Grapes:Guidelines

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GUIDELINES: GRAPE PRODUCTION


STATISTICS

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OUTLINE OF MANAGEMENT ACTIVITIES

Cultural Practices

_____ Transplant when the vines are in late dormancy in well-drained soils. _____ Apply 1-1.5 inches of water every two weeks during the actively growing season. _____ Test soil for nutrient status and pH every year. Maintain records of test results and fertilizer applications. _____ Contact a local Extension Agent to apply the proper amount of fertilizer according to soil test results. _____ Carefully avoid fertilizing closer than six inches from the vines to avoid chemical burn. _____ Apply heavy mulches around the trunks to conserve moisture and control weeds. _____ Herbicide programs can be implemented on well-established vines for controlling weeds.



Pesticide Management

_____ Use approved and registered pesticides according to label. _____ Maintain application records including date, location, applicator, target pest, pesticide name, EPA registration number, formulation, rate and number of acres treated are maintained. _____ All sprayers are calibrated at the start of the season. _____ Minimize pesticide drift. _____ Develop and implement a resistance management plan. _____ Select pesticides which will preserve natural enemies of pests. _____ Use separate sprayers for herbicides and insecticides. _____ Check sprayer(s) calibration at least once during the season. _____ Recalibrate each sprayer as needed. _____ Maintain records of planting dates for treated fields. _____ Keep records of stage of crop of treated field. _____ Use water-sensitive spray cards to test coverage of leaf surfaces.



Insect Pest Management

_____ Scout "SUSPECT INSECTS" Branch and Twig Borer Click Beetle Cutworms False Chinch Bug Grape Bud Beetle Grape Leaffolder Grape Mealybug Grape Phylloxera Hoplia Leadcable Borer Leafhoppers Omnivorous Leafroller Orange Tortrix Sharpshooters Thrips Vinegar Fly Webspinning Spider Mites Western Grapeleaf Skeletonizer

_____ Identify major insect pests. _____ Keep a scouting record. _____ Identify control measures and implement according to thresholds.



Disease Pest Management

_____ Identify major diseases. _____ Keep a scouting record. _____ Identify control measures and implement according to thresholds, which should include spraying shoots when they are 3-4 inches long. Spraying should continue at intervals of 10 days to two weeks until 7-10 days before harvest.



Weed Pest Management

_____ Scout "SUSPECT WEEDS" asparagus (Asparagus officinalis) barley, hare (Hordeum murinum ssp. leporinum) barnyardgrass (Echinochloa crus-galli) bermudagrass (Cynodon dactylon) bindweed, field (Convolvulus arvensis) blackberries (Rubus spp.) bluegrass, annual (Poa annua) bromegrasses (Bromus spp.) canarygrasses (Phalaris spp.) catsear, spotted (Hypochaeris radicata) chickweeds (Stellaria spp.) clovers (Trifolium spp.) cockleburs (Xanthium spp.) crabgrass, large (Digitaria sanguinalis) cudweeds (Gnaphalium spp.) dallisgrass (Paspalum dilatatum) dandelion (Taraxacum officinale) dock, curly (Rumex crispus) fescues (Festuca spp.) fiddlenecks (Amsinckia spp.) filarees (Erodium spp.) fleabane, hairy (Conyza bonariensis) fluvellins (Kickxia spp.) foxtails (Setaria spp.) goosefoot, nettleleaf (Chenopodium murale) groundcherries (Physalis spp.) groundsel, common (Senecio vulgaris) henbit (Lamium amplexicaule) johnsongrass (Sorghum halepense) knotweed, common; prostrate knotweed (Polygonum arenastrum) lambsquarters, common (Chenopodium album) lettuce, prickly (Lactuca serriola) lovegrasses (Eragrostis spp.) mallow, little; cheeseweed (Malva parviflora) lettuce, miner's (Claytonia perfoliata) mustards (Brassica spp.) nettles (Urtica spp.) nightshades (Solanum spp.) nutsedge, yellow (Cyperus esculentus) oat, wild (Avena fatua) pigweeds (Amaranthus spp.) pineapple-weed (Chamomilla suaveolens) poison-oak, Pacific (Toxicodendron diversilobum) polypogon, rabbitfoot (Polypogon monspeliensis) puncturevine (Tribulus terrestris) purslane, common (Portulaca oleracea) redmaids; desert rockpurslane (Calandrinia ciliata) rocket, London (Sisymbrium irio) ryegrasses (Lolium spp.) sandburs (Cenchrus spp.) shepherd's-purse (Capsella bursa-pastoris) sorrel, red (Rumex acetosella) sowthistles (Sonchus spp.) speedwells (Veronica spp.) sprangletops (Leptochloa spp.) spurges (Chamaesyce spp.) thistle, Russian (Salsola tragus) velvetleaf (Abutilon theophrasti) witchgrass (Panicum capillare)


