Notes on Stone Fruit Insects & Mites
Tarnished plant bug

Identification

Tarnished plant bugs (TPB) have mouthparts that pierce and suck and are used to sting fruit. When they feed they kill plant cells and, as a result, fruit is deformed as it continues to grow. Damaged fruitlets may also exude a clear gummy substance. Pest injury varies between site and cultivar.

Period of activity

Humid, hot, windy or dry weather can promote TPB migration from weedy alternate hosts or crops into orchard blocks. Adult TPB overwinter under leaf debris, bark, logs and under broadleaf weed litter. They become active on warm days early in the spring and may attack developing buds and fruitlets. In late spring around early May and June, they migrate to herbaceous weeds, flowers and vegetables where they lay eggs into stems and stalks.

Monitoring and thresholds

Use sweep nets to monitor TPB on weedy hosts. Monitor the development of nymphs through the later instars. When new summer adults appear, start to watch for fruit injury. Monitor fruit for damage by sampling a minimum of 100 fruit/block. Apply a border spray when 2% of fruit collected from the edge of the orchard is damaged. Apply a second spray to the entire block when injury levels reach 2%-5% throughout the block.

Management notes

Cover crop management is important to prevent TPB from moving into trees at critical points in plant development. Use these management practices, together with insecticides, to minimize the size of TPB populations within the orchard and to provide an alternate food source for the summer generations of migrant plant bugs.

• Adopt a weed-free sod culture. This is an excellent way to reduce TPB damage in orchards.
  
• Apply a contact herbicide in the herbicide strip to kill early season hosts of plant bug. Early season hosts are mainly mint, creeping charlie, and annual and perennial chickweed. In most years, apply herbicide by about April 20 in southwestern Ontario and May 1 in the Niagara Peninsula.
  
• Apply a second herbicide, such as a contact plus residual, to the herbicide strip in the latter part of May to provide season-long control of weeds.
  
• Where clean cultivation is practised, begin as early as possible and continue up to about May 15 in southwestern Ontario and June 1 in the Niagara Peninsula. Early cultivation reduces the number of resident plant bugs. Stop cultivation in June to encourage weeds such as pigweed and lamb's-quarters to establish. This provides an alternate food source for first generation plant bugs and discourages feeding on peach fruit.
  
• In sod culture, mow frequently, every two weeks for example. Use fertilizer and herbicides as needed to encourage weed-free sod. Creeping red fescue or other grasses are the preferred species for sod. Avoid clover.
  
• If you use cover crops in cultivated peach orchards to lower nitrogen levels and check tree growth, delay the preparation and sowing of the cover crop until July 10, when the major danger of extensive plant bug injury is over.
  

Learn more...

• OMAFRA Publication 360 Tender Fruit Calendar
  • Apricot Calendar
  • Peach Calendar
    
  • Pear Calendar
    
  • Plum Calendar
    
  • Sour Cherry Calendar
    
  • Sweet Cherry Calendar
• OMAFRA Publication 360 Fruit Production Recommendations
• OMAFRA Tender Fruit Index page

  
  

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