There is a good chance that unirrigated crops will die in the coming week due to the approaching heat wave and associated solar radiation. As soon as the heat wave, which may last an extremely long time, is over, there is a risk of further growth in ware potatoes.
If it is sunny from early morning to late evening for a week and the temperature rises above 30 degrees every day, burning in, for example, unirrigated silage maize is inevitable. The foliage of consumption potatoes will also die more quickly. This is what Agrowin advisor Gerben Houwers from Winterswijk (Gld.) predicts.
Soil quality is decisive
It is precisely under these conditions that soil quality becomes visible. The organic matter content is particularly decisive on sandy soils. In contrast to last year, the silage maize on the sandy soils of the East Netherlands is in reasonably good condition. In 2018 and 2019, extreme drought and sunburn caused mediocre flowering and a lack of cobs.
"That is not the case now," says Houwers. "Even without irrigation, I think the silage maize on good soil will withstand the heat without any problems, because it is a tropical crop." But if the soil quality is poor and there is no irrigation, there is a risk of premature death, according to the advisor. "Irrigating silage maize is not easily profitable. But if I had an installation available, I would certainly irrigate the maize, so that the cobs in it also fill well," says Houwers.
Delphy advisor Bert Aasman
Alternaria fungus
There is also a risk of significant yield loss in the cultivation of potatoes for consumption if irrigation is not possible. In addition, the Alternaria fungus can cause problems. "It is time to combat this fungus," recommends Delphy advisor Bert Aasman, whose working area is the sandy soils of East Brabant and North Limburg. There is plenty of irrigation in this region.
Aasman underlines the importance of irrigation. "Last year we measured with a drone that the temperature on the soil in the potato crop remained below 25 degrees on very hot days with an air temperature of more than 35 degrees. This is how great the effect of irrigation is. The evaporation and moisture ensure cooling." According to Aasman, 800-1000 kilos of growth per hectare are at stake in the coming weeks. This is how many potatoes can grow per day at this crop stage.
Purge control
As soon as the heat is over and rain falls, there is a threat of overgrowth in potatoes for consumption. Aasman: "I recommend checking this in any case. This can be done by measuring the temperature in the back of the tubers. Once the temperature has passed 25 degrees, the tubers will start to form sprouts again as soon as the heat and the lack of moisture have passed."