Forecasting of Airborne Conidia Quantities and Potential Insect Associations of Cryphonectria parasitica, the Causal Agent of Chestnut Blight, in England.

Sweet chestnut, an Asiatic tree introduced in many parts of Europe including the United Kingdom, is planted for nut production, timber, and amenity. Its major threat is the disease called blight, caused by the fungus Cryphonectria parasitica, which infects through wounds by airborne spores. Field trapping using sticky rods rotating traps was performed in an infected area in Devon (between May 2021 and April 2023). An improved dual hydrolysis Taqman probes real-time PCR was used. The number of spores was calculated by comparing the cycle threshold to the Ct of standards with known amounts of conidia or known target fragment copies cloned into a plasmid. Weekly spore counts were in the range of around 60 to approximately 8.5 × 103, with fluctuations of peaks (mainly in late summer-autumn 2021) and troughs. The effects of weather parameters were modelled, finding correlations between spore numbers and temperature, humidity, dewpoint, rainfall, wind speed, and wind duration. Additionally, an insect trapping was performed to confirm the presence/absence and quantity of C. parasitica conidia potentially phoretic on some insects by using the same molecular approach. None of the ten collected insect species harboured spores of this fungus.

Abiotic variables effect differential expression of latent infections in beech (Fagus sylvatica).

• Effects of temperature and gaseous regimes on development of fungal communities, from latent infections in twigs, branches and stems of European beech ( Fagus sylvatica ), were investigated through controlled drying. • Hypoxylon fragiforme was identified as a latent invader within the xylem of all orders of host stem and branch material. Explanations for the incongruence of this finding with results from previous experiments are considered. • Incubation under an atmosphere of 100% CO 2 prevented the growth of the endophytic fungi present, despite drying of the wood. Fungal growth at low temperatures and at low oxygen tensions was less than could be explained through direct effects, and there was evidence for an indirect effect involving active host defence. Elevated temperatures favoured establishment of the early-colonizing ascomycete Biscogniauxia nummularia and the late-colonizing basidiomycete Coniophora puteana , while low oxygen tensions favoured colonization by Trichoderma sp. • The ecological significance of these observations is discussed.