Description of the Pest
Adults are small, black to gray flies with yellow markings. Females puncture leaves to feed on plant sap and lay eggs within the leaf tissues. After 2 to 4 days, eggs hatch and larvae feed between the upper and lower surface of the leaves, making distinctive winding, whitish tunnels or mines that are often the first clue that leafminers are present. Larvae emerge from the mines and pupate on the leaf surface, or more commonly, in cracks in the soil. Many generations occur each year, and the entire life cycle can be completed in less than 3 weeks when the weather is warm.
Damage
The primary damage caused by the chrysanthemum leafminer is the mining of the leaf by the larvae. When infestations are severe, the plant's photosynthetic capacity is reduced, and there is a reduction in crop yield.
Management
Chrysanthemum leafminer is usually kept in control by naturally occurring parasites and does not require any additional control efforts. All precautions should be taken to ensure that the parasites are not killed by pesticide sprays applied for other pests. In cases of severe infestation, a treatment may be warranted.
Biological Control
Biological control normally keeps leafminers in check, but outbreaks may occur following the disruption of their parasites with broad-spectrum insecticides. These leafminers are attacked and effectively controlled by an eulophid wasp (Chrysacharis ainsleii) as well as other species in the Diglyphus, Haltocoptera, and Opius genera.
Organically Acceptable Methods
Biological controls and sprays of the Entrust formulation of spinosad are acceptable for use on organically certified crops.
Pesticides and Natural Enemy Releases
Not all registered pesticides are listed. The following are ranked by their IPM value, with the most effective and least harmful to natural enemies, honey bees, and the environment listed at the top of the table. When choosing a pesticide, consider information related to water and air quality, resistance management, and the pesticide's properties and application timing. Use PestManage to compare summarized management options for different pests in the same crop. Always carefully read the label of the product being used and take all necessary precautions when handling pesticides.
| Rank | Active ingredient | Example trade name | Group | Group Order | MoA 1 | Amount per acre | REI (hours) ‡ | PHI (days) ‡ | Comments | Selectivity 2 | Bees 3 | Predatory mites 4 | Predators 5 | Parasitoids 5 | Residue duration 6 | Leaching(fish) 7 | Adsorbed runoff(fish) 8 | Solution runoff(fish) 9 | Leaching(human) 10 | Solution runoff(human) 11 | Last updated 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Brigade WSB | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
3A |
16 oz | 12 | 5 | Do not exceed 16 oz/acre between bud for... | broad | high | high | high | long | intermediate | low | extra high | very low | intermediate | 02/2020 | ||
|
|
Radiant SC | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
5 |
6–8 fl oz | 4 | 2 | Label suggests adding an adjuvant to imp... | Narrow | low/high | moderate 13 | low/moderate | moderate 14 | low | low | low | very low | low | 02/2020 | ||
|
|
Entrust # | Application Timing Varies (See UC IPM Pest Management Guidelines and Label) | 8 |
5 |
1.5–3 oz | 4 | 2 | For resistance management, do not make m... | narrow | low | moderate 13 | low/moderate | short to moderate | very low | low | low | very low | low | 02/2020 |
Legend
- ‡ a b Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of the two intervals is the minimum time that must elapse before harvest.
- # ↩ Acceptable for use on certified organic crops. Check with your certifier to confirm before application.
- 1 ↩ Group numbers for insecticides and miticides are assigned by the Insecticide Resistance Action Committee (IRAC). Insecticides with unknown modes of action are assigned mode-of-action group numbers (MoAs) that begin with UN. Rotate pesticides with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B.
- 2 ↩ Range of insect and mite groups affected by a pesticide. Broad means the pesticide affects most groups of insects and mites; narrow means the pesticide affects only a few specific groups.
- 3 ↩ Risk of harm to honey bees. For more information, see Bee Precaution Pesticide Ratings.
- 4 ↩ Risk of harm to predatory mites. Toxicities are generally to western predatory mite, Galendromus occidentalis. Where differences have been measured in toxicity of the pesticide-resistant strain versus the native strain, these are listed as pesticide-resistant strain or native strain.
- 5 a b Risk of harm to parasitoids and general predators. Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific insecticide depends on factors including the application rate, environmental conditions, and the life stage and species of a parasitoid or predator.
- 6 ↩ Length of time residue affects natural enemies. Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
- 7 ↩ Risk of harm to fish from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 8 ↩ Risk of harm to fish from adsorbed runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 9 ↩ Risk of harm to fish from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 10 ↩ Risk of harm to humans from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 11 ↩ Risk of harm to humans from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
- 12 ↩ Date information was last updated in the UC IPM Pest Management Guidelines.
- 13 a b Toxic to some natural enemies (lacewing and syrphid fly larvae, predatory beetles, and thrips) when sprayed and up to 5 to 7 days after.
- 14 ↩ Residual is moderate if solution is between a pH of 7 and 8.
UC IPM Pest Management Guidelines: Artichoke
UC ANR Publication 3434
M.A. Bari, Artichoke Research Foundation, Salinas
E.T. Natwick (emeritus), UC Cooperative Extension Imperial County
A. Del Pozo-Valdivia, UC Cooperative Extension Monterey County
Acknowledgement for Contributions to Invertebrates
W.E. Chaney (emeritus), UC Cooperative Extension Monterey County
W.L. Schrader, UC Cooperative Extension San Diego County
L. Handel, Kleen Globe, Inc., Castroville
T.K. Shannon, Kleen Globe, Inc., Castroville
