Growing Environment

Question 1

What makes up the structure of a grapevine?

Answer 1

Grapevine structure is divided into 4 sections: the shoots, one-year-old wood, permanent wood and the roots

Question 2

What are the major structures of shoots?

Answer 2

Buds, leaves, tendrils, lateral shoots and inflorescence / grape bunches

Question 3

Describe a prompt bud

Answer 3

Prompt buds burst within the current growing season producing lateral shoots

Question 4

Describe a compound bud

Answer 4

Compound buds remain dormant until next spring and provide shoots for the next growing season.

Question 5

Describe what lateral shoots are

Answer 5

Lateral shoots grow from buds formed in the current year (prompt buds).

They are smaller and thinner than primary shoots. Have a stem, leaves, buds, tendrils and sometimes inflorescences.

Main function is to allow plant to carry on growing if tip of primary shoots are damaged.

Question 6

In modern viticulture, describe the two way that vines are propagated

Answer 6

Cutting - a section of vine shoot is planted and then grows as a new plant. Permits use of rootstocks, onto which vine cutting can be grafted.

Layering - method of filling in grapes in a vineyard by using shoots from an established neighbouring vine to produce a new vine. A cane is bent down and a section is buried in the ground. Tip if the cane points up out of the ground. The section that is buried takes root.

Question 7

Describe what a clone is

Answer 7

Methods of cutting and layering usually produce vines that are genetically identical to the parent vine. Cell division during plant growth there is a risk that random mutations in genetic code will occur.

Question 8

Describe clonal selection

Answer 8

Traditional technique where vineyard owners take cuttings from vines in their own vineyard(s) and cultivate the cuttings.

Cuttings taken from several different vines, usually the best-performing vines selected. These vines are selected after several years of monitoring and recording their performance.

Question 9

Define photosynthesis

Answer 9

CO2 + sunlight + water = glucose + oxygen

Photosynthesis is a biochemical process that occurs primarily in the leaves of grapevines, where chlorophyll captures heat from sunlight and uses it to transform carbon dioxide from the atmosphere and water from the soil into sugar and oxygen.

Question 10

Describe transpiration

Answer 10

Transpiration is a process where water is diffused out stomata, which are pores on the underside of leaves. The process draws water and nutrients from the soil, up through the roots and xylem to the leaves and rest of the vine.

Question 11

What are the requirements of the vine? (inputs and outputs)

Answer 11

Inputs - Carbon dioxide, sunlight, heat, water, nutrients

Outputs - Oxygen

Question 12

What are the phases of the vine growth cycle?

Answer 12

Green Growth - Dormancy, budburst, flowering & pollination, shoot formation

Grape Development - Grape formation, veraison, ripening, extra-ripening

Question 13

Describe coulure

Answer 13

Coulure is a condition of grape bunches where fruit set has failed for a high proportion of flowers. It occurs when ovule fertilization is unsuccessful and no grape develops.

It is caused by low rates of photosynthesis and low carb levels caused by cold, cloudy conditions or hot, arid conditions with high water stress.

Question 14

Describe Millerandage

Answer 14

Millerandage is a condition of grape bunches where there is a high proportion of seedless grapes. It is a result of some of vine’s flowers remaining unpollinated or forming very small berries that have no seeds.

It is caused by cold, wet, windy weather at fruit set.

Question 15

Describe the climate classifications.

Answer 15

GST = growing season temp

Cool climate - average GST of < 16.5 C
Moderate climate - average GST 16.5 - 18.5 C
Warm climate - average GST 18.5 - 21 C
Hot climate - average GST > 21 C

Question 16

Describe the Maritime climate category

Answer 16

Maritime - low annual differences between summer and winter temps

Rain spread evening throughout the year.

Example: Bordeaux

Question 17

Describe the Mediterranean climate category

Answer 17

Mediterranean - low annual difference between summer and winter temps

Annual rainfall tends to fall in winter months, giving dry summers.

Examples - Napa Valley, Coonawarra

Question 18

Describe the Continental climate category. Give an example.

Answer 18

Continental - more extreme differences between summer and winter temps.

Short summers, cold winters with temps rapidly changing in spring and autumn

Examples - Burgundy, Alsace

Question 19

Describe Growing Degree Days (GDD)

Answer 19

GDD is a model of heat summation during the growing season that was created by Winkler and Amerine in 1944.

For Celcius, subtract 10 C from average mean temp of a month in the growing season. Multiple that number by the number of days in the month. Do calculation for April - October in Northern Hemisphere and October - April in Southern Hemisphere.

