Image: CSIRO Austrailia Source:www.ento.csiro.au Copyright: public domain
These small mites (<1mm.) are cigar-shaped and twice the length of their width. Adult mites are light yellow but can be white or orange. Adults are slender and have only 4 legs, all at the front of the body.
Host Plant: Timothy (Phleum pratense), barley (Hordeum vulgare), wild rye (Elymus triticoides), cultivated wheat (Triticum aestivum), Kentucky bluegrass (Poa pratensis), sedges, and hay crops.
Evidence of their presence on the plant is off-colored foliage and leaf or bud abnormalities. Symptoms appear as retarded growth, stunting, and plant discoloration. Injured plants appear to be drought stressed even when adequate moisture is available for plant growth. A large infestation of mites can severely reduce crop yield; and if the fields can be harvested their monetary value is considerably reduced. Abacarus hystrix is also known to vector ryegrass mosaic virus (RMV), a serious disease of temperate grasslands, and may be a vector of agronpyron mosaic virus (AMV), a minor disease of wheat and other grasses. These diseases cause substantial losses to pasture production in other parts of the world; thankfully, RMV and AMV have not been detected in the USA.
The mites overwinter in the adult and egg stages. Overwintering adults deposit eggs in the leaf vein grooves. The eggs appear as very small yellow spheres. The immature stages are similar to the adult, but smaller. Immature mites begin hatching in March, with the peak adult populations being reached peaking in April. Damage is most evident in April and May. As leaves unfold, eggs and the immature stages are distributed higher in the canopy. Adult mites move downward into the plant crown, where they prefer to feed on the youngest tissues of the plant. The mites undergo numerous generations per year, with a generation time of 16-18 days. Unlike most pest mite species, this mite prefers cooler temperatures and tends to be less active during warmer summers months.
It was discovered in Maryland in the early 1990s and by 1999 it as confirmed as the cereal rust mite. Since then it has spread to other Northeastern United States.
U.S. Habitat: Temperate pastures or crop fields with timothy, rye, barley or hay crops.
U.S. Present: DE, MD, PA
As a precaution, fields should be checked regularly for mites before spring. When checking, look for eggs and juvenile mites in the specific area of the leaf veins. A potential management option is to reduce the length of the grass in the cooler months. Studies have shown that trimming grasses reduces the number of mites. If rust mites become a problem, Sevin XLR Plus is still the only labeled, effective material available.
Gibson, R. 1974. Studies on the feeding behaviour of the eriophyid mite Abacarus hystrix, a vector of grass viruses. Annals of Applied Biology, 78 (3), pp. 213-217.
Gibson, R. 1976. Effects of Cutting Height on the Abundance of the Eriophyid Mite Abacarus hystrix (Nalepa) and the Incidence of Ryegrass Mosaic Virus in Ryegrass. Plant Pathology, 25(3):152-156.
Skoracka A. and Kuczynski L. 2004. Demography of the cereal rust mite Abacarus hystrix (Acari:Eriohyoidea) on quack grass. Experimental and Applied Acarology. 32:231‐242.