Nutritional Disorders

Geranium with “Brown Speckle” Symptoms Due to Low pH

The symptoms on this geranium are due to iron and manganese toxicity, a nutritional disorder associated with low growing medium pH (below 6.0). This problem is sometimes called "bronze speckle" due to the numerous small brown spots on the leaves. Zonal geranium, American marigold and all types of impatiens are susceptible.

See the fact sheets: pH and Fertility Review for Annuals, University of Massachusetts

Geranium - Nitrogen Deficiency

When temperatures are cool during March, growers may fertilize geranium hangers at very low rates. However with the increase in the angle of the sun and increasing day temperatures the plants are pushing more growth therefore requiring more nutrients. This has resulted in plants showing nitrogen and magnesium deficiency in this photo. Nitrogen is an important component of nucleic acids, amino acids, enzymes and chlorophyll in the plant. Deficiency of nitrogen may cause the plants to appear stunted with light green lower leaves while upper leaves remain green.

Over-fertilization and Soluble Salts Injury on Mums

Providing adequate fertility is important in maintaining optimum plant growth in mums. However over-fertilization can result in high concentrations of soluble salts that can cause injury to the plants seen in this photo. Chrysanthemums are among a number of plant species known to have susceptibility to soluble salts injury. Over-fertilization results in high concentrations of soluble salts in the medium. As the salts are translocated throughout the plant they accumulate at the leaf tip and margins and when they reach toxic levels they cause “salt burn”.

Calcium deficiency - Ornamental cabbage

Hot, humid summer weather may cause poor transpiration resulting to calcium deficiency in the ornamental cabbage. Leaf edge burn (tip burn) is a symptom of calcium deficiency.   Calcium is immobile in the plant therefore deficiency symptoms show up first on young growing leaves. In cabbage the young leaves are internal leaves. Margins of the inner leaves may turn brown to black.

New Guinea Impatiens - Twisted leaves

Twisted growth can be caused by physiological or nutritional disorders, broad mites or ethylene.

New Guinea impatiens may exhibit twisted foliage and edge burn as a result of high soluble salts. Cupping and wavy leaves also appear to be favored by dry soil and cool moist air. These symptoms commonly show up in March and April and usually disappear as weather improves later in spring. Orange cultivars appear to be prone to this condition and have exhibited these symptoms in early spring.

Uneven Transplants

This photo shows uneven distribution of controlled release fertilizer prills in 72 size cells used for growing vegetable transplants for the field. One cell had 2 prills, another had 7 or more prills. Controlled release fertilizers pre-mixed in the growing media can cause uneven growth if the fertilizer prills are not uniformly distributed between the cells. Growers should work with their media suppliers to match the proper growing media with the cell size being used. Growers can count the prills in the individual cells to determine the accuracy of the distribution of prills.

Soluble salt injury on pansies

These pansies were first thought to be nutrient deficient due to the light green color of the foliage. An electrical conductivity (EC) test revealed high soluble salts. High growing medium EC can injure or inhibit the growth of plants. Common causes of high EC include: excess fertilizer (too high level or too frequent application), subirrigation, root disease, or restricted drainage. A soil test is almost always needed to confirm a soluble salts problem.

Soluble salt injury on geranium root

Notice damaged, dark colored roots on this geranium. Combination of controlled release fertilizer (see prills at top left of roots) and liquid fertilizer contributed to high soluble salts. Roots are just beginning to regrow after plants have been leached. These symptoms could also be caused by Pythium root rot. In many cases, injured geranium roots also have Pythium.


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