Potato/Tomato Psyllid

Bactericera cockerelli

Potato/Tomato Psyllid

Potato/Tomato Psyllid

Legal Status: No Status
Status in New Zealand: Established
Organism: Insects, worms and other land invertebrates

This pest is established in New Zealand.

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If you suspect you have found this pest on your crops you should contact your horticultural crop adviser.

Information

The tomato/potato psyllid native to North America was first found in New Zealand in 2006, and is still spreading throughout the country.

MAF Biosecurity New Zealand has become aware of a growing interest in the damage caused by this psyllid by home gardeners and have taken the initiative in sending a fact sheet containing further information out to over 300 garden centres through out the country.

The fact sheet Link to PDF document (212 KB), produced by Plant & Food Research, will help home gardeners recognise the pest and its associated diseases. It describes what damage the psyllid can cause to garden crops and how to manage the psyllid itself.

A full edition of this fact sheet Link to PDF document (212 KB) is available online at the Horticulture New Zealand website (www.hortnz.co.nz (offsite link to www.hortnz.co.nz)).

If you would like additional information please refer to the insectwatch website or Horticulture New Zealand website. We also suggest that you contact your local garden centre staff who can recommend the most suitable product to deal with any psyllid infestation. Plant & Food Research, Horticulture New Zealand and MAF Biosecurity New Zealand are unable to recommend specific commercial products to the public.

Description

The psyllid has three lifestages. The lifestages are egg, nymph and adult.

Outdoors in North America there are thought to be 4-7 overlapping generations per year. In greenhouses development and survival can occur from between 15.5°C and 32.2°C, optimum development occurring at 26.6°C. The development threshold is 7°C. In a greenhouse averaging 18°C psyllids will take 33 days to complete the life cycle.

Psyllid adults can mate more than once. The first mating usually occurs 2-3 days after emergence.

Females lay up to 510 eggs over their lifetime. Eggs are laid over a period of about 21 days. Eggs hatch 3-9 days after laying.

Eggs are oval in shape and yellow to orange in colour. The eggs are attached to the leaf by a stalk.

Eggs can be laid on all parts of the leaf and are very obvious when on the leaf edges.

The nymph goes through five scale-like nymphal stages. The psyllid remains a nymph for between 12-21 days. Over this time they change from light yellow to tan to greenish brown in colour. The nymph will grow to 2mm in length and feed on the underside of the leaf. Wing buds appear in the third instar and become obvious in the fourth and fifth instars. The wing buds distinguish the psyllid from whitefly nymphs.

Adult psyllids are 3-4mm in length with long clear wings. The adult can resemble miniature cicadas. On emerging the adults are light yellow in colour. After 2-3 days they change to brown or green in colour. After 5 days they become banded grey or black and white in colour.

Psyllids feed like aphids. Psyllids insert stylets into the plant, suck the sap and excrete the excess water and sugar as honey dew or as a solid waste (psyllid sugar). Psyllid sugar is the symptom that you are most likely to see on your plants. Nymphs and possibly adults inject a toxin into the plants when they feed. The toxin causes discolouration of leaves and the plant to become stunted exhibiting ‘psyllid yellow’ and ‘purple top’. Leaf edges upturn and show yellowing or purpling. The plants internodes shorten and new growth is retarded.

If the psyllids are removed, the plant may start to grow normally.

Impact

In tomatoes, psyllid feeding can cause plants to produce numerous small poor quality fruit or prevent fruit forming. In potatoes, the psyllid can cause a reduction in the numbers of tubers, size of tubers and production of secondary tubers. Harvested tubers often sprout prematurely. Not all host plants show ‘toxic’ plant reaction symptoms.

Potato / tomato psyllids can cause unacceptable crop losses to potato and tomato crops. Until recently it was primarily a problem for outdoor crops. In California the western population has become a serious pest of tomato greenhouse crops. The psyllid has caused tomato production losses exceeding 80% in 2001 and 50% in 2004. Damage to capsicums is reported to be less severe, with no yellowing of plants, though fruit can be contaminated with psyllid sugar. Tomato cultivars vary in susceptibility to the psyllid, but there is no information on the susceptibility of cultivars grown in New Zealand.

Spread

Potato / tomato psyllids are found in the USA, northern Mexico, southern Canada, and now New Zealand.

