Tuesday, April 3, 2018

Organic Compost.

Compost contains organic carbon and nutrients whilst also adding soil moisture retention, structure and increasing root mass. It is added to vines after harvest to integrate into the soil over winter.

Above - Bulk Organic Compost is applied with a Marshall spreader.

Organic matter is vital for good soil health and adding quality compost with organic carbon to the soil helps to improve soil condition. McLaren Vale soils are generally low in organic carbon. We record levels in vineyards between 0.5% to 3.0%.

Remember that value is not just about how much compost costs. While chicken manure is cheap per cubic meter, per tonne of nutrient it is expensive and can have side effects.


As the Willunga based composters Petes Soil say on their website,
"Poorly or non-composted materials pose the risk of introducing pests and pathogens, weed seeds and may behave less predictably than material which has undergone the stabilising phase of the composting process. Non-composted manures may conceal a surprising amount of salt, contributing significant amounts to the soil with prolonged use."
Banded compost applied under the vine row as a soil amendment - Willunga, McLaren Vale Wine Region, SA.

Wednesday, March 14, 2018

Shoot Growth Post Harvest - Is this a problem?

The importance of the post-harvest period is largely determined by climate, variety, yield, and management prior to harvest. Vines will tolerate a season or two with limited post-harvest irrigation, but productivity will eventually be reduced if this continues over many seasons. In the same vain they are thought to tolerate excessive irrigation and fertiliser for one or two seasons before  the vine becomes unbalanced. 

Clearly in the picture below the rate of fertiliser and irrigation has been too high and the vines have re-shot.
Excessive shoot re-growth in Shiraz - 3/4/13.
With all organic options it is best to check with us and your certification body before use! 

For conventional vineyards DJ's also recommend using 'soft' fertiliser products instead of Urea which is straight Nitrogen. DJ's use techgrade MAP, NutriPHlow or a specialist fertiliser like KRISTALON which contain a combination of Nitrogen, Phosphorous and Potassium.

We recommend this because:
  • Like carbohydrates, grapevines require a supply of nutrients from stored reserves to support growth in early spring. Nitrogen in the roots and wood follows a similar pattern to carbohydrates and post-harvest applications will influence the nitrogen status of the vine in the following season.  
  • These products are highly soluble.
  • The role of other nutrient reserves is less well understood, but post-harvest uptake of phosphorus does appear to be important. To a lesser extent, magnesium, calcium and potassium uptake after harvest will also contribute to growth in the following spring. Little is known about the role of other nutrients carried over winter in grapevine tissues.
Further reading.

Mod1-PostHarvestCare

Thursday, May 11, 2017

Bud Dissection - Q&A

Hi,

I am curious about looking at grapevine buds under the microscope.

Could you also please let me know how many buds you can dissect in an hour, as I have a uni project to do on yield analysis and the number would be of assistance.

Many thanks,

Andrew



Dear Andrew,

Almost anyone can learn to dissect buds, but not everyone has the patience to sit down and complete many samples. We use a compound microscope with to eye lenses that give a stereoscopic view of the inside of the bud.  This allows us to assess the internal bud structure and look at the inflorescence primordia which are the structures that develop into grapevine flowers.



Bud Dissection.


We would average two to three buds a minute, therefore it takes us between one and one and half hours to complete a vineyard (30x; 5x bud canes).  We would generally limit ourselves to three vineyards per day to keep our eyes fresh.

 
The time it takes to dissect buds under a microscope varies from variety to variety. Sauvignon Blanc has small buds and small inflorescences which make it the slowest variety to assess. Grenache has large buds and large inflorescences which are the quickest to assess.


Low bud fruitfulness and high primary bud necrosis is linked to vigourous vineyards.

 


Internal bud structure.
We perform dissections to look for low fruitfulness and assess the level of primary bud necrosis.

If we find problems with fruitfulness eg. levels below 1 bunch per bud (inflorescence primordia per bud), or high levels of bud death from primary bud necrosis, we advise growers to change their pruning in the short term and look at their management in the long term.

It is when you find blocks like these bud dissections come into their own as a vineyard tool.

DJ's agronomist Matthew Wilson says,  

"Vineyards with high levels of lateral shoot growth can show low levels of fruitfulness. Primary bud necrosis is often common in vigorous vines and this is contributing to low fruitfulness. If you can catch this before pruning you can take action to prevent correspondingly low yields at harvest."

Primary Bud Necrosis (PBN) note how the centre bud has died but the two secondary buds are viable. This would indicate that secondary buds will burst in place of the larger primary bud.

For more information refer to bud dissection and primary bud necrosis.