One of the most well-known hardy annual plants, pansies make up a significant part of fall production for greenhouse growers. Diagnosing nutrient problems early can help prevent problems from persisting. Where an issue is spotted on a plant can give important clues as to what the nutrient deficiency is. Here’s some advice from North Carolina State University’s Brian Whipker on how symptoms on different parts of plants can help identify the disorder.
Deficiencies in mobile nutrients manifest themselves in the lower leaves of plants.
Purpling. Lower leaf purpling in pansies can be a sign of a lack of phosphorous. These symptoms can also be an indicator that there’s another physiological problem that led to a nutrient deficiency, such as root rot, oversaturated substrates or cold growing conditions. In one example, plants with root rot caused by pythium or phytophthora exhibit the lower leaf purpling associated with a phosphorous deficiency.
“Without a root system, the plants cannot take up phosphorous, so lower leaves are turning purple,” Whipker says. “It’s always wise to inspect the roots to help determine what is ailing the plant.”
Yellowing. Completely yellowed lower leaves are often a symptom of nitrogen deficiency or overall low electrical conductivity (EC).
“Check the EC to see if the fertilizer level is adequate,” Whipker says. “Lower leaf necrosis is usually caused by high EC. When plants are grown dry, lower leaves can develop a brown necrosis.
“To confirm your diagnosis, send a substrate or tissue sample for a complete nutritional checkup.”
Interveinal chlorosis is a sign of magnesium deficiency, although this is not a common problem in pansies.
Black/bronze/brown coloration. And although low pH symptoms do not often occur on pansies, lower leaves can develop a blackish purple coloration or overall plant growth can be slowed.
Blackish-purple spotting that eventually affects the entire leaf can occur when pansies are grown with low pH and low temperatures during the winter.
“Excess boron will also result in a marginal necrosis of the lower leaves,” Whipker says.
Leaf burn. Plants suffering from water stress can succumb to the drydown symptoms of brown leaf tips evident on the entire plant, especially on the lower leaves.
Deficiencies in immobile nutrients manifest in the upper leaves of plants.
Interveinal Chlorosis. One of the major nutritional problems with pansies is iron deficiency, which is manifested in upper leaf interveinal chlorosis. In advanced cases of high pH-induced iron deficiency, interveinal chlorosis is more pronounced and covers the entire leaf. In these cases, new growth becomes white and necrotic spotting can appear. Root rot can also limit plants’ uptake of iron and cause interveinal chlorosis and could ultimately cause plant death.
Distorted plug growth. Another problem of the upper foliage is distorted plug growth. A deficiency of boron leads to this situation. During rapid plant growth, boron uptake is inhibited, which can lead to a temporary deficiency.
“Improving airflow and avoiding excessive irrigation helps prevent the problems from occurring,” Whipker says.
Mottling. If you find distorted new pansy growth and leaves that are mottled with white, your crop may have the rare pansy mottle syndrome.