetic engineering changes a specific gene which in turn causes a plant to change, hopefully, in a predicted way.
This new, or changed, gene provides the plant with different guidance than before. When new genes are spliced into existing DNA, the plant responds differently according to which gene was changed. The result is a mutation, but scientists have a much more accurate guess as to how this new plant will act. Genetic engineering causes the “Hyundai” to become something different, maybe a pickup truck. This newer form of the same plant, scientists hope, will be an improved version of the old one.
People who are skeptical of this type of science, cautious or opposed to genetic engineering, are concerned this new plant might be something dangerous to human health, dangerous to other plants, to our environment or cause a result scientists have not anticipated.
Q: I cut down a mesquite tree I thought might lift my walkway leading to my residence. I was worried about waterlines and roots. Will the roots die or will they continue to grow?
A: If the mesquite tree was cut down so that its crown was removed (the part of the trunk at the soil surface and a little bit below), the roots should die. There are some trees which grow from the roots after they have been cut down, but most mesquite trees do not.
Roots of most mesquite trees do not sucker and continue to live after the tree was cut down. If you see no new growth from the roots after the tree was cut down, then the entire tree is dead and the roots will decompose in the soil.
If a short stump remains after the tree was cut down, consider taking a 1-inch wood bit and an electric drill and drill vertical holes as deep as you can in the remaining stump. Drill them within an inch of the outside bark. Drill as many as you can but put them no further than 1 inch apart.
It is not necessary to drill vertical holes in the center of the trunk because that wood is already dead. The only living part of the trunk is close to the bark.
Pour salt down these holes or copper sulfate to kill the crown or use diluted weedkiller if the label permits it. Some do, and some don’t. Read the label and it will tell you what the dilution should be, but it is usually the same dilution that is recommended for weed control.
Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to [email protected]
Rick Dunst, Viticulturist, Double A Vineyards, Inc.
Over the years (25 and counting!), Double A Vineyards has built a large clientele with varied interests that range from commercial vineyard and winery owners to the backyard hobbyist. This article is aimed at the latter, especially our customers who decide they want to grow grapes or grapevines in their backyard, but who may or may not know what to expect. We hear almost daily from new growers: “I didn’t know what I was getting myself into.” Rest assured, even those of us who have chosen grape growing, winemaking, and perhaps even the grapevine nursery business, ask ourselves some variation of this question on a regular basis.
WHY DO YOU WANT TO GROW GRAPES?
There are a lot of answers to this question. The most common are “home winemaking,” “growing grapes to eat,” “shade from an arbor,” and my favorite, “I thought it would be cool.” These are all legitimate reasons to grow grapes, and they all require a basic understanding of what it takes to grow a grapevine to fruition (pun definitely intended).
WHAT DO GRAPEVINES NEED?
Everyone knows that plants need sun, water, and nutrients to grow, and this is true of grapevines. But grapevines also need good air movement and soil drainage to be grown successfully. Why is this? Although grapevines vary widely in their susceptibility to disease, every variety of grape is susceptible to one or (typically) more diseases or insects that can attack the leaves, fruit, and (sometimes) roots. While some intervention, typically in the form of pesticide application, is necessary to grow healthy leaves and fruit, grapevine access to sun, water, nutrients, good air movement, and soil drainage should be primary considerations when deciding where you should locate your vineyard.
SELECTING A LOCATION TO GROW GRAPES
This section could easily be titled, “Where should I plant my vines?” Or even better, “Where SHOULDN’T I plant my vines?” You should plant your vines in an open location that receives as much direct sunlight as possible, with good airflow, and which rarely (if ever) has standing water. Planting along a chain-link or similar type of fence on the perimeter of your property is OK as long as it is not shaded by trees. Planting along a solid wood fence is less desirable since air flow will be impeded and the vines will be in the shade for at least part of the day. Planting next to the house is usually a mistake since the vines will be growing in at least partial shade. Additionally, airflow will be impeded and soil may be saturated for several days, especially if located near gutter downspouts.
