New rules mean that those who grow plums can only use pesticides every three years. It makes life miserable for those who grow Norwegian plums. – This pest can make me stop growing plums. Agnar Nornes is in the midst of plum harvesting at his orchard along the Sognefjord. 1,900 plum trees that produce around 16 tonnes of fruit. PICKING AND CHECKING: Agnar Nornes has to look a little extra carefully at the plums he picks this year. Photo: Sondre Dalaker / news Every plum must be checked a little extra carefully this year Because inside the fruit there may be a little guest hiding that you don’t want to find after you’ve taken a bite: A small larva of around one centimeter called plum squirms. – I’m looking for a small wound in the plum where she has entered. Then she lies down by the stone and a fruit pulp there. Find me signs of plums that have larvae in them, the plums must be taken out of the garden and destroyed, says Nornes. Loss of access to pesticides Previously, Nornes could use pesticides every year to get rid of the pests. But not anymore. Now they can only use chemical pesticides every three years. – We have to get approval for a new pesticide that kills the pest. That is the only solution. Without that, it may soon happen that we have to make do with plum cultivation, he says. Nornes has been lucky and only found around ten plum curlers in total in their crop this year. Other producers at the Sognefjord have been more unlucky, with some producers finding larvae in up to fifteen percent of the crop. PLUM WRAPPER: This is what the plum plover looks like as a caterpillar and summer bird. Photo: Sondre Dalaker / news Feeling defenseless Without being able to spray annually, both producers and biologists are at a loss in the orchards. – We feel quite defenseless against a pest that can potentially do a lot of damage to the crop, says Tonje Fjågesund. She is an adviser in the Norwegian Agricultural Advisory Service (NLR) at Hermansverk in Sogn. UROA: Tonje Fjågesund, biologist at Norwegian Agricultural Advisory Service, is concerned about the damage potential of the plum wrapper. Photo: Sondre Dalaker / news She lists two main reasons why they have found more larvae in Western Norway this year than before. – One is that we can no longer use pesticides every year. The second is probably climate change. The plum curler needs warm summers to lay eggs. The problem is that the license to use pesticides was withdrawn, without there being a good replacement, says Fjågesund. – How urgent is it? Can they research this for four years before finding a solution? – No, there is really a rush to find new measures. We are already worried about how the plum borer and other pests will affect the 2023 season, she says. Photo: Sondre Dalaker / news First time in Hardanger Researcher Gunnhild Jaastad at NIBIO says that the scope is increasing in Viken, Telemark and Sogn. In Viken county, investigations in the plum fields have shown that in one field there was as much as 40 percent damage this year, writes Nibio on its homepage. And for the first time, Jaastad has seen larvae in Hardanger. – If it increases as much as it looks like it is doing now, it looks ugly. If the producers have to throw away up to half of their crops, I would have given up anyway, says Jaastad. Cardboard traps around the tree trunks There are other ways to overcome the insect. Fixing corrugated cardboard around the tree trunks is one of them. After the larva has finished molting inside the plum, it crawls out again to overwinter in the ground or in the tree trunk. But instead of finding a crack in the bark of the tree, it crawled into the cardboard. When winter comes, the farmers can take away the cardboard with the larva inside and burn it. Nornes tried this on around 130 trees this winter and found larvae in around 100 of the traps. But exactly how effective this is is still uncertain. In addition, it is very labor intensive. TRAP: Corrugated cardboard around the tree trunk has proven to work. But neither Nornes nor Fjågesund know exactly how effective it is yet. Photo: Sondre Dalaker / news Jaastad says that botanical pesticides may be something to investigate further. Odor traps, so-called pheromone traps, to confuse the animals so that they do not mate can also be a solution. But it takes time and costs money to get it approved on the Norwegian market. – First it has to be tested. Then you have to work to get it imported and such. And it is a small market in Norway and it is expensive to apply for approval, says Jaastad. For example, the Norwegian Food Safety Authority has not been available for an interview about why the pesticide Calypso, which the farmers used before, was banned. But they write the following in an e-mail: “Calypso was banned because the active substance thiacloprid can harm reproduction in humans and several of the breakdown products of thiacloprid can contaminate groundwater in concentrations above the permitted limit value. The ban applies throughout the EEA area.”
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Pests in the plum orchards make the future uncertain for the fruit farmer – news Vestland
