Season-long control of insects in apple, 2025

The objective of this trial was to compare season-long ­applications of insecticides and insecticide programs targeting codling moth and other common Michigan apple pests against an untreated control and a standard conventional spray program. Treatments were applied to 2-tree plots in a 37-year-old planting of semi-dwarf ‘Red Chief’ apple trees on an 18 × 20 ft tree by row spacing at the Trevor Nichols Research Center in Fennville, MI. Treatments were replicated 4 times in an RCB design. Applications were made using an FMC 1029 tractor-mounted airblast sprayer calibrated to deliver 100 gpa at 2.5 mph. Treatments were designed as season-long programs beginning at the pink bud stage (28 Apr), followed by petal fall (10 May), and then were degree day-driven timings for CM. Degree-days were calculated with a base temperature of 50 °F, and the weather station at the Trevor Nichols Research Center was used for these calculations (https://enviroweather.msu.edu/). CM biofix for the first generation was 13 May, and the biofix for the CM second generation was 28 Jul. On 11 Jun, 50 terminals per plot were assessed for OFM flagging damage. Plots were also assessed for the number of terminals with PLH nymphs on 25 Jun. Following the completion of the CM’s first generation flight, fruits were evaluated for OFM/CM entries (apples with frass) on 50 fruits per plot on 1 Jul and PC oviposition sting damage on 15 Jul. Harvest evaluation occurred on 5 Sep. Fifty fruits were collected per plot and assessed for PC stings and internal lepidopteran tunneling (OFM/CM). Internal lepidopteran tunneling was assessed by cutting the fruit at the exit/entrance holes. When live larvae were found, they were identified as CM or OFM. A negative binomial distribution in a generalized linear mixed model was used (Proc Genmod, SAS v 9.4) for analysis. Post hoc comparisons of treatment effects were conducted using Tukey’s HSD. Phytotoxicity was evaluated 6 times on 2 Jun, 11 Jun, 24 Jun, 9 Jul, 24 Jul, and 15 Aug; no phytotoxicity was found. Terminals with OFM damage were lower in Senstar/Assail/Delegate/Altacor eVo and Senstar/Assail/Bronte/Delegate/Altacor eVo plots compared to the untreated control, but did not significantly differ from the other 2 treatments (Table 1). All treatments had significantly lower numbers of terminals with potato leafhopper nymphs, and Senstar/Assail/Delegate/Altacor eVo had the fewest terminals with PLH nymphs (Table 1). Although the Apta treatment applied season-long had consistently fewer plum curculio oviposition stings, there were no significant differences between treatments for the number of apples with PC damage on 15 Jul and 5 Sep, but all treatments had fewer PC stings than the untreated control at harvest (Tables 2 and 3). All treatments had significantly fewer apples with OFM/CM internal damage compared to the untreated control on 15 Jul and 5 Sep, and fewer apples with CM live larvae found on 5 Sep (Table 3). Means followed by same letter do not significantly differ (P ≤ 0.05, Tukey’s HSD). A = Apr 24 (Pink Bud), B = May 19 (Petal Fall), C = May 29 (Petal Fall reapplied), D = June 6 (CM Biofix + 250DD50ºF), E = June 16 (D + 10 d), F = June 27 (E + 10 d), G = July 8 (F + 10 d), H = July 18 (G + 10 d), I = Aug 8 (2nd Gen. CM Biofix + 250DD), J = Aug 14 (I + 10 d), K = Aug 14 (J + 10 d). LI700 adjuvant was added to treatment at 0.25% (v:v). Means followed by same letter do not significantly differ (P ≤ 0.05, Tukey’s HSD). A = Apr 24 (Pink Bud), B = May 19 (Petal Fall), C = May 29 (Petal Fall reapplied), D = June 6 (CM Biofix + 250DD50ºF), E = June 16 (D + 10 d), F = June 27 (E + 10 d), G = July 8 (F + 10 d), H = July 18 (G + 10 d), I = Aug 8 (2nd Gen. CM Biofix + 250DD), J = Aug 14 (I + 10 d), K = Aug 14 (J + 10 d). LI700 adjuvant was added to treatment at 0.25% (v:v). Means followed by same letter do not significantly differ (P ≤ 0.05, Tukey’s HSD). A = Apr 24 (Pink Bud), B = May 19 (Petal Fall), C = May 29 (Petal Fall reapplied), D = June 6 (CM Biofix + 250DD50°F), E = June 16 (D + 10 d), F = June 27 (E + 10 d), G = July 8 (F + 10 d), H = July 18 (G + 10 d), I = Aug 8 (2nd Gen. CM Biofix + 250DD), J = Aug 14 (I + 10 d), K = Aug 14 (J + 10 d). LI700 adjuvant was added to treatment at 0.25% (v:v). This research was supported by industry gifts of pesticides and research funding. None declared.