Cone, Wyatt W.

Wright, Larry C.

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Section 1Mites and Sap-Sucking InsectsASPARAGUS APHID CONTROLIN DRIP IRRIGATED ASPARAGUSBY DISULFOTON'INJECTIONT. WildmanWSU-IAREC, Box 30, Prosser, WA 99350ABSTRACTA 0.03 ha planting of asparagus irrigated by a biwall tubing dripirrigation system was used in 1983 and 1984 to test the efficacy ofdisulfoton (di-syston , Mobay Chemical Corporation) for control of theasparagus aphid Brachycorynella (=Brachycolus) asparagi Mordvilko wheninjected into the lines of the system. A single injection of di-syston 8EC was administered at the rate of 1.1 kg ai/ha in early August of bothyears. In 1983 the aphid was controlled for at least 50 dayspost-treatment. The mean numbers of aphids were significantly lower in thetreated than in the untreated asparagus fern on all sample dates (P<0.0005,Student's t). Residue analysis by gas-liquid chromatography revealed thattotal disulfoton residues in the treated asparagus peaked at 4.25 ppm 23days post treatment and declined to 0.35 ppm after 54 days. In 1984 theaphid was controlled for at least 40 days post-treatment. The mean numbersof aphids per sample in the treated asparagus fern were significantly lower(P<0.01, Student's t) than in the untreated on 3 of 6 sample dates.Residue data from 1984 was unavailable at the time of this writing.DEVELOPMENT OF A SAMPLINGPLAN FOR THE HOP APHIDL.C. Wright and W.W. ConeIAREC Washington State UniversityProsser, WA 99350ABSTRACTTwo sampling methods were used due to the growth of hop vines: onebefore and one after the vines grew to the top of the trellis. Before thevines reached the top of the trellis, aphid numbers on main stem leavesgenerally increased with height on a vine. After the vines reached the topof the trellis, there was no clear relationship between aphid numbers onmain stem leaves and height. However, there were fewer aphids on side armleaves than on main stem leaves. Before and after the vines reached thetop of the trellis, the number of aphids on main stem leaves at 2 meterswas highly correlated with the mean number of aphids per vine. Sampling atthis height is not only accurate but alscu relatively easy. Taylor's powerlaw (log variance=a + b log mean) fit the data extremely well and was usedto calculate the number of samples needed for the desired level ofaccuracy. A sequential sampling plan which can reduce the number ofsamples was also constructed using Taylor's power law.

Development of a Sampling Plan for the Hop Aphid

https://ir.library.oregonstate.edu/downloads/dv140028g

Development of a Sampling Plan for the Hop Aphid

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