Beginner

Scientific Name
            Empoasca fabae

Identification
Nymphs:

• Young nymphs are 1.5 mm in length, yellowish-green, and move very quickly on the underside of leaves.
• Older nymphs develop “wing pads” that distinguish them from the fully winged adults.
• Nymphs have the curious ability to walk sideways or backwards, and rapidly move to the other side of the leaf if disturbed.

Adults:

• Light green,
• Long and narrow body,
• Wedge-shaped (forward pointing) head,
• About 3 mm long,
• They have sucking mouth parts,
• Can fly, walk and hop,
• Well-developed back legs and transparent wings that fold tent-like across their back.   

Damage:

• Leaf margins turn yellow and curl downward, eventually turning brittle and brown – a condition known as “hopper burn”

Often Confused With
Grapevine leafroll virus:  leaves curl downward but no leafhopper nymphs or adults present; leaves of red varieties turn red but retain green veins; leaves of white varieties turn yellow between main veins

Grape/three-banded/Virginia creeper leafhopper:  nymphs do not run sideways; adults pale yellow with three black spots or some zig-zag lines of deeper yellow or brown on the forewings; injury is stippling of leaves rather than marginal yellowing and downward curling

Early symptoms of deficiencies of Nitrogen, Potassium, Magnesium or Manganese:  yellowing extends from margins toward middle of leaf and no downward curling or nymphs present

Period of Activity
Adult potato leafhoppers arrive first and lay eggs in the leaves, and the eggs hatch into nymphs in early-mid June. 

Scouting Notes
Sample 100 shoots on the shadiest(east) side of the canopy .  Shaking the foliage of a vine can be used to see if any adult potato leafhoppers are present (they will fly off the vine), but this will not help in detecting the nymphs, which cannot fly. Nymphs can be found on the undersides of leaves and on stems. Examine leaves by turning them over slowly. Bias sample to upper part of canopy and select younger leaves on shoot from midway to the newest fully expanded leaf near the growing tip. Yellow sticky cards can be placed in the vineyard canopy close to the young shoots to monitor adults as they move into the vineyard and subsequent generations.  

Threshold
There are no spray thresholds established for potato leafhopper in Ontario. A rule of thumb is that treatment with insecticides is necessary when active leafhoppers are found in the apical half of the shoots AND detectable injury is observed on 25% of shoots.  If vines are under stress, the threshold should be reduced to 10%. 

Advanced

Scientific Name
            Empoasca fabae

Identification

Nymphs:

• Young nymphs are 1.5 mm in length, yellowish-green, and move very quickly on the underside of leaves.
• Older nymphs develop “wing pads” that distinguish them from the fully winged adults.
• Nymphs have the curious ability to walk sideways or backwards, and rapidly move to the other side of the leaf if disturbed.

Adults:

• Light green,
• Long and narrow body,
• Wedge-shaped (forward pointing) head,
• About 3 mm long,
• They have sucking mouth parts,
• Can fly, walk and hop,
• Well-developed back legs and transparent wings that fold tent-like across their back.   

Damage:

• Leaf margins turn yellow and curl downward, eventually turning brittle and brown – a condition known as “hopper burn”

Often Confused With
Grapevine leafroll virus:  leaves curl downward but no leafhopper nymphs or adults present; leaves of red varieties turn red but retain green veins; leaves of white varieties turn yellow between main veins

Grape/three-banded/Virginia creeper leafhopper:  nymphs do not run sideways; adults pale yellow with three black spots or some zig-zag lines of deeper yellow or brown on the forewings; injury is stippling of leaves rather than marginal yellowing and downward curling

Early symptoms of deficiencies of Nitrogen, Potassium, Magnesium or Manganese:  yellowing extends from margins toward middle of leaf and no downward curling or nymphs present

Biology
Potato leafhoppers do not overwinter in Ontario. Each spring adults are carried by wind currents from southern Gulf States and across the Great Lakes into Ontario. The first adults arrive as early as mid May and continue to arrive well into June. Adults are first noticed in vineyards in early or mid June, generally just after the first cut of alfalfa hay in the area. The removal of the food source (alfalfa) usually causes potato leafhoppers to migrate to nearby alternate host crops, including grapes. Adults mate and females deposit two to three eggs per day throughout their life span. Eggs are laid on leaves or stems in the upper part of the canopy and hatch in about 10 days. Potato leafhopper nymphs take about 25 days to pass through five life stages (instars), each larger than the previous stage. Only the last three instars possess visible wing pads, which become wings in the adult. As the insects molt from one instar to the next, they leave behind white cast skins. Three or four generations are produced each year and remain active until killed by a hard frost. In hot, dry summer weather, leafhopper populations can build to tremendous numbers and insecticide treatments may be necessary. Adults and nymphs feed by sucking plant juices from leaves. They inject a toxin into the plant while feeding, blocking vascular system flow. Feeding reduces plant vigour and plugs off the vascular system, preventing normal movement of water and nutrients to the affected area of the plant.

Period of Activity
Adult potato leafhoppers arrive first and lay eggs in the leaves, and the eggs hatch into nymphs in early-mid June. 

Scouting Notes
Sample 100 shoots on the shadiest(east) side of the canopy .  Shaking the foliage of a vine can be used to see if any adult potato leafhoppers are present (they will fly off the vine), but this will not help in detecting the nymphs, which cannot fly. Nymphs can be found on the undersides of leaves and on stems. Examine leaves by turning them over slowly. Bias sample to upper part of canopy and select younger leaves on shoot from midway to the newest fully expanded leaf near the growing tip. Yellow sticky cards can be placed in the vineyard canopy close to the young shoots to monitor adults as they move into the vineyard and subsequent generations.

Threshold
There are no spray thresholds established for potato leafhopper in Ontario. A rule of thumb is that treatment with insecticides is necessary when active leafhoppers are found in the apical half of the shoots AND detectable injury is observed on 25% of shoots.  If vines are under stress, the threshold should be reduced to 10%. 

Management Notes
Potato leafhoppers prefer to feed on young succulent leaves so managing canopy vigour through the use of balanced pruning, cover crops and appropriate fertilizer applications will reduce food sources for them. 

Management with insecticides – Insecticides are used to control potato leafhopper in most commercial vineyards. See OMAFRA Publication 360, Fruit Crop Protection Guide - Chapter 5 Grapes : Recommendations for potato leafhopper at Trace bloom and Immediate post-bloom to early fruit set, when threshold is reached.  If Surround is the product of choice, applications should be started as soon as activity is detected and complete coverage of foliage must be maintained.