Recently by Matthew Smallwood

If you are a potato grower in Scotland then you may now start to wonder what you have done wrong in the world. The only comfort is that it's not just Scottish growers. Planting is varied with many seed growers still to start while some ware producers have over 60% in the ground.

Crops planted in March into dry warm soils appear to have gone through their lag phase prior to the cold, wet April. These crops have or are emerging under fleece and in open crops. Those crops planted just before the heavy rains have moved little and their destiny hangs in the balance with an increased risk of poor emergence, rhizoctonia and free living nematode feeding damage.

When planting does restart growers need to think about strategy. There could be a benefit in increasing spacing in ware crops by 10-15% in all but very low tuber number varieties.

Unlike last season size is likely to be at a premium and wider spacing will provide crops with more chance in getting to size without extending the harvest window and jeopardising quality. There is no advantage to reducing planned nitrogen other than in indeterminate varieties or processing crops where sugar stability is required.

If there is one way to sum up the season ahead it is one word: unpredictable. To illustrate this, the heat wave in Scotland at the end of March has vanished and April has started with >15 degree drop in temperature.

By the time you read this some of the planted ridges may well be covered by a couple of inches of snow. Good progress had been made in the later end of March by most growers subject to attitude to frost risk and whether they had finished cereal drilling.

While Scotland will never be in drought it has experienced an unusually dry winter. Growers that were patient and waited for land to dry to plough have reaped the benefit, with soils with good structure, comparatively dry and in good condition to plant with high soil temperatures .

Early plantings have gone in well. Dry soil conditions may increase the risk of soil borne Rhizoctonia particularly if soil temperature drops and delays emergence. Growers should consider use of azoxystrobin in furrow where fields have a history of Rhizoctonia problems.

Harvest for most is finally finished although a few large growers are still struggling and there a number of fields that can not be lifted. While growers are now preoccupied with preserving quality in store and grading seed for export, it is worth considering next season.

This season has shown that marginal land is marginal for a reason and this is also true for virgin land. While combinable crop growers reduce costs and increase profitability by increasing scale, most potato growers need to reduce the number of marginal fields they plant instead. 

Furthermore, it has also shown that if a field has a past history or is high risk for powdery scab then there is only so much variety, and in the case of seed growers fluazinam, can do to reduce it. These fields also run the risk of potato mop top virus that has also proved problematic.

Better harvesting weather recently (light rain rather than torrential) has enabled better progress to be made with the potato harvest north of the border.

Overall there is estimated to be about 25% of the crop still in the ground. Most growers have left heaviest land till last and 5 acres a day per harvester has been the norm. But conditions have meant bruising has not been a problem, unlike English crops. 

Slow store filling means getting the cold store doors shut and temperature pulled down are the priority for quality. Tuber temperatures going into store have not fallen below 10C, which means curing should have been completed within 7-10 days of lifting.