In recent years, the agricultural sector has been struggling not only with climate-related disasters, such as drought, frost, hail and excessive rainfall, but also with diseases and pests that cause yield and quality losses in crops. While producers are trying to reduce the impact of changing climate conditions, they are also implementing chemical, biological and mechanical control measures against fungal diseases and invasive pests.
Currently, hazelnuts, pistachios and almonds are among the crops most affected by agricultural pests, with yield losses reported to reach up to 20 percent in some regions.
The brown marmorated stink bug has emerged as the most prominent agricultural pest in recent years, affecting the yield and quality of hundreds of agricultural products.
Hazelnuts are among the crops most heavily impacted by the invasive species. Türkiye accounts for approximately 70 percent of global hazelnut production, with cultivation concentrated in the Black Sea region. The brown marmorated stink bug has become a major concern for hazelnut producers in the region.
Atakan Akça, president of the Altınordu Chamber of Agriculture and a representative of the Union of Turkish Chambers of Agriculture (TZOB), described the fight against the pest in the Ordu province as their “most important agenda item.” According to Akça, there are four main factors affecting hazelnut yield and quality. The first is the brown stink bug, while the others are shoot borer, powdery mildew disease and cone mite. He said chemical, mechanical and biological methods are being used to combat these pests and diseases.
Akça noted that the brown stink bug damages more than 300 crops, not only hazelnuts, and requires continuous control efforts throughout the season due to its rapid reproduction rate.
Damage caused by the pest reached up to 30 percent in some parts of Ordu during the 2023-2024 season, he said. Thanks to intensive control measures, this rate declined to around 8 percent in 2025. With systematic efforts continuing this year, damage across Ordu is expected to remain between 2 percent and 4 percent.
Akça also stated that efforts to combat the brown marmorated stink bug have increased production costs. Pesticide use in the field has risen by approximately 50 percent over the last two to three years, according to Akça. He said the fight against the pest has added roughly 5 percent to hazelnut production costs per ton, as farmers have been forced to carry out multiple pesticide applications.
In Konya, fungal and rust diseases have become prominent due to climate-related challenges.
Rıfat Kavuneker, president of the Karatay Chamber of Agriculture, said that pesticide costs alone create an additional burden of 10 percent to 15 percent for farmers each year.
In Şanlıurfa, severe drought experienced last year both reduced yields and increased pest populations.
Hikmet İpar, president of the Hilvan Chamber of Agriculture, said insect infestations have increased, especially in pistachio and almond orchards, as pests deprived of food sources in dried-out areas have moved onto trees. He said drought had already reduced yields, while pests caused an additional yield loss of between 10 percent and 20 percent, although this had no impact on prices.
İpar stated that excessive rainfall this year has brought different challenges. While rainfall reduced pest populations, rust disease has appeared in wheat crops. Producers have had to spray fields two or three times during the season against both rust disease and sunn pest infestations, İpar said.
He noted that damage caused by sunn pests lowers the quality of durum wheat, turning it into bread wheat and creating a price difference of 1 to 2 Turkish Liras per kilogram.
İpar also said that excessive rainfall this year prevented adequate pollination by male pistachio trees, leading to approximately 30 percent grain loss in clusters.
