TRELLISING OF GRAPEVINES INCREASING YIELD AND QUALITY Andrew Teubes Viticultural Consultant

In this presentation Different types of trellising systems used in the world Factors influencing long term grape fruitfulness Reasons for trellising or non-trellised cultivation Advantages of trellising Comparison between yields of different trellis systems

Grape fruitfulness Fruitfulness=potential of vine to yield fruit Two main factors Sunlight on leaves of basal buds during spring period, especially during flowering and fruit set Temperature during flowering and fruit set Any trellis system that will increase the sunlight exposure of the leaves will result in increased fruitfulness

Types of trellis systems Bush vines (traditional) – no trellis Vertical Shoot Positioning (VSP) – I-trellis Semi-horizontal Shoot Positioning Y-trellis Double Gable Trentina (Factory roof) Horizontal shoot positioning T-trellis Pergola (Spanish Paron, Roof system) Unconventional systems

Mazar Traditional bush vine Afghanistan Shomali

Traditional bush vine Egypt (Nile delta)

Traditional bush vine Spain South Africa

Traditional bush vine Uzbekistan

Why bush vine and not trellis? Reasons for bush vine cultivation Soil potential medium, therefore do not expect high vigour in plants (shoot growth stops naturally at 70-80 cm) No irrigation or Low availability of irrigation water Bush vines naturally yield smaller crops than trellised vineyards No capital available for installation of trellising materials (poles, wires, anchors)

Advantages of bush vines Low cost No expensive capital investment required

Disadvantages of bush vines Low yield potential Not suitable for cane pruning (increased bud load) No support for shoots under high vigour situations Disease control not effective Poor penetration of sprays into canopy Weed control very difficult (only by hand) Grape clusters have lower quality Temperature of clusters higher close to soil surface Physical damage to clusters close to soil More dust on clusters All labour activities problematic Pruning, shoot removal, leaf removal, harvesting

Dust Grape clusters very close to soil Sun exposure – sun burn

Advantages of trellising Vine has natural climbing growth habit; trellis provides larger surface area for growth and fruiting Increase yield potential Allows differential pruning techniques (spurs and canes) Increase quality of fruit Above soil surface, no dust or physical damage Better micro climate around clusters Easy management and mechanization Weed control Disease- and pest control Labour

Management advantages Clusters have protection -sun -dust -physical damage Comfortable height for working and picking grapes Easy control of weeds

Vertical Shoot Positioning (I-trellis) South Africa Chile

Semi Horizontal (Y-trellis) Turkey Mexico

Semi Horizontal (Double Gable) South Africa

Semi Horizontal (Trentina) South Africa

Horizontal (T-trellis) South Africa Saudi Arabia

Pergola (Roof trellis) Chile South Africa

Unconventional systems When are they used? When trellis materials are not available or too expensive (poles, wires) When climatic factors limit the use of conventional systems Continental climates with extreme winter chilling Vines must be covered with soil in winter to protect from freezing Parts of Northern China, old USSR, Afghanistan, Korea

Egypt Reeds from Nile River is used as trellising material

Afghanistan (Samangan region)

China Deep ditch plantation to resist winter freeze of roots Close vine spacing to increase vines per hectare Deep ditch plantation to resist winter freeze of roots

Uzbekistan

Comparison of performance of trellising systems (Chenin blanc/R99, 1980) Treatment Bush vines Single wire Two Three Four Wire Five 1.5 m Slanting (5 wire) Plant spacing 2.6 x 1.3 1.3 x 1.3 2.75 x Plants/ha 2 959 5 917 2 797 Material costs (Rand/ha) - 480 750 5.4 t 900 1430 1720 12.3 t 2400 Yield (ton/ha) 12.5 0% 22.9 26.1 27.5 220% 30.3 32.7 33.6 270% 42.6 Yield (kg/plant) 4.2 3.9 8.8 9.3 10.2 11.1 11.4 14.4 Income (Rand/ha @ R140/t) 1750 3206 3654 3850 4242 4578 4704 5964

4.2 kg per vine Bush vines pruned with short spurs

Single wire system Post Wire 70 cm Soil surface

. Single wire trellis 8.8 kg per vine Shoot growth Wire position Soil surface 8.8 kg per vine Single wire trellis

Wire 2 30 cm Wire 1 70 cm Soil surface Two (2) wire system

. Soil surface 9.3 kg per vine Two wire trellis

Three (3) wire system Wire 3 Parallel Wire 2 30 cm Wire 1 70 cm Soil surface Three (3) wire system

. . . Three wire trellis 10.2 kg per vine Position of parallel wires Soil surface Three wire trellis

Four (4) wire system Wire 4 30 cm Wire 3 Parallel Wire 2 30 cm Wire 1 Soil surface Four (4) wire system

. . . . . 11.1 kg per vine Soil surface Four wire trellis

Five (5) wire system Wire 5 Parallel Wire 4 30 cm Wire 3 Parallel Soil surface Five (5) wire system

. . . 11.4 kg per vine . . . Soil surface Five wire trellis

Single slanting trellis Wires Single slanting trellis 5 wires 140 cm Soil surface

Single slanting trellis . . . . . 14.4 kg per vine Soil surface

Summary Trellis systems will always increase yield potential, because Creates larger area for vine to grow Allows better sunlight penetration into canopy, increasing fruitfulness Long term high yield will only be sustainable together with Correct pruning practices Effective summer shoot management (shoot thinning, shoot positioning, leaf thinning) Regular maintenance of trellis sytem