Horticultural mineral oil applications for apple powdery mildew and codling moth, Cydia pomonella (L.)

Abstract

Horticultural mineral oil (Orchex 796) was tested in two treatment regimes, either a three-spray early season program targeting apple powdery mildew, Podosphaera leucotricha (All. & Evherh.) Salm. (Oil/Disease treatment) or a six-spray program targeting both generations of codling moth, Cydia pomonella (L.) (Oil/CM treatment), on apple, Malus domestica Borkhausen. These treatments were compared with a check, which received no post-bloom applications of oil. Apple powdery mildew shoot infestation was suppressed only in 1 year of the study (1999) by the Oil/Disease treatment, but no differences in fruit damage were found. The six-spray program of horticultural mineral oil produced the highest percentage of clean fruit, and the lowest level of codling moth-damaged fruit, but only one out of the 3 years of the study. Even in the best treatment in this year, codling moth damage was unacceptably high. Campylomma verbasci (Meyer-Dür) fruit damage was reduced by the oil sprays timed for mildew, probably because of the petal fall spray included in this treatment. Rosy apple aphid, Dysaphis plantaginea (Passerini), densities were suppressed (1 year only) by both oil treatments, while apple aphid, Aphis pomi De Geer, populations were not influenced by oil treatments at any time during the study. White apple leafhopper nymphs, Typhlocyba pomaria McAtee, and tetranychid mite populations were consistently suppressed by both oil treatment regimes, with generally higher levels of suppression occurring with the higher number of applications, despite the lack of specific timing. The same was true of apple rust mite, Aculus schlechtendali (Nalepa), and the western predatory mite, Galandromus occidentalis (Nesbitt).