Question marks about the potential of potato crops

Yields at Aviko growers reached 60 tons gross two weeks ago and rose slightly in week 34. With a 15% deduction, this amounts to 51,85 tons per hectare, across all growing regions and all varieties. The lots are quite large, with 85% being 50 millimeters or larger. This is a slight decrease compared to the previous week. The underwater weight increased significantly, to 400 grams.

Best result in five years
The picture at the Belgian potato company Bruwier is similar. Fontane achieved a net yield of 34 tons per hectare in week 53,5, with 87% of the crop being 50 mm or larger. This is the highest yield in the last five years. Challenger achieved 52 tons and, with 76% of the crop being 50 mm larger, is slightly less coarse. Nevertheless, this is also the best result in five years.

The high yields can be explained by the early planting dates, which is also reflected in the underwater weights. Fontane averages 414 grams and Challenger 419 grams. Ripening is reported to be 50% on average, with a fairly wide range of 30% to 90%. This means that growth will have already stalled for a large portion of the crops, especially after two dry and warm weeks.

Coarse potatoes
The 35 Fontane plots sampled by Viaverda and Fiwap were less mature at the last sampling point. On average, over 20% ripening was achieved, but this was on August 11th, a week earlier than the figures above. This likely explains the measured yield of 44 tons per hectare. This is considerably higher than the average of 34 tons/ha for this date. Here too, the tubers are already quite large, with 83% in the 50 mm+ grading. This is due to a lower number due to a dry spring.

On August 11th, the crops had an average of 121 growing days. Looking at this timeframe, yields in 2021 and 2023 were higher. Plots in the coastal provinces, in particular, are lagging behind due to drought. The lower limit is 28 tons, while the best plot yields 66 tons. The differences between Flanders and Wallonia are relatively small this season, at just two tons.

Potency
Over the past two weeks, an average of 385 kilos per hectare per day has been harvested. This is just in line with expectations. The highest yield is achieved after 145 days on average. This means that the potatoes still had to grow for just under a month after the last sampling. What followed was a very warm and dry week. After a more moderate week, warm and dry weather will return in the coming days. This will cause the crops to wear out quickly, according to growers. September will likely be somewhat changeable, but it remains to be seen whether most crops will be able to benefit from this.

Viaverda concludes that, given the current situation, a net final yield of 47 tons per hectare is achievable. This isn't bad, but not a great result either. As expected, the underwater weight is high, often exceeding 400 grams, but there are also some lower outliers. One plot is experiencing significant growth. Six plots had 10% or more of the tubers showing growth. Growth cracks and hollows were rarely, if ever, encountered.

Precipitation coming
After a warm week, with locally tropical temperatures on the way, we'll be experiencing very changeable weather in northwest Europe. Heavy rain is possible along the coast, according to current weather models, due to the warm seawater. Temperatures will also drop, especially on rainy days. At 17 to a maximum of 20 degrees Celsius, temperatures in early September will be two to three degrees below average.

With a shifting southerly wind in mid-September, warmer and drier weather may return. Could this mean an ideal start to the main harvest? Almost all fields could use a shower of rain before harvesting. The clay is already being irrigated to facilitate harvesting. If harvesting can be done properly in the second half of September under moist conditions, followed by a cooling-off period at lower temperatures, that's an excellent starting point. If rain doesn't disrupt the harvest, it could mean a perfect early harvest.