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'musc-mg' ~ electronic advisory from NC Cooperative Extension Service for muscadine growers
Vol. 4 No. 4
May 23, 2008
Contributors to this advisory:
Connie Fisk, Muscadine Extension Associate, Dept. of Horticultural Science, NCSU
Bill Cline, Extension Plant Pathologist, Dept. of Plant Pathology, NCSU
Wayne Mitchem, Extension Associate – Vineyard Weed Management, Dept. of Horticultural Science, NCSU
Topics in this issue:
*Mulching around grapevines
*Time to start fungicide sprays
*Control of woody perennial weeds in the vineyard 
Mulching around grapevines
Mulching has several advantages in the vineyard: 1) it helps to suppress weed growth, which reduces competition for soil moisture and nutrients,
2) it helps to conserve soil moisture, increases rainfall penetration, and reduces erosion, and 3) it often helps to maintain or increase vine vigor with fewer fertilizer inputs, as nutirents are supplied by the mulch as it decays. If you decide to try mulching use a durable mulch such as chipped hardwood. Many other organic materials such as straw and sawdust can also be used as mulch, but be sure to replenish the mulch layer each year. Black plastic, landscape fabric, or other shredded materials can be used, so long as they do not leach chemicals into the soil around the vines. Avoid mulching on poorly drained soils - muscadines do not like wet feet and mulching may actually increase moisture in the root zone. In addition, keep in mind that mulching can increase
fire and rodent hazards.
If you choose to mulch a new vineyard, be sure to pull the mulch a few inches away from the tender young plant so that it receives adequate air and sunlight (see photo at right).
Time to start fungicide sprays
Pre-bloom fungicide sprays should be applied now (mid-May) for control of black rot, which we're already starting to see in Eastern NC. The black rot fungus (Guignardia bidwellii f. muscadinii) causes a circular brown leaf spot and a black scab on berries. Occasionally, lesions occur on the young stems and tendrils. Nova (myclobutanil) is the product of choice, but most other fungicides will also control black rot. Black rot seldom causes much damage in sprayed vineyards.
Fungicide applications should be repeated every two weeks, to coincide with bloom (early June) post-bloom (mid-June) and small green fruit stages (July) for control of bitter rot and powdery mildew. Early-season sprays (June-July) are also more efficacious and cost-effective for fruit rot control than are late-season (July-August) sprays, and early sprays are less likely to leave objectionable residues on the fruit.
The 2008 Muscadine Management Guide is available on-line:
http://www.smallfruits.org/SmallFruitsRegGuide/Guides/2008/2008muscadineIMG22108.pdf
Control recommendations and disease descriptions may be found at:
http://ipm.ncsu.edu/agchem/7-toc.pdf
http://www.ces.ncsu.edu/depts/pp/notes/Fruit/fdin012/fdin012.htm
Control of woody perennial weeds in the vineyard
Glyphosate applied as a spot spray is the most effective means of controlling woody perennial weeds in your vineyard. Glyphosate is the active ingredient in Roundup and there are various generic formulations. Honeysuckle should be treated when it is in full bloom up to one month (about now or the next couple of weeks) afterwards with a 2% solution of glyphosate. If you are trying to control blackberry briars they should be treated with a 1.5 to 2% solution in late summer up through Thanksgiving. In the mean time managing them with Rely is the best option until the appropriate application time for glyphosate. If you have green briar as opposed to blackberry it should be treated when it has 5 fully expanded leaves (probably now) with a 3% solution of glyphosate. You will need to be careful not to allow these concentrated solutions to contact the grape vines and as always with perennials, be prepared to make a follow up application. It may take 2 years to get these cleaned up to your satisfaction but it can be done.
Using Surflan when the weeds are small is also good advice since a preemergence herbicide program reduces the need for postemergence applications. In addition to the Surflan you may want to add simazine (Princep) with it for broader spectrum residual control. That is assuming your vineyard has been established at least 3 years. Next year you could rotate Chateau as your preemergence herbicide rather than the Surflan+simazine combination.
Upcoming Events
- Mark your calendar for the 35th Annual NC Muscadine Grape Association Annual Meeting, Trade Show, and Bus Tour July 31 and August 1, 2007. The tour will leave from Williamston, NC both Thursday and Friday, visiting historic sites, vineyards and wineries in the northeast corner of North Carolina. You don’t want to miss this fun-filled educational event. More details to come in late May. Visit the NCMGA website at http://www.ncmuscadine.org for the latest information.
- Planning is underway for the 4th Annual North Carolina Muscadine Festival at the Duplin Commons Agribusiness Center. Plan on joining us for educational seminars, wine tasting, and live music Saturday, September 27. Visit http://www.muscadineharvestfestival.com for details.
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