Sap activity, which transforms excess ingested sugar into long-chain oligosaccharides." A much larger set of animals do however consume phloem sap by proxy, either "through feeding on the honeydew of phloem-feeding hemipterans. Honeydew is physiologically less extreme than phloem sap, with a higher essential:non-essential amino acid ratio and lower osmotic pressure," or by feeding on the biomass of insects that have grown on more direct ingestion of phloem sap. Maple syrup is made from reduced sugar maple xylem sap. The sap often is harvested from the Sugar Maple, "Acer saccharum". In some countries (e.g., Lithuania, Latvia, Estonia, Finland, Belarus, Russia) harvesting
Plant tissue test performed by a commercial company will cost the grower a fee. Laboratory tests take at least a week to complete, usually 2 weeks. It takes time to dry the samples, send them to the lab, complete the lab-tests, and then return the results to the grower. This means the results may not be received by the grower until after the ideal time to take action. Nitrogen tissue tests that can be performed quickly in the field make tissue testing much more useful. Another issue with laboratory tissue tests is that the results are often difficult to interpret. Non-destructive tissue tests