Managing mite vectored viruses of wheat

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Managing mite vectored viruses of wheat

Jacob A. Price and Charlie M. Rush

If you see this message, it means that your browser doesn’t support frames or they are disabled. You can access the information shown in this frame here: Mite Movement. Three common viral pathogens that affect wheat in the Texas High Plains are Wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), and Wheat mosaic virus (WMoV). These virus complexes causes severe damage to wheat production and are transmitted from one plant to another during feeding by a microscopic mite called the wheat curl mite Fig. 1.

Green Bridge Illustration

Fig. 2

Volunteer wheat and other grass hosts serve as a green bridge (Fig, 2) for the wheat curl mite which and are blown by winds into wheat fields during the fall and spring, where they transfer the viruses during feeding. Due to the small size of the wheat curl mite scouting for infestation is impossible and producers usually do not realize infestation has taken place until symptoms of virus infection appear in late March to early April.

WSMV foliar symptoms

Fig. 3

Producers commonly mistake virus symptoms (Fig. 3) for other abiotic stresses such as drought and nutrient deficiency causing them to increase inputs such as fertilization and irrigation. During infection these pathogens not only reduce grain and forage yields but also reduce the plants ability to uptake water from the soil. This is of particular importance in irrigated agricultural systems where the cost of irrigation is high and water resources are low. Therefore, management and detection of these diseases before and after infection is of great importance.

How do I reduce my risk of virus infection?

There is no one way to reduce the risk of infection and multiple methods must be used together in an integrated system.

  • Most importantly destroy all volunteer wheat at least two weeks before planting
  • Plant late whenever possible
  • Use mite and virus resistant cultivars
    • TAM 112 has been found to have good resistance to the wheat curl mite
    • Virus resistant cultivars such as RonL and Mace have temperature sensitive resistance and must be used in conjunction with late planting only when temperatures remain below 25° C (75° F).
  • Early detection of infection – Samples can be submitted to the Plant Diagnostics Clinic at the Texas A&M AgriLife Research and Extension Center in Amarillo.

Funding by the Texas Wheat Board and the Ogallala Initiative

Future Research

Many factors that affect wheat curl mite movement from reservoir areas such as volunteer wheat and perennial grasses are still unknown. Movement of the wheat curl mite within infested fields also causes plants to become infected at different times throughout the wheat season. At this time the extent of damage caused by these pathogens and how it relates to water use and yield losses at different times of infection is largely unknown. Also, factors such as temperature and rain fall have on disease severity and spread of the wheat curl mite still remains a mystery. Only after answering these questions, then can a truly affective integrated pest management system be produced to reduce the effects of these diseases. Future research projects are being developed to answer these questions and create an affective integrated pest management system for use not only in the Texas High Plains, but also throughout the wheat growing regions of the United States.Future directions for research

  • Develop an economic threshold for mite-vectored virus diseases including Wheat streak mosaic virus
  • Development of integrate pest management options that will impact mite populations and reduce subsequent disease development and yield loss
  • Reduce overall mite populations by evaluation of genetic resistance and timely and effective pesticide application by cite specific management practices

Any questions about the above projects or information please contact Dr. Charlie Rush or Jacob Price, Texas A&M AgriLife Research, Amarillo, TX.

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