Tarnished PLant Bug
Beginner
This pest affects:
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Scientific Names
Lygus lineolaris
Identification
Nymphs
- Greenish with black spots
- Wing pads are present on older nymphs
Adults
- Oval, 5-6mm long, with a brown-yellow mottled appearance
- Yellow Y on the triangular area between the wings
- Overwintering generation tend to be much darker than the summer generation
Injury
Buds
- Injured fruit and leaf buds dry up
- The plant exudes clear liquid ooze around the damaged area, which becomes amber after several hours. Affected buds do not develop and subsequently abort
- Open blossoms damaged prior to fruit set abort
Fruitlets |
Most fruitlets stung shortly after fruit set will fall off the tree during the June drop period.
Those that hang on until harvest have a large dimple or a deeply sunken conical area caused by the injection of a toxin during feeding. Early season tarnished plant bug damage tends to occur near the calyx end. |
Fruit |
Later season damage may be present anywhere on the fruit.
Developing fruit will have a shallow dimple or depressions where feeding occurred and this area will become soft and corky. Longitudinal sections cut through the depressions or dimples show that tarnished plant bug feeding causes a narrow tube extending almost to the core. |
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Early season feeding causes severe catfacing of the fruit.
Most severe catfacing damage is done immediately following bloom, from petal fall until peaches are ½ to ¾ inch in diameter. This is observed more in SW Ontario (Essex-Kent). Scarred sunken areas become corky and lack fuzz. Fresh feeding that has not calloused over has clear and sticky gumming, either in small lumps or in a single strand exuding from the fruit. There may be a number of injury marks on the same fruit. Water-soaked areas may also appear in multiple spots on the same fruit and are more likely to be observed on nectarines and plums. The summer generation (June to early July) is more of a problem in Niagara. Cells are destroyed and fruit development inhibited at the feeding site, while surrounding tissues continue to grow and expand. |
Often confused with
Stink bug adult – Green, relatively large, with well-developed shield shaped bodies
Stink bug damage- Stink bug damage appears as is sunken and often dark green spots on fruit. Cutting below the skin reveals spongy cells, often with brown discoloration (similar to bitter pit, but is typically present at the top of the fruit –not the bottom.) Injury occurs throughout the growing season
Oak bug injury – Sections of fruit surface injured as opposed to localized stings. Fruit surface damage will have irregular shaped margins. Often the damage is localized to border areas that are surrounded by bush where host trees are present (oak and hickory)
Period of Activity
Adult tarnished plant bugs begin feeding on pear buds on warm days in early April. Adults continue to feed on developing flowers from white bud through the petal fall period, when most abandon the crop in search of alternative flowering hosts.
Warmer spring temperatures throughout bloom and petal fall will increase overwintering adult activity resulting in more potential for early season fruit injury and greater summer generation pressure. Cool springs usually result in less damage. While damage to bearing orchards is minimal after June, nurseries and newly planted blocks are susceptible throughout the summer.
Scouting Notes
For pears, monitor 100 fruit/block minimum (minimum 10 fruit from 10 different trees in block) Weed indicators can be used to monitor new summer adults and levels of resident plant bug. Humid, hot windy, dry weather can promote migration into blocks. Identify nearby migration sources eg. bush, weeds.
Monitoring in peaches and nectarines is critical at petal fall to shuck fall in southwestern Ontario, where early damage is most critical. In Niagara most damage is observed between the first and second Oriental Fruit Moth generations. Sweep net sampling of blooming ground cover in sections of orchards bordering woodlands, fencerows, or other favourable hibernation sites is used to indicate populations that can move into the trees. Two hundred fruit should be checked periodically per block to pick up fresh feeding, ooze near or on flower buds gives an indication of adult feeding activity.
Alfalfa is a favoured host and when it is harvested, adults will move to adjacent crops in large numbers. Identify other migration sources like ditch areas with heavy weed growth, bush areas and nearby hay fields. Net sweeps of weeds in and around the orchard may also be an effective method of monitoring.
Thresholds
Since it is a direct pest, no more than one or two percent fruit injury should be tolerated at any one time.
Injury threshold of 2% at periphery of orchard, border spray is required.
Complete block sprays injury threshold 2-5% injury throughout block.
