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Search Results for: Vitis | Search the catalog for: Vitis

Plant Answer Line Question

Keywords: Vitis

Do you have any information on a new grape variety called Sweet Seduction? I am interested in vigor, fruit set, and ripening time.


Depending on the source, this is either a beautiful and productive grape or a straggly one with poorly filled clusters. It received praise from Lon Rombough, a grape expert from Oregon. The Home Orchard Society has a brief discussion about Sweet Seduction. These first two sources do not think much of this seedless grape. It is also mentioned in a list of American grapes and hybrids in the book McGee and Stuckey's Bountiful Container (Workman, 2002):
"Introduced by Oregon grape grower Bill Schulz, Sweet Seduction is an unusual variety with exceptional flavor. It produces beautiful golden yellow seedless grapes with a muscat-like taste that we usually associate with European grapes (...) Vigorous and productive, [it] bears large and attractive clusters of its seductively flavored fruit."

Anecdotal comments on the web suggest that this variety begins to bear fruit at between 2 to 3 years after planting, and may produce 10 to 15 pounds of grapes. It is hardy in Sunset zones 5 - 9 and can grow 15 to 20 feet.

Date 2017-05-04
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Plant Answer Line Question

Keywords: Grapes--Diseases and pests, Vitis, Viticulture

I am looking to install wine-producing grapes in my back yard, but I want to purchase vines from a reputable company, especially since I want to minimize the chance of exposure to Phylloxera. Where would you recommend I shop for the 12-20 vines I would like to install in my back yard?


While I cannot guarantee that any of these nurseries sell stock that is free of Phylloxera, here are three reputable nurseries that may have what you are looking for:

Raintree Nursery
Burnt Ridge Nursery & Orchards
Cloud Mountain Farm

Source: Susan Hill. The Pacific Northwest Plant Locator 2000-2001.

If you would like to know more about Phylloxera, Oregon State University's booklet, Grape Phylloxera: Biology and Management in the Pacific Northwest discusses the subject in great detail.

Date 2017-08-15
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Plant Answer Line Question

Keywords: Vitis, Pruning

I have a grapevine that is totally out of control and growing from the arbor into the trees. How and when should it be pruned back? I cut one vine that was up in the tree and it seemed to "bleed water."


From the American Horticultural Society Pruning and Training Manual, ed. by C. Brickell (1996, p. 289.):
"Prune only in midwinter when the risk of sap bleeding from cuts is at a minimum; any later, and bleeding may be difficult to stop (cauterization with a red-hot poker is the traditional remedy)."

From the book The Grape Grower, by L. Rombough (2002, p. 44-45.):
"Pruning Neglected or Overgrown Vines...If the trunk of the vine is straight, or is otherwise healthy, you may be able to short-cut the process by cutting everything back to the head of the trunk. You will have no crop that season, but you can easily train the new shoots that emerge as canes or new cordons to bear a full crop the following year.
More often, the vine will be such a mess of old growth and oversized wood combined with twisted, multiple trunks that the simplest way to prune it is with one quick cut, through the base of the trunk(s), right at ground level.
Kill the vine? No! Almost without fail, the vine will bounce back and refill the arbor or trellis in one season, because it has the full vigor of a large, established root system behind the new growth. The newly regrown vine should resume full production the very next year."

Date 2017-08-15
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Plant Answer Line Question

Keywords: Vitis

What grapes for eating ripen in the Seattle area? I do grow concord, but are there any red or green grapes that ripen in this climate?


Both WSU and OSU Fruit Research Stations recommend Buffalo, Canadice, Van Buren, Vanessa and Venus. Following is WSU's entire list:

  • Table grape varieties (*currently planted at Mount Vernon)
  • Buffalo - midseason Concord type, blue
  • Canadice* - early pinkish red
  • Interlaken Seedless* - early white, vigorous
  • Lynden Blue - very early blue, seeded
  • Mars* - medium early, blue
  • Reliance*- early, red, table and juice
  • Saturn* - medium early, red
  • Van Buren - blue Concord type, early
  • Vanessa* - early red
  • Venus* - early red
  • NY 78.836.06* - selection from Geneva, NY breeding program
(Source: Washington State University, Mount Vernon)

You may find Oregon State University's publication about Growing Table Grapes by Bernadine C. Strik of interest as well.

Date 2018-04-11
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Plant Answer Line Question

Keywords: Vitis, Viticulture

I have purchased 150 grape vine, bare-root plants packed in damp wood shavings, covered by plastic. I have been storing them for about 1 1/2 weeks. A number of circumstances have prevented me from planting them and I am concerned they are going to begin to mold. The current weather forecast suggests I need to do something temporarily with them before permanent planting or I am going to lose, most if not all of them.

