DISTRIBUTION AND MANAGEMENT OF THRIPS (THYSANOPTERA, THRIPIDAE) ON NECTARINE IN THE MID-ATLANTIC REGION

Adult thrips flight activity was monitored with water traps in nectari ne orchards in 4 locations in the mid-Atlantic region in 1992. Thrips infestation at bloom and subsequent injury at harvest were evaluated. Twenty-nine species of thrips were recovered in water traps. Western f lower thrips, Frankliniella occidentalis (Pergande), comprised 92% of the thrips in water trap samples at a site in south central Pennsylvan ia where 16% of the nectarines were silvered (thrips damage). At anoth er site in south central Pennsylvania and at sites in north central Pe nnsylvania and southern New Jersey, flower thrips, F. tritici (Pitch), were most numerous and silvering did not occur. The only injurious th rips recovered from blossoms was pear thrips, Taeniothrips inconsequen s (Uzel), at the north central Pennsylvania site where increased scarr ing was observed. Silvering was correlated with the number of thrips p er fruit and was most extensive in the lower 3rd of the canopy in 2 ne ctarine orchards. In held applications, formetanate hydrochloride and methomyl both reduced silvering injury by western flower thrips, with the former providing a longer period of protection. Cumulative thrips days were highly correlated with the percentage of fruit receiving mod erate levels of silvering.