Severe decline was observed on a mature stand of western hemlock (Tsuga heterophylla) (Fig. 1) in late August 2021 during the Forestry Commission's annual aerial surveillance for Phytophthora ramorum in south-west England. Site visits followed in September to investigate the cause of the decline. Affected trees showed crown dieback, nee-This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

No abstract

Six pea cultivars and their Fl and F2 progenies were assessed for resistance to pea leaf-roll (top-yellows) virus infection under natural epidemic conditions. Two cultivars were highly resistant, two moderately resistant, and two highly susceptible; all Fl and the majority of F2 hybrids between any two cultivars showed a lower mean resistance than the better of the two parents. Resistance to infection was controlled by an additive system of inheritance, with "moderate" resistance being dominant to both susceptibility and high resistance. The effect of disease on components of yield was also shown to be inherited in a quantitative manner, but no hybrid combination exhibited high economic value for all characters. The effect of top-yellows infection on yield in the New Zealand pea experiment was similar to that on infected field beans in England.

No abstract

No abstract