Potato Review Group

Contents

Principles for all crops

Requirements for different types of crops

Further information

 

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Principles for all crops

  1. The aim is to produce the number and size of tuber required.
  2. Other quality factors for specific markets should also be considered.
  3. N.B This page summarises information from other pages. Reference links are therefore to other pages, rather than the PRG Notes directly.

Physiology

  • Analysis of the PRG data base has shown great variability in the rate of bulking of the mean individual tuber, for crops with the same progeny tuber populations.
  • The number of tubers and their rate of bulking may be influenced at different stages of development.
  • At present it is not possible to produce “designer crops” but removing constraints will help to maximise progeny tuber production per seed and the rate of bulking of the mean individual tuber.
  • Tuber size distribution may be narrow in crops where tuber bulking begins relatively late, in ideal conditions. Tuber size distribution may be wider if tuber bulking occurs in poor conditions or if crops are stressed during the period of tuber formation and early bulking, e.g. following early planting, by foliar nutrient applications at onset of stolon tip swelling (Os) or by chemical or physical damage.

See the Physiology page for further information.

Management

Suggestions for crop management assumes:

  1. use of a suitable cultivar
  2. use of high quality, disease-free seed tubers
  3. control of pests, diseases and weeds
  4. alleviation of local nutrient deficiencies, such as manganese or boron

Manipulation

  1. Attempts to manipulate a crop by restricting growth may have more than one effect, e.g.
    • reducing nitrogen application for early maturity may reduce the rate of bulking, with the result that tubers are too small
    • reducing phosphate application to restrict the number of tubers may also restrict root growth
  2. It is easier to produce consistent crop performance by providing optimum than sub-optimum conditions.
  3. For example, it is most likely that a consistent number of progeny tubers can be achieved from large seed, not pre-sprouted, planted in warm soil with sufficient phosphorus and water. See the Seed pages for further information.

Harvest

For all crops an early harvest is beneficial to:

  1. restrict the development of blemishing diseases
  2. reduce the risk of “harvest diseases” (gangrene, etc.)
  3. allow harvest when soil conditions are good
  4. reduce the risk of bruising at low temperatures
  5. reduce the risk of reducing sugar accumulation at low temperatures

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Requirements for punnet / salad crops

  1. A high number of tubers is of primary importance.
  2. A high rate of bulking of the mean individual tuber will generally be important to ensure that these tubers reach the required size by a reasonable date.

Seed

  1. Use the largest seed which can be planted accurately.
  2. Is an early harvest / maturity important?
  3. NO: do not pre-sprout.
  4. YES: consider pre-sprouting in the light at a relatively low temperature to a maximum of 10 mm sprouts.

Seed the Seed pages for further information.

Planting

  1. Plant at a high seed tuber population.
  2. A higher population can be achieved in beds than in rows.
  3. Plant into warm soil but do not plant very late in hot conditions.

See the Planting page for further information.

Water

  1. Start monitoring soil moisture as soon as plants begin to grow and particularly during stolon and tuber formation.
  2. Ensure that soil is not drier than – 25 kPa during this period.
  3. Continue monitoring soil moisture during early tuber growth to reduce the risk of common scab.

See the Soil moisture page for further information.

Nutrition

  1. Use the standard PRG phosphate application.
  2. Make a foliar application of phosphate at stolon formation if it has not been possible to maintain moist soil.
  3. Make a foliar application of magnesium at emergence if there is a probability of low uptake of magnesium.
  4. Avoid high concentrations of fertiliser (particularly potassium) close to developing sprouts and stolons.
  5. Use the standard PRG nitrogen rate.

Biostimulants

  1. If there has been any risk of “sugar stress” apply a product which will supply sugars or stimulate sugar production by the onset of stolon tip swelling (for rate of bulking and / or number of tubers – particularly if seed has been pre-sprouted).
  2. If there is a risk of heat / drought stress apply a suitable amino acid product.
  3. Do not apply any other biostimulants unless their affect on progeny tuber production is known.

See the Biostimulants page for further information.

