Purple Lace Elderberry and verticillium wilt

(Question)

This plant has been doing well over the last 10 years. It has been watered regularly but suddenly in August I noticed it dying and took this photo attached. It is on the west side front garden and gets sun half the day, because we have a huge Norway Maple in the centre of the front yard. I do recall that last year I removed a dead branch. I am told that there is a fungus in the soil – Verticillium? and that the soil would affect other plants – Mint Juniper next to it has been there for 24 odd years, seems to be o.k. In front of the Purple Lace are tulips,been there several years. Also next to the Purple Lace are other flowering plants. I need to dig the Purple Lace up. What do I do about my soil. Is there anything I can add to it to get rid of this fungus?

(Answer)

Elderberries are susceptible to verticillium wilt, although other factors may be contributing to your plant’s demise.   Assuming that the plant is afflicted by verticillium, it is unfortunate that cutting off the branch last year may have just slowed progress of the disease a bit.  Verticillium is a fungus that affects the ability of the plant to transfer moisture and causes the plant to decline in vigour, resulting in sudden wilting of branches, yellow leaves, stunted growth and premature defoliation.  Branches may have green or black streaks.  Sometimes the disease appears on one branch, then seems to go away for awhile, taking several years to be fully evident. Verticillium infection usually starts in the roots and spreads from there (via xylem, the plant’s “circulatory” system) throughout the plant, although it can enter via wounds on branches or trunks.  Ultimately the infection cuts off water flow, causing wilting.

You are right to get rid of the shrub if it is infected with verticillium. Make sure that you dig up both the shrub and a large area of soil surrounding it.  Dispose of the plant/soil you dig up in regular garbage (do not compost it or this could spread the verticillium).  Clean your tools thoroughly to prevent spread.  As some strains of verticillium fungus can live for many years in the soil and there is no way to eliminate it from the soil, make sure you do not move the infected soil or leaf/other debris from that spot to other parts of the garden.  And plant only species that are resistant/immune to verticillium wilt in these spots (see link below).

It is important to keep your plants as healthy as possible.  This includes ensuring there is lots of space between plants (increased air circulation discourages fungal growth) and regular fertilization (healthy plants are more likely to resist attacks by fungus).  Do not allow the soil to become soggy, which would encourage fungal growth; use compost to enhance the health of the soil and promote good drainage.

I suggest that you investigate whether any of your other plants are susceptible to the fungus (e.g., Norway maple is highly susceptible; junipers are resistant) – and watch for signs of disease.

The following resources provide additional information:

  • Ask a Master Gardener Plant/grass disease, which discusses verticillium wilt and steps to take to prevent its spread.
  • Missouri Botanical Garden. Verticillium wilt.  This resource includes lists plants that are susceptible to or resistant/immune to verticillium wilt, which may help you select a replacement plant for the elderberry.
  • University of California Integrated pest management program. Pests in gardens and landscapes. Elderberry—Sambucus spp.Family Caprifoliaceae (Honeysuckle family).  This site highlights insects and diseases other than verticillium wilt that can affect elderberries – you may want to review this in case there might be another culprit.
  • University of Guelph. Plant testing services. This provides information concerning testing that can confirm whether verticillium wilt is responsible for your shrub’s demise.  This is costly, but may be worth investigating.

All the best with minimizing damage done by verticillium!