Iron deficiency symptoms have been observed on petunias. At this time in the growing season, Iron (Fe) deficiency symptoms are starting to appear on bedding plants and other spring greenhouse plants. The main symptom of Iron (Fe) deficiency is chlorosis or yellowing, usually starting at the shoot tip and newly developed leaves. The yellowing or chlorosis may appear only between the veins (interveinal chlorosis) or the entire leaf may be chlorotic. As the problem gets worse the color of the chlorosis may change from yellow to white.
Because of cool temperatures some growers have been fertilizing geranium hangers at very low rate. However with the increase in the angle of the sun and increasing day temperatures in the growing the plants are pushing more growth therefore requiring more nutrients. This has resulted in plants showing nitrogen and magnesium deficiency. 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.
Cercospora leaf spot caused by Cercospora violae, can damage the overall appearance of pansies and reduce their marketability and value. The disease is favored by extended periods of high humidity with nighttime leaf-wetting and daytime drying. The disease can come in through infected seed or weeds of the Viola family. The fungus overwinters in seed, infected crop residues, or in weeds of viola family. A few infected plants can produce large amounts of inoculum causing a lot of plants in the house to be infected.
Plant growth regulator (PGR) recommendations vary from species to species & with plant age but from a practical matter growers need to control plant growth across a wide range of plant species at the same time and as efficiently as possible. In practice, growers face two complicated situations on a regular basis (1) relatively small plantings of many different species and or varieties are in the same house at the same time, and (2) relatively small of plantings at different stages of development are present in the same house at the same time.
Another complicated situation in spring is how one handles growth when different species are mixed in the same container.