Question 20

Describe the mean temp of the warmest month (MJT). What else does it measure?

Answer 20

MJT was created by Smart and Dry in 1980. It uses the mean temp of July (Northern Hemisphere) and January (Southern Hemisphere).

MJT - Mean January/July Temperature

Also measure continentality, humidity and hours of sunshine.

Divided into 6 bands - cold to very hot

Question 21

Describe Growing Season Temperature (GST)

Answer 21

GST uses mean temp of the whole growing season. Closely related with Growing Degree Days (GDD).

Grouped into climatic bands from cool to hot.

Question 22

List nutrient requirements for vines

Answer 22

Nitrogen, Potassium, Phosphorus, Calcium, Magnesium

Question 23

List the hazards to vineyards

Answer 23

Freeze, Frosts, Hail, Sunburn, Fire, Smoke Taint, Drought, Excess Water, Untimely Rainfall

Question 24

Describe the vine cycle phase called Dormancy. Describe vine needs and adverse conditions.

Answer 24

NH - Nov - Mar SH - May - Sept

Vine needs - Temps below 10C
Adverse conditions - Extremely cold temps, unusually mild temps

-20C - vines damaged or killed
-25C - kills most v. vinifera

Winter pruning takes place

Question 25

Describe the vine cycle phase called Budburst. Describe the vine’s needs and adverse conditions.

Answer 25

NH - Mar - Apr SH - Sept - Oct

Vine needs - Average air and soil temps above 10C
Adverse conditions - Frost, Cold soils

Buds swell, open and green shoots start to emerge. Timing depends on - air temp, soil temp, grape variety, human factors

Question 26

Describe vine cycle phase called Shoot & Leaf Growth

Answer 26

NH - Mar - Jun SH - Sept - Dec

Vine needs - Stored carbohydrates, warmth, sunlight, nutrients, water
Adverse conditions - Low carbohydrate levels (caused by previous growing season), water stress

Shoots continue to grow leaves and inflorescences mature.

Question 27

Describe vine cycle phase called Flowering & Fruit Set. Describe what the vine needs and adverse conditions.

Answer 27

NH - May - Jun SH - Nov - Dec

Vine needs - Warm temps ( > 17C), sunlight, warmth, water, nutrients for bud fruitfulness in next growing season
Adverse conditions - rainy, cloudy, windy, cold temps

Flowering - opening of individual flowers within an inflorescence

Fruit Set - flowers pollinate and grapes form

Question 28

Describe vine cycle phase called Grape Development

Answer 28

NH - Jun - Sept SH - Dec - Mar

Vine needs - Sunlight, warmth, mild water stress
Adverse Conditions - Too much water and nutrients, excessive shading of grapes, very cold or very hot conditions throughout day and night

Question 29

Describe the early grape growth stage which is part of the Grape Development vine cycle phase

Answer 29

Earth grape growth starts soon after fruit set. Hard green grapes start to grow in size and tartaric and malic acids accumulate.

Some aroma compounds / precursors (methoxypyrazines) develop.

Tannins accumulate, but are very bitter.

Sugar levels are low.

Question 30

Describe the veraison stage which is part of the Grape Development vine cycle phase

Answer 30

Grape growth slows down for a few days, called lag phase. Grape cell walls become stretchy and supple, green-coloured chlorophyll in skin cells is broken down.

Grapes of black varieties become red in colour due to the synthesis of anthocyanins

Question 31

Describe the ripening stage which is part of the Grape Development vine cycle phase

Answer 31

Most important process in determining final grape quality.

Shoot growth slows down. Cells in grapes expand rapidly, sugar and water accumulate and acid levels fall. Tannins, colour and aroma precursors / compounds develop.

Harvest marks the end of this stage.

Question 32

Describe the extra-ripening stage which is part of the Grape Development vine cycle phase

Answer 32

If grapes left on the vine, they start to shrivel. No more sugar or water important into grape. Water loss through grape transpiration means sugars become concentrated.

Extra-ripe aromas develop.

Question 33

List the influences on regional and site climate

Answer 33

Latitude, Altitude, Mountains, Slopes/Aspect, Soil, Water, Air

Question 34

Describe how latitude affects temperature and sunlight

Answer 34

Lower latitude (near Equator) receive more solar radiation than regions at higher latitudes (nearer the Poles)

Regions near Equator receive more intense solar radiation than nearer poles. Solar radiation is absorbed and scattered as it travels through Earth’s atmosphere, decreasing its intensity.

