Potato management notes

October 2015

Reducing damage

With the potato harvest ongoing, keep an eye on mechanical damage to tubers.

Damage occurs with drops from harvesters into boxes or trailers, bruising caused by insufficient soil on the web, slicing by exposed sharp edges or an incorrect share setup and crushing due to oversize tractor tyres running in the drill bottom or stacking overfilled boxes. Excessive damage often leads to increased problems in store and eventual down-grading of the produce. Early identification of damage is critical. Take daily samples of the harvested crop, wash and inspect for damage. Hot boxing gives a quicker indication if damage has occurred. The entire harvesting team should be made aware of the importance of damage and bruise prevention, as they are often in the best position to identify problem areas.

Drying and curing

Drying potatoes quickly, post harvest, prevents the development of skin blemish diseases and soft rots. Drying within 48 hours using positive ventilation systems significantly reduces the development of diseases such as silver scurf. The curing period immediately following harvest is one of the most important storage phases. Wound healing occurs most rapidly at high temperatures and high humidity. Maintaining the crop at 12 to 15 degrees centigrade and 85 per cent relative humidity for a period of about two weeks, often referred to as ‘dry curing’, allows wound healing to take place, whilst minimising the risk of disease development. Ventilating the store on dry afternoons during the curing period will normally provide adequate curing conditions.

September 2015

Late season management

Regularly inspect crops to ensure blight does not establish as crops begin to senesce. Maintain blight spray programmes until after haulm desiccation.Regular trial digs should be carried out to indicate when tuber size has reached your market specification, allowing desiccation to betimed accordingly. Allow sufficient time for full skin set before harvesting the crop into a controlled environment store.

Store hygiene

Clean stores are essential for maintaining tuber health and quality post harvest. Spores of many storage diseases lie dormant in the dust and debris in stores, boxes and equipment. Significant reductions in infection can be achieved by thoroughly power hosing and vacuuming stores and equipment before the new crop is harvested and between batches of potatoes, particularly if there was any disease in the previous lot. Effectiveness can be further improved by applying an approved disinfectant after washing and vacuuming.

Reducing damage

Mechanical damage was a significant problem last year due to the very dry September and resulted in problems in store and the down-grading of produce. It is important to set machinery correctly and ensure all involved in harvesting and handling are aware of the importance of damage and bruise prevention. Damage can occur with drops from harvesters into boxes or trailers, bruising caused by insufficient soil on the web and crushing due to oversize tractor tyres running in the drill bottom.
Early identification of damage is critical and samples of the harvested crop should be taken daily, washed and inspected for surface damage and hot boxed to quickly reveal any bruising.

Drying and curing

Drying potatoes quickly after harvesting prevents the development of skin blemish diseases and soft rots. Drying within 48 hours using positive ventilation systems significantly reduces the development of diseases such as silver scurf. The curing period immediately after harvest is one of the most important storage phases. Maintaining the crop at 12 to 15 centigrade and 85 percent relative humidity for a period of about two weeks, often referred to as ‘dry curing’, allows wound healing to take place, whilst minimising the risk of disease development. Ventilating the store on dry afternoons during the curing period will normally provide adequate curing conditions.

May 2015

As planting progresses it is important to ensure good quality seed beds are produced. Increasing soil contact around the developing tuber helps reduce scab and also allows residual herbicides to work effectively. Also check now and again to ensure correct planting depth and spacing.

Plans should be in place for early weed control to ensure key timings are not missed. Where pre-emergent products are used check crops regularly to ensure herbicides are applied on time to avoid crop damage.

April 2015

Soil compaction is increasingly blamed for below par yields of potatoes. As planting gets under way the advice is to: set tyre pressures correctly, limit the amount of field traffic where possible and avoid working damp soils which are more prone to damage.

Seed management prior to planting

It is important to carefully check seed as it arrives on farm, and have a sample hot-boxed to determine the presence of disease and overall sprouting vigour. Treat seed with a fungicide pre-planting with the aim of reducing disease transmission and maximising marketable yield. Monitor seed carefully as conditions warm up, particularly where cold storage is not available, to prevent any deterioration of quality which can occur quickly at this time of year prior to planting.

