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Georgina E Reyes Solorio, Jacob A Wenger, Sanjeev K Dhungana, Sandipa G Gautam, Efficacy of foliar applied insecticides on citrus mealybug in San Joaquin Valley California, 2023, Arthropod Management Tests, Volume 49, Issue 1, 2024, tsae094, https://doi.org/10.1093/amt/tsae094
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A field trial was conducted in July 2023 to evaluate the efficacies of six treatments to manage citrus mealybug (CMB). The trial was conducted in a 10-acre block of 13-year-old Spring Navels on trifoliate rootstock planted at a spacing of 19 × 17 ft in Ivanhoe, California (36°25ʹ14.6″N 119°11ʹ33.0″W). Six pesticide treatments and one untreated control were randomly assigned and replicated four times in an RCB design. Plot size was 1 row by 9 trees. Two applications were made for each treatment, the first on 7 July and the second on 3 August. All applications were made using a Gearmore model APL 400 air blast sprayer. Rates and volumes followed manufacturer recommendations (125, 300, or 750 gpa) and standard grower practices for crop production (Table 1). Each application included 0.5% oil and either Exit or Nu-Film P as an adjuvant. Pre- and post-treatment evaluations were done 1 and 3 WAT1 and 1, 3, 4, and 10 WAT2. Assessments were done by counting the number of fruits with live mealybugs present on 30 pieces of fruit inside the tree canopy/tree. The proportions of fruit infested within each plot were compared using ANOVA followed by a posthoc Fisher’s LSD test (P < 0.05) of arcsine (squared root (x/100)) transformed data.
| Treatment/ Formulation (1st, 2nd) 1 . | Rate-amt form/acre or v:v (1st, 2nd) 1 . | Spray volume (GPA) (1st, 2nd) 1 . | Adjuvant (rate/100 gal) (1st, 2nd) 1 . | Proportion of fruit infested with citrus mealybug . | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pre 23 Jun . | 1 WAT1 14 Jul . | 3 WAT1 28 Jul . | 1WAT2 11 Aug . | 3 WAT2 26 Aug . | 4 WAT2 5 Sep . | 12 WAT2 28 Nov . | ||||
| Untreated control | 17.9 | 54.4ab | 27.9a | 36.7a | 45.2a | 39.3a | 67.5a | |||
| Actara, Exirel | 5.5 oz, 20.5 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.8 | 58.8a | 26.7a | 21.8bc | 35.9b | 31.1b | 57.6b |
| IAP Summer 415 Spray Oil × 2 | 0.5 gal/100 gal | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 14.3 | 53.0ab | 12.9b | 19.0cd | 20.5c | 14.6c | 35.6c |
| Movento, Danitol 2.4 EC | 10 oz, 16 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.3 | 11.5c | 29.4a | 16.9cd | 8.0d | 12.3cd | 31.2cd |
| Cinnerate, Aza Pro | 50 oz/100 gal, 2.6 pt | 300, 300 | Nu-Film P (8 oz), Nu-Film P (8 oz) | 2.9 | 52.4ab | 11.4b | 25.1b | 8.9d | 7.6de | 22.3de |
| Senstar, Sefina Inscalis | 20 oz, 14 oz | 300, 750 | Exit (12 oz), Exit (0.5 qt) | 3.9 | 56.8a | 8.5b | 14.8d | 6.4d | 4.5e | 16.4e |
| Centaur WDG, Beleaf 50SG | 46 oz, 4.28 oz | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 5.9 | 47.8b | 8.5b | 19.0cd | 3.2d | 4.3e | 12.7e |
