Most hypovirulence in the chestnut blight fungus, Cryphonectria parasitica, is associated with infection by fungal viruses in the family Hypoviridae. Hypovirulence has controlled chestnut blight well in some locations in Europe and in Michigan in the United States. In contrast, with few exceptions, biological control has failed almost completely in eastern North America. Therapeutic treatment o...

Short-term greenhouse studies with soybean (Glycine max cv. Bragg) were used to examine interactions between the soybean cyst nematode (Heterodera glycines) and two other common pests of soybean, the stem canker fungus (Diaporthe phaseolorum var. caulivora) and the soybean looper (Pseudoplusia includens), a lepidopterous defoliator. Numbers of cyst nematode juveniles in roots and numbers of cys...

Black walnut, a valuable economic and environmentally important species, is threatened by thousand cankers disease. Systemic imidacloprid and dinotefuran applications were made to mature black walnut trees to evaluate their translocation and concentration levels in various tissue types including leaf, twig, trunk core, nutmeat, and walnut husk. The metabolism of imidacloprid in plants produces ...

Within the past decade an unusual decline of black walnut (Juglans nigra) has been observed in several western states. Initial symptoms involve a yellowing and thinning of the upper crown, which progresses to include death of progressively larger branches (Figure 1). During the final stages large areas of foliage may rapidly wilt. Trees often are killed within three years after initial symptoms...

Since 1996, the primary objective of the New Crop Pathology Program at the University of the Free State has been to conduct a systematic survey of diseases occurring in cactus-pear [Opuntia ficus-indica (L.) Miller] orchards throughout the country and to investigate possible relationships between disease-causing microorganisms and various insects, specifically Drosophila sp. Numerous fungal gen...

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 south-west England. Site visits followed September to investigate cause decline. Affected trees showed crown dieback, needle drop, branch and stem cankers. Mortality young, regenerated understorey ...

Beetles (Scolytinae) form intimate associations with a taxonomically and functionally diverse suite of nematodes that are phytopathogens, fungal feeders, entomoparasites. Despite their ubiquity, the ecological significance in lifecycles economically important bark ambrosia beetle species (Curculionidae: Scolytinae) associated plant diseases remains largely unexplored. Thousand cankers disease (...