Lower latitudes - temps are warmer, sunshine more intense - grapes have higher sugar, lower acidity

Question 35

Describe how altitude affects temperature and sunlight

Answer 35

Temp falls by approx. 0.6 C for every 100 m increase in altitude.

High altitude sites can be favourable in areas of low latitude that would be too hot.

Sunshine more intense at high altitudes - solar radiation travels through less atmosphere.

High altitude has high diurnal range (difference between day and night temps). In warm climates, high diurnal range can be beneficial for retention of avidity during grape ripening.

Question 36

Describe how mountains affect water availability

Answer 36

Mountain ranges can force winds of warm most air upwards over high altitudes. This causes water vapour to cool, condense and precipitate.

Regions on one side of mountain experience greater rainfall, while regions on the other side are sheltered from rain-bearing winds and often have very dry conditions.

Question 37

Describe aspect and how it affects temperature and sunlight

Answer 37

Aspect - vineyards planted on slopes face a certain direction. Important characteristic of vineyard site, especially in cool climates.

Vineyards that face the sun through most of the day receive more solar radiation than those facing opposite direction.

Importance of aspect and steepness of slope increases at high latitudes because solar radiation hits Earth at a low angle at high latitudes

Question 38

Describe slope and how it affects temperature and sunlight

Answer 38

Slope - or incline, an important characteristic of any vineyard site that isn’t completely flat.

Slopes increase the angle at which solar radiation hits Earth’s surface, increasing the intensity of heat and light.

Slopes facing east benefit from morning sun - heat up atmosphere when air and soil are lowest. Can extend hours of vine growth and grape ripening each day, especially in cool climates.

Slopes facing west receive afternoon sun and may become too hot (warm climates) and there is a risk of sunburn.

Question 39

Describe how proximity to water affects temperature and sunlight

Answer 39

Large bodies of water have significant impact on nearby vineyards. Water heats up and cools down more slowly than dry land.

During the day, the water and air above the body of water remains cool and lowers average temp in local area.

Air above dry land heats up more quickly than that above water - this warm air rises.

Opposite happens at night - water retains warmth gained during the day, whereas, without solar radiation, the land loses heat quickly. Warmth of water keeps the local area warmer.

Question 40

Describe how winds affects temperature and sunlight

Answer 40

Winds and breezes have a warming or cooling influence on wine regions. Areas near bodies of water may experience cool breezes during the day, moderating diurnal range of regions.

Valleys that face the coast can mean winds are felt far inland. Valleys can lead to stronger winds as moving air is funnelled.

Winds that have travelled over hot land masses can bring warm air that heats the vineyard area.

Question 41

Describe how the characteristics of soil affects temperature and sunlight

Answer 41

Soil can have an effect on temp. Drainage of soil, its texture and colour all influence warmth of soil and air directly above it.

Soil that drain freely (stony, sandy) warm up more quickly in spring than damp soils. Rising soil temp encourages breakdown of starch in roots, which stimulates budburst and shoot growth.

Desirable for cool-climate areas to have free-draining soils to promote early budburst and potentially longer growing season to help grapes ripen

Light coloured soil reflect some energy from solar radiation. Useful in cool and cloudy climates because extra light energy reflects into lower parts of canopy that receives less sunlight. Dark coloured soils absorb more energy and re-radiate most of it when temps are cooler at night. Useful in cool climates.

Question 42

Describe how mist, fog and clouds affect temperature and sunlight

Answer 42

Depending on density of fog/mist or amount of cloud cover, sunlight can be limited and photosynthesis reduced.

With less solar radiation, temps can be lower, especially if morning fog or cloud delays time at which morning sun begins to warm the land.

Where mist/fog is common, it can slow down sugar accumulation and acid degradation in grapes, which may be beneficial in warm regions or when growing early-ripening varieties.

Mist/fog made up from water droplets that occur at ground level, can increase humidity in the vineyard, which can increase occurrence of fungal diseases, or in areas with dry, sunny afternoons, noble rot.

Question 43

Describe how rainfall affects water availability

Answer 43

Rainfall is a natural source of water for vines - amount and timing is important in producing high quality grapes. Moderated by water-holding capacity and depth of soil.

Warm temps cause moisture from land to evaporate. As warm moist air rises in atmosphere, it cools and condenses into clouds and eventually rain.

In areas where there isn’t sufficient rain, irrigation may be needed.

