Got Mites? Scout Timothy for Infestations of Timothy Mites
High numbers of Cereal Rust Mites feeding on a timothy leaf blade. Image Credit: A. Frankenfield, Penn State Extension
Timothy mite, which is a form of cereal rust mite that has specialized on timothy, can cause headaches for many timothy growers, particularly in eastern and southeastern Pennsylvania, where the pest seems to have spread to most pure timothy fields, reducing growth and crop quality.
To determine whether this pest species is active in your timothy fields, scout fields for signs of damage. Mite feeding causes leaf blades to roll up. Look for leaf blades that are rolled up tightly, rather than leaf blades that are flat and normally expanded. The mites are very small, so to see them you will need a good hand lens or other magnifying device. Pick rolled leaves from around the field and inspect them carefully; mites tend to occur in grooves between the leaf veins. Treatment is recommended if 25% of tillers show the leaf curling within several weeks of green-up.
There is only one chemical option: Sevin XLR Plus has a supplemental label in Pennsylvania allowing its use against mites on timothy. Carrier rates of 20-25 gallons per acre and higher pressure than usual are needed to get the material into the leaf rolls.
Feeding by mites causes two negative impacts, yield loss and quality. Yield losses have been estimated at 30-70% and hay quality is reduced due to dead, brown leaves. Timely application and spray coverage is important for effective control. Typically, first-year fields are not as likely to have high populations of mites as older fields. If your fields meet the threshold of 25% of leaves being curled, then treatment is recommended to prevent mites from being successful and spreading, causing more leaves to roll.
