Onvihreä

Onvihreä is a Finnish term that translates to "green sickness" or "green illness." It describes a phenomenon observed in some coniferous trees, particularly pine and spruce, where needles turn a distinct yellowish-green or pale green color, often appearing sickly. This discoloration is not typically a sign of rapid death but rather a stress response by the tree.

The causes of onvihreä are varied and can include environmental factors such as nutrient deficiencies, particularly a lack of magnesium or nitrogen, or soil pH imbalances. Waterlogged or poorly drained soils can also contribute to the condition by impairing root function and nutrient uptake. In some instances, onvihreä can be exacerbated by adverse weather conditions like late frosts or prolonged drought.

While the appearance of onvihreä can be concerning to forest owners and gardeners, it is important to note that it is often a reversible condition. Correcting soil deficiencies through appropriate fertilization or improving drainage can help trees recover their healthy green coloration. In cases where the stress is severe or prolonged, however, the tree's growth may be stunted, and it may become more susceptible to other diseases and pests. Monitoring the overall health of the tree and its surrounding environment is key to understanding and managing onvihreä.