Presented are the results of 4 years of research in north Florida on dicrotophos trunk implantation to control Dioryctria spp. coneworms and the slash pine seedworm, Laspeyresia anaranjada Miller, on 2nd-year cones of slash pine, Pinus elliottii var elliotti Engelm. Dicrotophos technical liquid (1.08 kg active ingredient (AI) per liter) was implanted in early May into holes drilled in the tree stems. Dosage rates of 0.8–2.0 g AI per cm of tree diameter at waist height gave 86–94% control of Dioryctria spp. and 94–100% control of M L. anaranjada on mature cones harvested in mid-September of the year of treatment. Dicrotophos implanted by Mauget® injectors at dosages of 0.6–1.4 g/cm diameter resulted in 30–81% control of Dioryctria spp. and 56–97% control of slash pine seedworm. Date of treatment may be advanced to early April and good control of both insects still be obtained. Foliage of trees implanted with dicrotophos in early May showed no phytotoxic symptoms at the dosages tested. Seeds from trees implanted with a 1.4 g per cm-diameter dosage of dicrotophos for 3 consecutive years showed no decrease in full-seed germination percentage when compared with seeds from untreated trees. Seed losses caused by the hemipteran seed bugs Leptoglossus corculus (Say) and Tetyra bipunctata (Herrich-Schaeffer) were also reduced with dicrotophos implants.
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Merkel et al. (1971) studied this question.