_____ Prepare weed maps in mid-to-late season, indicating significant weed species and their location. _____ Use last year's scouting records to begin this year's scouting. _____ Base all herbicide rate, selection and spot or strip sprays on weed survey results. _____ Weeds may be controlled by cultivation, with no herbicide applied. _____ Use reduced rates of herbicide through banding of herbicides and cultivation. _____ Do not use herbicides of the same class on the same field in succeeding years. (Use crop rotation and corresponding herbicide selections.) _____ Prevent weeds within the field, alleys and roadways from going to seed. _____ Use an experimental plot to test different weed management techniques and record the results.



Weather and Crop Monitoring

_____ Monitor weather and crop parameters _____ Keep daily records. Date: Min/max temperatures: Rainfall: Hours of leaf wetness: Stage of tree development (by cultivar, weekly):



PROPAGATION

Rooted grape nursery stock is usually produced from 9-10 month old wood. The canes that are used for hardwood cuttings should be about 12 inches long with two or more buds, pencil sized or a little larger in diameter, straight, and have green wood throughout. The bottom cut should be just below the lowest bud and the top cut one inch or more above the top bud. Each cutting is grouped in bundles of about 50 or less with the bottom ends cut evenly and placed in a cool, shady location to callus. Cuttings should be set with almost the entire length covered with soil and kept moist until rapid growth occurs. Budwood for scions should be chosen from healthy vines and are 5-8 inches long with a 1/4 - 1/2 inch diameter with two or more buds. Grafts must be mounded with clean, moist soil so that the scion does not dry out. Transplanting should be done in the late dormancy period at the same depth that it was grown in the nursery. Grapes can adapt to a wide range of soils, many having sandy soil near the surface with a layer of underlying clay about 3 feet deep. Poorly drained soils are not recommended.


PLANTING

Bunch grapes grow well on level or slightly rolling land in straight rows. Because they are not quite as vigorous as muscadine grapes, they require only 10 feet of row for each vine. When planting the vine, prepare a hole large enough to accommodate the entire root system without bending or cutting any roots. Set the plant at or slightly below the level it grew in the nursery. Fill the hole with topsoil, pack it firmly and then water. It is not necessary or recommended to apply fertilizer at the time of planting. After planting, cut the vine back to a single stem with two or three good buds remaining and later determine which of these buds is most vigorous and remove the others.


CULTIVATION

Grapes should have sod or another means of reducing soil erosion established between rows before planting the vineyard. This should be kept mowed and controlled so that it does not present other problems. A good herbicide program can also be utilized for bunch grapes after the third season and the vine is producing fruit. Finally, hand weeding or hoeing can control weeds but is labor intensive for large productions and careful consideration must be made for the shallow root system. Mulches may be used to help control weeds and conserve moisture.


TRELLIS

Trellising allows the grapes to grow like vines and be off the ground to prevent diseases. Trellises are constructed using 9 or 10 galvanized steel wire and 7-8 feet treated posts, for braces. There are three trellis systems that are commonly used. The single wire trellis is the least common and involves a single wire being attached to the posts in a fashion similar to a clothesline. This system is good in areas where diseases are a big problem because it allows the vines to dry off quickly. The two wire vertical trellis has two wires attached to the posts, one being 2.5 feet above the ground and the top wire about five feet above the ground. This system allows shading of the foliage on the lower fruiting cane by the upper canes which reduces the quality and productivity of the grapes on the lower level. The double curtain trellis is the most desirable of the common systems because it allows greatest yields due to more grape foliage being exposed to direct sunlight. In this system, two wires are placed four feet apart, five feet above the ground.


