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Evaluating Plant Moisture Stress in Cabernet Sauvignon with the Introduction of Genesis Soils Rhizo-Gen Mycorrhizal Components.
Bruce Coulthard Genesis Soils 10-27-09


I. Objective:

To quantify levels of stress in four to eleven year old Cabernet vineyards using a Plant Moisture Stress Indicator, (PMS), also known as a Pressure Bomb. The objective was to compare the differences of stress using beneficial fungi compared to non inoculation.

II. Materials and Methods:

The product used is Genesis Soils Rhizo-Gen. Rhizo-Gen is a trade name which includes an extremely high grade of mycorrhizal inoculum with five species of indigenous mycorrhizal species for grapes. Also inclusive are several proprietary components that differentiate Genesis Rhizo-Gen from a rudimentary approach. Simply put, mycorrhizae alone will not give you the results that this combination offers.

Each vine was inoculated with Rhizo-Gen liquid through the existing drip system by means of an Ag Solution Master in field mixing unit. Inoculation took place in early July, 2008.
Vines were pre irrigated with two gallons of water, then the inoculation followed with an additional one gallon, followed by a post inoculation irrigation of two gallons. Careful consideration was taken for the following 30 days to add additional two gallon irrigations two weeks apart to ensure adequate moisture at the root zone to aid in the colonization of the mycorrhizae.

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Fertilization was corrected by using California Organics Phytamin 4-3-4 liquid. Applications were on a regular basis as recommended by the label each time irrigation was used. Correction was from a generic synthetic high P and N which inhibit mycorrhizal hyphal colonization to the organic based fertilizers which allow colonization to occur. All six vineyard blocks had two control rows next to each other in various locations in the vineyard blocks. All other rows were inoculated.

PMS readings were taken by the same employee, at the same vines, at the same time each day. Commencement of readings was 7-2-09 and completion was 9-25-09. The readings were a total of 432, control, inoculated. Air temperatures were taken simultaneously.

The vineyard location is Spring Mountain Vineyard and the application was under the direction of Ron Rosenbrand, vineyard manager.

III. Test Progress:

During the data accumulation period, careful consideration was given to keep the normal irrigation regimes in place to keep the stress levels in check. The PMS readings that are typical in this hillside vineyard are 10-14 Bars for this time of year. Once the readings reach 15 or greater, water is applied to reduce the transpiration rate. We were working within a 10-14 bar active window during the summer months.

IV. Results:

Consistently all readings that were Genesis applied were 1-2 bars lower than the control rows. This equates to a 25-50% reduction in stress levels as evidenced by the PMS readings. The estimated water savings were estimated at an early stage to be 20-40%.

V. Observation:

It is clear the use of Genesis Rhizo-Gen has significantly reduced the stress level and water needs for this hillside vineyard. Most interesting from my perspective was the rate of recovery in the Genesis vines after irrigation was applied. This tells us that the vines that were Genesis applied are able to store more water and nutrients due to their excessive healthy root structure. By increasing the root volume, naturally you will increase the roots water reservoir that each plant needs to use during excessive stress periods. This in simple terms allows the plant to continue its natural growth and maturity without unwanted periods of stress.

Roots are what bring life to the plant, when stress occurs especially in young plants the root will simply stop growing, get progressively smaller until it is able to access water. This natural phenomenon of constriction in roots is similar to girdling a tree by cutting back or off its water supply. A root when growing in a healthy environment will grow; let’s say the size of a pencil. When excessive stress affects the root it will grow smaller in size, like a pencil lead. When the root resumes natural growth again, it increases in size back to the size of the pencil. The constriction that has occurred in the root system is permanent. Plants will naturally grow new roots in time, but damage has occurred. Many farmers are fooled by this into thinking the plant is showing signs of stress thinking it needs more water, and this misread leads to more irrigation and potential drowning of the root systems.

This information that we have gathered is ground breaking for Genesis, simply due to the fact we only have had data for vineyards from 1-4 year old. We know the results are astounding from nursery level through 4 year plants. Blocks from Spring Mountain Vineyard varied from 4th leaf all the way to 11th leaf.

It is mandatory to understand that mycorrhizae alone will not give you the results we know through many crops, grapes included. It is the holistic approach of the many other components included that separate Genesis Rhizo-Gen from other rudimentary attempts. This differentiates Genesis from others.

VI. Conclusion:

It is evident the difference is substantial. The water savings that are now available due to the efficiencies of the plants due to the introduction of Genesis Rhizo-Gen are also very appealing financially. In areas where water is at a premium or only available by building reservoirs, now the vineyard owners have a very attractive option.

Fruit maturity and flavors were attained easily, as the vines were on the healthy curve of stress and their was no additional delay at harvest.

We were asked three years ago by the vineyard industry to specifically show the differences, control verses Genesis Rhizo-Gen mycorrhizal applications in Napa vineyards to better understand specifically the differences to better evaluate its importance. This report is a very large step in that direction as far as water conservation and plant stress is concerned.

There are literally some 50,000 technical papers on the effects of beneficial fungi on agricultural crops. We know plant health is foremost in the grape industry for the production of world class wines. Mycorrhizae and its natural associates are at the pinnacle of healthy productive soils.

Please email us for our Excel supporting data.


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