Any suggestions?


If at all possible you should place your plants in refrigeration or in the coolest place possible. Store them in the dark, and uncover the plastic. Check frequently to make sure the wood shavings stay barely damp.

Alternatively you can "heel them in" which means unpacking, but leaving the plants in bunches and temporarily "planting" them in either the ground or in large containers of peat moss based potting soil.

Source: Oregon Viticulture, ed. Hellman (2003).

Date 2017-05-10
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Plant Answer Line Question

Keywords: Vitis, Propagation

I am having difficulty propagating Vitis coignetiae. The cuttings are not taking. Any advice?


Here is what I found in the Plants for a Future Database:

Seed - best sown in a cold frame as soon as it is ripe. Six weeks cold stratification improves the germination rate, and so stored seed is best sown in a cold frame as soon as it is obtained. Germination should take place in the first spring, but sometimes takes another 12 months. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in a cold frame for their first winter. Plant out in early summer.

Cuttings of mature wood of the current seasons growth, December/January in a frame. These cuttings can be of wood 15 - 30cm long or they can be of short sections of the stem about 5cm long with just one bud at the top of the section. In this case a thin, narrow strip of the bark about 3cm long is removed from the bottom half of the side of the stem. This will encourage callusing and the formation of roots. Due to the size of these cuttings they need to be kept in a more protected environment than the longer cuttings. Cuttings are difficult from this species.

Layering: This is the best method for this species.

See the Royal Horticultural Society for general layering information.

Date 2017-12-08
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Plant Answer Line Question

Keywords: Grapes--Diseases and pests, Vitis

We've got an established grapevine that has acquired erineum mites, and a horticulturist advised us to use dormant spray this fall. The dormant sprays are rather nasty things, and I recently ran across Neem oil, which says it acts as a miticide. It sounds like the concentrated Neem oil is pretty nasty, too, but I'm wondering: (1) will Neem oil work to get rid of the mites; and (2) is it any less harmful to the environment than the traditional dormant sprays?


According to the University of California, Davis Integrated Pest Management program, Erineum mites will not adversely affect your grape crop, they merely cause an aesthetic problem (disfigured leaves).

Washington State University Extension does mention using dormant-season horticultural oils or wettable sulfur. Excerpt:

"The grape erineum mite, Collomerus vitus, is actually a type of eriophyid mite. They are very tiny, whitish, worm-like, and spindle-shaped. Their bodies have definite annulations or rings, and only two pairs of legs directly behind the mouthparts. They overwinter under outer bud scales and feed on leaves during summer. The upper leaf surface becomes blistered, and blisters on the lower leaf surface turn white, yellow, or brown. Colonies of mites live inside the blisters (erinea) formed by their feeding on the lower surfaces. The blisters contain masses of enlarged leaf hairs. Large infestations can cause major stress on young vines. From mid-August to leaf drop, the mites migrate back to the overwintering sites beneath bud scales.

"Apply according to label instructions. Dormant-season horticultural oils or wettable sulfur applications may be helpful."

I have only seen references to serious damage from this pest when the grapevine affected is very young, so you may be able to do nothing at all. Neem's effectiveness as a miticide is as yet unproven, and when selecting a Neem-based product, you have to make sure it actually contains the active ingredient said to affect insects, Azadirachtin--some "Neem" products do not. (Also, Azadirachtin affects good bugs as well as the ones you may be trying to control, so it is definitely not risk-free).

Paghat's Garden website article on the "Myth and Reality of Neem Worship"

Although most horticultural oils are petroleum-based, there are supposedly a few out there which are being made with vegetable oil, which would be a preferable alternative if you really needed to spray for the erineum mites. Colorado State University Extension has an article on dormant oil.

Date 2017-07-18
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Plant Answer Line Question

Keywords: Vitis, Fruit ripening

My grape vine is about 8 years old. Every year the grapes fall before they are ripe, around late July. The plant looks very healthy and has a lot of foliage. It is growing horizontally on several cable lines against a concrete wall. I don't water and fertilize the plant much except for half a bag or a bag of manure in mid- to late winter. At first I thought the fruit wasn't getting enough sun, so early on, I cut all the leaves around the grapes, but they all fell off the vine from mid-July onward. I prune the grape vine very aggressively in fall, leaving only several year-old branches with several buds on them. The vine is very healthy and grows about 30 feet a season. Could the problem be due to too much foliage?


