Description of the Pest
The wingless summer form of the willow carrot aphid is pale green with the cornicles, cauda (tail-like structure), and legs pale to slightly dusky. They are medium-size aphids with elongate oval-shaped bodies that are flattened front to back. The upper surface of the body may be roughened by numerous small depressions. The wingless forms have a second tail-like process called the supracaudal process directly above the cauda, giving the aphid the appearance of having twin "tails" when viewed with a hand lens. This supracaudal process may be triangular or fingerlike in shape.
The winged forms have a black head and thorax. The abdomen is pale green with dark areas on the sides and dark bands on the top. The antennae are black. The legs are pale in color and black at the tips. The cornicles are somewhat swollen near the tip.
Damage
Willow carrot aphid is of concern primarily because of its efficiency in vectoring a number of serious virus diseases. It transmits carrot motley dwarf, carrot red leaf, and parsnip yellow fleck. It is also a vector of Celery mosaic virus, Sugarbeet mosaic virus, and Cauliflower mosaic virus. It seldom reaches numbers that require the need for chemical intervention.
Management
Biological Control
Little is known regarding the parasites of willow carrot aphid. The presence of bloated mummies indicates parasite activity. Predators such as green green lacewing larvae , lady beetles , and syrphid fly larvae prey on this aphid as well as on other aphid species.
Cultural Control
Sanitation is important in curbing the spread of the viruses that this insect vectors. Disc all crop residues under as soon as harvest is complete. Keeping fields, ditch banks, and fence lines weed-free may also help in reducing virus inoculum.
Organically Acceptable Methods
Biological and cultural controls, applications of insecticidal soaps, narrow range oils, entomopathogenic fungi (such as Beauveria bassiana), azadirachtin (Neemix), and neem oil (Trilogy) are acceptable for use on organically certified cilantro and parsley.
Monitoring and Treatment Decisions
Treatment thresholds have not been established for this pest. Pesticides do not prevent virus transmission, and this aphid rarely builds up in numbers high enough to cause economic damage by direct feeding.
| Common name | Amount per acre** | REI‡ | PHI‡ | |
|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | ||
| Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees , and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used. | ||||
| A. | AZADIRACHTIN | |||
| (Neemix 4.5)# | Label rates | 4 | 0 | |
| (Aza-Direct) | 2–3.5 pts | 4 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: un | ||||
| B. | NEEM OIL# | |||
| (Trilogy)# | 1–2% | 4 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: un | ||||
| C. | BEAUVERIA BASSIANA
|
|||
| (BotaniGard ES)# | Label rates | 4 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: un | ||||
| ** | See label for dilution rates. | |||
| ‡ | Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. | |||
| 1 | Rotate chemicals 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; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers (un = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee). | |||
| # | Acceptable for use on organically grown produce. | |||
| — | Not recommended or not on the label. | |||