Grape varieties differ substantially in their susceptibility to diseases and insects, and grape growers differ in their willingness to apply measures (especially pesticides) to control them. Backyard growers should select varieties that are winter hardy at their location and are less susceptible to diseases such as black rot, powdery mildew, downy mildew, and botrytis. These diseases are endemic to humid regions across the United States. This information can be found in our Grapevine Variety Characteristic Chart. Growers need to understand that low susceptibility to disease does not mean the vines are immune to disease. During periods of extended rainfall, disease can become established on cultivars even with low disease susceptibility, and once they become established, disease inoculum will be present that can further spread the disease later in the growing season, as well as into the next season.
Regardless of what variety is selected and grown, some pesticide applications will likely be needed to grow healthy vines with disease-free fruit. Information about pesticides available to the homeowner can be found in a recent article on our website entitled “Grape Pest Management for the Homeowner.” Generally speaking, native and hybrid varieties are less susceptible to diseases than are vinifera. Vinifera varieties are especially problematic for the small grape grower as they are very susceptible to most or all of the major diseases and need to be sprayed more often than native and hybrid cultivars. Varieties that are susceptible to Botrytis and other fruit rots (including some hybrid cultivars) are especially problematic as there are no pesticide products available in homeowner-sized packages to control these diseases.
Grapevine arbors deserve some special consideration. Typically, the homeowner is looking for a shaded entry to the house, or perhaps a shaded backyard area during the summer. The photo that accompanies this article shows an attractive grapevine arbor at the Double A residence planted to 3309 Couderc (commonly referred to as 3309 or 3309C), a grapevine variety typically used as rootstock. Why 3309? It is winter hardy, disease resistant, and produces no fruit (it is a male-sterile variety). Winter hardiness means that you don’t have to worry about re-training from ground level following a harsh winter. Disease resistance means you never have to spray it (although, in a wet season, you may get some downy mildew established on the shaded parts of the canopy). No fruit means not dealing with birds that are attracted to ripening fruit and the associated bird droppings, nor over-ripe fruit falling to the sidewalk underneath the arbor. It may be possible to grow fruiting varieties on an arbor, but do you really want to walk, eat, or entertain guests in an area that requires pesticide applications and may have fallen fruit or bird droppings beneath the arbor, and may be attractive to bees if ripe or overripe fruit is present?
As mentioned, with the exception of growing grapevines on an open (chain-link) fence, training vines along a solid fence or next to the house is undesirable due to shade and lack of air movement. These unfavorable conditions impede drying of leaves and fruit, and lead to an increase in disease pressure.
Trellis construction is an art in itself, the goal is to install a trellis that requires little maintenance. Wood posts are usually preferred, especially if vines are trained to a high wire training system. Metal posts with notches for catch wires are more appropriate if a vertical shoot positioned system is used. Newly-planted grapevines can be trained on a bamboo stake during the first growing season. Depending on how much the vines grow the first year, a low wire may be necessary for vine training during the year of planting; in any case, trellis construction needs to be completed prior to the initiation of vine growth in the second year so that the vine can be attached to the trellis and trained to the desired system. Several links with references pertaining to training systems and trellis design and construction can be found at the end of this article.
One of the most common problems we see with grapevine establishment is lack of weed control. This is the time of year that we receive daily emails from new growers wondering why their vines are not thriving in the middle of a manicured lawn, or worse, in an unmowed field with weeds or sod towering over the newly-planted vines. Established grasses have extensive root systems that quickly overtake bare areas, such as the small weed-free patch you may have established around young vines. For further discussion about weed management in vineyards, view last month’s article.
Spacing of grapevines is determined by many factors, including inherent vigor of the variety and of the soil. Our Grapevine Characteristic Chart lists spacing most commonly used by commercial growers to produce these varieties, which is based on the optimum spacing to produce healthy vines with high quality fruit. Planting vines too close together can result in vine shading that results in poor fruit quality and an increase in disease and the need to spray fungicides. Planting vines too far apart results in less fruit production than is possible, which is an especially important consideration when space is limited. If there is sufficient space to produce the desired quantity of fruit, consider using wider spacing between vines to increase grapevine canopy exposure to sunlight and air movement around the vines.
