leafhopper is an important insect pest of alfalfa, fruits, and vegetables.
Though its host range extends to over 100 plants including alfalfa,
soybean, beans, apples, potatoes, and grapes, the potato leafhopper
causes the most significant amount of injury to alfalfa and clover.
Yield losses of up to 50% may result in severe infestations. Potato
leafhoppers often go unnoticed until injury symptoms appear, which
is much later than when economic levels of the pest occur.
leafhoppers are small (1/8 inch long), wedge-shaped insects. The
body of the insect is widest at its head and narrowest at its wing
tips. Potato leafhoppers have piercing andsucking mouthparts, which
allow them to remove nutrients from host plants. This species of
leafhopper is pale green with a rowof six white spots located behind
the head. In order to observe these small white spots very well,
a hand lens may be required. Immature potato leafhoppers, or nymphs,
are smaller than the adults and yellow to pale green. Adults have
whitish or translucent wings, while the smaller nymphs or immatures
are wingless. When disturbed, adult leafhoppers readily jump or
fly away. The hind legs are long and explains the excellent jumping
capabilities possessed by potato leafhoppers. Leafhopper nymphs
can not fly, yet are very quick and move sideways across the leaves
when disturbed. Potatoleafhopper eggs are white, slender, and very
small, approximately 1/24 inch long.
leafhoppers cannot survive the winter in Illinois. Infestations
require spring migration from southern Gulf Coast States where
reproduction occurs throughout much of the winter. Female
potato leafhoppers live approximately one month and during
this time insert two to three small white eggs per day into
the stems and larger leaf veins of suitable plants.
nymphs hatch from the eggs in 7 to 10 days. Immatures pass through
five nymphal stages, taking approximately 2 weeks for the nymphs
to become adults. The entire life cycle requires about 1 month
to complete and three to four generations of leafhoppers may
be observed each year in Illinois. During the summer months,
it is common for generations to overlap. Potato leafhoppers
can be found in fields until the first killing frost in the
potato leafhopper adults and nymphs may cause injury to plants.
The chief concern for alfalfa producers is a type of injuryreferred
to as “hopper burn.” This effect is caused by
the removal of fluids from vascular tissues and the simultaneous
injection of toxic substances into the plant. An early symptom
of “hopper burn” is characterized by a V-shaped
yellow area on the leaf tip. Leafhopper damage may require
a few weeks before symptoms begin to show, and consequently
older leaves generally display the “hopper burn”
symptomology. Yield loss generally occurs before symptoms
are readily seen. Symptoms should not be confused with disease
and nutritional deficiencies, inwhich yellowing of foliage
typically begins at leaf margins. Boron deficiency, although
displaying similar leaf symptoms, usually is limited to the
“Hopper burn” injury
damage potential of potato leafhopper is greatest during dry
years. Field margins often display the first signs of leafhopper
injury and are frequently the most severely damaged portion
of a stand. Feeding on the new regrowth following the first
hay crop may severely stunt or slow further plant development.
The second and third cuttings of hay in Illinois are susceptible
to moderate to severe injury from potato leafhoppers. The
first cutting of hayis seldom damaged by potato leafhopper
in Illinois. Severe leafhopper injury can reduce both theprotein
and vitamin A content of alfalfa. This will result in asignificant
loss in the nutritional value of hay for livestock. If injury
occurs late in the season, plants may enter winter dormancy
in a weakened state.
Boron deficiency in alfalfa
leafhoppers may also be found in soybean, snap bean, and potato
fields. Injury caused by the leafhopper results in a yellowing
at the tip of the leaves, in a V-shaped pattern. Heavy infestations
may cause stunting of plants and cupping of leaves. In many
instances, leafhoppers found in soybean fields rarely cause
significant injury. Movement to soybean fields by the potato
leafhopper generally occurs when a nearby alfalfa field is cut.
less common, potato leafhoppers may also be a pest in fruit
orchards in Illinois. In apples, potato leafhoppers may be
a threat to young, tender foliage of young fruit trees. Injury
to fruit trees is similar to that found on other host plants
of the potato leafhopper. Injured foliage has the characteristic
V-shaped “hopper burn,” severe injury may cause
the entire leaf margin tobe affected. Injured leaf margins
generally curl downward. Other leafhoppers that may be present
in orchardsare the white apple leafhopper and rose leafhopper.
order to effectively monitor alfalfa for potato leafhoppers,
a 15-inch sweep net is required. At a minimum, hay should
be sampled once each week following the first cutting of hay.
