How to Manage Pests
UC Pest Management Guidelines
Apple
Leafhoppers
Scientific name:
White apple leafhopper: Typhlocyba pomaria
Rose leafhopper: Edwardsiana rosae
(Reviewed 8/06,
updated 8/06)
In this Guideline:
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There are two generations of white apple leafhopper per year. Eggs
of this species overwinter in the apple trees and hatch shortly after bloom.
Adults of the first generation appear in the last part of May to early June.
Nymphs of the second generation develop in July and August.
Rose leafhoppers do not
overwinter in apple trees; instead they overwinter on plants of the rose family
such as blackberries. In spring, the first generation develops on the
overwintering host; adults then migrate to other hosts, including apples. The
second generation and apparently a third generation may be spent on apples.
This species often reaches great abundance near to or after apple harvest.
The
adults of both species are white, about 0.12 inch long and cannot be readily
distinguished from one another. Rose leafhopper populations can be identified
by the presence of black spots at the base of thoracic setae on older nymphs;
these spots are not found on nymphs of
the white apple leafhoppers.
Leafhoppers feed by sucking on leaf tissue. Their feeding causes a
white stippling on
leaves. In heavy infestations, fruit may be reduced in size and buds may be
weakened. Excrement dropped by leafhoppers will appear as black specks on
apples. These specks are easily removed by washing. Leafhoppers also produce
honeydew, which forms into sticky droplets around the calyx end after rainfall
or overhead sprinkling, and is not easily removed.
White apple leafhopper has become an increasing problem in the past
decade because it has developed resistance to organophosphate insecticides.
Start monitoring at petal fall to determine need for treatment.
Biological Control
Parasites of the white apple or rose leafhopper have
not been studied in California apple orchards. In other areas, parasitization
of eggs may be significant in holding populations in check.
Monitoring
and Treatment Decisions
Insecticides are most effective when applied during
the first four nymphal instars of the first generation, especially in the
fourth instar. These stages occur between petal
fall and the first codling moth spray. Start monitoring for this leafhopper at petal
fall. At weekly intervals sample four leaves per tree from 25 trees dispersed
throughout the orchard. Peak nymphal emergence typically occurs 3 to 4 weeks
after the first nymphs are found. Treatment is warranted when populations
exceed an average of 0.5 nymphs per leaf or when 30% of the leaves are
infested. Rose leafhopper is a concern when high populations of nymphs exist
near harvest; treatment of nymphs may be warranted at this time.
| Common name |
Amount to Use |
P.H.I.+ |
| (trade name) |
(conc.) |
(dilute) |
(days) |
|
| When
choosing a pesticide, consider information relating to the impact
on natural enemies and honey bees and
environmental impact.
|
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| A. |
IMIDACLOPRID |
| |
(Provado) 1.6F |
4–8 fl oz |
1–2 fl oz |
7 |
| |
MODE
OF ACTION: A neonicotinoid (Group 4A)1 insecticide.
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COMMENTS:
Allow 10 days between applications. Repeat applications of any neonicotinoid insecticide (acetamiprid-Assail; imidacloprid- Provado; and
thiacloprid-Calypso) can lead to resistance to all neonicotinoids.
Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance. |
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| B. |
ACETAMIPRID |
| |
(Assail) 70WP |
1.1–1.7 fl oz |
0.275–0.425 fl oz |
7 |
| |
MODE
OF ACTION: A neonicotinoid (Group 4A)1 insecticide.
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COMMENTS:
Repeat applications of any neonicotinoid insecticide
(acetamiprid-Assail; imidacloprid- Provado; and thiacloprid-Calypso) can lead
to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance. |
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| C. |
INDOXACARB |
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(Avaunt) |
5–6 fl oz |
— |
14 |
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MODE
OF ACTION: An oxadiazine (Group 22)1 insecticide.
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COMMENTS:
Must be timed for leafhoppers and not other pests to be effective. Do not
apply dilute applications of more than 200 gal water/acre. For best results,
use 50-150 gal water/acre. Minimum interval between treatments is 7 days.
Make no more than 4 applications/season or 3 applications before hand-thinning. |
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| D. |
DIAZINON* 50WP |
3–4 lb |
0.75–1 lb |
21 |
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MODE
OF ACTION: An organophosphate (Group 1B)1 insecticide.
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COMMENTS:
Apply when nymphal stages are present. Applications made during the foliage
season are very disruptive of beneficials. Avoid drift and tailwater runoff into surface waters. |
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| E. |
CARBARYL* |
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(Sevin) 80S |
1.875 lb |
0.5 lb |
3 |
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MODE
OF ACTION: A carbamate (Group 1A)1 insecticide.
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COMMENTS:
Will thin apples up to 30 days after full bloom. May cause severe outbreaks
of spider mites. One application early in the season does not cause mite increase in coastal areas. |
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| F. |
ENDOSULFAN* |
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(Thionex) 50WP |
4 lb |
1 lb |
30 |
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MODE
OF ACTION: An organochlorine (Group 2A)1 insecticide.
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UC IPM Pest Management Guidelines: Apple
UC ANR Publication 3432
Insects and Mites
J. L. Caprile, UC Cooperative Extension, Contra Costa County
L. R. Wunderlich, UC Cooperative Extension, El Dorado County
P. M. Vossen, UC Cooperative Extension, Sonoma and Marin counties
W. W. Coates, UC Cooperative Extension, San Benito County
H. L. Andris, UC Cooperative Extension, Fresno County
L. G. Varela, UC IPM Program, Sonoma County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to the insects and mites section:
C. Pickel, UC IPM Program, Sutter and Yuba counties
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