ORGANIC GRAPE PRODUCTION
We often get inquiries from our customers who find they have disease issues in their grapevines but who want to grow their fruit “organically.” Organic farming emphasizes cultural practices aimed at reducing chemical inputs (such as soil cultivation instead of herbicide use), and plant sanitation practices such as removing disease inoculum from the vineyard. However, the term “organic” is often confused with “grown without the use of pesticides,” and this notion is rarely true. Organic farmers typically follow guidelines established by state and federal agencies that prohibit the use of synthetic pesticides but allow the use of naturally-occurring substances with pest control activity.
Double A Vineyards offers several pesticides for the homeowner, some certified as organic, and some not. Organic pesticides include the following:
Elemental sulfur controls powdery mildew only. Unfortunately, many of the native and hybrid varieties that are less susceptible to certain diseases are sulfur-sensitive, meaning they are injured from sulfur application. Even varieties that are considered “sulfur tolerant” can be injured if applications are made when temperatures are above 85˚F.
Horticultural spray oil, a petroleum product, controls young powdery mildew infections and some insects by smothering them. Repeated use of oils can reduce grapevine photosynthesis and result in a decrease in fruit sugar content at harvest.
Copper fungicides provide good control of downy mildew, some control of powdery mildew, and only moderate control of black rot. Black rot is often referred to as the “Achilles Heel” of organic grape production in the Eastern US as there are no organically certified fungicides that provide the level of black rot control that can be obtained using certain synthetic fungicides. Repeated applications of copper often lead to injury to grapevine foliage and can be associated with reduced photosynthesis and sugar accumulation in fruit.
There are many reasons for wanting to become a grape grower. Being realistic about what you can grow at your location, where your vineyard should be located, and what inputs are needed will increase your likelihood of success.
Trellis design and construction:
Learn About Grapes
Common Disease Problems
Botrytis Bunch Rot: Flattened, black masses of fungus appear on canes. Open flowers can become infected which in turn infect the berries. Berries become mummified. Burpee Recommends: Prune to improve air circulation. Allow fruit to ripen in an open canopy by pruning accordingly. Remove mummified fruit as the disease overwinters in the berries.
Crown Gall: Rough, wart-like growths or galls appear on the crown at or just below the soil surface. These can also form on the stems or canes. Plants can become stunted, subject to drought stress and wind damage. Large enough galls may cause girdling which results in plant death. Burpee Recommends: Examine the canes prior to planting for any indication of galls. Avoid injury of the plant. You can remove the gall if it is small enough by cutting around it into healthy wood allowing that area to dry out, cutting into healthy tissue as little as possible. If plant is severely infected, remove it.
Downy Mildew: This fungus causes whitish gray patches on the undersides and eventually both sides of the leaves and all green parts of the plant. Burpee Recommends: Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Do not work around plants when they are wet. Contact your Cooperative Extension Service for fungicide recommendations.
Pierce’s Disease: The severity of this disease varies depending on time and length of infection. Leaves become slightly yellow or red along the margins in white and red varieties respectively, eventually causing the margins to dry or die. Fruit clusters will shrivel. Leaves will fall off leaving petioles attached to the stems. New wood will mature irregularly. Burpee Recommends: Remove infected vines during the dormant season. If severely infected, harsh pruning may be required.
Powdery Mildew occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Common Pest and Cultural Problems
Ants: Feed on the fruit. Burpee Recommends: Avoid using cover crops near grape plantings, unless using common vetch, which helps deter ants from eating grapes. Control mealybugs and aphids, which attract ants.
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Discolored Foliage: Brown foliage can result from drought stress, particularly in mid-summer. Burpee Recommends: Water regularly and use mulch to conserve water and control weeds.
Grape Bud Beetle: Light gray beetles open crop buds and eat the centers. Burpee Recommends: Contact your Cooperative Extension Service for control assistance.
