Thursday, January 29, 2009

Extreme heat damage - UPDATE 29/1/2009

Shiraz at Blewitt Springs, McLaren Vale, SA

Day 2 of heatwave has caused sunburn on leaves and fruit

Shiraz grape berries shriveling.
Leaf cupping.
Cupped and scorched leaves have been seen. Some fruit is showing signs of shrivel like it can before harvest, however the fruit is only 9-10 oBe.

The most significant sunburn has been seen on blocks that face the western sun and have sandy soil which reflects heat back into the canopy. We need to wait until the hot weather passes to see how the vines will re-hydrate and resume 'normal' ripening.

In the medium term post harvest care of vineyards takes on an increased importance. Vineyards have experienced tough, dry growing conditions for 3 out of the last 4 years (2007, 2008, 2009). Many vineyards have been reduced in vigour compared to 2006. If this trend of devigouration continues vines will reach a point where they are too weak for quality fruit production. A drive around McLaren Vale will show some vineyards at this point already.

Play close attention to your vines after harvest, the heatwave will pass, and the condition of your vines will play a large part in future vintages.

Leaf scorching.

Tuesday, January 27, 2009

Do sunscreen products work on vines?

Obviously with the extreme weather many growers have been wondering 'what if?'

Some growers have asked about using sunscreen products to prevent heat stress and sunburn in grapes. Many consider the use of this products but few have actually applied them. Would they have made any difference with the extreme weather we have had?

Some growers worry about the residues they leave on fruit. A white residue is fine on vegetables which are scrubbed clean after harvest, but grapes are not able to be cleaned.

Parasol is a calcium carbonate liquid that can assist in the reduction of sun damage on fruit. Calcium carbonate is commonly know as chalk. Parasol is sprayed directly on the produce surface forming a dry, white film. It is supposed to reflect heat.

Another family of anti-stress products are based on kaolinite clay. Surround and Screen are commercially available products based on clay.

We are curious to see if this technology would have helped.

Hot weather and harvest - UPDATE 27/1/2009

Lower leaf yellowing.
The growth stages recorded early this week have ranged from 100% verasion in Pinot Noir and Pinot Gris, to 40% coloured in Grenache. Where tested for maturity these varieties are testing above 10oBe.
Many vineyards are now showing lower leaf yellowing as pictured above.

Some of the early season white varieties, Sauvignon Blanc, Verdelho and Chardonnay are nearing ripeness. The run of hot weather this week is expected to push much of this fruit to be near harvest within 5-10 days. This is particularly true for vineyards used for sparkling base wines.

It is likely that this hot spell before harvest will cause some harsh phenolics if vines are temperature stressed. Also be careful harvesting in warm temperatures to avoid oxidisation. Many wineries advise the use of PMS (Potassium Metabisulphate) in picking bins.

At this time of year in the Adelaide Hills and Southern Fluerieu ripening begins to slow compared to the warmer climates of Barossa and McLaren Vale. Over the last few days dews have occurred and in general night-time temperatures are much cooler. These blocks still have 4 weeks to harvest ripeness for the early varieties.

Thursday, January 22, 2009

Powdery Mildew Cleistothecia - UPDATE 22/1/2009


A light infection of Powdery on the berries – if you look closely you can see Cleistothecia. Cleistothecia are small fungal fruit-bodies that contain microscopic ‘seeds’ (called ascospores). These seeds fall off and lodge in bark to survive over winter. Powdery infection next spring comes from these spores, or alternatively flag shoots which are buds that were infected with powdery early this season.

Apple Moth - UPDATE 22/1/2009


Stressed fruit; Slow Veraison - UPDATE 22/1/2009


Small berries are not always a good thing in red grapes. In the last week vineyards with very small berries have been slow to change colour. This would indicate the vines have been under water stress in the lead up to veraison, and their leaves are not functioning well. This late colouring fruit may cause uneven ripeness at harvest.

Pictured is a block of Shiraz (above) at Willunga on heavy Biscay Soil is only 15% veraison this week - neighbouring vineyards with larger berries and a healthy have raced ahead to be 90% veraison.

