Description of the Pest
Root mealybugs are belowground dwelling mealybugs that feed on the roots of plants. These mealybugs have a thin, uniform waxy coating and lack the terminal wax filaments typical of their foliar-feeding relatives.
Damage
The only outward sign of root mealybug feeding may be a decline in the health of infested plants. When plants are removed from the pot, the whitish mealybugs feeding on the roots are then observed.
Management
Biological Control
Biological control has not been investigated.
Cultural Control
Discard infected and surrounding plants. Control ants.
Monitoring and Treatment Decisions
Examine plant root balls when monitoring and when plants are declining. The presence of ants climbing on the plant can also indicate a problem with mealybugs. Rogue and discard infected plants. Treat with a soil drench or discard the surrounding plants.
Treatment
Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity. Also consider pesticide resistance management and environmental impact.
| Class | Pesticide (commercial name) |
Manufacturer | REI1 | Mode of action2 | Comments | ||
|---|---|---|---|---|---|---|---|
| botanical | A. | pyrethrin/PBO3 (PT Pyrethrum TR) |
Whitmire MicroGen |
12 | 3/— | An aerosol. | |
| neonicotinoid | A. | imidacloprid (Marathon 1G) (Marathon II) |
OHP | 12 | 4A | Not to be used more than once every 16 weeks. Do not apply to soils that are water logged or saturated. Do not apply to bedding plants intended to be used as food crops. | |
| (Marathon 60 WP) | As above, but apply only as a drench. | ||||||
| organophosphate | A. | acephate (Acephate 97UP) |
United Phosphorus | 24 | 1B | ||
| B. | acephate (Orthene T,T&O Spray) |
Valent | 24 | 1B | A number of chrysanthemum varieties have exhibited phytotoxic reactions. In greenhouse, only labeled for use on anthurium, cacti, carnation, rose, orchids, some foliage plants, young poinsettia and some varieties of chrysanthemum. Can stunt new growth in roses. | ||
| pyrethroid | A. | bifenthrin (Talstar Professional) |
FMC | 12 | 3 | Label permits low-volume application. | |
| B. | cyfluthrin (Decathlon 20 WP) |
OHP | 12 | 3 | Label permits low-volume application. | ||
| C. | fenpropathrin* (Tame 2.4 EC Spray) |
Valent | 24 | 3 | Label permits low-volume application. | ||
| D. | fluvalinate (Mavrik Aquaflow) |
Wellmark | 12 | 3 | Label permits low-volume application. Also labeled as a cutting dip at 5 fl oz/100 gal. | ||
| E. | permethrin (Astro) |
FMC | 12 | 3 | Direct application to blooms may cause browning of petals. Marginal leaf burn may occur on salvia, diffenbachia and pteris fern. Label permits low-volume application. Do not apply more than 2 lb a.i./acre/year. | ||
| pyrethroid/
neonicotinoid |
A. | cyfluthrin/imidacloprid
(Discus) |
OHP | 12 | 3/4A | ||
| 1 | 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. |
| 2 | 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 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 are assigned by IRAC (Insecticide Resistance Action Committee). |
| 3 | PBO = piperonyl butoxide. |
| * | Restricted use material. Permit required for purchase or use. |