Compiled by Mark Hoffmann, Small Fruits Extension Specialist, NC State University, Raleigh
JUNE – SEPTEMBER (Post-fruit Set – Veraison – Harvest)
The main muscadine chores for this summer are: canopy management, weed management, disease and insect control and frequent scouting of your vineyard (minimum once a week) for insect, disease and environmental problems.
The importance of good muscadine canopy management often is overlooked. However, canopy management is critical to the success of your crop and involves for the main part frequent hedging and skirting. Hedge early July and, with vigorous varieties, hedge again in August. Some varieties will require skirting as well: Please make sure that shoots at the edge of a cordon don’t grow into the neighboring vine. High yielding, but low vigorous fresh-market varieties might require fruit thinning as well. Especially the variety ‘Supreme’ can be easily over cropped, which can then lead to subsequent cold-damage and often die-off of those vines. Early fruit thinning is highly recommended for those varieties.
Fruit rots (black rot, bitter rot, ripe rot, macrophoma rot) as well as angular leaf spot can be problematic and often need to be controlled. Good sanitation and canopy management will lower chemical input. Try to remove affected fruit as early as possible and scout frequently. Manzate products (e.g. mancozeb) 1.5 lbs – 4 lbs / acre should have been used in the earlier season. Depending on your disease pressure and your management style, one application all the way up to a 14 day spray routine should have been applied from dormancy to fruit set. Manzate products have a 66d PHI, and growers often switch to a Captan based fungicide program in summer. Early fruit producing varieties (Darlene, Early Fry, Hall, Lane, Triumph) might require an earlier switch to Captan/Prisine than late producing varieties (Late Fry, Granny Val, Doreen). Effective cover sprays for summer should include tank mixes of Topsin M/Rally with Captan/Pristine or Flint. Frequent canopy management and sufficient spray equipment (airblast/high pressure sprayer) are essential to have effective control of fruit rots such as Antrhacnose, Black Rot and/or Macrophoma. Please rotate fungicides between FRAC codes. In non-chemical or organic muscadine vineyards, variety choice, canopy management and weed management becomes much more important, as well as the frequent and year-round sanitation of the vineyard (means the removal of infected material and old wood on a frequent basis), as well as a balanced pruning during dormancy. Visit the Southern Region Small Fruits Consortium website and download the Muscadine Grape Integrated Management Guide.
Marmorated stink bugs, Japanese beetles and the grape berry moth can be problematic in vineyards. Please scout your vineyard frequently (min once a week) for those insects before applying insecticides! Frequent canopy and weed management will help with scouting and also with insect control. Danitol (10-21 fl.oz/ac) and Imidian (1.33-2.125 lbs/ac) will control stink bugs, Sevin (1.25-2.5 fl.oz/ac) and Danitol will control Japanese beetles. Sevin and Entrust (4-8 fl.oz/ac) will control the grape berry moth. In case you need to use insecticides, make sure to rotate between IRAC codes. Too heavy insecticide use can increase spidermite populations. In non-chemical or organic muscadine vineyards, canopy management and weed management becomes much more important to control insects! Scouting should be performed more often, and insecticidal soap and beneficial insects (if available) should be applied at lower thresholds than chemical insecticides would be applied. Visit the Southern Region Small Fruits Consortium website and download the Muscadine Grape Integrated Management Guide.
Grape Root Borer:
The grape root borer is one of the most dangerous insect threats to muscadine vineyards. The larvae of the borer can feed through the roots for one to two years, leading to die-back and often die-off. The adult root borer lives as a moth and mates in summer. Adult grape root borer population numbers/acre often peak in July. There are three control options. Each muscainde vineyard should monitor root borer activity during this time, using Phermone traps (one trap per 1-2 acres). Mounding or covering the soil will help to reduce the amount of egg laying, Lorsban will control larvae stages, and Isomate GB can effectively disrupt the mating of adult root borers. Mating disruption (Isomate GB) is very effective but expensive and is only one part of an integrated approach to pest management. Use 100 dispensers per acre. Lorsban has a 35PHI, and need to be applied as soil drench (4.5pt/100 gal of water). The traps and the mating disruption can be used in organic vineyards. Visit the Southern Region Small Fruits Consortium website and download the Muscadine Grape Integrated Management Guide.
Please make sure that you keep your row middles mowed at all times. This is especially important for non-chemical or organic vineyards. If you have a low-chemical policy in vineyard, weed management should be the one area to use chemical control at least twice a year. Not very well managed row middles can be a source for insect pests (e.g. marmorated stink bug) and several diseases. Make sure keep weeds under the vine to a minimum at all times! Canopy management is crucial to have access under the row middles. To chemically control row middles in a mature vineyards, use Paraquat, Glufosinate or Poast as needed. Visit the Southern Region Small Fruits Consortium website and download the Muscadine Grape Integrated Management Guide.
Take a tissue samples (petiole and leaf blade). Use the newest fully developed leaf on a fruitful shoot. Take 40-60 samples per block and variety and send leaf samples to the North Carolina Department of Agriculture and Consumer Service, Agronomic Division. Apply fertilizer according to the sample results (NPK fertilizer such as a 10-10-10 or a 6-6-18 can be used). Vines should not be fertilizer anymore after July, to avoid overproduction, vegetative growth and to ensure that the plant go into dormancy.