How to Manage Pests

Pests in Gardens and Landscapes

Mineral deficiencies

Certain nutrients, in relatively small amounts, are required for healthy plant growth. Deficiencies can cause tip chlorosis or necrosis or cause foliage to discolor, fade, distort, or become spotted, sometimes in a characteristic pattern that can be recognized to identify the cause. Fewer leaves, flowers, and fruit may be produced, and these can develop later than normal and remain undersized. More severely deficient plants become stunted and exhibit dieback. Nutrient deficiencies rarely occur in most woody landscape plants. When they do occur, nitrogen and iron are the most commonly seen deficiencies. However, nutrient deficiency symptoms usually are not due to a deficiency in the soil but are caused by conditions that reduce a plant's access to them. Poor root growth caused by water-logged soil, root diseases, and nematodes can cause deficiency symptoms. Commercial laboratories can conduct foliage tests or soil analysis to verify deficiencies.



Fertilize only as needed and only if other problems have been eliminated as the cause of poor growth. Most woody ornamentals don't require regular fertilization. Avoid overfertilization, especially with high-nitrogen fertilizers. Slow-release formulations of nitrogen or organic fertilizers reduce some risk of overfertilization. Correcting deficiencies of minerals is tricky. Apply only the mineral found to be deficient. In some cases, soil characteristics may exacerbate deficiencies. Alkaline soil (high pH) often makes iron or manganese less available; reducing alkalinity with sulfur or organic amendments (peat moss) may be all that is needed. Some minerals such as iron, manganese, and zinc are absorbed more rapidly as a foliar spray than a soil application.

For more information refer to the publication Abiotic Disorders of Landscape Plants.

Yellowing of leaves with nitrogen deficiency

Statewide IPM Program, Agriculture and Natural Resources, University of California
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