Spud Special: Dry brings common scab fears

After anything up to 8 weeks from planting, March and most of April planted crops have emerged and are away, with no signs of any detrimental effects so far from their prolonged period underground. Also, there is currently no sign of damage from soil borne Rhizoctonia and feeding damage from free living nematodes, despite nearly record high numbers of free living nematode present pre-planting in some areas.

May plantings look like they will start to come through in the next week as the warmer weather has heated the top 2-4 inches of the ridge and sparked more movement, with last planted crops probably coming through in around four weeks from planting – still substantially slower than normal.

Herbicides have been tricky to apply, with winds resulting in very small spray windows when the ridges have been moist. One thing that has been noticeable has been a comparatively large flush of annual meadow grass (AMG). This has meant diquat rates in pre-emergence tank mixes have had to be increased more than usual to ensure control of emerged AMG at the time of spraying.

March planted Marfona and Osprey under fleece have now met along the rows and have double the canopy of comparative open ground crops. With the lack of rain, low blight risk and no emergency weed control required, the decision has been made to leave the fleece on for the time being.

These conditions have also led to need to start irrigating for common scab, not seen for some years in most areas north of the border. This may be the cue for at least an inch of rain, but so far no sign of this. Open crops still have moisture in the centre of ridge, but pipes are being laid in preparation for applying irrigation prior to TI which looks 7-10 days away for most early crops.

Blight programs will commence soon with a starting fluazinam for ware crops. Continuing cold nights, lack of rain and comparatively low humidity in the day means the situation is relaxed at present, but possibly this is the calm before the storm.

As predicted aphids are also scarce, although a good weeks’ weather may stir some up. In Scottish traps aphid catches so far are less than 1% of the 10 year average, with only very low levels of cereal aphid present. Most seed crops are probably not going to emerge for another 10-14 days so things may be different by then, but it’s unlikely to be a high risk year at present.

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