Apple Rust Mite – Aculus schlechtendali

Apple Rust Mite: Appearance, Territory, Damage, and Life Cycle

Latin Name: Aculus Schlechtendali (Nalepa)

Appearance: A tiny mite called the apple rust mite (ARM) lives on an apple leaf. This eriophyid is found in apple orchards all over the world. It is widespread in managed blocks despite being more prevalent in untreated trees. Two pairs of legs are located at the front of the body of the vermiform adult. They have a color that is brownish yellow and cannot be seen without a minimum magnification of 15X.

Hosts Plants: The apple rust mite preys on domesticated apples as well as various other Malus species. It has been discovered in mixed populations with the pear rust mite and can also live and breed on pears.

Territory: Eastern North American states and provinces that grow the majority of fruits.

Damage Insect Cause: The apple rust mite inserts its mouthparts into plant cells and sucks off the liquid inside. This feeding gives the leaf a silvery cast in the early stages, which develops to brown as the season passes. Apple rust mite bronzing is finer-grained than spider mite bronzing and lacks the stippling generated by spider mites. Rust mite damage leads leaves to roll lengthwise on occasion.

Damage, like other pests that harm the foliage, impairs photosynthesis and the water balance of the plants. Rust mite feeding can cause early terminal bud set in addition to decreasing fruit size. Rust mites can also eat directly on fruit skin, causing a tan russeting.

Life History and Habits: This mite’s motile stages are cone- or sausage-shaped and difficult to see with the naked eye. A powerful hand lens is usually required to examine the leaf midrib for mite presence.

Adult female apple rust mites overwinter behind the bud scales of apple trees. They start actively at bud break and feed and reproduce until July or early August when overwintering females are generated. Apple rust mites are considered advantageous in low numbers because they provide an alternate food source for predators of European red mites and two-spotted spider mites.

Using a 15X magnifying glass, keep an eye on populations on leaves during the summer. Miticides can be utilized if the population is very high, but smaller populations are valuable as prey for predator mites.