December in the Tamar Valley, Tasmania

In the Cellar

Fruit set

Fruit set

Early December sees the flowering grapes set fruit.

It is desirable that during this period we have even mild weather so that there are no undue stresses on the inflorescence during pollination.

The photo left shows fruit forming in its early stages on a Pinot Noir Vine.

Normally there are at least 2 florescences on each growing cane within 40 cm of the wire.

If your vines are vigorous and demand pruning, a good time to do this just on flowering.

It stops the vines putting energy into growth and concentrates fruit set.

Lateral growth will commence after this type of pruning,

so it is important that you either remove fruit clusters that form on the lateral growth

or at least not include these higher bunches in your later sampling.

Naturally being 3 or 4 weeks behind the primary fruit set,

they will develop much later and severly compromise sugar levels and flavour if included in the harvest.

Estimating bunch numbers

Now is good time to check the fruit set on your vines and do an early estimation of bunch numbers.

Ideally I like my vines to crop at about 3-4 kg per vine.

This means that with 24 canes on each vine producing an average of 2 bunches per cane, with an average mature bunch weight of 90 grams,

you can expect a harvest of about 4 kg per vine.

This is a very approximate estimate, however it gives a guide as to whether you need to consider fruit thinning if your estimates exceed this.

A compromise on fruit quantity is usually the result if you attempt to crop at a higher level than this.

Pinot Noir is prone to overcropping. Whilst you may get a good harvest one year, the next year will be compromised due to a poorer bud development in the season prior.

This is caused by the vine putting too much energy into ripening fruit rather than developing buds.

If you aim at the 3-4 kg per vine for Pinot Noir, you will find that this is about right.

Some growers prefer to thin their vines to crop at 2-3Kg per vine.

In a small vineyard, I cannot afford this luxury. The quality of my wines to date has been excellent at the levels I suggest.

Fruit thinning

If your figures show that buch numbers are high, it is a good time to thin bunches.

There a two ways you can attempt to do this.

1. Remove the small cluster at the top of each bunch .

At the top of each bunch there is usually a small cluster on a separate stem to the main cluster.

This usually ripens at a slower rate than the main cluster.

2. Remove one bunch per cane or a proportion of the fruit evenly through your vines.

This is best done early so that the energy of the vine goes into producing for the ripening of the fruit remaining.

Canopy management

As I have said before, December is a time when you will probably need to trim your canopy once it reaches the top of your trellis system.

Allowing the vines to continue their vigorous growth will lead to them overhanging your lower leaves and shading them.

It is essential in cool climate areas to allow the maximum sunlight to reach the leaves which are producing sugar for your fruit.

Keep your canopy to no more than 12-14 healthy leaves per cane.

I will feature a video clip in the January notes on this management practice.

Spraying Program

December usually brings with it rising temperatures and a risk of Powdery Mildew

Powery Mildew occurs in all vineyards especially in temperatures between 24 - 30 degrees celsius.

Once temperatures start to rise, you need to be vigilent for the signs of this disease,

as grapes infected by this fungal disease taint wine beyond repair.

Grape vines are most susceptible to Powdery Mildew from flowering to 4-5 weeks after fruit set.

A dense canopy with poor air circulation will increase the risk of a severe powdery Mildew outbreak.

Regular spraying with Ecocarb each 10-14 days and a reapplication after rain will lower the risk of a severe infection.

Early symptoms of Powdery Mildew include flagshoots: stunted diseased shoots with ash-grey growth and upward-curled or distorted leaves.


The life Cycle of Powdery Mildew


Look for in shoots

The Centre for Environmental Stress and Adaptation Research has an excellent data base that allows a search for the harmful effects of active ingredients in chemical sprays commonly used in Australian vineyards.


In The Cellar


Next Month:

Trimming the Canopy

Balance in the vine

The importance of water for fruit development













This page was last updated on 13/11/2013