Vineyard and Winery Information Series:
Vol. 14 No.6, November - December, 1999
Dr. Tony K. Wolf, Viticulture Extension Specialist
II. Weed management for grapes
III. Upcoming meetings
Table 1. Utilization of grapes for wine: 1997-1998 (from, USDA National Agricultural Statistics Service; www.usda.gov/nass/pubs/agr98).
Absent from the above list is the state of Arizona, which produced 23,000 tons of grapes in 1998. Most of that crop was for fresh and dried (raisin) use though, and the amount used in wine appeared to be less than 1,000 tons, although wine utilization was not shown. If weıre to accept the data in table 1, Virginia would then rank 7th, nationally, in production of "wine" grapes in 1998. Please contact the VA Agricultural Statistics Service (804-771-2493) if you grow one or more acres of grapes (bearing or non-bearing) and you do not receive a grape crop acreage/production survey questionnaire by 15 December.
A temporary farewell: I will be in South Australia from December through late-April. During this period my extension assistant, Alison Hectus, will be handling basic viticultural extension questions that arise. Please excuse my delay in personally handling your inquiries to me until my return. After 14 years service as viticulturist with Virginia Tech I am taking the opportunity by way of a Sabbatical Leave Research Appointment to broaden my viticultural horizons. My posting will be at the University of Adelaide and I will be involved with an on-going grape (Shiraz, of course) training experiment in the Barossa Valley. I am seeking and will have exposure to aspects of minimal pruning, deficit irrigation, and other aspects of SA viticulture. My host is Dr. Peter Dry, who visited our growers at the VSHS/VVA meeting in Roanoke last January. I will also have numerous opportunities to visit with other faculty in the Plant Research Centre at the University of Adelaide, and at the Australian Wine Research Institute. I will also attend and participate in the 5th International Symposium on Cool Climate Viticulture and Oenology, 16-20 January 2000, in Melbourne (http://www.icms.com.au/coolclimate). I enjoy travel and Iım looking forward to the interaction with Australian viticulturists. I expect to return next April with lots of new ideas and points of interest for the Virginia grape community.
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Editor's note: March of 2000 is just around the corner and now is the time to begin putting your pest management plans for the 2000 season together. Weed control is one of the perennial issues that face grape producers and the range of chemical options can bewilder the uninitiated. In this article Dr. Derr discusses the options for postemergence weed control in the vineyard. A future VN issue will discuss the preemergence herbicide options. Dr. Derr will also be speaking and providing additional herbicide registration information at the VSHS/VVA meeting in Williamsburg in January 2000.
A weed management program for vineyards can integrate nonchemical and chemical means of control. Chemical control utilizes preemergence and postemergence herbicides. Herbicide use can be a confusing topic, due to the introduction of new chemicals and new formulations. In this article, I would like to discuss postemergence herbicide use in grapes. There has been little change in the preemergence herbicides registered for vineyards, although I am evaluating new chemistry that will improve control options. I will inform growers of any new registrations for preemergence herbicides in vineyards in future communications.
Postemergence herbicides are applied after weed emergence. Most postemergence herbicides have little to no soil activity, so preemergence herbicides are frequently added to extend the period of weed control. One example would be Roundup (postemergence) plus Surflan (preemergence), although there are many possible combinations. Postemergence herbicide can be classified as nonselective (injure all plants, including crop plants) or selective (control some weeds but not others, tolerance in certain crops). Ideally we would like chemicals that control all weed species yet do not injure grapevines. Currently none of the available chemicals fit this situation. There are several nonselective herbicides available to grape growers. Since all of these chemicals pose some risk of crop injury, we need to utilize application methods that minimize any potential for crop damage.
Postemergence can also be classified as contact (no movement in plants; only the tissue receiving the spray is affected) or systemic (compound moves in the vascular system of plants to reach other plant tissue after application). Systemic herbicides tend to be slower acting than contact herbicides, but provide greater control of perennial weeds than contact materials due to their translocation to, and effect on, root systems.
Postemergence herbicides should be applied under good soil moisture when weeds are actively growing. Applications to drought-stressed weeds under hot, dry conditions can result in poor weed control. Do not spray if rain showers are imminent. For certain herbicides, we need six hours without rain after application for sufficient chemical to be absorbed. The ideal situation for postemergence herbicide application is no rain within 24 hours of application.
The postemergence herbicides used in grape production are listed below. I have listed trade names (what one would buy from a chemical distributor), along with the common name. A given chemical may be sold under different trade names but the common name will be listed on the label for each product.
