The hot-off-the-press climate atlas 'Bosatlas van het Klimaat' has taken a leaf out of Wageningen: the apple trees of PPO Fruit blossom in tune with the climate.
Rohnstock plotted the blossoming data of the Golden Delicious apple from 1955 to 2010 in a graph. The same graph also shows the average temperature from February to April in these years. Both these lines are perfect mirror images, says Van Vliet. The warmer it was, the earlier the apple trees blossomed.
The graph is featured on page 27 (Chapter 2, Temperature) of the Atlas of the Climate, compiled jointly by the Dutch meteorological institute KNMI and publisher Wolters Noordhof. The Golden Delicious at PPO blossomed already in the first week of April in 1990. The average temperature in spring of that year was eight degrees Celsius. The graph clearly shows the effect of warming-up in the last decades: apple tree blossoms have appeared about three weeks earlier than before.