Year: 2025
Type: article
Abstract: We evaluated the effect of selected insecticides on 6 mature Shademaster honey locust trees (Gleditsia triacanthos L., ‘Shademaster’) which were planted in 2 rows along a roadside on the University of Kentucky’s campus. We used a randomized complete block design where each tree represented a block, and within each tree, the effect of insecticides on scales was evaluated on separate labeled branches. All trees had been heavily infested with calico scale (CS) for multiple years. On each tree we sectioned off 11 randomly selected 30-cm branch sections with zip-ties. We applied treatments on 28 May 2024, when CS crawlers were emerging. We applied all products to the branches and both sides of all leaves following labeled rates using separate Chapin 2000 handheld pump sprayers pressurized to 60 psi with a hollow-cone nozzle. The volume of each application was approximately 121 ml. All treatments were applied on 0 and 14 DAT, while treatments 3–7 were also re-applied 7 DAT. We recorded settled crawler density across 2 randomly selected leaves and all leaflets attached to these leaves per treated branch. For collections at 3,7,14, and 28 DAT, we cut all leaves in half to reduce the amount of time needed to count scale crawlers due to the high densities found on sampled leaves and leaflets. One sample on 3 DAT (T5—Tetracurb Max, replicate no. 4) was lost in the process of transferring it from the field to the lab. On 0 DAT, we only recorded total CS density and did not separate living from dead scales. On all other sample dates, we recorded total, living, and dead CS density. We took photos of all leaves against a white background with a ruler in the image to calculate the area over which CS were counted using ImageJ software. We recorded phytotoxicity on all leaf photos and ranked discoloration on a scale of 0–10, where 0 indicated minimal discoloration and 10 indicated leaf death. We square-root transformed scale density (counts/cm2) and used type-II ANOVAs and follow-up Tukey HSD tests to determine if total, living, and dead CS density varied across treatment within each sampling period. We ln(x + 1) transformed phytotoxicity rankings and used type-II ANOVA and Tukey HSD tests to determine if phytotoxicity varied across treatments within each sampling period. Total CS density was not affected by treatment on any sampling date (Table 1). Living CS density was influenced by treatment on 28 DAT such that ISM-555 SC200 + capsil 0.05%_high and ISM-555 SC200 + capsil 0.05%_low treated leaves hosted fewer living CS relative to the untreated check and Distance treatments and the ISM-555 SC200 + capsil 0.05%_high hosted fewer scales relative to the OAT 1401EC treatment (Table 2). On 7 DAT and 14 DAT, dead CS density was influenced by treatment (Table 3). On 7 DAT, leaves treated with Tetracurb Max or ISM-555 SC200 + capsil 0.05%_low hosted more dead CS relative to Bountify (Table 3). On 14 DAT, dead CS density on ISM-555 SC200 + capsil 0.05%_low treated leaves was higher than the untreated check, Distance, and OAT 1401 EC treatments (Table 3). On 28 DAT dead CS density on leaves treated with Epishield_high and ISM-555 SC200 + capsil 0.05%_low were higher than the untreated check (Table 3). Phytotoxicity rankings were not significantly different across treatments within each sample period (Table 4).1 Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aScale densities per square centimeter were square-root transformed for statistical analyses. bAll treatments were applied at 0 DAT. cTreatments 3- 7 were re-applied at 7 DAT. dAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aScale densities per square centimeter were square-root transformed for statistical analyses. bAll treatments were applied at 0 DAT. cTreatments 3- 7 were re-applied at 7 DAT. dAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aScale densities per square centimeter were square-root transformed for statistical analyses. bTreatments 3- 7 were re-applied at 7 DAT. cAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aScale densities per square centimeter were square-root transformed for statistical analyses. bTreatments 3- 7 were re-applied at 7 DAT. cAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aScale densities per square centimeter were square-root transformed for statistical analyses. bTreatments 3- 7 were re-applied at 7 DAT. cAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aScale densities per square centimeter were square-root transformed for statistical analyses. bTreatments 3- 7 were re-applied at 7 DAT. cAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aPhytotoxicity rankings were ln(x + 1) transformed for statistical analyses. bAll treatments were applied at 0 DAT. cTreatments 3- 7 were re-applied at 7 DAT. dAll treatments were re-applied at 14 DAT. Means with the same letter(s) are not significantly different. Treatment main effect P-values determined by ANOVA. Tukey’s HSD test was used for post-hoc tests. aPhytotoxicity rankings were ln(x + 1) transformed for statistical analyses. bAll treatments were applied at 0 DAT. cTreatments 3- 7 were re-applied at 7 DAT. dAll treatments were re-applied at 14 DAT.
Source: Arthropod management tests
DOI: 10.1093/amt/tsaf099
Authors: Caleb J Wilson, Zoë K York
Institution: University of Kentucky
Language: English
Topic: Research on scale insects
Subfield: Insect Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $300
OpenAlex ID: W4411256619