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Requirements for packing / processing crops

  1. Tuber quality is of primary importance.
  2. A high rate of tuber bulking may be necessary to meet market requirements for a relatively early date of harvest.

Packing crop requirements

The following are important:

Processing crop requirements

The following are important:

See the following pages for further information:

Seed

  1. Use medium – large seed, avoid smaller seed grades particularly if it has in the past been difficult to achieve adequate progeny tuber numbers.
  2. Is an early harvest / maturity important?
  3. NO: do not pre-sprout.
  4. YES: consider pre-sprouting in the light at a relatively low temperature to a maximum of 10 mm sprouts.

See the Seed pages for further information.

Planting

  1. Plant at medium – high populations if progeny tuber number is important.
  2. Plant at medium – low populations if progeny tuber size is important.

See the Seed size and rate page for further information.

Water

  1. The latest times to begin monitoring soil moisture are:
    • the start of stolon growth, for number of tubers,
    • the start of tuber formation, to reduce the risk of common scab,
    • the onset of tuber bulking, for a fast and continued rate of bulking.
  2. Packing crops: continue irrigating for as long as possible, to reduce the risk of bruising.
  3. Processing crops: end irrigation early if dry matter concentration is too low but remember that drought stress can increase reducing sugar concentration.

See the Soil moisture page for further information.

Nutrition

  1. Use the standard PRG phosphate application.
  2. Apply phosphate to foliage at stolon formation if number of tubers is important or if soil is dry.
  3. Use the standard PRG potassium rate.
  4. Use the standard PRG nitrogen rate.
  5. If there is a probability of magnesium deficiency:
    • apply to foliage at emergence (particularly if number of tubers is important)
    • make foliar applications during bulking (to maintain bulking and reduce the risk of bruising).
  6. If there is a probability of zinc deficiency:
    • apply to foliage at emergence (particularly if rate of tuber bulking is important)
    • make foliar applications during bulking (to reduce the risk of formation of phenols – for bruising or free amino acids – for poor fry colours).

Biostimulants

  1. If there has been any risk of “sugar stress” apply a product which will supply sugars or stimulate sugar production by the onset of stolon tip swelling (for rate of bulking and / or number of tubers).
  2. If there is a risk of heat / drought stress apply a suitable amino acid product.
  3. There may be benefits from other biostimulants such as “soil improvers”.

See the Biostimulants page for further information.

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Requirements for baker Crops

  1. Large tubers are of primary importance.
  2. A low number of tubers will be required.
  3. A high rate of tuber bulking of the mean individual tuber will be necessary to ensure that the tubers reach the required size.
  4. Skin finish (appearance and freedom from blemishing diseases) and freedom from bruising will also be important.

Seed

There are a number of possible options:

  1. large seed planted at a low population
  2. medium – small seed planted at low – medium population (very small seed has a risk of a low rate of bulking)
  3. physiologically aged seed (may have advantages for early maturity)

Seed the Seed pages for further information.

Planting

  1. If planting early for a long duration of bulking, use large seed (more robust) at a low population.
  2. If using medium – small seed plant at a low – medium population in warm conditions (for a fast rate of bulking).

See the Planting page for further information.

Water

  1. Monitor water from the start of tuber development, to reduce the risk of common scab.
  2. Continue irrigation until as late in the season as practical, to reduce the risk of bruising large tubers.

See the Soil moisture page for further information.

Nutrition

  1. Use the standard PRG phosphate application.
  2. Use the standard PRG potassium rate.
  3. Use the standard PRG nitrogen rate.
  4. If there is a probability of early zinc deficiency apply zinc to foliage after emergence (for a fast rate of bulking of individual tubers).
  5. If there is a probability of magnesium deficiency make foliar applications during bulking (to maintain bulking and reduce the risk of bruising).

Biostimulants

  1. If there has been any risk of “sugar stress” apply a product which will supply sugars or stimulate sugar production by the onset of stolon tip swelling (for rate of bulking).
  2. If there is a risk of heat / drought stress apply a suitable amino acid product.

See the Biostimulants page for further information.

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Further information

This page summarises information from other pages. Reference links are therefore to other pages, rather than the PRG Notes directly.

 

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