Oak decline presenting symptoms of tracheomycosis have been observed globally over long periods of time. Since the 1990s, oak decline has been considered to be a multifactorial process where abiotic predisposing factors play a significant role. Nevertheless, biotic factors, such as subcortical insects and fungal pathogens, may influence the decline process, as some insect species transmit spores of tracheomycotic pathogens. We investigated biotic agents (subcortical insects, Ophiostoma spp. and Phytophthora spp.) in six declining oak stands located within mesophytic and thermophytic zones in the Czech Republic, where five dry years occurred from 2015 to 2019. The spectrum of insect pests of oak stands was investigated using two methods: reared from logs from each stand and window traps. The presence of Ophiostoma fungi was assessed from cultivated woodblocks; Phytophthora pathogens were isolated from soil samples. In total, 2931 subcortical insect individuals were captured during the 2021 vegetation period. The most species-rich group of the subcortical insect complex involved in oak decline consisted of the families Cerambycidae: Xylotrechus antilope; Curculionidae: Scolytus intricatus, Xyleborus monographus; and Buprestidae: Agrilus biguttatus, A. sulcicollis. The presence of Ophiostoma was detected in all stands with different intensities between tree parts. Several important oak pests were positively correlated with the occurrence of Ophiostoma. On the contrary, from all soil samples, Phytophthora plurivora was found at only one studied oak stand. Based on the results, a new modified model of biotic and abiotic factors involved in the oak decline is proposed.

We present concise results of method validation for trehalose quantitation by LC-MS/MS in spruce ectomycorrhizal roots in order to describe spruce health status, mainly in connection to contamination by a pathogenic fungus, Gemmamyces piceae. The procedure is based on Rogatsky et al. (2005) developed for human plasma. We found out that the best extraction yield was achieved with 80% methanol/water (v/v) solution and optimal extraction temperature was set between 50-60°C. In contrast to previous papers, we minimized the activity of trehalase enzyme by putting root samples into liquid N₂ immediately after root excavation, followed by freeze-drying in order to stop trehalase activity. Higher content of trehalose was recorded in healthy trees, confirming the idea that ectomycorrhiza plays a significant role in plant-pathogen interactions.

Two diseases, Rhabdocline needle cast caused by Rhabdocline pseudotsugae Sydow, and Swiss needle cast caused by Phaeocryptopus gaeumannii (Rohde) Petr., recently became a severe threat to Central European Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) stands. Both pathogens infect assimilative organs causing needle chloritization and drop off. Pervasive infection by these pathogens has been recorded at the Hůrky provenance trial (Písek, South Bohemia, Czech Republic), established in 1971 as part of a series of experiments by International Union of Forest Research Organizations (IUFRO). The intensity and duration of needle cast sporulation were monitored using a Burkard spore trap, and the health status of 24 Douglas fir provenances from the original areal of distribution (British Columbia, Washington, Oregon) was evaluated under this trial. While comparing provenances, the following characteristics were surveyed: trunk volume, defoliation rate, and the difference in tree diameter between measurements in 2011 and 2016. A statistical evaluation was performed using the regression model and a decision tree. The highest sporulation rates on needles for both needle casts were observed from April to July. The Washington provenances 1069 North Bend, 1075 Enumclaw, and 1089 Cathlamet can be recommended for plantation, considering the provenances’ satisfactory productivity and low extent of damage from needle casts, while the provenances such as 1104 Brookings, 1028 Merritt (due to high mortality) and 1010 Barrière, 1021 D’Arcy, and 1067 Skykomish (due to high defoliation) are not suitable for plantation under Central European conditions.

Central European forestry faces severe climate-driven challenges, notably the accelerated spread of needle cast pathogens (Lophodermium seditiosum, Dothistroma septosporum) among vulnerable Pinus outplants. Warmer winters have advanced ascospore release, rendering traditional calendar-based fungicide regimens potentially less effective. This communication presents a conceptual Integrated Pest Management (IPM) perspective utilizing a tank-mix of azoxystrobin-based fungicides and magnesium-hydroxide mineral suspensions. Unlike highly soluble inorganic salts that induce acute hyperosmotic stress and localized necrosis, these suspensions function as slow-release carriers, potentially modifying spray rheology to facilitate the formation of a form a stable protective film. This co-application is hypothesized to yield a physiological synergy: the acropetal translocation of azoxystrobin provides systemic protection and delays needle senescence, while the gradual release of magnesium supplies the essential substrate for accelerated photosynthetic activity. Crucially, this targeted foliar approach may potentially be less disruptive to vital ectomycorrhizal networks and microbiome integrity compared to soil drenches. This communication suggests that the dual-action strategy may enhance seedling resilience, offering a potential adaptation to climate-induced biotic stress.