The psyllid was initially discovered in an Auckland greenhouse tomato crop operating an Integrated Pest Management (IPM) programme. A survey of IPM tomato growers in the Auckland area found other affected greenhouse crops. Potato plants, growing in a field adjacent to an affected greenhouse, were found to be affected. The psyllid has also been found in a greenhouse capsicum crop near Taupo.

It is not known how the psyllid arrived in New Zealand.

Overseas the psyllid is reported to have host plants in 20 families, but has only been found breeding on three families, one of which (Lamiaceae) was in a greenhouse only. Solanaceous species (capsicum, egg plant, potatoes, tomatoes and black nightshade) are the preferred hosts, but it may breed on species of Convolvulaceae, including kumara, especially if high populations are nearby.

Known wild hosts present in New Zealand include Solanum nigrum (black nightshade), Physalis spp (cape gooseberry), Ipomoea purpurea (common morning glory) and Convolvulus arvensis (field bindweed). Ornamental solanaceous plants are potential hosts. The native species of Solanum (ie porapora) may also be a suitable host.

In North America the psyllids migrate in spring from southern USA and northern Mexico to northerly locations (Utah, Colorado, Wyoming and Nebraska). The psyllid is intolerant of high temparatures and unable to withstand sub-zero tempartures. Winged adults have been known to travel up to 1524m. The psyllid is probably able to survive outdoors in many parts of New Zealand. It is not known if it will undertake long distance travel here.

Adult psyllids are strong fliers and are dispersed by the wind. They will spread from outdoor crops when the plants are no longer suitable. They will also be spread by the movement of plants, e.g. from nurseries and garden centres. Affected greenhouse vegetable crops can be a major distributor of adults. In particular prunings and old plants when removed from the greenhouse, especially if they are dumped outside and left uncovered. Adults fly readily when disturbed, so once in a greenhouse they will spread through a large area as a result of people working the crop.

Management

It is best to carefully monitor for these pests within your crops.

In Greenhouse crops you can:

  • Hang yellow sticky traps close to the top of the plant canopy to capture adults.
  • Hang yellow sticky traps by vents to check for adult psyllids entering from outside.
  • Check plants weekly for signs of eggs, nymphs and ‘psyllid sugars’.
  • Check plants for ‘psyllid yellows’ symptoms. This is yellowing of leaves, curling up of leaf edges and shortening of internodes.

In outdoor crops you can:

  • Check plants that display symptoms, such as stunted growth, ‘psyllid yellows’ or ‘purple top’, for the presence of “psyllid sugar” and psyllids.
  • Place sticky yellow cards at field margins near the tops of tomato plants to capture adults.
  • In Californian potato crops, adult psyllids are monitored with sweep nets or with yellow pan traps containing a small amount of ethylene glycol. For more information on this method visit www.ipm.ucdavis.edu (offsite link to www.ipm.ucdavis.edu).

There are a range of actions can be undertaken to control the psyllids. These include:

  • Remove and destroy affected leaves from greenhouse crops. Plant material should be kept in a covered container until removed from the property. If kept on the property, plant material should remain covered with edges sealed for 4-6 weeks. Old crops being removed should be treated the same way.
  • Remove and destroy alternative host plants from outside greenhouses. This is especially important before crop removal and replanting.
  • Biological control: Generalist predators may kill psyllid adults and nymphs. Overseas parasitoids are known and one is used in Canadian greenhouses. Entomopathogenic organisms may be able to provide control of psyllids in IPM growing systems (Growing Today July 2006).

Insecticides that control aphids are likely to control psyllids.

  • Overseas some pyrethroid, organophosphate and endosulfan products have been used for control. These products do tend to kill natural enemies of the psyllid and other pests.
  • Other insecticides have had variable levels of success. Products containing abamectin and spinosad appear promising. Data on products containing imidaclopria and pymetrozine are less promising. Buprofezin has be able to control some psyllid species.
  • Insecticide should be applied at intervals of 10-14 days. Good coverage of the underside of leaves is essential.
  • Insecticides appear to give greater efficacy on least favoured host plants.
  • Greenhouse crop growers who are using bumble bees as pollinators and biological control for some pests should consult their horticultural crop advisor on how to control the psyllid.

Page last updated: 8 December 2014