Russet Mites: A Tiny Threat to Greenhouse Tomatoes
As we approach the end of February 2025, greenhouse tomato growers should be on high alert for a microscopic menace that can wreak havoc on their crops: the tomato russet mite (Aculops lycopersici). These minuscule pests, barely visible to the naked eye at just 0.17 mm in length, can quickly lead to severe plant damage if not addressed promptly. Despite their size, the impact of russet mites on greenhouse tomatoes can be substantial, making early detection and effective management crucial for maintaining healthy, productive plants.
The symptoms of a russet mite infestation often begin subtly but can escalate rapidly. Initially, growers may notice browning on the stems near the substrate, often accompanied by a slight curling of leaves and a silvery sheen on their undersides. As the infestation progresses, a characteristic bronzing or "russeting” appears on stems, leaves, and fruits. Leaves may yellow and curl, eventually turning brown and brittle, while losing their trichomes. The damage typically moves upward as mites migrate to higher parts of the plant. In severe instances, stems can turn a rusty brown color and may even break under severe stress. Fruits aren't spared either, often developing a coarse skin with a reddish-brown hue and possible deformities. Overall plant vigor, health, and flower production can be significantly reduced as the infestation progresses.
To combat russet mites effectively, greenhouse tomato growers should implement an integrated pest management (IPM) approach. Biological control methods, such as introducing predatory mites like Transeius montdorensis or Amblyseius swirskii, can be highly effective. These beneficial predators should be released regularly, along with additional breeding prey to ensure their sustained presence and efficacy. Chemical control options include sulfur-based products and horticultural oils, though these should be avoided during flowering stages. Azadirachtin-based sprays like can be useful during vegetative growth phases. Cultural practices play a crucial role as well; maintaining proper sanitation by removing plant debris and infected material, along with optimizing environmental conditions, can help deter mite populations. Some growers may also consider planting tomato varieties with fewer sticky trichomes, which can facilitate better establishment of predatory mites.
Regular monitoring is essential in the fight against russet
mites. Growers should inspect their plants frequently, starting from the lower
portions and gradually moving upward. Given the mites' tiny size, a loupe or hand
lens with at least 14X magnification is necessary for spotting these elusive
pests. By combining vigilant monitoring with a multi-faceted control approach,
greenhouse tomato producers can effectively manage russet mite populations and
safeguard their crops from significant damage. As we move through this growing
season, staying informed and proactive about pest management will be key to maintaining
a healthy greenhouse tomato crop.
W. Garrett Owen
Assistant Professor of Sustainable Greenhouse and Nursery Systems, The Ohio State UniversityW. Garrett Owen is an Assistant Professor of Sustainable Greenhouse and Nursery Systems in the Department of Horticulture and Crop Science at The Ohio State University. He has an appointment in research, teaching and Extension. His area of expertise is plant nutrition; plant growth regulation; and production problem diagnostics.