Topography can influence rain patterns. Mountain ranges force winds of warm moist air upwards causing rain. Regions on one side of mountain experience greater rainfall; regions on other side are sheltered and often have dry conditions.

Question 44

Describe how characteristics of the soil and land affects water availability

Answer 44

Amount of water available to vine depends on how easily water drains, the water-holding properties and soil depth.

Hawke’s Bay receives 1000 mm rain annually, but has extremely free draining gravel soils, so irrigation often required.

Jerez, Spain - receives 650 mm ran in winter with virtually no rain in summer months. Main soil type is albariza, which is a clay soil with good water retention and releases water slowly to vines.

Waterlogged soils are harmful to vine - reduces oxygen available to roots and can kill the vine.

Greater surface run-off in vineyards on slopes - less penetration of water available to vine roots - may be advantageous in regions with high rainfall.

Question 45

Describe what evapotranspiration rate is

Answer 45

Evapotranspiration rate is the amount of transpiration from the vine, combined with the evaporation of water from soil surfaces. It is the rate at which water is no longer available to the vine, that is either taken up by the vine or because it is lost to the atmosphere.

It depends on temp, humidity and wind. Hot, dry, windy weather leads to faster rates of evapotranspiration. This means more water is needed to satisfy needs of the vine. Vines in hot, dry, windy conditions need more water than vines in cool and humid conditions.

Question 46

Explain why Nitrogen is an important nutrient for grape vines and symptoms of a deficiency

Answer 46

Nitrogen is essential for vine growth. It can have a major impact on vine vigour and grape quality. It is a component of proteins and chlorophyll and required for Photosynthesis.

Too much nitrogen in soil causes excessive vegetative growth, with sugars diverted to growing shoots and leaves rather than grapes, hindering ripening.

A nitrogen deficiency results in reduced vigour and yellowing of vine leaves.

Question 47

Explain why Potassium is an important nutrient for grape vines and symptoms of a deficiency

Answer 47

Potassium is essential for vine growth and helps regulate the flow of water in the vine. High potassium in soils can cause problems with uptake of magnesium, which can lead to reduced yields and poor ripening.

High potassium in soil leads to high potassium in grapes, which has significant effect on wine quality, as it is linked to high pH.

Low levels of potassium can lead to low sugar accumulation in grapes, reduced yields and poor vine growth.

Question 48

Explain why Phosphorus is an important nutrient for grape vines and symptoms of a deficiency

Answer 48

Phosphorus is important for photosynthesis. Vines only need a small amount and there is usually enough present in soil.

A deficiency leads to poorly developed root systems causing a diminished ability to take up water and nutrients, reduced vine growth and lower yields.

Question 49

Explain why Calcium is an important nutrient for grape vines and symptoms of a deficiency

Answer 49

Calcium has an important role in structure of plant cells and photosynthesis. Deficiency is rare but can have negative influence on fruit set.

Question 50

Explain why Magnesium is an important nutrient for grape vines and symptoms of a deficiency

Answer 50

Magnesium is found in chlorophyll and has a key role in photosynthesis. Deficiency can result in reduced grape yields and poor ripening.

Question 51

Describe what chlorosis is

Answer 51

Chlorosis is a condition where leaves turn yellow and photosynthesis stops. Grape ripening and yields are negatively affected.

It is caused by iron poorly available in soils with high pH (soils with high proportion of calcium carbonate such as limestone)

Question 52

Describe what organic nutrient compounds are

Answer 52

Organic nutrient compounds found in and added to soils are not available in a form that vines can take up and needs to be converted into inorganic compounds.

Organic describes compounds that contain carbon.

Organisms that live in the soil (bacteria, fungi, earthworms) are important in this process, feeding on organic matter and converting it into available inorganic forms. These organisms can also convert organic matter into humus.

Question 53

Describe what the mineralization process is

Answer 53

Organisms that live in the soil (bacteria, fungi, earthworms) are important in this process, feeding on organic matter and converting it into available inorganic forms.

Question 54

Describe what weather is

Answer 54

A region’s weather is the annual variation that happens relative to the climatic average. Some regions experience greater variation in this pattern than others.

Weather can have a significant influence on the style and quality of wines produced in that year and is often termed vintage variation.

Question 55

Describe what climate change is

Answer 55

The main measurable effect of climate change is a rise in temperatures. It has the consequent effect of greater evapotranspiration and likelihood of water stress. Other effects include changes in geographical distribution of rainfall, greater weather variability and greater frequency of extreme weather events

Question 56

Describe the management options for drought conditions

Answer 56

Where allowed, irrigation systems should be considered as part of initial design of the vineyard.