| P-value | <0.01 | <0.01 | 0.015 | <0.01 | <0.01 | <0.01 | ||||
| Treatment/ Formulation (1st, 2nd) 1 . | Rate-amt form/acre or v:v (1st, 2nd) 1 . | Spray volume (GPA) (1st, 2nd) 1 . | Adjuvant (rate/100 gal) (1st, 2nd) 1 . | Proportion of fruit infested with citrus mealybug . | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pre 23 Jun . | 1 WAT1 14 Jul . | 3 WAT1 28 Jul . | 1WAT2 11 Aug . | 3 WAT2 26 Aug . | 4 WAT2 5 Sep . | 12 WAT2 28 Nov . | ||||
| Untreated control | 17.9 | 54.4ab | 27.9a | 36.7a | 45.2a | 39.3a | 67.5a | |||
| Actara, Exirel | 5.5 oz, 20.5 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.8 | 58.8a | 26.7a | 21.8bc | 35.9b | 31.1b | 57.6b |
| IAP Summer 415 Spray Oil × 2 | 0.5 gal/100 gal | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 14.3 | 53.0ab | 12.9b | 19.0cd | 20.5c | 14.6c | 35.6c |
| Movento, Danitol 2.4 EC | 10 oz, 16 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.3 | 11.5c | 29.4a | 16.9cd | 8.0d | 12.3cd | 31.2cd |
| Cinnerate, Aza Pro | 50 oz/100 gal, 2.6 pt | 300, 300 | Nu-Film P (8 oz), Nu-Film P (8 oz) | 2.9 | 52.4ab | 11.4b | 25.1b | 8.9d | 7.6de | 22.3de |
| Senstar, Sefina Inscalis | 20 oz, 14 oz | 300, 750 | Exit (12 oz), Exit (0.5 qt) | 3.9 | 56.8a | 8.5b | 14.8d | 6.4d | 4.5e | 16.4e |
| Centaur WDG, Beleaf 50SG | 46 oz, 4.28 oz | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 5.9 | 47.8b | 8.5b | 19.0cd | 3.2d | 4.3e | 12.7e |
| P-value | <0.01 | <0.01 | 0.015 | <0.01 | <0.01 | <0.01 | ||||
1Each treatment was applied twice, with the first application on 7 July and second on 3 August.
Means within each column followed by different letters are significantly different (P ≤ 0.05). The proportions of fruit infested with CMB were arcsine (square root (x)) transformed before analysis. Untransformed means are reported.
| Treatment/ Formulation (1st, 2nd) 1 . | Rate-amt form/acre or v:v (1st, 2nd) 1 . | Spray volume (GPA) (1st, 2nd) 1 . | Adjuvant (rate/100 gal) (1st, 2nd) 1 . | Proportion of fruit infested with citrus mealybug . | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pre 23 Jun . | 1 WAT1 14 Jul . | 3 WAT1 28 Jul . | 1WAT2 11 Aug . | 3 WAT2 26 Aug . | 4 WAT2 5 Sep . | 12 WAT2 28 Nov . | ||||
| Untreated control | 17.9 | 54.4ab | 27.9a | 36.7a | 45.2a | 39.3a | 67.5a | |||
| Actara, Exirel | 5.5 oz, 20.5 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.8 | 58.8a | 26.7a | 21.8bc | 35.9b | 31.1b | 57.6b |
| IAP Summer 415 Spray Oil × 2 | 0.5 gal/100 gal | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 14.3 | 53.0ab | 12.9b | 19.0cd | 20.5c | 14.6c | 35.6c |
| Movento, Danitol 2.4 EC | 10 oz, 16 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.3 | 11.5c | 29.4a | 16.9cd | 8.0d | 12.3cd | 31.2cd |
| Cinnerate, Aza Pro | 50 oz/100 gal, 2.6 pt | 300, 300 | Nu-Film P (8 oz), Nu-Film P (8 oz) | 2.9 | 52.4ab | 11.4b | 25.1b | 8.9d | 7.6de | 22.3de |
| Senstar, Sefina Inscalis | 20 oz, 14 oz | 300, 750 | Exit (12 oz), Exit (0.5 qt) | 3.9 | 56.8a | 8.5b | 14.8d | 6.4d | 4.5e | 16.4e |