Gramoxone Extra (paraquat) is a nonselective contact herbicide. It provides rapid burndown of weed foliage. Gramoxone Extra is a restricted use pesticide since it has greater acute toxicity to animals than most herbicides. Since Gramoxone Extra does not translocate in plants, it poses less risk of crop damage that the available systemic herbicides. Thorough coverage of weed foliage is essential for effective weed control with Gramoxone Extra. A nonionic surfactant is added to the spray to ensure coverage of leaf tissue. Treat annual weeds when small for optimum results. Since Gramoxone Extra does not affect root systems, perennial weeds will regrow from underground tissue after application.
Rely (glufosinate) is a nonselective herbicide with primarily contact action, although there is a degree of translocation in plants. Rely works faster than Roundup Ultra, but slower than Gramoxone Extra. Rely is in-between Gramoxone Extra and Roundup Ultra in activity. Rely provides greater control of perennial weeds than Gramoxone Extra but lower control than Roundup. Rely poses greater safety to grapes than Roundup, however, because it is less mobile in plants. Grape foliage contacted by Rely will be damaged, but Rely will not cause the systemic injury seen with more mobile chemicals. Because of this lack of translocation, Rely can be used to control suckers in fruit production. Rely, like Roundup, can injure green bark so directed sprays are needed to minimize contact of grape foliage and stems.
Roundup Ultra (glyphosate) provides the best control of perennial weeds but poses the greatest hazard of crop damage. Shielded sprays are one way to minimize spray drift on to grape foliage. Glyphosate has been and continues to be sold under a variety of trade names, with some of these formulations registered for use on grapes. Some of the formulations contain a surfactant while others do not. Roundup Ultra contains a surfactant so no additional adjuvant is required when applying this formulation.
Touchdown (sulfosate) is a relatively new nonselective systemic compound available to grape growers. Touchdown has been described as a different salt formulation of glyphosate, the active ingredient in Roundup. In my trials, Touchdown has performed essentially identically to Roundup Ultra and is used in exactly the same manner. Touchdown provides the same weed control spectrum and crop injury potential as Roundup. Like Roundup, the major use of Touchdown will be control of perennial, broadleaf weeds.
There are also several selective postemergence herbicides for grapes. Poast (sethoxydim), Fusilade DX (fluazifop), and Prism (clethodim) control annual and perennial grasses. The labels for Fusilade DX and Prism are for nonbearing use in grapes (at least one year between application and harvest). Poast can be used in bearing vineyards but cannot be applied within 50 days of harvest. These three herbicides are all systemic in plants. Repeat applications, though, are generally needed to completely kill the root systems of well-established perennial grasses like bermudagrass. The advantage of these three herbicides is excellent crop safety (no hazard to the vine if the vinesı tissues are contacted). The disadvantage is that Poast, Fusilade DX, and Prism will not control any broadleaf weed or sedge. There are also subtle differences in the grass control spectrum for these three herbicides. For example, Prism will control annual bluegrass while the other two will not. Poast is more effective for tall fescue control than is Fusilade DX. All three will control the major annual grasses, such as crabgrass and foxtail, as well as the perennial grasses johnsongrass, quackgrass, and bermudagrass. Certain formulations require addition of an adjuvant for maximum grass control.
Some preemergence herbicides, such as Karmex and Goal, will control small weed seedlings. Since these chemicals have limited postemergence activity, they are generally applied with a postemergence herbicide for consistent control of emerged weeds.
Read label directions when applying herbicides to the vineyard. The label will list the weed control spectrum, as well as any limitations on use, such as age of the vineyard. Postemergence herbicides can be integrated into a grape weed management program, especially for addressing perennial weed species.
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Trickle irrigation program schedule
|8:30-9:00||Registration -- Coffee and Donuts -- Welcome|
|9:00-9:30||Assessing the Need for Irrigation:|
Blake Ross- Extension Specialist -- Irrigation and Water Supply, Virginia Tech
Charles O'Dell -- Extension Specialist, Commercial Vegetable Production, Virginia Tech
Rich Marini -- Extension Specialist, Tree Fruits, Virginia Tech
|9:30-10:00||Irrigation Development and Resources, Blake Ross, Virginia Tech|
|10:00-10:30||Micro Irrigation Emitters and Distribution, Lew Gilliam -- Mid Atlantic Irrigation -- Farmville, VA|
|10:30-11:00||Break and View Trade Show|
|11:00-11:30||Water Quality and Filtration, Joe Davison -- Berry Hill Irrigation, Buffalo Junction, VA|
|11:30-12:15||Injectors, Pumps & Maintenance, John Nye, Trickle-EEZ Company -- Biglerville, PA|
|1:15- 1:45||Ground Water Availability, Scott Eaton -- Professor of Geology, JMU|
|1:45- 2:00||Well Drilling Guidelines (Speaker TBA)|
|2:00- 2:15||Surface Water & Ponds, Mike Liskey -- National Resource and Conservation Serv., Winchester, VA|
|2:15- 2:45||Economic Analysis of Trickle Irrigation, Jack Dunford -- Area Farm Management Agent, VA Tech Cooperative Extension|
|3:15- 4:00||Producer Experiences, Steve Brown -- Grape Grower, Woodstock, VA|
Registration: Pre-registration will be required. The cost for the course will be $16.00 per person and will include lunch. Please make your check payable to "Virginia Cooperative Extension-Frederick County", and mail to:
Frederick County Extension Office
107 N. Kent St.
Winchester, VA 22601
Your registration must be received by December 3, 1999.