If new vineyard being planted, drought-resistance should be high on list of priorities in choosing a rootstock. Rootstocks from V. rupestris and V. berlandieri parentage (110R and 140R) .

Choose drought tolerant grape varieties such as Garnacha

Question 57

Describe the management options for excess of water conditions

Answer 57

If excess rain happens on a regular basis, planning of vineyard must ensure the issue is addressed. Where possible, plant on a slope or on free-draining soils to improve drainage. Or a drainage system can be constructed at the time that the vineyard is established.

Question 58

Describe the management options for untimely rainfall in the vineyard

Answer 58

Nothing can be done about the incidence of rain. Choice of site (climate, slope), condition of soil, choice of whether or not to grass land between rows of vines and adequacy of drainage can mitigate some effects of untimely rainfall.

Monitor weather forecasts. If forecast for heavy rain, winemakers may have to decide to harvest early with potentially less-ripe fruit or taking a chance on weather improving in time for successful harvest later or risk losing part or all of the crop.

Question 59

What temperatures can a vine be damaged or killed by winter freeze

Answer 59

Temps below -20C can damage or kill a vine by winter freeze

Question 60

List the high level management options for freeze in the vineyard

Answer 60

Site Selection - hillside sites, vineyards near large or deep bodies of water, vines planted where snow settles most thickly, as deep layer of snow can provide insulation for vine

Choice of Varieties - choose grapes resilient against winter freeze - Cab Franc, Riesling, American and Mongolian vine species and their hybrids

Protecting vines - build up soil around vine graft, bury vines, vines pruned to have several trunks as those killed in winter can be replaced

Question 61

Describe the 2 types of frost

Answer 61

Advective frosts - caused by large volumes of cold air moving in from very cold areas

Radiative frosts - result of heat being lost on still, cool nights. Earth heated by sun during the day and releases it during the night. Amount of heat lost depends on cloud cover. Windless nights will allow a layer of freezing cold air to develop just above the surface of the soil.

Question 62

List the management options to reduce the risk of frost in the vineyard

Answer 62

Site selection - avoid frost pockets, choose hillside sites where cold air can drain away

Delay pruning postpones budburst into warmer months.

Choose late-budding varieties - Riesling

Vines trained high off ground offers more protection.

Have bare soil between vines - absorbs more heat during the day and radiates heat during the night

Question 63

List management options when frost does threaten in the vineyard

Answer 63

Water sprinklers (aspersion) - water freezes around parts of vine and it releases latent heat, which protects the plant

Wind machines - large fans, 4-7 m high, pull warmer air from above ground level to ground level and raises the temp

Oil/propaine gas burning heaters (smudge pots) and wax candles (bougies) can be placed in vineyard and lit. High cost of fuel and labour, low heating efficiency and contribution to pollution

Question 64

List management options when hail threatens the vineyard

Answer 64

Rockets fired into thunderclouds, seeding them with silver iodide to cause rainfall rather than hail.

Net the fruit zone to protect ripening grapes. Nets create some shading and can only be used in areas with high sunlight - Argentina

Hail damage is selective. In high risk areas growers may seek to have a number of plots in different areas to ensure continuity of production.

Growers have to consider additional cost of crop insurance against hail.

Question 65

List management options in prolonged hot weather to prevent sunburn to grapes

Answer 65

When designing new vineyards, row orientation and aspect can reduce impact of hottest afternoon sun. In hot regions in NH, east-west row orientation should be avoided so grapes on south side of row are not subject to intense afternoon sun.

Leverage canopy management techniques. Growers can choose to partially shade the fruit zone in hot regions.

Apply additional irrigation if heatwave forecast. Can reduce water stress and chance of sunburn.

Special agricultural sunscreen spray can be applied or vines can be shaded with a cloth or net.

Question 66

List management options for fires that affect vineyards

Answer 66

Install fire detectors and sprinklers

Install and maintain water tanks

Provide employee training for action in event of emergency

Question 67

List management options of vineyards are affected by smoke taint

Answer 67

Affected musts can be tested analytically in days leading up to harvest.

Some aroma precursors are present in grape skins, so grapes should be handled gently or use whole bunch pressing, lower fermentation temps and reduced maceration times to reduce uptake of compounds.

Winemakers may be able to rescue affected wines by combination of these measures and by blending with unaffected wines.

