Gerbera: Distorted New Growth
Around 5 gerbera plants were found in a commercial greenhouse with new leaves that were darker in color, thicker, and distorted. This type of damage can be the result of a number of possible issues. A few of the more common possible causes include (1) a boron deficiency [distorted upper leaves], (2) herbicide drift [but these plants were in the middle of the bench and one would expect a drift situation to appear closer to the air intake vent for instance], (3) aphids [aphid damage results in leaf curling and one should be able to notice actual insects, and none could be seen with the naked eye], (4) Western flower thrips [damage is more notching of the leaves and distortion when they grow out. One should also be able to observe thrips on the leaves.], and finally (5) broad/cyclamen mites [these cause distorted new growth, are known to feed on gerbera, and require a 100X microscope to view].
Based on prior experience, a boron deficiency or broad/cyclamen mites topped the possibilities list. So first I headed to a 100X microscope to look for mites. Bingo! They were fairly easy to find and identify as broad mites with their unique eggs. It always surprises me that the degree of damage than only a few mites can cause.
Additional information about mites and to view photos, please the following e-GRO Alerts:
e-GRO Alert 1.16 Broad Mites on New Guinea Impatiens
e-GRO Alert 5.38 Broad Mites on Ornamental Peppers
e-GRO Alert 5.23 Broad Mites on Ornamental Ipomoea
Brian WhipkerProfessor, Horticulture, North Carolina State University
Brian E. Whipker is a professor of floriculture at North Carolina State University. He has an appointment split between extension and research, but also teaches the graduate level plant nutrition course at NC State. His specialization is plant nutrition, plant growth regulators, and problem diagnostics. He brings over 30 year of experience in diagnosing grower plant problems.