Advanced
This pest affects:
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Scientific Names
Lygus lineolaris
Identification
Nymphs
- Greenish with black spots
- Wing pads are present on older nymphs
Adults
- Oval, 5-6mm long, with a brown-yellow mottled appearance
- Yellow Y on the triangular area between the wings
- Overwintering generation tend to be much darker than the summer generation
Injury
Buds
- Injured fruit and leaf buds dry up
- The plant exudes clear liquid ooze around the damaged area, which becomes amber after several hours. Affected buds do not develop and subsequently abort
- Open blossoms damaged prior to fruit set abort
Fruitlets |
Most fruitlets stung shortly after fruit set will fall off the tree during the June drop period. Those that hang on until harvest have a large dimple or a deeply sunken conical area caused by the injection of a toxin during feeding. Early season tarnished plant bug damage tends to occur near the calyx end. |
Fruit |
Later season damage may be present anywhere on the fruit. Developing fruit will have a shallow dimple or depressions where feeding occurred and this area will become soft and corky. Longitudinal sections cut through the depressions or dimples show that tarnished plant bug feeding causes a narrow tube extending almost to the core. |
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Early season feeding causes severe catfacing of the fruit. Most severe catfacing damage is done immediately following bloom, from petal fall until peaches are ½ to ¾ inch in diameter. This is observed more in SW Ontario (Essex-Kent). Scarred sunken areas become corky and lack fuzz. Fresh feeding that has not calloused over has clear and sticky gumming, either in small lumps or in a single strand exuding from the fruit. There may be a number of injury marks on the same fruit. Water-soaked areas may also appear in multiple spots on the same fruit and are more likely to be observed on nectarines and plums. The summer generation (June to early July) is more of a problem in Niagara. Cells are destroyed and fruit development inhibited at the feeding site, while surrounding tissues continue to grow and expand. |
Often confused with
Stink bug adult – Green, relatively large, with well-developed shield shaped bodies
Stink bug damage- Stink bug damage appears as is sunken and often dark green spots on fruit. Cutting below the skin reveals spongy cells, often with brown discoloration (similar to bitter pit, but is typically present at the top of the fruit –not the bottom.) Injury occurs throughout the growing season
Oak bug injury – Sections of fruit surface injured as opposed to localized stings. Fruit surface damage will have irregular shaped margins. Often the damage is localized to border areas that are surrounded by bush where host trees are present (oak and hickory)
Biology
The tarnished plant bug has a very broad host range, feeding on more than 300 plant species including weeds, vegetables, fruit, flowers, shrubs and trees. They prefer feeding on floral buds and immature fruit. Adults are mobile and move from one crop to another as the season progresses, in search of alternate hosts.
Adult tarnished plant bugs overwinter under leaf debris, bark, logs, and under broadleaf weed litter. They become active on warm days in early spring and attack pear buds before green tissue is even present. In late spring (late May and early June), the insects migrate to herbaceous weeds, flowers and vegetables where they insert eggs into stems and stalks. Nymphs progress through five instars before molting to adults. The final three instars have wing pads. There are two generations per year, and a partial third generation.
Tarnished plant bugs can be present in peach and pear orchards by the time buds begin to swell. Temperatures of 17-20 °C at shuck will increase overwintering adult activity resulting in early season injury (fruit dimpling) and egg laying in weeds resulting in high summer generation pressure. High humidity and wind for adult dispersal also promote infestations. They feed on the flower buds of peach and pear trees. Injury appears 5-7 days following adult emergence. TPB adults are strongly attracted to orchards with winter annual weeds in bloom. Egg laying begins shortly after adults emerge, most eggs being laid in the tender shoots or flower heads of herbaceous weeds, vegetables, and legumes. Few eggs are laid in peaches. Eggs hatch in about 10 days and emerging nymphs begin to feed. The nymphal stage lasts about a month. There are several generations of tarnished plant bugs each year, but the bugs normally begin to leave peaches shortly after petal fall and move to other hosts. Populations in peach trees usually decline significantly by shuck fall.
Period of Activity
Adult tarnished plant bugs begin feeding on pear buds on warm days in early April. Adults continue to feed on developing flowers from white bud through the petal fall period, when most abandon the crop in search of alternative flowering hosts.
Warmer spring temperatures throughout bloom and petal fall will increase overwintering adult activity resulting in more potential for early season fruit injury and greater summer generation pressure. Cool springs usually result in less damage. While damage to bearing orchards is minimal after June, nurseries and newly planted blocks are susceptible throughout the summer.
Scouting Notes
For pears, monitor 100 fruit/block minimum (minimum 10 fruit from 10 different trees in block) Weed indicators can be used to monitor new summer adults and levels of resident plant bug. Humid, hot windy, dry weather can promote migration into blocks. Identify nearby migration sources eg. bush, weeds.
Monitoring in peaches and nectarines is critical at petal fall to shuck fall in southwestern Ontario, where early damage is most critical. In Niagara most damage is observed between the first and second Oriental Fruit Moth generations. Sweep net sampling of blooming ground cover in sections of orchards bordering woodlands, fencerows, or other favourable hibernation sites is used to indicate populations that can move into the trees. Two hundred fruit should be checked periodically per block to pick up fresh feeding, ooze near or on flower buds gives an indication of adult feeding activity.
Alfalfa is a favoured host and when it is harvested, adults will move to adjacent crops in large numbers. Identify other migration sources like ditch areas with heavy weed growth, bush areas and nearby hay fields. Net sweeps of weeds in and around the orchard may also be an effective method of monitoring.
Thresholds
Since it is a direct pest, no more than one or two percent fruit injury should be tolerated at any one time.
Injury threshold of 2% at periphery of orchard, border spray is required.
Complete block sprays injury threshold 2-5% injury throughout block.
Management Notes
Practice good sod management by reducing or eliminating alternate weed hosts, particularly alfalfa, chickweed, dandelion, clovers, pigweed, and lamb’s quarters.
Avoid mowing orchard rows while plant bugs are present to prevent adult plant bugs from flying into trees and feeding on fruit.
Maintain clean herbicide strip in tree row. Control weeds at headlands, these act as alternative hosts and resting sites.
Avoid situations where orchards are adjacent to hay (alfalfa) fields, strawberry patches, or other susceptible crops.
TPB injury is more pronounced around the borders of the orchard. Frequently only the outer 4 to 6 rows require sprays.
For more information on control for tarnished plant bug, see OMAFRA Publication 360, Fruit Crop Protection Guide:
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Chapter 5 Peach Calendar Recommendations for Tarnished Plant Bug at Special sprays (when monitoring indicates the need during early green fruit stage to pit hardening) |
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Chapter 5 Pear Calendar: Recommendations for tarnished plant bug at White bud |
Some information included above excerpted from;
