Matteson, Nancy A.

Morrison, Melinda

Sandvol, Larry E.

Stoltz, Robert L.

Whitmore, Jim

Undetermined

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Section IVBARLEY THRIPS SURVEY IN IDAHO, EASTERN OREGON AND WASHINGTONNancy A. Matteson, Robert L. Stoltz, Larry Sandvol, JimWhitmore andMelinda MorrisonUniversity of Idaho, Twin Falls R & E Center, P. O. Box 1827, Twin Falls, ID 83303-1827INTRODUCTIONThe barley thrips (Limothrips denticorrtis Haliday) is a new pest in Idaho. In theU.S. it hasbeen found to cause economic damage in barley but is found in winter grains and early springgrasses. Feeding damage causes symptoms that include a characteristic whitened or bleachedappearance of the plants and misshapen or gooseneck shaped stems. Feeding by both adultsand immature thrips is by rasping and sucking the juices from plant leaves and stems. Thisresults in the loss of color and, as the damage progresses, the drying and death of the leaves,stems and grain head.Adult barley thrips are dark brown toblack in color and small, between 1.1 and 1.8 mm (0.04to 0.07 in) long. It has a long, narrow body shape, usually appearing pointed atboth ends. Itis found from Canada to the central United States but is native to Europe, parts of Asia andSiberia. It was first found in the United States in 1923 and by the early 1950's had beenobserved in large numbers in North Dakota spring barley. In 1990 the first reports of barleythrips in Idaho barley were reported in the Tetonia area. In the Fall of 1991 more informationwas requested of the University of Idaho Extension Service by eastern Idaho barley growersconcerning the biology and damage potential of barley thrips. A sampling program funded bythe Idaho Barley Commission was begun in eastern Idaho in 1992 to help determine thefollowing: 1. Adult overwintering sites. 2. Time of adult female migration into the barleycrop and early season damage assessment. 3. Test North Dakota treatment thresholds underIdaho conditions. 4. Distribution of barley thrips within Idaho.RESULTSAfter preliminary sampling of soil and plant tissues, it was determined that barley thrips mostlikely overwinter in soil rather than the plant tissues of aspen bark or sagebrush. Further soilsampling was concentrated within three major vegetative zones; sagebrush, aspen stands andCRP areas. The results of this sampling showed significantly more barley thrips in sagebrushthan in aspen stands with virtually none being found in CRP plantings.Observations of early spring migrations from overwintering sites were made by utilizing whiteand yellow sticky cards. Sixteen sites were monitored weekly from mid-April to 10 August1992. Data collected indicated barley thrips catches on the white cards were significantlygreater than on the yellow cards. Yellow cards were discontinued on 8 July and counts werethen made from the white cards only until 10 August. Peak flights were observed in mid- tolate May and again in early August. The first flight peak represents the migration fromoverwintering sites to, and probably within the barley fields. The second flight peakrepresents themigration outof thematuring barley crop back tooverwintering sites.Barley plant tissue sampling was conducted weekly at the same 16 sites when fields reached atleast the 3 to 4 leaf stage (early June) and continued through harvest. Adult counts (100%female bias sex ratio) increased to mid-June, dropped slightly through July with a secondincrease peaking in early August. Immature barley thrips were first observed in early Julywith counts increasing to a single peak in late July. The peak of immature thrips probablyresulted in the early August adult peak. Data also indicated a single generation was producedm eastern Idaho during the 1992 growing season.47The Idaho, Washington and Oregon aphid suction trap system coordinated by Dr. SusanHalbert, University of Idaho, Aberdeen Research and Extension Center, was made available in1992 to determine, within the systems limits, the range of barley thrips in Idaho. This systemalso provided valuable information concerning barley thrips in eastern Washington andOregon. Barley thrips were collected in suction traps from Tetonia, Bonners Ferry, Moscow,Lewiston, Craigmont and Ririe. In Washington, with several sites still to be counted, thripswere collected in trap samples from Wilbur, Prescott, Ritzville and Central Ferry. With onlyhalf of the Oregon locations counted at this time, no barley thrips have been counted inCorvallis, Pendleton orMoro. Although in 1992 none of these locations, other than Tetonia,have reported economic losses in barley to the barley thrips, further monitoring of these areasis indicated. Proposed projects for the 1993 season include repeating many of the samesampling procedures from 1992 with the addition of chemical efficacy and thrips densityeffects on yield.48

Barley Thrips Survey in Idaho, Eastern Oregon and Washington

https://ir.library.oregonstate.edu/downloads/b27741932

Barley Thrips Survey in Idaho, Eastern Oregon and Washington

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