Monitoring Grapevine Nutritional Status
Bloom is here and it is a great time to get an accurate assessment of the nutritional status of your grapevines.
What to sample? Soil or leaf petioles.
Soil sampling should be performed before planting and every 3 years, primarily to track the pH. Sample each block as you would for other crops.
The more direct method for determining the nutrient status of the vine is tissue sampling, specifically petiole sampling (Figure 1. Grape leaf blade and detached petiole). Petiole sampling should be performed every 2-3 years in established plantings. You may need to sample annually when establishing the vineyard.
Figure 1. Grape leaf blade and detached petiole
When to sample? Sampling at full bloom is the most common time, as it provides a longer window for in-season corrective actions. Sampling during early veraison is the most stable time of the season. Time of day matters, sample in the morning.
How to sample? Pick leaves of uniform age. Choose a leaf on a primary shoot opposite the basal flower cluster (Figure 2. Grape leaf opposite the basal flower cluster), if sampling during bloom time. Collect the youngest fully expanded leaf, if sampling during veraison.
If possible, pick only one leaf from each vine.
Avoid damaged leaves, whether from insects, disease, or mechanical injury. Avoid dirty leaves and vines near roadways or from the outer rows of the block when possible.
Remove the petiole from the leaf and place into a clean paper bag. Avoid contact with metal surfaces. Use your fingernails to separate the petiole from the leaf blade.
Sample from both sides of the canopy.
Sample from throughout the entire block that is managed as one unit. Large vineyard blocks with substantial variation (e.g. in elevation, or vigor) may require multiple samples.
If you observe mineral deficiency symptoms, sample affected and unaffected leaves separately.
Figure 2. Grape leaf opposite the basal flower cluster
How many pieces to sample? One hundred petioles for each sample. If the cultivar has very short petioles then collect two hundred petioles.
How to handle the sample pieces? Make sure they are clean. If they are dusty or have been sprayed with foliar fertilizer or a phosphorous acid fungicide, rinse in distilled water. Do not soak them. Dry the sample on paper towels until fully dry or in an oven at 200°F and then place in clean paper bags at room temperature and send to the laboratory.
Sufficiency values for nutrients in vineyards
| Sufficiency range | |||
| Nutrient (symbol) | In soil | In petioles at bloom | In petioles at veraison |
| Total Nitrogen (N) | -z | 1.2 – 2.2% | 0.8 – 1.2% |
| Phosphorus (P) | 20 – 50 ppm | 0.17 – 0.30% | 0.14 – 0.30% |
| Potassium (K) | 75 – 100 ppm | 1.5 – 2.5% | 1.2 – 2.0% |
| Calcium (Ca) | 500 – 2,000 ppmy | 1.0 – 3.0% | 1.0 – 2.0% |
| Magnesium (Mg) | 100 – 250 ppm | 0.3 – 0.5% | 0.35 – 0.75% |
| Boron (B) | 0.3 – 2.0 ppm | 25 – 50 ppm | 25 – 50 ppm |
| Iron (Fe) | 20 ppm | 30 – 100 ppm | 30 – 100 ppm |
| Manganese (Mn) | 20 ppm | 25 – 1,000 ppm | 100 – 1,500 ppm |
| Copper (Cu) | 0.5 ppm | 5 – 15 ppm | 5 – 15 ppm |
| Zinc (Zn) | 2 ppm | 30 – 60 ppm | 30 – 60 ppm |
| Molybdenum (Mo) | -x | 0.5 ppm | 0.5 ppm |
| Aluminum (Al) | < 100 ppmy | ||
| Organic matter | 3-5% | ||
| pH | 5.5 (for natives) 5.0 (for hybrids) 6.5 (for V. vinifera) |
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| Notes: ppm is the abbreviation for parts per million.If soil values are reported in lbs./Acre, divide by 2 to convert to ppm.If values are reported in percentages, multiply by 10,000 to convert to ppm.If values are reported in ppm, divide by 10,000 to convert to percentages. Adapted from: Wine Grape Production Guide for Eastern North America. Editor T.K. Wolfe. (Cooperative Extension NRAES-145) |
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z Soil nitrogen is not normally evaluated for vineyards in eastern North America
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Where to send the samples?
| Your local chemical supplier may provide this service. | A & L Great Lakes Lab, Inc. 3505 Conestoga Drive Fort Wayne, IN 46808(219) 483-4759 |
| Rutgers Soil Testing Laboratory *(soil only) Rutgers, The State University of New Jersey 57 US Highway 1 New Brunswick, NJ 08901-8554(848) 932-9295 |
Plant Analysis Laboratory/ICP Fruit & Vegetable Science Dept. Cornell University Ithaca, NY 14583 (607) 255-1785 |
| Agricultural Analytical Services Pennsylvania State University University Park, PA 16802(814) 863-6124 |
Virginia Tech Soil Testing Lab 145 Smyth Hall Blacksburg, VA 24061(703) 231-6893 |