Pattern of infection by honeysuckle leaf blight, a possible accumulating pathogen, on invasive Amur honeysuckle (Lonicera maackii) shrubs in understory and open habitats

Effects of honeysuckle leaf blight (Insolibasidium deformans, Platygloeaceae) on Amur honeysuckle (Lonicera maackii, Caprifoliaceae) stand and stem structure in northern Kentucky

“…Reverse-J diameter distributions are typical of shade- and mid-tolerant woody species, and previous studies have shown that L. maackii is shade tolerant ( e.g ., Castellano and Boyce 2007). The leaf blight caused by I. deformans has been shown to attack a larger fraction of leaf mass in smaller, open-grown shrubs (Helton and Boyce 2022), which is why I predicted that mortality caused by leaf blight would decrease the smallest shrub size classes, leading to a change from a reverse-J shape to a unimodal one. However, I found no evidence of that at the shrub level.…”

“…Helton and Boyce (2022) found that long shoots are more susceptible to leaf blight than short shoots. Flowers and fruits are usually born on short shoots, which are part of more mature branches, while long shoots are rapidly growing stems that are usually produced to quickly exploit light resources.…”

“…maackii is shade tolerant (e.g., Castellano and Boyce 2007). The leaf blight caused by I. deformans has been shown to attack a larger fraction of leaf mass in smaller, open-grown shrubs (Helton and Boyce 2022), which is why I predicted that mortality caused by leaf blight would decrease the smallest shrub size classes, leading to a change from a reverse-J shape to a unimodal one. open-grown and (B) forest-understory stands sampled in 2022 (mean 6 95% confidence interval).…”

“…(2020) carried out a greenhouse study on seedlings that had been infected with the blight and found that the blight decreased growth in infected seedlings, although it did not cause mortality. Work has also indicated that small shrubs, particularly in open stands, are most susceptible to leaf blight and thus would be most susceptible to any blight-related mortality (Helton and Boyce 2022).…”

“…Work has also indicated that small shrubs, particularly in open stands, are most susceptible to leaf blight and thus would be most susceptible to any blight-related mortality (Helton and Boyce 2022).…”