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Ministry of Agriculture, Food and Rural Affairs

Potato leafhopper (PLH)

Potato leafhopper nymph (NRAES-75, Mid Atlantic Orchard Monitoring Guide. Edited by Henry Hogmire) Potato leafhopper adult Leaf curling on terminal due to feeding “Hopper burn” on leaf edges
Click to enlarge.

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 underside of the leaf if disturbed.

Adults:

  • Light green,
  • Wedge-shaped,
  • About 3 mm long,
  • They have sucking mouth parts,
  • Can fly, walk and hop,
  • Body structure resembles a grasshopper with well-developed back legs and wings that fold tent-like across their back. 

Damage:

  • Leaves turn pale green and curl downward at the margins,
  • Leaf margins eventually turn brittle and brown (hopperburn).

Often Confused With

  • White apple leaf hopper nymphs- White apple leafhopper nymphs can be differentiated from potato leafhopper nymphs by the way they walk when disturbed – white apple leafhoppers walk forward and backward, while potato leafhoppers walk sideways in a crab-like fashion. Potato leafhoppers are also more lime green in colour, while white apple leafhoppers are more yellowish white.
  • White apple leafhopper adults- White apple leafhopper adults hold their wings over their back when resting while potato leafhoppers fold their wings across their back.
  • Rosy apple aphid damage- Leaf curling damage can be confused with the rosy apple aphid, however rosy apple aphid is usually more focused on fruit spurs, while leafhopper damage is more prevalent on terminals.

Period of Activity
Potato leafhoppers should be monitored from petal fall through harvest.  Adults are first noticed in apple orchards in early or mid June, generally just after the first cut of hay in the area.

Scouting Notes
Check for potato leafhopper during weekly orchard monitoring beginning in early June. Look for curled leaves and shoots that are not growing as vigorously as they should. Check the undersides of leaves for nymphs and adults.

Assess leafhoppers in the field as they are easily disturbed and move off the leaf. Turn the leaf over slowly when monitoring to assess how many leafhoppers are on the lower leaf surface.

Thresholds
There are no spray thresholds established for potato leafhopper in Ontario. It has been documented on other crops that potato leafhopper feeding can affect the rate of photosynthesis, yield and crop quality at fairly low populations, and before leaf symptoms occur. In apples, one or two nymphs per leaf cause leaf curling if allowed to feed for a prolonged period of time (four to seven days).

Insecticides – particularly on nursery trees and in non-bearing blocks – are recommended at the first sign of injury

Advanced

Scientific Name
Empoasca fabae

Identification
Young nymphs are 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 (1.5 mm in length) have the curious ability to walk sideways or backwards, and rapidly move to the underside of the leaf if disturbed. Adults are light green, wedge-shaped insects about 3 mm long. They have sucking mouthparts and can fly, walk and hop. Their body structure resembles a grasshopper with well-developed back legs and wings that fold tent-like across their back. 

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. Leaves turn pale green and curl downward at the margins. Leaf margins eventually turn brittle and brown – known as hopperburn – and exhibit symptoms resembling aphid injury. However, it takes dozens of aphids on a leaf to cause it to curl, whereas the same curling will occur with only two or three potato leafhoppers.

Often Confused With

  • White apple leaf hopper nymphs- White apple leafhopper nymphs can be differentiated from potato leafhopper nymphs by the way they walk when disturbed – white apple leafhoppers walk forward and backward, while potato leafhoppers walk sideways in a crab-like fashion. Potato leafhoppers are also more lime green in colour, while white apple leafhoppers are more yellowish white.
  • White apple leafhopper adults- White apple leafhopper adults hold their wings over their back when resting while potato leafhoppers fold their wings across their back.
  • Rosy apple aphid damage- Leaf curling damage can be confused with the rosy apple aphid, however rosy apple aphid is usually more focused on fruit spurs, while leafhopper damage is more prevalent on terminals.

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 apple orchards in early or mid June, generally just after the first cut of hay in the area. The removal of the food source (alfalfa) usually causes potato leafhoppers to migrate to nearby alternate host crops, including apple. 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.

Period of Activity
Potato leafhoppers should be monitored from petal fall through harvest.  Adults are first noticed in apple orchards in early or mid June, generally just after the first cut of hay in the area.

Scouting Notes
Check for potato leafhopper during weekly orchard monitoring beginning in early June. Look for curled leaves and shoots that are not growing as vigorously as they should. Check the undersides of leaves for nymphs and adults.

Assess leafhoppers in the field as they are easily disturbed and move off the leaf. Turn the leaf over slowly when monitoring to assess how many leafhoppers are on the lower leaf surface.

Thresholds
There are no spray thresholds established for potato leafhopper in Ontario. It has been documented on other crops that potato leafhopper feeding can affect the rate of photosynthesis, yield and crop quality at fairly low populations, and before leaf symptoms occur. In apples, one or two nymphs per leaf cause leaf curling if allowed to feed for a prolonged period of time (four to seven days).

Insecticides – particularly on nursery trees and in non-bearing blocks – are recommended at the first sign of injury.

Management Notes

  • There are no parasitoids or predators that provide biological control. If feasible, do not plant alfalfa or establish hay fields near orchards.
  • For recommended materials, see OMAFRA Publication 360, Guide to Fruit Production - Chapter 3 Apples (PDF) or Apple Calendar only (PDF) :