Once conditions are suitable for planting, check ridges regularly to ensure correct seed spacing and planting depth for your variety are being achieved, to ensure optimum plant populations and even emergence.

March 2015

Early fertiliser

By now most fields intended for spring cropping should be soil sampled. If there is a high requirement for potash (K) it is advisable to apply this as soon as the ground is ploughed, particularly where muriate of potash is the main source.

Seed preparation for planting

Attention to detail during handling and preparation of seed prior to planting can result in an increased early tuber yield, while optimising fry colour and skin quality. It is important to carefully check the seed when it arrives on farm and have a sample hot boxed to determine the presence of disease and overall sprouting vigour. Treat seed with a fungicide pre-planting to reduce disease transmission and maximize marketable yield.

Sprouting and chitting

A number of systems are available for pre-sprouting including tray and bag systems. Systems must ensure adequate temperature control, ventilation and light. Set seed of early potato varieties up in sprouting boxes to promote apical dominance, that is, one strong sprout per seed tuber, one stem and a small number of large tubers early. The opposite holds for maincrop potatoes where multiple sprouting is encouraged to produce many tubers which can increase in size over a longer growing season.

September 2014

Early Fertiliser

By now most fields intended for spring cropping should be soil sampled. Where there is a high requirement for Potash (K) it is advisable to apply this as soon as the ground is ploughed particularly where muriate of potash is the main source.

Seed Preparation for Planting

Attention to detail during the handling and preparation of seed prior to planting can result in an increased early tuber yield, while optimising fry colour and skin quality.
It is important to carefully check the seed as it arrives on farm, and have a sample hot boxed to determine the presence of disease and overall sprouting vigour. Seed should be treated with a fungicide pre-planting with the aim of reducing disease transmission and maximizing marketable yield.

Sprouting and Chitting

A number of systems are available for pre-sprouting including tray and bag systems. Systems must ensure adequate temperature control and ventilation (to control sprout growth and protect against frost) and light (to control sprout growth). Seed of early potato varieties should be set up in sprouting boxes with the aim of promoting apical dominance i.e. producing one strong sprout per seed tuber, one stem and a small number of large tubers early. The opposite holds for maincrop potatoes where multiple sprouting is encouraged to produce many tubers which can increase in size over a longer growing season.

Mini-chitting

This system of seed preparation aims to produce seed tubers with sprouts no more than 2 mm long. Seed is stored at 3-4 oC until close to planting time. The refrigeration unit is then turned off for seven to ten days to allow chitting to occur.
Once sprouts of 1-2 mm have formed evenly, the seed should be cooled down again to 3-4 oC to prevent further sprout growth up to planting. Mini-chitting, whilst not having the benefits of earlier harvesting associated with pre-sprouted seed, produces a crop that emerges quickly and evenly.

May 2014

As planting progresses it is important to ensure good quality seed beds are produced providing good soil contact around the developing tuber to help reduce scab and also allow residual herbicides to work effectively. Also check periodically to ensure correct planting depth and spacing are being achieved.

Plans should be in place for early weed control to ensure key timings are not missed. Where pre-emergent products are used check crops regularly to ensure herbicides are applied on time to avoid crop damage.

April 2014

Soil compaction is increasingly blamed for below par yields of potatoes. As planting gets under way growers are advised to take care to ensure tyre pressures are set correctly. Limit the amount of field traffic where possible, and avoid working damp soils which are more prone to damage.

Seed management prior to planting

It is important to carefully check the seed as it arrives on farm, and have a sample hot boxed to determine the presence of disease and overall sprouting vigour. Treat seed with a fungicide pre-planting with the aim of reducing disease transmission and maximizing marketable yield. Monitor seed carefully as conditions warm up, particularly where cold storage is not available, to prevent any deterioration of quality which can occur quickly at this time of year prior to planting.

Once conditions allow planting to begin check ridges regularly to ensure correct seed spacing and planting depth for your variety are being achieved, to ensure optimum plant populations and even emergence.