Tuesday, January 20, 2009

Grapevine Mealy Bug - Identifcation Photos




Veraison - UPDATE 20/1/2009


The maturest red varieties are not at 80-90% veraison. We have observed that in vineyards with good, balanced canopies with good irrigation, veraison has moved quickly and evenly. Vines that are showing signs of water stress have been much slower in progressing through veraison. Some of these vineyards are still only at 10% verasions meaning only 10% of their fruit is coloured.

Saturday, January 17, 2009

Bulk Wine and 2009


Of great interest to grape growers is the latest report from Jim Moularadellis from Auswine Bulk Wine Brokers as seen on pg 84 of the January's Australia and New Zealand Grape Grower and Winemaker.

It gives a simple insight into scale of the problems now faced by the industry. To put things in context their are 29 million litres of Chardonnay on the bulk market, 24 million litres from last year alone. There are 22 million litres of Shiraz available, with 16.7 million being from the 2008 vintage.

Assuming crops of 15 tonnes to the hectare, in area terms, this is equal to ten times the amount of wine a region the size of McLaren Vale planted entirely to Chardonnay would produce. Ten Chardonnay only McLaren Vale's on the market. There are also seven McLaren Vale's of Shiraz, five of Cabernet Sauvignon and the area equivalent to four Langhorne Creek's of Merlot for sale.

It is a lake of a problem with exports dropping.

Of particular interest is this comment;

"In times of over supply, the price of all grapes becomes nearly the same, regardless of where they are from. In such circumstances, if presented with a choice, winemakers will more likely buy (generally better quality) cooler climate grapes and leave warmer inland grapes unpicked. This is what happened during 2005 and 2006 when conditions were similar to those expected for 2009. Not that this is great news for cooler climate growers because 2009 spot prices are likely to be below the cost of production in most regions," says Bill.

In summary prices for grapes for cool-climate regions are being forced down, as they are being used in place of warm-climate grapes which are going unpicked. Both sections of the grape growing community are under extreme pressure.

Thursday, January 15, 2009

Sunburn and heat stress - UPDATE 15/1/2009


Hot, dry conditions have persisted throughout the district and have reduced yield expectations in some vineyards.

Veraison in reds and softening in whites are well underway.

Sunburn and heat stress can be commonly confused with disease incidence. Brown or pink berries exposed in the sun can be confused with botrytis bunch rot. Scorched leaves may also be confused with downy mildew oil spots which can worry growers.

Botrytis - UPDATE 15/1/09


No Botrytis has been seen in McLaren Vale vineyards at this stage. It pays to think of botrytis in terms of rain events different varieties can sustain before showing signs of the disease.

This is a simple rule or thumb. There is more in determining why botrytis a problem at harvest in some vineyards and not others.


Botrytis level is dependent on three things in equal parts.

1= Canopy and bunch size.
2= An effective spray plan.
3= The weather conditions pre-harvest.

Late season chemical control is a protective measure and best applied before wet weather is forecast. Late season botrytis sprays reduce the spread of rot during wet weather.
Once established, botrytis is difficult to kill. Only sustained hot, dry weather will dry out the damaged and infected fruit.

Late in the season always consult your winery about your actions.

Non Chemical Options


Botrytis is suited by warm, wet conditions. Varieties with open canopies, thick berry skins and loose bunches dry much quicker then heavy canopies after rain events.

During the season there are several techniques that can be used to reduce the risks of botrytis. Pruning, irrigation and the use of foliage wires can reduce the bunch & canopy density improving the speed of bunch drying after rain or heavy dews. Good nutrition (low to moderate Nitrogen + high Calcium) helps thicken up berry skins.

Late in the season trimming can be used to increase airflow around bunches and decrease the amount of time canopies take to dry out. When considering trimming big canopies remember leaves ripen fruit! Sunburn is a real concern for fruit quality and it reduces crop yield. Vines need leaves and good cover from the afternoon sun.

One solution that has been used for vigorous Chardonnay in Blewitt Springs has been trimming the morning side of the canopy only. This is done late in the season after the vines have stopped growing. Trimming the eastern side only has the positive effect of increasing airflow around bunches, while leaving the west reduces sunburn risk, and leaves enough leaf area for ripening.

