Monday, November 28, 2011

Downy Mildew Oilspots at Berries Peasize - UPDATE 28/11/2011

The reverse side of a downy mildew oilspot showing sporulation.
Above - A series of pictures of downy mildew oilspots on leaves.

FAQ on downy mildew post infection products.

These are the answers to some common questions we receive. 

What is the hectare rate of Ridomil Gold Plus?

Ridomil Gold Plus

Preflowering - 150g/225g per 100lts
Post Flowering - 225g per 100lts
Therefore we work on 2.25kg/ha at this time of the year.

Axiom Plus is 150g per 100lts
Therefore 1.5kg/ha with a 1000 lt Dilute Spray Volume canopy size.

What is the price per kg and ha?

Ridomil Gold Plus

$ per ha = $120
$ per kg = $53

Axiom Plus

$ per ha = $74
$ per kg = $49

Zeemil MZ

$ per ha = $120
$ per kg = $47

What is the shelf life of the product?

When tested the shelf life of Metalxyl is indefinite and it lasts for many years. Samples have been tested that are 10 years old and still 99% effective. As long as the product is well stored it has an excellent shelf life. You can contact the manufacturer of your Metaxyl for more information.

The shelf life on the protectant component of Ridomil Gold Plus, copper, is considered to be good also if stored correctly. Note that all downy mildew post infection fungicides have additional protectant added to them when applying to vineyards.

The shelf life on Mancozeb (in Zeemil MZ) is 2 years. Therefore it is recommended for in season use not storage unless there are no other options.

Tuesday, November 22, 2011

GWRDC's Trial Tasting.

Thursday the 15th of December at Jacobs Creek.

You are invited to a wine tasting workshop hosted by the South Australian Research and Development Institute (SARDI) to taste wines from a hotter and drier future.

The wines to be tasted were made from grapes grown in a GWRDC project investigating the effect of elevated temperature on grapevine physiology and wine attributes.

Through GWRDC’s project, SARDI has established a trial with:

• four varieties grown under current conditions versus a 2-4oC increase in daytime temperature, and
• a Shiraz trail grown under current versus elevated temperatures in combination with frequent irrigation versus water deficit.

Unlike comparisons between wines from hot versus cool regions or between hotter and cooler vintages in the same region, these trials allow for a direct, unequivocal assessment of temperature effects.

The tasting of wines from the 2011 vintage will be held on Thursday 15 December from 1–4pm at the Jacob's Creek Visitor Centre, Barossa Valley Way, Rowland Flat.

Drop in any time between 1 and 4 pm to taste the wines and discuss the research behind the wines with Dr Victor Sadras and the team.

Please contact Martin Moran (martin.moran@sa.gov.au or 0448 928 513) to register your interest in the free workshop.

Monday, November 21, 2011

Latest Downy Mildew photos - UPDATE 21/11/2011

Our message –

“Take downy mildew seriously in the Adelaide Hills and those sites in on the Fleurieu that are like the Adelaide Hills. Use eradicants if uncovered as spread now will affect grape yield because flowers are highly susceptible to downy mildew.

For McLaren Vale prevent downy mildew building up to high levels like it did in some vineyards last season.”



 

What does this mean for my vineyard?


You fruit is immune to Downy infection once berries are appx. 2-5mm in size but leaves (and berry stems) remain at risk until harvest.

There is a low risk of Adelaide Hills grape growers losing bunches to Downy Mildew. CropWatch is more concerned about of further warm wet nights through December and January causing a build up of Downy Mildew Oilspots on vine leaves causing defoliation.

Thursday, November 3, 2011

Downy Mildew Oilspots at 80% Capfall - UPDATE 3/11/2011

A Downy Mildew Oilspot

Sodium Toxicity - What to look for

Sodium Chloride on older leaves.
Salt (sodium) toxicity blackens and scorches leaf margins. Look for older leaves with darkened edges which later scorch tan and curl upwards (sodium) and scorching extending inward to form patches between main veins (chloride).

Salt affected vines will show poor growth of vines and will have early leaf drop beginning with the older leaves first.

Wednesday, November 2, 2011

Powdery Mildew Flagshoot - UPDATE 2/11/2011

Powdery Mildew Flagshoot.

Dormant buds can be infected with Powdery Mildew and survive over winter. When these buds shoot they are deformed and covered with the Powdery Mildew spores. Note the stunted growth and ash-grey growth with distorted or upward curled leaves.

Tuesday, November 1, 2011

Wind Damage Vine Shoot Tips - UPDATE 1/11/2011



These are a pictures of wind damaged shoot tips taken in the Sellicks Foothills sub-district of McLaren Vale. The vineyard has just begun flowering (EL-19 Early Flowering) and is still rapidly growing. The main growing tip has been rubbed away by high winds and lateral shoots are beginning to push to compensate for this.

Fast growing vines and certain cultivars are more prone to wind damage. Damage to shoots is most common in spring and early summer when new shoots are fast growing and weak (green). Later in the season, after shoots have lignified (turned brown), leaf damage is more common. This late season wind damage is very common in the Sellicks Foothills sub-district of McLaren Vale.

Heavy leaf wind damage, late in the season, can cause a reduction in photosynthesis that may impact fruit quality.