Manganese deficiency occurs primarily in palms. It also occurs when plants grow in adverse soils, such as soil that is alkaline (high in pH) because high pH reduces manganese availability to roots. Manganese deficiency also occurs where soil is compacted or poorly drained, which causes aeration deficit and impedes roots ability to take up nutrients.
Identification
In manganese-deficient palms new leaves are uniformly chlorotic with necrotic streaks. Younger leaves remain smaller than older fronds. As manganese deficiency worsens, emerging new leaves and older leaves become distorted, necrotic, and withered, giving palm canopies a scorched, shriveled, undersized appearance.
Manganese deficiency in broadleaves causes new leaves to be yellow to whitish with relatively wide, green areas along the veins. On severely affected leaves, brown dead spots develop between veins. Leaf margins may become crinkled, curled, or wavy, and shoot growth can be reduced.
In conifers, manganese deficiency symptoms closely resemble iron deficiency. New needles are stunted and chlorotic, while older, lower-canopy foliage remains green.
Phytotoxicity from preemergence herbicides causes similar symptoms but primarily damages older leaves first, while manganese deficiency symptoms occur mostly in newer leaves. Manganese deficiency symptoms closely resemble iron deficiency and any differences are too variable and unreliable to visually distinguish these maladies.
Solutions
Diagnose and remedy this malady as described for iron deficiency under "Solutions." Lower soil pH, increase soil organic matter, and otherwise improve the plant’s cultural practices and growing environment.
Manganese chelates can be applied to new foliage as a quick, temporary remedy. Follow product labels and avoid excess application as too much manganese can be toxic to the plant and cause marginal yellowing and brown spotting of leaves and stunting of plant growth. See "Soil and Fertilizer Management" in the California Master Gardener Handbook for more information.
Adapted from the publication above, Abiotic Disorders of Landscape Plants, UC Agriculture and Natural Resources, and Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, University of California Statewide Integrated Pest Management Program (UC IPM).
