Status: 09/26/2022 08:26 a.m
The climate crisis threatens the apple harvest of German fruit growers. Too early flowering and intense sunlight cause problems. Early warning systems for extreme weather should remedy the situation.
Quickly set the weather alarm clock before going to bed: It’s the nightly ritual of Hein Lühs from Jork in the Altes Land. He grows fruit on 40 hectares, mainly apples, and they need special care. Should it start to rain heavily at night, the alarm bells would immediately ring and the Lühs would wake up from their sleep. The fruit grower has purchased a weather station for his plantation: an early warning system that supplies all relevant weather and climate data – online and in real time.
“Of course, experience plays a major role in my job, but a weather early warning system gives you a lot more facts,” says Lühs. He has seven to eight hours after a certain amount of rain has fallen to apply a spray to protect his fruit from apple scab infestation.
companies network
Around 7,000 companies in Germany grow fruit trees on almost 48,400 hectares. Apples, as the most important crop, take up 70 percent of this cultivated area. More than 600 farms already use a weather early warning system, according to the German Farmers’ Association. Ascending trend. In addition to temperature and humidity, rainfall, wind speed and direction are measured and the degree of leaf moisture is determined. All data can be called up immediately, including data from other farms and plantations. Since the entire fruit growing system is very susceptible to climatic changes, the farmers benefit from this network.
An increasing danger for local apples is the increasing solar radiation, which can lead to sunburn. With intense radiation, the shell burns. The apples turn brown, mushy and taste fermented. These fruits can no longer be marketed, they are ripe for the bin. “We didn’t have this problem before,” says Obstbauer Lühs. “There was a risk of sunburn on a maximum of one or two days a year. Now we have to sprinkle large amounts of artificial water to cool us down.” In the years 2019 and 2020, large areas of the Altes Land had to be rained on for ten days each.
In order to minimize the risk of sunburn, fruit growers can feed limit values into the early warning system. If dryness and temperature exceed critical values during a specified period, a signal is automatically sent and an alarm is triggered. In this way, fruit growers can react in an even more targeted manner. In the record summer of 2022, fruit trees in the Altes Land “only” had to be sprinkled seven times.
Fruit blossom starts earlier and earlier
As a result of climate change, fruit blossoms start much earlier in spring. In the case of the “Roter Boskop” this is now starting three weeks earlier than in 1975 and is even putting the entire harvest at risk. Late frost can cause immense damage to fruit trees. In the case of freshly opened buds, where the petals can already be seen, a temperature of minus two degrees is still just within the tolerance range. With completely open flowers, the limit is zero degrees.
With the help of the early warning system, fruit growers know exactly when to start frost protection irrigation. A fine spray mist is distributed over the tree. If the water freezes on the flowers, crystallization heat is released. The ice encloses the flowers like a protective coat and keeps the temperature constant at zero degrees. In this way, flowers and buds are not damaged.
In 2022, the orchards were able to counteract the consequences of climate change. The Federal Statistical Office expects an apple harvest of around 1,051,000 tons. Compared to the previous year, the yield is expected to be almost 46,000 tons and thus 4.6 percent higher.