Tarnished Plant Bug I

• Tarnished Plant Bug II

Biology

Tarnished plant bugs are about 5-6 mm long and 2.5 mm wide. They vary from pale green to reddish-brown and have a distinct triangle or "V" mark about one-third of the distance down the back, just in front of the wings. There legs and antennae are relatively long. Young nymphs are a dull blue-green. They look like aphids but are much more active. Colour in the older nymphs becomes more variable and is similar to that of the adults. Nymphs develop prominent black dots on the top of the thorax and abdomen.

Symptoms of Damage

Plant bugs physically damage the plants by puncturing the tissue and sucking plant juices, affecting the strawberry crop in both quality and quantity. Feeding on the flower blossoms and developing fruit causes uneven pollination. This results in "cat facing" or apical seediness. Yields are also affected. Most damage occurs after petal fall. In extreme cases, up to 85 per cent of the fruit may be damaged.

Monitoring

Early monitoring of fields is important if damage is to be minimized. It is easily done using a standard, insect sweep net, being sure to sample throughout the field on a regular basis, starting at the bud stage. Growers often sample by tapping the blossom clusters of strawberry plants into shallow trays. This works fine for the nymphs (the most injurious stage). However, the adults fly quickly when disturbed and are often unseen. Because the adults can fly long distances, an outbreak may occur suddenly. Regular sampling and sweeping is needed to detect such infestations.

Economic Thresholds

One or more plant bugs per flower or fruit cluster (based on sampling 15 plants using the beating tray method) will usually warrant immediate chemical control. A registered insecticide may be used according to label directions just prior to blossoms opening and again when fruit begins to colour.

Comments

Because many weeds serve as alternate hosts, it is important to eradicate weeds in and near strawberry plantings. Because these insects sometimes over-winter in tall grass, any permanent sod should be mowed in late fall. They can be controlled in ornamental plantings by weed control and by keeping lawns or grassy areas mowed to eliminate breeding sites. If alfalfa is grown near strawberry fields, avoid cutting the alfalfa until after the strawberry fruit has been harvested. If cut before this time the insects that are infesting the alfalfa will move directly onto the strawberries.

For further information, contact your GO representative.