Spud Special: Spot disease risks early

Once again the weather is playing a big part in proceedings. Soils are now very wet in some areas after more than 3 inches of rainfall over the last 10-14 days.

Seed harvest in Yorkshire seems to be progressing well with acceptable yields and generally good quality. Harvest of main crop into store has only just got started, with yield, size and quality hugely variable.

Crop intelligence pre harvest is crucial for understanding what issues might affect storage and what action may be required at or after harvest to maintain quality and health. Regular digging of crops pre harvest enables growers to identify potential problem crops and plan their storage accordingly.

Common scab and raised lenticels are the biggest concerns for me at present as essentially they are wounds through which disease infection can enter.

Therefore if bacterial inoculum is present, in the form of blackleg, wet rots, from water logging or blight, and mother tubers, then infection can take place, giving rise to major storage issues.

Positive ventilation of stores is best, if drying is needed. Remember to use air that has less than a 4oC temperature differential otherwise condensation will occur. The time taken for curing will vary depending on tuber temperature. Tubers coming into store at 10C will usually take 7-14 days, whereas tubers coming into store at 5C may take 21-42 days.

Bruising is always a consideration, remember, some varieties are more susceptible than others:

Tuber temperature: Bruising is less where tuber temperatures are more than 12C.

Soil moisture at haulm destruction: Bruising is considered a greater risk when dry at haulm destruction.

Soil moisture at harvest: Dry soil conditions at harvest mean more damage risk and thus more bruising risk

Tuber turgidity:  When tubers are turgid they are less prone to bruising

Stock has bold tubers: Larger tubers are more prone to bruising than small ones

Harvester settings:  Set up with minimal impacts and sufficient soil on the web

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