Question 68

List the pests that can harm grape vines

Answer 68

Phylloxera, nematodes, grape moths, spider mites, birds, mammels

Question 69

Describe how phylloxera spreads and harm vines

Answer 69

Phylloxera is an aphid-like insect that feeds and lays eggs on roots of grapevines. The insects spread through crawling, but most commonly transported by humans on roots of young vines, in soil, on equipment and by irrigation water.

Phylloxera harms vines by damaging roots, reducing uptake of nutrients and water. Damaged roots are vulnerable to additional attacks by bacteria and fungi. These attacks lead to a weakening of the plant (reduced growth, yield) and then to death of the vine.

Question 70

Describe the management options that can prevent the spread of phylloxera

Answer 70

Use of American vine species (V. berlandieri, V. riparia, V. rupetris). Graft European varieties onto rootstocks from American vines.

Use rootstocks derived from American species that can deal with other problems - nematodes, extremes of soil pH, water stress, salinity and control vigour of the vine.

Today grape growers get professional advice on choice of rootstock and grape variety to match appropriate rootstock to vineyard soil, pests to be combatted and level of vigour desired.

Question 71

Describe how Nematodes spread and damage grape vines

Answer 71

Nematodes are microscopic worms common in soils, that are too small to see with the naked eye. To most common are root-knot and dagger nematodes.

They cause damage by feeding off vine roots, reducing yields and vigour. They cause a slow, gradual decline.

Nematodes are either present in the soil already or spread by unclean nursery stock, irrigation water or vehicles. Once they are present, they can only be managed, not eliminated.

Question 72

Describe the management options for Nematodes

Answer 72

Soil samples taken and analyzed in a lab to determine number and type of nematodes present.

Fumigate the soil, but chemicals are banned now.

Plough in a cover crop of mustard plant - contains compounds that work as biofumigants, killing nematodes.

Best solution is to use nematode-resistant rootstocks and ensuring plants bought from nurseries have been heat-treated to kill nematodes. Ramsey and Dog Ridge (V. Champini) are examples of nematode-resistant rootstocks.

Question 73

Describe how grape moths and how they damage grape vines

Answer 73

Different grape moths - Light brown apple moth (Australia), European grapevine moth (Southern Europe), Grape berry moth (central and eastern North America)

They feed on flowers and grapes. They have several generations per season, attacking flowers in spring and grapes later in season.

Wounds created are vulnerable to further attach from bacteria and fungi, including botrytis and significant crop losses

Question 74

Describe the management options for grape moths

Answer 74

Biological controls used include bacterium bacillus thuringiensis, which produces substances toxic to moths.

Use of pheromone capsules to disrupt mating and cause sexual confusion. Insecticides can also be used.

Natural predators can be used like parasitic wasps, green lacewings and some spider species.

Question 75

Describe how spider mites spread and how they damage grape vines

Answer 75

Several different species from region to region. Pacific spider mite (California), Red spider mite and 2 forms of yellow spider mites (Europe)

They feed on surface of cell leaves, leading to discolouration of leaves, a reduction in photosynthesis, delayed ripening and reduction in yields. They thrive in dusty conditions and must damaging when vines are already water stressed.

Question 76

Describe the management options against spider mites

Answer 76

Make environment inhospitable by use of water sprinklers and/or cover crops or mulches to reduce dust.

Encourage predatory mites (plant host species) that feed on spider mites.

General pesticides may kill mites. Specific sprays can be applied to kill only mites problematic in vineyard, but can add a cost

Question 77

Describe the damage that birds and mammals can make in the vineyard

Answer 77

Mammals damage vineyards by eating shoots, grapes and leaves, by breaking skins of grapes making them vulnerable to rot.

Question 78

Describe the management options against birds and mammals

Answer 78

Netting, bird scarers or noises (noises rotated regularly) and falcons can be used to manage birds.

Mammals can be kept out by fencing, but it has to be high and sunk into the soil to stop burrowing animals.

Question 79

Name the fungal diseases that affect grapes vines

Answer 79

Powdery Mildew, Downy Mildew, Grey Rot, Eutypa Dieback, Phomopsis Cane and Leaf Spot, Esca

Question 80

Name the bacterial diseases that affect grape vines

Answer 80

Pierce’s Disease, Grapevine Yellows

Question 81

Name the viruses that affect grape vines

Answer 81

Fanleaf Virus, Leafroll Virus

Question 82

Describe the fungal disease powdery mildew

Answer 82

Caused by fungus Erysiphe or called oidium tukeri. It overwinters in buds and on canes. It attacks young, green parts of the vine.