For more information contact the Frederick County Extension Office at (540) 665-5699, email email@example.com, fax (540) 722-9354.
B. Combined VA State Horticultural Society and Virginia Vineyards Association annual meeting and exposition
When: 10 12 January 2000
Where: Radison Fort McGruder Inn, Williamsburg, VA
Directions: Take I-64 east from Richmond towards Norfolk. Take exit 242A (Busch Gardens/Williamsburg) for highway 199. Stay on highway 199 for about two miles and then take Rt 60 east/west (Busch Gardens/Williamsburg) exit. Turn left at end of ramp onto Rt 60 west. The Radison Fort McGruder Inn is about one mile on the left.
Program: The VSHS/VVA meeting will be similar to that held in Roanoke last January. It will feature concurrent grape and apple technical seminars, a large trade show, a reception (10 January evening), and buffet breakfast (11 January). The vineyard/winery seminars start on Monday morning, 10 January (see program details).
Registration: Contact Ms. Alison Hectus (540-869-2560 or firstname.lastname@example.org) for meeting and hotel registration forms.
Combined VVA/VSHS Meeting program
|Monday, 10 January|
|9:30 -- 10:00||Registration|
|10:00 -- 11:00||ABC panelists to discuss "dos and don'ts" of establishing a Virginia Farm Winery, Mary Davis-Barton (VDACS), moderator|
|11:00 -- 12:00||Winery and vineyards communications and advertising with the public, Mary Davis-Barton (VDACS), moderator|
|12:00--1:00||Lunch on own|
|1:00 -- 2:00||"Update on VDACS Grape Growing Task Force" (Panel of speakers), Bill Dickenson, Jr., moderating (Virginia Department of Agriculture and Consumer Services)|
|2:00 -- 3:00||"Phomopsis cane and leaf spot, and late-summer fruit rots", Dr. Michael Ellis (Ohio State Uni.)|
|3:30 -- 5:30||Grower "Best materials and management practices" panel discussion|
Chis Pearmund, President, Virginia Vineyards Association (moderator)
J. McCloud (GDC supports, deer fencing, irrigation design)
S. Brown (experiences with irrigation)
Jeanette Smith (state-wide perspectives)
Doug Fabbioli, Tarara Vineyards (cost-saving measures in the vineyard and winery)
Jim Law, Linden Vineyards (wine making in the vineyard)
Fernando Franco, Barboursville Vineyards (wind machine, trellising)
|6:00 pm||VSHS/VVA reception|
|Tuesday, 11 January|
|8:00 -- 12:00||"Taxes, grape sale contracts, long-term land lease arrangements and regulatory issues" Larry Christensen, vice-president, Virginia Vineyards Association (moderator) Multiple panelists|
|12:00 -- 1:30||Lunch on own|
|1:30 -- 2:30||"Comprehensive disease management review", Mike Ellis (Ohio State)|
|2:30 -- 3:00||"Strategies to minimize fungicide resistance development", Anton Baudoin (Virginia Tech)|
|3:30 -- 4:00||"Crop oil research", Sarah Finger (Virginia Tech)|
|4:00 -- 4:30||"Mite interactions in vineyards". Doug Pfeiffer and Jessica Metzger (Virginia Tech)|
|4:30 -- 5:30||"Update on novel wine grape varieties for Virginia: What works and what doesn't"
A review of novel variety performance with wine tasting Bruce Zoecklein, VA Tech, moderator|
Dennis Horton (Horton Cellars)
Fernando Franco (Barboursville Vineyards)
|Wednesday, 12 January|
|7:30 -- 8:30||Buffet Breakfast|
|9:00 -- 9:30||Virginia Vineyards Association business meeting, Chris Pearmund, moderating|
|Combined grape and apple program|
|9:45 -- 10:15||"Worker Protection Standards", Glenda Mah, (VDACS)|
|10:15 -- 11:00||"Herbicides for apples, grapes, and peaches", Jeffrey Derr (Virginia Tech)|
"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: email@example.com
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.
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