| Centaur WDG, Beleaf 50SG | 46 oz, 4.28 oz | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 5.9 | 47.8b | 8.5b | 19.0cd | 3.2d | 4.3e | 12.7e |
| P-value | <0.01 | <0.01 | 0.015 | <0.01 | <0.01 | <0.01 | ||||
| Treatment/ Formulation (1st, 2nd) 1 . | Rate-amt form/acre or v:v (1st, 2nd) 1 . | Spray volume (GPA) (1st, 2nd) 1 . | Adjuvant (rate/100 gal) (1st, 2nd) 1 . | Proportion of fruit infested with citrus mealybug . | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pre 23 Jun . | 1 WAT1 14 Jul . | 3 WAT1 28 Jul . | 1WAT2 11 Aug . | 3 WAT2 26 Aug . | 4 WAT2 5 Sep . | 12 WAT2 28 Nov . | ||||
| Untreated control | 17.9 | 54.4ab | 27.9a | 36.7a | 45.2a | 39.3a | 67.5a | |||
| Actara, Exirel | 5.5 oz, 20.5 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.8 | 58.8a | 26.7a | 21.8bc | 35.9b | 31.1b | 57.6b |
| IAP Summer 415 Spray Oil × 2 | 0.5 gal/100 gal | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 14.3 | 53.0ab | 12.9b | 19.0cd | 20.5c | 14.6c | 35.6c |
| Movento, Danitol 2.4 EC | 10 oz, 16 oz | 125, 750 | Exit (12 oz), Exit (0.5 qt) | 4.3 | 11.5c | 29.4a | 16.9cd | 8.0d | 12.3cd | 31.2cd |
| Cinnerate, Aza Pro | 50 oz/100 gal, 2.6 pt | 300, 300 | Nu-Film P (8 oz), Nu-Film P (8 oz) | 2.9 | 52.4ab | 11.4b | 25.1b | 8.9d | 7.6de | 22.3de |
| Senstar, Sefina Inscalis | 20 oz, 14 oz | 300, 750 | Exit (12 oz), Exit (0.5 qt) | 3.9 | 56.8a | 8.5b | 14.8d | 6.4d | 4.5e | 16.4e |
| Centaur WDG, Beleaf 50SG | 46 oz, 4.28 oz | 750, 750 | Exit (0.5 qt), Exit (0.5 qt) | 5.9 | 47.8b | 8.5b | 19.0cd | 3.2d | 4.3e | 12.7e |
| P-value | <0.01 | <0.01 | 0.015 | <0.01 | <0.01 | <0.01 | ||||
1Each treatment was applied twice, with the first application on 7 July and second on 3 August.
Means within each column followed by different letters are significantly different (P ≤ 0.05). The proportions of fruit infested with CMB were arcsine (square root (x)) transformed before analysis. Untransformed means are reported.
Prior to treatment, there were no significant differences in treatment means that ranged from 2.9% to 17.9% of fruit infested, with individual plots ranging from 2 to 26%. After one insecticide application, Movento had a lower proportions of fruits infested with CMB compared to the control and all other treatments at 1 WAT, but not 3 WAT. On the other hand, the proportion of fruit infested with CMB after application of Senstar, Cinnerate, Centaur WDG, and IAP Summer Oil was similar to the control at 1WAT, but significantly lower at 3 WAT. Actara was similar to the control at 1 and 3 WAT. Following the second insecticide application, all treatments lowered the proportion of fruit infested on all evaluation dates. Among treatments, the lowest overall mealybug densities (<25% of fruit infested) were consistently found in plots treated with Cinnerate-AzaPro, Senstar-Sefina Inscalis, and Centaur WDG-Beleaf 50 SG.
Funding
This research was supported in part by the Citrus Research Board with additional industry gifts of pesticides and funding.