Please consult your winery about trimming pre-harvest.

Friday, January 9, 2009

Rust Mite - UPDATE 9/1/2009


Rust mite bronzing has been seen this week.
If you have a high level of rust mite on your leaves look at your practices this season. Rust mite is caused by an imbalance of natural predators and other environmental factors. Some newly planted vines are showing symptoms of rust mite. It is likely these have come in from the nursery and are now building up to a level that can be seen.

Veraison Irrigation


With the season looking like it may run later than last year, it is important to assess if you will have enough water to irrigate into March. Limiting water at veraison can be risky as hot weather is expect next week.

The next two weeks will be critical to your harvest and your end wine quality. If your vines stress too much you risk excessive leaf loss and poor ripening.
The first signs of sunburn have been seen this week.

Remember vines use the most water during veraison so avoid water stress to vines when berries soften and colour. Do not perform RDI (regulated deficit irrigation) during veraison.

Light Brown Apple Moth - UPDATE 9/1/2009

Light Brown Apple Moth egg mass on a green berry.
Light Brown Apple Moth Caterpillars may be active in bunches, particularly in tight bunched varieties where they are shielded from high temperatures. Pictured above; an egg mass has been laid on a developing berry.

LBAM caterpillar feeding on the leaf surface.
Light Brown Apple Moth don't damage leaves very much and not a great concern in young or grafted vines. The only exception is if they are active in shoot tips.

Thursday, January 8, 2009

Young Vines - Q&A


I need some help guys, I have been seeing red leaves in my new shiraz block. I have attached photos.


Many thanks,

Richard




There are several problems that will turn vines red like the one shown above. Redness is a sign of restriction. There are four possibilities;


Red vines.
1- String restriction. Young vines can be ring-barked by the string used to tie them. Also wind damage can damage the young vine, cracking it and turning the leaves red or yellow.

2- Nematodes. On light, sandy soils nematodes can attack the roots of young vines restricting growth and causing stunted growth and red leaves.

3- Cutworm or African Black Beetle. These insects live under the soil and ring-bark vines under the ground. They both also damage leaves. They are best seen at night when they are active above ground, otherwise search the soil.

4- Graft failure. For grafted vines check the union between the scion and the rootstock. If this is damaged or has failed it will cause red vines as shown above.

Healthy vines like the ones below are have now been topped and the grower is waiting for lateral growth to wrap down on the wire. Watch for Powdery Mildew building up on young vines as it can limit shoot growth and lead to disease issues in future seasons. Good control now makes control easier next season.

Healthy vines. Good leaf colour.

Powdery Mildew on Bunches - Identification Photos


Friday, January 2, 2009

Downy confirmed in Blewitt Springs - UPDATE 2/1/2009



A low level of oilspots has been found in Blewitt Springs, near Schuller Rd. This confirms the weather was suitable in at least some parts of the district to caused a 10:10:24 Primary event.
This is not a serious concern and no action is required. It is very late in the season and fruit is immune to infection.
One of these spots was tagged for future inspection. The others are being propagated for growers to see.
Interestingly another vineyard monitored nearby had no signs of Downy oilspots.

Severe Powdery Infection - UPDATE 2/1/2009


This is the most severe infection seen this year in a commercial vineyard. Fortunately for the grower is was only a localised patch of vines and all of the fruit has been dropped. The vines around this patch only have minor signs like the one shown below. This is more typical of the powdery we have been finding.

Yellow Speckle Virus - Identification Photos


Cabernet Sauvignon showing Yellow Speckle Virus. It shows up in some seasons by giving some leaves a yellow 'spray paint' look.

This is a common virus, like leaf roll which only has minor effects on the vine. In most cases you cannot notice any difference between clean and infected vines unless they have the speckled leaves. In trial work in the 1990's it reduced yield by 23%. http://www.ajevonline.org/cgi/content/abstract/43/1/31

Once vines have a virus, it continues for the life of the vine. Also any cuttings taken and propagated from these vines will have virus. It is best to get virus free cuttings when grafting or establishing a new vineyard.