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¶ Grapes (Vitus rotundifolia, e.g. "Muscadine" variety)
¶ A: Full bloom
Plant Part: Petioles from most recently developed, matured leaf
Sampling Procedure: "Full bloom" considered to be when about two-thirds of the flower caps have been shed. Collect a representative sample from 25 to 40 vines of the same variety. Collect petioles from two mature, fully expanded leaves on each vine, usually the fifth to seventh leaves from the shoot tip. Avoid young or senescent leaves. Detach each petiole from the leaf blade immediately.
| Analysis | Tissue Concentration Guidelines | ||||||||
| Low/Marginal Range | Sufficiency Range | Excessive, toxic? | |||||||
| Nitrogen, % N | 1.35 | - | 1.65 | 1.65 | - | 2.15 | |||
| Phosphorus, %P | 0.10 | - | 0.12 | 0.12 | - | 0.18 | |||
| Potassium, % K | 0.70 | - | 0.80 | 0.80 | - | 1.20 | |||
| Calcium, % Ca | 0.60 | - | 0.70 | 0.70 | - | 1.10 | |||
| Magnesium, % Mg | 0.12 | - | 0.15 | 0.15 | - | 0.25 | |||
| Sulfur, % S | 0.13 | - | 0.15 | 0.15 | - | 0.60 | |||
| Zinc, ppm Zn | 15 | - | 18 | 18 | - | 35 | |||
| Iron, ppm Fe | 50 | - | 60 | 60 | - | 120 | |||
| Manganese, ppm Mn | 50 | - | 60 | 60 | - | 150 | |||
| Copper ppm Cu | 3 | - | 5 | 5 | - | 10 | |||
| Boron, ppm B | 10 | - | 15 | 15 | - | 25 | |||
| Nitrogen-to-sulfur ratio (N:S) | 15 | - | 20 | 10 | - | 15 | |||
| Sodium, % Na | > 0.35 | - | 0.60 | ||||||
| Chloride, % Cl | > 0.30 | ||||||||
| Nitrate, ppm NO3-N | |||||||||
| Phosphate, ppm PO4-P | |||||||||
¶ Figure A.
Note: Overall vine vigor and leaf appearance are the best indicators of nitrogen status. Weak growth, poor leaf color and fruit set, and early defoliation indicate low levels of one or more nutrients. Delayed vine and fruit maturity and excessive vigor suggest an over-application or late application of nitrogen. Highly vigorous vines may not not need nitrogen, regardless of tissue levels.