Affected parts of the vine show as dull grey patches that become black patches. The patches damage young shoots, inflorescences and grapes and reduces yields

Grapes can split at veraison and become targets for other infections.

Optimum temp is 25C and it thrives in shady conditions. It doesn’t require high humidity and can spread in dry conditions, especially dense, shady canopies

Question 83

Describe the management options for powdery mildew

Answer 83

Preferred approach is to keep an open canopy to reduce shade and density of leaves.

Application of sulfur helps prevent and treat the disease. Spray a few weeks after budburst and up to veraison. Important to spray early in season as it is easier to prevent than it is to contain once established.

Systemic fungicides can be effective - they penetrate green tissue of the vine and not washed off by rain. Fungus can become resistant to some fungicides, so only limited applications in a year

Question 84

Describe the fungal disease Downy Mildew

Answer 84

Caused by Peronospora, a water mould that lives in vine tissue, not on the surface. It attacks green parts of the plant, especially young leaves and flowers, reducing yields by defoliating the vine. Grapes can be affected, but less important than the threat of defoliation.

It needs rainfall and warm temps (20C) to spread. High-risk periods are warm springs and stormy but warm summers.

Symptoms are yellow, circular ‘oil spots’ and then white, downy fungal growth on underside of leaves

Question 85

Describe the management options for Downy Mildew

Answer 85

Spray made of copper salts used to prevent spread, but only lasts until 20 mm of rain has fallen. Bordeaux mixture (combo of copper sulfate and lime) became standard treatment in 1880s. Concerns about build-up of copper in soil - EU looking to reduce and ultimately eliminate its use.

Other fungicides can be used. Good drainage and open canopy that dries quickly are helpful to avoid the fungus from developing and spreading.

Question 86

Describe the fungal disease grey rot and how it effects grape vines

Answer 86

Fungus is called botrytis cinerea that causes significant damage to fruit resulting in loss of yield and drop of quality in wine.

Grapes vulnerable if any entry points (grapes rubbing together in tight bunches) leading to whole bunches being attacked.

If flowers affected, fungus can stay dormant in grape and re-emerge after veraison. Spores typically present in vineyard and become active in periods of rainfall and high humidity.

Question 87

Describe the management options for grey rot

Answer 87

Select varieties with small grapes, thick skins and high levels of resistance; protect grapes against other pests that can split skin.

Keep an open canopy and remove leaves around bunches can reduce spread of grey rot

Traditional sulfur and copper sprays are ineffective; other fungicides can be used. Apply fungicides at key points in season - flowering nearly complete, end of grape formation, bunch closure and veraison. Fungicides become quickly ineffective if fungus develops resistance.

Attention turning to using antagonistic bacteria like bacillus subtilis and other forms of biological control

Question 88

Describe the fungal disease eutypa dieback and how it effects grape vines

Answer 88

Also called dead arm, Eutypa Dieback is a fungal trunk disease that leads to rotten wood in vines that can affect the whole vineyard. Reduces yield and kills vines over 10-year period

Spores spread by wind over long distances. Infection occurs through pruning wounds in moderate temps, especially during rain.

Effects evident in spring with affected vines displaying stunted shoot growth and yellow leaves.

Widespread in South Australia, south-west France and parts of California.

Question 89

Describe the management options for fungal disease Eutypa dieback

Answer 89

Difficult to control, but pruning late and applying fungicides to pruning wounds can be effective.

Affected trunks can be cut back 5-10 cm beyond visible symptoms and treated with fungicides. Dead wood must be burnt to avoid spores spreading.

Some biological controls (Bacillus subtilis) may be effective.

If plant badly affected, can retrain from a sucker (shoot that grows from base of vine) left on trunk (causes loss of yield for 2 years) or removing the vine and replanting it.

Question 90

Describe the fungal disease phomopsis cane and leaf spot and how it effects grape vines

Answer 90

Phomopsis is a fungal disease that causes a reduction in yield. Prevalent in years with cool/wet springs followed by humidity and moderate temps.

Infected canes whiten and break off easily; shoots growing from these canes develop brown cracks at their base. Leaves also affected.

Question 91

Describe the management options for phomopsis cane and leaf spot

Answer 91

Fungicides should be applied every 3 weeks after budburst and then every 2 weeks if wet conditions persist.

