Most growers are making good progress with lifting, in some cases at record speed, some only slowed by delay in skin set. While there are some exceptional yields, some have not bulked in terms of ware, due to high tuber numbers and there are a lot of crops that lack baker content.
Poorer crops may have identifiable reasons for it, such as compaction, irrigation etc. However, there are a number of cases with identical soil type, pests and pathogens, cultivation, planting date, irrigation and agronomy and yet there could be >20% difference in final yield. This only goes to show how much we still need to learn about potatoes in order to maximise yields in the future.
Generally seed yields are slightly above average, except for where dry soils have reduced tuber number, with good quality. Common scab has affected some export markets, Desiree being one. There have been isolated cases of pink rot, but other than that little sign of tuber rots.
Many large growers are now using windrowers in seed, unless it is too dry to carry soil on the web. Last year there was no evidence it increased spread of rots and this season no apparent increase in damage. Looking at the speed which tubers dry in windrow compared to the box there may even be some advantages to that initial drying phase and for seed crops there is still enough soil to cushion tubers and prevent excessive bruising. For seed it is critical to get good ventilation in the first 48hrs, preferably on a drying wall or under a tent. Stacking outside on a windy day is better than using the passive airflow of a cold store.
Skin set is a problem for some late maturing and thin skin varieties, with Markies seed taking over five weeks in some cases. Skin set is the biggest problem where crops were not naturally senescing prior to burn off and the soil in the ridge is very dry. Growers need to be flexible in lifting programs and have patience. If the skin can be moved with the thumb nail it is going to scuff over the harvester.
Bruising is becoming an issue for some ware growers, although not to extent it is further south. Growers need to identify crops that are going to bruise before they have 300 tonnes in the shed. You can identify hypersensitive crops pre-lifting, in susceptible varieties such as Maris Piper, by dropping a tuber on its stolon end from 15-20cm on to a table top or use a bruising pendulum, hot box the tubers overnight and look for bruise development.
If the sample shows significant bruising then there is no way in the crops current physiological and biochemical state that it is possible to lift a marketable crop. If you are changing fields try to time it so you get a couple of loads off and are able to hot box them overnight to see if the level of bruising you are causing is acceptable. Tubers can change in bruising sensitivity within 24hrs, so keep checking and you may find you will be able to lift it without bruising.