יומן של Honeysuckle Leaf Blight Survey

As temperatures fall and daylight decreases, most deciduous plants like honeysuckle begin to lose their leaves and go dormant for the winter. The same is true for pathogens that cause plant diseases, including honeysuckle leaf blight. Once conditions become unfavorable for disease development (decreased temperature and humidity), the pathogen also goes dormant and overwinters in an inactive state. Therefore, once fall sets in, we don’t expect to see characteristic honeysuckle leaf blight symptoms till the next year in late spring (mid-May). Trying to identify lingering honeysuckle leaf diseases in the fall can be challenging because natural leaf senescence can mimic the symptoms of some plant diseases, and secondary leaf spot diseases that are not honeysuckle leaf blight can pop up, taking advantage of the leaf’s weakened state. Some honeysuckle plants, like Japanese honeysuckle, may retain leaves over the winter, but any spots that might look like disease are most likely not honeysuckle leaf blight.

Thank you all for your contributions to this project, and we look forward to scouting for honeysuckle leaf blight next season!

University of Kentucky Forest Health Extension Team

There are many different species of honeysuckle (Lonicera), both invasive and native, but honeysuckle leaf blight is most commonly found on invasive Asian bush honeysuckle, like Amur honeysuckle (Lonicera maackii). Amur honeysuckle grows as a perennial shrub and is one of the first understory plants to leaf out in the spring and the last to lose its leaves in the fall. Key identifying characteristics to look for include:

1. Leaves - oppositely arranged on stems with an oval shape and tapered end
2. Flowers - present in late spring, tubular in shape with a white to yellow color and sweet fragrance
3. Stems - mature stems are hollow in the middle
4. Fruit - bright red to orange berries are produced in clusters in late summer

Honeysuckle leaf blight may also be found on invasive Japanese honeysuckle (Lonicera japonica), which grows as a twining vine. The leaves are oval shaped with a more rounded end, the flowers are similar to those of bush honeysuckle, the stems are reddish-brown in color, and the berries are distinctly black in color.

Honeysuckle leaf blight symptoms are easily distinguished on bush honeysuckle, but Japanese honeysuckle can get many other leaf spots that can be difficult to tell apart without laboratory confirmation.

HLB disease symptoms first develop in mid to late spring and continue throughout the summer, peaking in prevalence and destruction in June and July. Here are some characteristic HLB symptoms to look for:

1. Early symptoms appear as yellow areas on young leaves that grow into tan/brown dead patches as the
   disease progresses.

2. Symptoms are often present on the edges of leaves, giving a scorched appearance.
3. Infected leaves become distorted or curled.
4. Sometimes a speckled pattern may emerge due to scattered plant cell death.
5. Severe disease may result in totally dry, dark brown, twisted leaves that fall off the plant prematurely.

6. A sign of the fungus may be seen on the underside of infected leaves (under humid conditions), which
   appears as a thin, silvery-white layer of fungal spores.

Hi all,

Want to learn more about this project and why we're interested in honeysuckle leaf blight? Watch this short video to see why invasive honeysuckle is a problem and how the disease honeysuckle leaf blight may help: https://www.youtube.com/watch?v=QtOlFTc89Ls

Thanks for being a part of our project and for all your observations!

University of Kentucky Forest Health Extension Team