Diseased and dead wood should be removed during pruning and removed wood then burnt or buried.

Canopy management to improve air flow with canopy may reduce risk of disease.

Question 92

Describe the fungal disease Esca and how it effects grape vines

Answer 92

Esca is a complex fungal disease caused by a group of organisms prevalent in warmer/drier climates (southern Europe, California)

It enters through pruning wounds. Symptoms include tiger-striping of leaves and spotting inside the wood.

Question 93

Describe the management options for Esca

Answer 93

No chemical controls. Pay attention to prevention. Sourcing disease-free stock, trying new, less detrimental pruning techniques, not pruning in the rain, removing prunings promptly from vineyard and disinfecting pruning wounds.

Research continues into using biological agents such as Bacillus subtilis.

Question 94

Describe the bacterial disease Pierce’s Disease and how it effects grape vines

Answer 94

Pierce’s Disease is a bacterial disease that quickly kills vines. Bacterium lives in sap channels of vines, which it clogs, leading to grape shrivelling, dropping leaves and death of the vine in 1-5 years.

Symptoms are unclear and vines must be tested in a lab.

Spread by sharpshooter insect, which acts as a vector (Glassy-winged sharpshooter)

Question 95

Describe the management options for Pierce’s Disease

Answer 95

No chemical control. Control by reducing the number of the vector. Remove vines close to rivers is effective as riverbanks can be habitat for vectors (blue-green sharpshooter)

Some chemical insecticides can be used. Introduce species of wasp that feeds on eggs of sharpshooters is effective.

Strict quarantine rules for movement of plants. Future work is being done to develop Pierce’s Disease-resistant vines

Question 96

Describe the bacterial disease Grapevine Yellows and how it effects grape vines

Answer 96

Group of bacterial diseases with no treatment. Spread by vectors (leafhoppers) and by nurseries selling untreated, diseased stock.

Symptoms include delayed budburst, drooping posture because new shoots fail to become woody, and canopy turning yellow (in white varieties) and red (in black varieties)

In some strains the vine dies as disease progresses, in others it can recover from an attack. Bacteria can live in a range of plants, including cover crops in vineyard.

Question 97

Describe the management options for bacterial disease Grapevine Yellows

Answer 97

There is no control against the bacteria.

Focus on controlling the vector. Leafhopper populations can be reduced by insecticides, and plants that host the hoppers, including cover crops, should be removed.

Best practice in nursery is to bathe pruning wood in hot water to kill the disease.

Question 98

Describe the viral disease fanleaf virus and how it effects grape vines

Answer 98

Fanleaf virus (fanleaf degeneration) is a group of viruses now found around the world. Early shoot growth is stunted, canes can grow in distorted ways and leaves are very pale, malformed and can look like a fan.

Effects vary widely from little effect to losing most of the crop in susceptible varieties like Cabernet Sauvignon.

Disease spread by moving grafted vines following phylloxera and inadvertent use of infected plant material. Otherwise, disease is spread slowly by dagger nematode.

Question 99

Describe the management options for fanleaf virus

Answer 99

There is no cure for fanleaf virus. Eventually, affected vines will have to be removed and replaced.

Before vineyards are replanted, soil tests should be done to check for presence of dagger nematodes and only virus-tested, clean planting material should be used.

Question 100

Describe the viral disease leafroll virus and how it effects grape vines

Answer 100

Leafroll virus is a group of viral diseases widely present in the world. It is spread by grafting and by mealy bugs, a key pest in South Africa, the Mediterranean, Argentina and some parts of California.

Condition does not kill vines. It can reduce yields by up to half and affect quality negatively. It slows down growth of roots and shoots.

Surviving fruit may take several additional weeks to ripen and have more acidity, less colour and lower sugar levels. Overall health of vine affected as it stores less carbohydrates.

Downward rolling of vine’s leaves occurs in autumn. Leaves change colour in autumn to red for black grapes and yellow for white grapes. Symptoms not always clear, so vines have to be tested in a lab.

Some vines and rootstocks carry the virus without showing symptoms.

Question 101

Describe the management options for fanleaf virus

Answer 101

There isn’t a cure for fanleaf virus. The only solution is to remove the unproductive vines and replant with virus-free stock. Nurseries can screen vines for infection.

Mealy bugs like humid environments, so open canopies help reduce the pest. Control by spraying is difficult because mealy bug’s waxy coating. Steps can be taken to encourage mealy bug’s natural predators: ladybugs, lacewings and others