According to The Grape Grower by Lon Rombough (Chelsea Green, 2002), the premature dropping of fruit is called 'shatter,' and excessive shatter can be caused by nutrient deficiencies. It's normal for a certain amount of unfertilized berries (i.e., grapes) to drop a week or so after the bloom stage, but dropping of fruit in July is a problem.

I wonder if you are giving them overly rich soil (by adding manure). If the manure is high in nitrogen, this encourages a lot of leafy growth, often at the expense of flowers and fruit. I grow grapes and have never fertilized them. The book mentioned above says not to apply fertilizer unless you know there is some kind of deficiency. Note in particular this quotation from the book:
"Excess nitrogen causes flower clusters to 'shatter' (flowers fall off), reducing fruit set. In fact, mature vines should not need any supplemental nitrogen when grown in a healthy soil with plenty of organic matter. A good general rule for fertilizing grapes is to use a mulch of well-rotted compost, which will supply small, but regular essential amounts of nutrients."

Also, the usual time to prune grapes is in mid- to late winter--I do mine in February. Pruning in the fall may be contributing to the problem your vine is having with poor fruit set.

Date 2017-04-19
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Plant Answer Line Question

Keywords: Leaf abscission, Vitis

Why do grape leaves fall off the vine in fall to early winter? What happens physiologically? What triggers dormancy?


The book Oregon Viticulture (Oregon State University, 2003) describes dormancy, acclimation, and cold hardiness:
"In autumn, the vine enters dormancy--the stage with no leaves or growth activity, which extends until budburst the following spring. Despite the apparent inactivity of this stage, it can be a critical time for grapevines when they may be exposed to potentially damaging low temperatures [...] There are three stages of the dormant season: acclimation, the period of transition from the non-hardy to the fully hardy condition; midwinter, the period of most severe cold and greatest cold hardiness; and deacclimation, the period of transition from fully hardy to the non-hardy condition and active growth."

This book does not address leaf drop (abscission) nor does it explain the physiological reasons a vine enters dormancy. The Grape Grower by Lon Rombough (Chelsea Green, 2002) says only that leaf drop follows harvest time, and is part of the vine's hardening off process: "The leaves drop, the shoots become woody to the tips, and the vine gets ready for winter. This is when the vine undergoes deactivation and reenters dormancy." To find the scientific explanation you are seeking, it might make sense to contact a plant physiologist who specializes in vines. There are specialists at University of California, Davis's department of Viticulture and Enology.

I consulted Plant Physiology (4th ed.) by Taiz and Zeiger (Sinauer Associates, 2006), and here is what it says about leaf abscission in general:
"These parts [leaves, flowers, fruits] abscise in a region called the abscission zone, which is located near the base of the petiole of leaves. In most plants, leaf abscission is preceded by the differentiation of a distinct layer of cells, the abscission layer, within the abscission zone. During leaf senescence, the walls of the cells in the abscission layer are digested, which causes them to become soft and weak. The leaf eventually breaks off at the abscission layer as a result of stress on the weakened cell walls.
Auxin [plant growth hormone] levels are high in young leaves, progressively decrease in maturing leaves, and are relatively low in senescing leaves when the abscission process begins."

Here is a little information about vine dormancy, from U.C. Davis.
"In late autumn, triggered by short days, petioles detach from the shoot and leaf drop occurs. The vines can no longer manufacture carbohydrates through the process of photosynthesis and are storing carbohydrates in the form of starch. This dormant state will continue until daylight hours and temperatures increase in spring, when axial buds that were formed before dormancy become activated to break."

Date 2017-07-18
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Plant Answer Line Question

Keywords: Vitis, Pollination

What causes some grapes to get to normal size and others to stay small? This is on a Concord vine about 7-8 years old.


Some varieties of grape produce naturally straggly clusters of fruit. According to The Grape Grower: A Guide to Organic Viticulture by Lon Rombough (Chelsea Green, 2002), Concord has a tendency to ripen unevenly in hot climates (such as the mid-South), but he doesn't note straggly clusters as a characteristic of this variety. That makes me think the uneven size of your fruit is more to do with pollination. See the following, from Oregon State University Extension, which suggests that a cool, wet spell around the time of bloom can interfere with pollination and result in large numbers of unset berries. Rain, which also inhibits pollination, can also be a factor in poor fruit set.

There are other possible reasons for the uneven fruit set. If you are growing a variety of grape which is not ideally suited to your climate, or if the soil is overly rich or overly fertilized, you may not get abundant fruit.

Date 2017-05-12
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August 01 2017 12:36:01