Labor Day Research

The algae on my red-leafed plant has prompted me to do some homework on my day off. Since I measured phosphates at 10 ppm (granted, I've been aggressive with them to keep down green spot algae, although I haven't eliminated green dust algae, but fortunately, it's non-toxic), I've done a 180 (I'm very fickle, which is probably not good), and decided to keep up the regular water changes for now. Let's try strict adherence to the EI method again, and see if that doesn't help out (keeping CO2 up, as well).

Anyway, while digging up on the internet for nutrient toxicity information (I was generally worried because of the high phosphates) I was very very impressed by this article on Tom Barr's website where he details the results of a report that outline deficiency and toxicity for a variety of nutrients. I'll quote it here in case it is taken down at some point (non-italicized words are Tom Barr's commentary).

Deficiency Symptoms for the Essential Elements in ppm
Element Symptoms

Nitrogen: Stunted growth, foliage becomes yellow (chlorotic) starting in older leaves. Some crops (corn, tomatoes) may show a reddish color instead of yellow.

Phosphorus: Plants are dwarfed with thin stems and small leaves. Anthocyanin pigments may accumulate giving plants a purplish color occurring first in older leaves.

Potassium: Older leaves develop marginal browning which can extend into the leaves, and forward curling of leaves.

Calcium: Shoot tips yellow and die back, young shoots have abnormal growth with eventual die-back. New leaves affected first with distorted leaf growth; roots tips die back leaving short stubby roots with black spots.

Magnesium: Interveinal chlorosis developing first on the older leaves. Withering of old leaves.

Sulfur: Yellowing (chlorosis) of leaves usually beginning in new leaves. Yellowing becomes off-tan in many crops.

Iron: Interveinal chlorosis beginning on younger leaves.

Manganese: Interveinal chlorosis on leaves near the tip of the plant. Leaves may develop necrotic lesions and drop.

Boron: Die-back of shoot and root tips, stunted growth. Internal tissues may discolor or become hollow in cauliflower and beets. Leaf symptoms include curling, brittleness, wilting, chlorotic spots.

Zinc: Shortened internodes, young leaves are small, may show interveinal chlorosis.

Molybdenum: Interveinal chlorosis beginning on older leaves moving up to younger leaves.

Toxicity Symptoms for the Essential Elements

Nitrogen: Foliage is heavy with many dark green leaves, few flowers and fruits.

Phosphorus: Rarely occurs, no symptoms noted. May lead to a deficiency of nitrogen, potassium, zinc or copper.

Potassium: Rarely occurs, expressed as magnesium deficiency.
Please note this reference, it was impossible(not today though) for me to finda good toxicity character for high K other than salinity type of stress factors.

Sulfur: Reduction in leaf size, leaves may show interveinal yellowing.

Calcium: Symptoms usually expressed as deficiency of potassium, magnesium, iron, manganese, or boron.
See this as it's a very popular suspect on the various forms and boards and is typically wrong!

Magnesium: Poor growth.
Note, no stunting of growth tip suggested here.

Iron: Dark green foliage may develop manganese or zinc deficiency.

Manganese: Chlorotic leaves with uneven chlorophyll distribution and dark brown spots.

Chlorine: Burning of leaf margins becoming necrotic in time, reduced leaf size.

Boron: Younger leaves deformed, yellowing or necrosis of leaves beginning at leaf tip.

Zinc: May result in iron deficiency.

Copper: Reduced growth, may lead to iron deficiency.

Molybdenum: Rarely occurs, leaves of tomatoes turn yellow.

Adapted from Resh, H.M. 1983. Hydroponic Food Production, 2nd Edition. Woodbridge Press Publishing Co., Santa Barbara, Ca. pp. 335. and Bergman, Ernest L. 1985. Nutrient Solution Culture of Plants. The Pennsylvania State Univ. College of Agriculture, Extension Service Hort. Mineo Series II:160. pp. 21.

Literature Cited
1. Arnon, D.I. and P.R. Stout. 1939. The essentiality of certain elements in minute quantity for plants with special reference to copper. Plant Physio. 14:371-375.
2. Cooper, A.J. 1973. Root temperatures and plant growth. IN: Res. Rev. 4, Commonwealth Bureau of Horticulture and Plantation crops. Commonwealth Agriculture Bureau, England.
3. Bergman, E.L. 1985. Nutrient Solution Culture of Plants. The Pennsylvania State University College of Agriculture, Extension Service Hort. Mimeo Series II:160. pp.21.
4. Hartman, H.T., W.J. Flocker and A.M. Kofranck. 1981. Plant Science Growth, Development and Utilization of Cultivated Plants. Prentice-Hall, Inc. pp. 676.
5. Ingratta, F.J., T.J. Blom and W.A. Straver. 1985. Canada:current research and developments, p. 95-102. IN: A.J. Savage (ed.). Hydroponics Worldwide State of the Art in Soilless Crop Production. International Center for Special Studies, Honolulu, Hawaii.
6. Jackson, M.B. 1980. Aeration in the nutrient film technique of glasshouse crop production and the importance of oxygen, ethylene and carbon dioxide. Acta Hort., 98:61-78.
7. Janick J. 1979. Horticulture Science. W.H. Freeman and Company, San Francisco. pp.608.
8. Joiner, J.N. 1983. Nutrition and fertilization of ornamental greenhouse crops, pp. 380-403. J. Janick (ed.).IN: Horticultural Reviews, Vol. 5, AVI Pub. Co., Inc. Westport, CT.
9. Jones, J. B. Jr. 1983. A Guide for the Hydroponic and Soilless Culture Grower. Timber Press, Beaverton Oregon. pp. 124.
10. Lorenz, O.A. and D.N. Maynard. 1980. Knott's handbook for vegetable growers, 2nd Edition, A. Wiley-Interscience Pub. John Wiley & Sons, New York, NY. p. 390.
11. Mastalerz, J.W. 1977. The Greenhouse Environment. John Wiley and Sons. pp. 629.
12. Noggle, G. R. and G. J. Fritz. 1983. Introductory Plant Physiology, 2nd Edition. Prentice-Hall Inc. Englewood Cliffs, New Jersey. pp. 625.
13. Resh, H. M. 1983. Hydroponic Food Production, 2nd Edition. Woodbridge Press Publishing Co., Santa Barbara, CA. pp 335.
14. Salisbury, F.B. and C. Ross. 1969. Plant Physiology. Wadsworth, Belmont, CA. P. 422.
15. Varley, J. and S. Burvage. 1981. New solution for lettuce. Grower April:19-22.
16. Wareing P.F. and I.D.J. Phillips. 1970. The Control of Growth and Differentiation in Plants. Pergamon Press, Ltd., New York. pp.303.
17. Westwood, M.N. 1978. Temperate Zone Pomology. W.H. Freeman and Co. pp. 428.
18. Wittwer, S.H. and S. Honma. 1979. Greenhouse Tomatoes, Lettuce and Cucumbers. Michigan State University Press, East Lansing. pp. 225.

So perhaps I need to stop worrying about toxicity so much...