TRAINING

During the first year, set a 5 1/2 foot stake by each plant and tie the stake to the top wire of the trellis. As shoots begin to grow from the plant, select the healthiest shoot and secure it to the stake with string or tape, being careful not to girdle the shoots. All other shoots should be removed. As the selected shoot grows, it will eventually become the trunk of the vine. It is important to keep the shoot growing straight up the stake and securing it with string, if necessary. Leave at least one lateral shoot growing in each direction along each trellis wire.


PRUNING

Grapes require heavy pruning to produce large clusters and berries, as opposed to excessive, unnecessary stems, but the pruning must be performed during the dormant season so the plants do not bleed internal sap through the wounds. Vines that do not reach the top trellis wire during the first year of growth should be pruned back to buds near the ground. If these vines do reach the top wire, then a single cane with 3-5 buds along each wire in each direction should be the result of pruning. After the second year of growth, four new wood canes with 8-12 buds each should be left on each cane. As the vines mature, 8-14 buds should be left on each vine for balanced pruning, or 30-60 buds for unbalanced pruning, leaving the greater number of buds on the most vigorous vines.


LOCATION

Bunch grapes should be planted in elevated grounds with a slight slope. Grapes do not like standing water near the base of the vine or areas where cold weather settles, which can be prevented by planting on a slight slope. They should also be planted in areas that receive full sun or sun most of the day. They can grow in many types of well-drained soils, but prefer sandy loams, loams, or clay loams with a high percentage of organic matter.


IRRIGATION

Grape vines should not stand in water or receive excessive amounts of irrigation. Younger plants are more susceptible to damage due to lack of moisture, but older plants will positively respond when stressed. Insufficient water during berry enlargement will keep the fruit from reaching its full size and this condition is not reversible assuming that latter irrigation will cause undersized grapes to become normal size. A severe shortage of readily available water during the ripening stage will cause delayed maturity, a dull color to develop and possibly sunburning. Generally, applications of 1-1 1/2 inches every two weeks is sufficient during the active growing months for both young and old vines.


FERTILIZING

Fertile soils should be established before the vines are planted so that the young vines may get off to a good start. This can begin by having the soil tested for nutrient deficiencies and moisture holding capacity. The amount of fertilizer will vary from area to area and a local extension agent will be able to assist in the proper application amounts. Generally, a balanced fertilizer of nitrogen, phosphorus, and potassium at a 1:1:1 ratio will be sufficient. Some soils may be deficient in essential micronutrients, which should also be applied according to soil test results. The applied fertilizer should never come closer than 6 inches from the vine to avoid burning the vines.


HARVEST

Bunch grapes are harvested before the warmest part of the growing season and should be picked and stored at 40ºF if not being immediately processed. Those grapes that are being processed for jellies, jams, or wines should be shipped directly to the processor. Most table grapes may be shipped several hundred or thousand miles away from where they are grown, so they must be harvested early enough to allow them to withstand the transportation time. Color is a poor indicator of maturity in grapes. Grapes should be harvested when ripe, which usually occurs when the seeds change from green to brown and the cluster stem turns brownish and slightly wrinkled. Maturity is often measured in large commercial operations using a measure of º Balling. Balling is a measure of the liquid and sugar content in the grapes. Some varieties may need to be harvested a day or two before reaching the peak of ripeness or sweetness because the grapes may begin to fall off the vines. Excessive rain during harvest can split the skins and promote disease problems. Grapes that will be harvested for dry wines may be picked when the sugar content is 18-23º Balling, while grapes for sweet wines are 24º Balling. The entire crop is usually harvested at one time for ordinary wines, but for the extremely fine wines, the grapes may be harvested several times. They are harvested mechanically and taken to be processed immediately. White grapes are usually crushed and the juice separated, then stabilized, clarified and bottled hot. For red juices, the grapes are crushed, heated, pressurized, then stabilized. Grape concentrate is produced under vacuum. Grapes for raisins are harvested at 23º Balling or more. This maturity is a compromise between leaving the grapes on the vine as long as possible for better yield and quality and early falling of the grapes. The grapes may also be dehydrated in ovens or sun-dried.



VARIETIES

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