Description of the Pest
Leafhoppers are small, light green, wedge-shaped insects that measure a little more than 0.12 inch (3 mm) in length. The western potato leafhopper is a pest throughout California whereas the southern garden leafhopper occurs mostly in the southern California desert areas. Adult females insert kidney-shaped eggs singly in the plant just below the surface. Eggs hatch and the nymphs pass through five instars. Nymphs are whitish to pale green and move rapidly (often sideways) when disturbed. They are found mainly on the underside of leaves.
Damage
The leafhopper has sucking mouthparts and can cause severe white stippling and yellowing of the leaves, green spotting of the fruit, and premature leaf drop. Large populations can reduce quality as well as yield.
Management
Generally good field sanitation and crop growing practices are adequate for preventing damage by these pests.
Cultural Control
Melons and other cucurbits can tolerate fairly heavy feeding provided they are not stressed for moisture and possess six to eight healthy noninfested terminal leaves. After harvest, destroy crop residue as soon as possible to eliminate breeding areas.
In desert production areas, exclude leafhoppers by applying row covers (plastic and spun-bonded materials) at planting and gradually removing them at first bloom or earlier if needed. Row covers are not recommended for the San Joaquin Valley.
- Do not remove the entire plastic row cover at one time because a drastic reduction in humidity will shock plants and can lead to collapse. Instead vent the covers and remove them gradually. Covers made of spun-bonded materials do not need venting because hot air is able to escape.
- Remove row covers if the air temperature underneath reaches 104° F before bloom.
- Remove row covers before plants grow high enough to touch hot plastic.
Organically Acceptable Methods
Cultural controls are acceptable to use in an organically certified crop.
Monitoring and Treatment Decisions
Treatment thresholds have not been established, but pesticide sprays are not usually required. If leafburn occurs, or if leafhoppers are moving into an immature field from nearby harvested sugarbeet, potato, or other crops, a treatment may be needed.
| 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. | DINOTEFURAN | |||
| (Venom) | See comments | 12 | See comments | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: Rates vary depending upon whether a soil or foliar application. Soil application preferred because it has less impact on beneficials. Preharvest intervals: foliar application—1 day; soil—21 days. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates may be lower and application timing may be restricted if using managed pollinators, applying more than one neonicotinoid active ingredient, or using more than one application method in the same season. |
||||
| B. | THIAMETHOXAM | |||
| (Platinum 75 SG) | 1.66–3.67 oz | 12 | 30 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: At seeding or transplanting, apply in sufficient water to ensure uniform application and incorporation into the soil. Provides about 40 days of protection. Use where field has history of these pests. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates may be lower and application timing may be restricted if using managed pollinators, applying more than one neonicotinoid active ingredient, or using more than one application method in the same season. |
||||
| C. | IMIDACLOPRID | |||
| (Admire Pro) | 7–10.5 fl oz | 12 | 21 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| COMMENTS: At seeding or transplanting, apply in sufficient water to ensure uniform application and incorporation into the soil. Use where field has history of these pests. Review and follow the California neonicotinoid regulations effective January 1, 2024. Permissible application rates may be lower and application timing may be restricted if using managed pollinators, applying more than one neonicotinoid active ingredient, or using more than one application method in the same season. |
||||
| D. | ESFENVALERATE | |||
| (Asana XL) | 5.8–9.6 oz | 12 | 3 | |
| MODE-OF-ACTION GROUP NUMBER1: 3 | ||||
| COMMENTS: Repeat as necessary to maintain control. Do not exceed 0.25 lb a.i./acre per season. Highly toxic to honey bees. | ||||
| E. | ACETAMIPRID | |||
| (Assail 30SG) | 2.5–4 oz | 12 | 0 | |
| (Assail 70WP) | 1.1–1.7 oz | 12 | 0 | |
| MODE-OF-ACTION GROUP NUMBER1: 4A | ||||
| F. | METHOMYL* | |||
| (Lannate LV) | 1.5–3 pt | 48 | See comments | |
| MODE-OF-ACTION GROUP NUMBER1: 1A | ||||
| COMMENTS: Labeled for use on cucumbers, melons and summer squash only. Use sufficient water for thorough coverage. Highly toxic to honey bees. PHI is 1 day if 1.5 pt or less is used per acre; if over 1.5 pt, PHI is 3 days. | ||||
| G. | DIMETHOATE | |||
| (Dimethoate 2.67 EC) | Label rates | 48 | 3 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: Labeled for use on melons and watermelons only. Highly toxic to honey bees. | ||||
| H. | DIAZINON | |||
| (Diazinon AG500) | Label rates | 72 (3 days) | 3 | |
| MODE-OF-ACTION GROUP NUMBER1: 1B | ||||
| COMMENTS: Labeled for melons. Highly toxic to honey bees. | ||||
| ‡ | 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 are assigned by IRAC (Insecticide Resistance Action Committee). |
| * | Permit required from county agricultural commissioner for purchase or use. |