This weekly schedule should be maintained since leafhoppersare
very capable of moving from field to field. Avoid sweeping
field borders or during cold and wet conditions. Sweeping
wet foliage produces results that are not reliable estimates
of the damage potential within a field.
sweeps should be taken in each of five areas of a field. Make
sure that representative portions of the field are sampled.
Avoid making sweeps along field edges. Record the average
number of potato leafhoppers (adult and nymphs) per sweep
in each of the five areas of the field. After all areas have
been sampled,calculate a field average of potato leafhoppers
per sweep. Collect 20 alfalfa stems at random from a good
cross section of the alfalfa field.
should be taken to avoid looking directly at stems that are
to be chosen; calculate the average stem length and plant
stage. If an insecticide application is necessary, based on
these suggested guidelines, plants should not be sprayed during
the bloom stage, but instead, harvested early.
is recommended to treat for potato leafhoppers in soybeans
when leafhoppers are numerous and the edges of the leaves
exhibit severe injury. Control may be warranted during bloom
when there are six or more leafhoppers per plant orduring
pod formation when 13 or more leafhoppers are found per plant.
greatest amount of injury caused by the potato leafhopper
occurs during the seedling stage. Using a sweep net, fields
should be sampled beginning in mid-May. Use the same method
as for alfalfa sampling: Take twenty sweeps in five areas
of the field and determine the average number of leafhopper
per sweep. In green beans, thresholds also may be used by
determining the number of leafhoppers per foot of row
to soybean field edge
adjacent to alfalfa field
of the management of the potato leafhopper in alfalfa has
relied on scouting, cultural control, and the use of insecticides.
The key management strategy for the potato leafhopper relies
on vigilantscouting. By scouting alfalfa fields and conducting
sweep samples, a grower can monitor the number of leafhoppers
and detect economic levelsbefore symptoms occur. Research
has proven that economic damagehas already occurred if leafhopper
injury is visible. Waiting until symptoms are visible in the
field before taking action is not recommended. If economic
thresholds are reached just prior to cutting, harvest the
alfalfa, and then monitor the regrowth to determine if treatment
harvest of alfalfa has been the primary control method of
reducing potato leafhopper egg, nymph, and adult populations.
As hay fields are cut, adult potato leafhoppers fly out of
the field. Nymphs remain in the field, but are unable to survive
without food. When infestations are above economic thresholds
and early harvest is not an option, insecticides may be used
as the primary control method. Avoid spraying during the bloom
leafhopper resistance or tolerance in alfalfa hybrids is based on
the presence of glandular hairs on the leaf surface of the plant.
These hairs act as mechanical barriers to the leafhopper feeding,
preventing them from reaching the leaf with their mouthparts. This
same type of tolerance is also functional in soybeans. Most soybean
varieties have highly pubescentleaves, but some varieties lack hair
on the leaf surface, especially food grade soybeans. Potato leafhoppers
may be a threat to very young soybean plants or whenalfalfa fields
are adjacent to the soybeans. As alfalfa fields are harvested, adult
leafhoppers maymigrate to soybean fields.
such as predators and parasites, play a very minor role in potato
leafhopper control. During cool and moist conditions, a fungal pathogen,
Zoophthoraradicans,may aid in suppressing leafhopper populations.
Heavy rains may help knock down leafhopper numbers, however, summer
storms may also bring in potato leafhoppers on wind currents.
in orchards and vegetable crops relies on the use of insecticides
when economic levels of potato leafhoppers are reached.
Leafhopper Management in Alfalfa, University of Nebraska.
Leafhoppers, University of Kentucky Entomology.
Management with emphasis on the Midwest.
(book, edited by R. Foster and B. Flood)
Kelly A. Cook (email@example.com)
Susan T. Ratcliffe(firstname.lastname@example.org)
Michael E. Gray (email@example.com)
Kevin L. Steffey(firstname.lastname@example.org)