Manganese is required in very small quantities, found in enzymes used in photosynthesis and in the production of a plant hormone called auxin. Plants use this nutrient to remove hydrogen peroxide from within cells.
Iron toxicity can indicate manganese deficiency, which will show on new growth with the leaf margins becoming paler to yellow with the veins remaining green, with dead or dying lesions spotted across them. Distinctive sunken white areas start to appear.
To correct a deficiency
- ensuring there is not an excess of iron
Toxicity will show up on the older leaves first, which will have pale green/yellow areas between the veins which turn red-brown. Purple spots can be seen on the petioles, stems and the leaf underside veins. Excessive manganese can cause iron deficiency.
To offset excessive Manganese
- foliar sprays of manganese sulfate
- ensure pH levels are not too high
Soil testing is an important activity for a successful garden. Soil stewardship is an ongoing process, where you test and amend, grow some stuff, then test, amend and grow some stuff….and so on. Focus on building soil tilth so it can really hold and make available to the plants all the important nutrients. You do this in part by adding compost, manure, rock dust, bone meal, kelp & fish emulsions. Read this article series to learn more about each of the 13 key nutrients for your garden.