Mealybugs: The grape mealybug has two generations each year and overwinters as an egg or as crawlers. They are flat, oval-shaped, white and waxy. They contaminate grape clusters with cottony egg sacs and leave behind black sooty mold. They can transmit grape viruses. Burpee Recommends: Introduce natural enemies to the area such as ladybugs. Contact your Cooperative Extension Service for control assistance.
The Best Fertilizer for Grapes
The careful process of growing grapes has been studied for centuries, all over the world. Finding the perfect balance of nutrients to grow the crispest grapes as early as possible is a challenge that continues to face grape growers. We tackled this challenge with science, performing extensive research on wine, juice, and table grapes to find the ideal fertilizer for different varieties.
Our grapevine fertilizer program is designed to give grapevines a balanced combination of nutrients, bolstering the health of the plant and helping more nutrients reach the fruit. Using soil testing, tissue sampling, Brix testing and other analyses, we formulated the best fertilizer for grapes to improve yield, taste, and vine health.
A Range of Benefits
Sure-K and Kalibrate liquid fertilizer products will provide the essential potassium – and sulfur when needed – for healthy growth. The slow-release technology in these products, combined with balanced micronutrients, improved the vines’ ability to process and transport sugars throughout the plant. This, in turn, improved the size, appearance, taste and growth of the grapes. In addition to the improved quality, the grapes were also ready to be harvested earlier in the season.
Growing Grapes in Your Backyard
Given good drainage, grapes are well adapted to a wide range of soils and generally have few nutritional needs. However, in some areas nitrogen, zinc, and potassium may become deficient. If deficiencies do appear applying these nutrients at the right time and in the proper amounts contributes significantly to a successful crop. Table 15.5, linked below, is a simple guide to fertilizer management for grapes.
What about nitrogen? Over-fertilizing with nitrogen can be a problem, whether the nitrogen source is a fertilizer or a leguminous cover crop that fixes nitrogen. Nitrogen fertilizer should be used sparingly on grapes unless a specific deficiency has been diagnosed. Fertilizing with high levels of nitrogen can contribute to excess vegetative vigor in the vines and may reduce fruit set, fruit quality, or both.
How do I apply zinc? If required, zinc can be applied in one of two ways:
- For spur-pruned varieties, daubing of a zinc solution onto fresh pruning cuts is easy and works well. During the early winter, when the vines are dormant and the sap is not flowing, prune so that ½ inch of wood is left above the dormant bud. Mix ¼ pound of zinc sulfate (36% metallic zinc content) into a quart of water. Daub the fresh pruning cuts with this solution (keep solution stirred) using a rag or sponge attached to a stick. Soak each cut thoroughly, but do not allow the solution to run down onto the dormant buds. Higher concentrations of this solution may damage buds so do not exceed the suggested rate. Daubing must be done within 3-4 hours of the pruning cuts to be most effective and the vine should not be daubed if the sap flow pushes the daubing solution off the pruning cut.
- A second alternative is to spray the leaf foliage in the spring, 1 to 2 weeks prior to bloom or during the bloom period (can be combined with gibberellic acid bloom spray in prescribed varieties). A full coverage spray, usually about ½ gallon of solution per vine is sufficient. Cane pruned varieties, such a Thompson Seedless, are usually sprayed in this manner. The material used for foliage spray is called Neutral Zinc Sulfate. This product contains 52% zinc and is sold under various trade names. The suggested concentration translates to approximately 2 packed, level teaspoons per one gallon (18.2 gm/gallon) of water. This is sufficient to spray 2 mature grape vines. Chelated zinc materials can be purchased through nurseries but have not proven to work as well as neutral zinc sulfate which is also cheaper.
- How do I manage the canopy and clusters in the spring?
- How do I thin shoots?
- Why should I, and how do I remove leaves?
- How do I increase fruit size on table grapes?
- How do I thin clusters and berries?
- What is trunk girdling and how do I do it?
- How and when do I irrigate?
- Do my grapes need fertilizing? – What about nitrogen? – How do I apply zinc?