Potato Review Group

Contents

Reasons for sampling and testing

Sampling

Laboratories

Further information:

Notes on tests for pests

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Reasons for sampling and testing

  1. Aphids
    • The number and species of aphid can indicate the risk of virus transmission.
    • This is particularly important for seed crops or cultivars which are very susceptible to virus infection.
    • Ware crops may not need an aphicide unless there is a high risk of virus transmission early in the season.
    • For more details see: Transmission of viruses.
  2. Potato cyst nematodes
    • Sampling is very important as part of integrated control.
    • This can indicate the need for
      • a resistant cultivar (where possible)
      • chemical (or biofumigant) control
      • monitoring hot spots
      • a longer rotation
      • not cropping the field with potatoes
    • For more details see: PCN control.
  3. Free living nematodes
    • Sampling can indicate the need for
      • chemical (or biofumigant) control
      • monitoring hot spots
      • not cropping the field with potatoes
    • Nematodes can also be analysed for tobacco rattle virus, to indicate the risk of spraing transmission.
  4. Slugs
    • Sampling is important to time appropriate application of molluscicide pellets.
    • These have a limited duration of efficacy.
    • Slugs will not move to the soil surface to encounter pellets unless conditions are suitable.
  5. Wireworms
    • Chemical treatment may suppress but does not control wireworms.
    • Infested fields may not be suitable for cropping with potatoes.

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Sampling

  1. Aphids
    • Method 1: DIY
      • Walk the crop in a “W” pattern.
      • Inspect leaves from the top, middle and bottom of the canopy.
      • Count the number of aphid colonies (species do not need to be identified).
    • Method 2: join the aphid trapping scheme.
      • This uses “yellow water” kits which are sent to the laboratory each week.
      • Ensure that the kits are positioned at the top of the canopy and the height changed as the crop grows.
    • For further details on both methods see: Aphid monitoring.
  2. Potato cyst nematodes
    • The more intensive the sampling, the greater the probability of detecting low populations.
    • Sample on a grid system but not not use contour mapping.
    • Record and sample hot spots separately.
    • For further details see: Sampling for PCN testing and: AHDB PCN soil sampling guide (external website)
  3. Free living nematodes
  4. Slugs
    • Slug populations may be assessed most effectively by examining fields at night, particularly after rain.
    • Caribid beetles are effective predators of slugs and their populations may be assessed by placing pitfall traps between the potato rows.
    • For further details see: Slugs.
  5. Wireworms
    • Wireworm populations are difficult to asses, so as many methods as possible should be used.
      • Soil sampling
      • Bait traps
      • Pheromone traps for adult click beetles in preceding crops.
    • For further details see: Assessing the risk of wireworms.

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Laboratories

See this Links page for laboratories which perform pest analysis.

Always check with the laboratories for analyses currently performed and for prices.

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Notes on tests for pests

Control of soil pests 2015 (Includes slug and wireworm risk assessments)

Growth of seed crops 2005 (Includes DIY method of monitoring for aphids)

Pest control 2010 (Includes statutory sampling for PCN)

PCN control 2000 (Includes sampling patterns and problems with contour mapping)

PCN sampling 1996 (Sampling efficiency increases with intensity of sampling)

PCN sampling 1996 (Inefficiency of sampling)

PCN sampling methodology:

AHDB PCN soil sampling guide.  This is an external website which opens in a new window and provides a link to the current industry standard guide on soil sampling for PCN.

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