Guidelines for plant tissue quick test

1. Standardized tissue sampling has not been developed for ornamentals. A suitable plant part, preferably a thick leaf petiole or midrib from recently matured leaves can be sampled. A few drops of tissue sap must be pressed from the sample. Standardize the sampling unit throughout the monitoring period.

. Obtain a representative sample. A minimum of 20 plants should be sampled. Sample at the same time of the day and from the same part of the plant. Keep samples cold until the tissue sap can be extracted. Allow the temperature of the sample to come to room temperature before pressing the tissue.

3. Place a composite sample in a garlic press and press a few drops of sap from the sample. The sap should be placed immediately on the nitrate-selective meter. Record the nitrate concentration.

4. Sufficient nitrogen values for the sap of ornamentals have not been established. Crops require different amounts of nitrogen at different growth stages. Recordkeeping is important to establish basic needs of the crop for different growth stages.

Record the levels of petiole nitrogen and corresponding crop quality. Consistent recordkeeping will help determine what the levels mean. Nitrogen level trends, whether they are increasing or decreasing, and maximum and minimum nitrogen levels are important to consider during crop evaluation. Weekly sampling is recommended.

© 2001 Branch-Smith Publishing