Delrio, G., Ortu, S., Prota, R., 1979.
Aspects of integrated control in the citrus cultures of Sardinia. Studi Sassaresi, 27: 205-232.
Abstract
Preliminary tests on integrated control were carried out in 2 areas of citrus culture (Simaxis, Siniscola) in Sardinia in 1979. On orange at Simaxis, Planococcus citri (Risso) was the most important pest, followed by Panonychus citri McG. and Dialeurodes citri (Ashm.). The natural enemies of the 1st 2 pests, which are listed, did not occur in sufficient numbers to control them, and 2 combined applications of an insecticide mixture of mineral oil and methidathion (against Planococcus) with an acaricide mixture of chlorfenson and propargite (Propargil) (against Panonychus) were required, this treatment also limited populations of D. citri, which were already reduced by the predator Clitostethus arcuatus (Rossi). Cryptolaemus montrouzieri Muls., Leptomastix dactylopii How. and Encarsia lahorensis (How.) (Prospaltella lahorensis) were introduced to supplement the biological control of Planococcus and Dialeurodes. At Siniscola, Ceratitis capitata (Wied.) was the most important pest of clementines. Population density was monitored by means of traps baited with trimedlure, and weekly catches reached a maximum of 150 males/trap. Owing to continuous rain in September and October, 3 applications of a bait-spray containing hydrolysed protein and fenthion were insufficient to control the infestation, in November, 40% of the fruits were punctured but only 2% contained living larvae. In June, a heavy infestation by aphids (especially Aphis citricola v.d. Goot) was recorded on about 50% of the clementine shoots. A single application of selective insecticides controlled the infestation without affecting coccinellids and other predators. On orange in the same locality, bait-spray applications reduced damage by C. capitata and no control measures were necessary against aphids, since the trees had low susceptibility and populations were small. On the basis of these results some sampling techniques and economic infestation thresholds are proposed. The infestion thresholds were 10% of the fruits for P. citri, 5--10 crawlers/leaf on clementine and 20--30/leaf on orange and lemon for D. citri, 2 mites/leaf for Panonychus citri (although this should in future be modified more realistically to give a percentage of infested leaves), 10--15% infested buds, combined with the 1st manifestations of leaf damage, for A. citricola, unless active predators are present, and 20 adults/trap caught in a week for C. capitata, although in case of wet weather bait-sprays are not effective and treatment is best carried out in October against the larvae with dimethoate
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