Hello, The 5 dogwood bushes on the north side of the house have a fungus...

Asked August 7, 2014, 5:54 PM EDT

Hello, The 5 dogwood bushes on the north side of the house have a fungus (dark spots on leaves, leaves turning red and falling off). One bush has no leaves, and the leaves bush next to it are all turning red. The other bushes are not showing the same signs yet. I have sprayed it with Fung-onil by Bonide (per the instructions from a local garden shop). My questions are will this fungus kill the bushes? What do I do to get rid of the fungus so it does not harm them any more? There is wood chips around the bushes, so will I need to remove and dispose of the wood chips? If so, do I need to burn the wood chips? Or can I use the wood chips somewhere else? Will this fungus spread to other plants and if so, what type of plants are typically affected? I really appreciate your help. Thank you so much, Kristine Strand 218-454-1025 klee55305@yahoo.com

Cass County Minnesota dogwoods

1 Response

Many strategies can be done collectively to reduce the disease on the shrub in following years. We are not certain that a fungus is the problem (you might check the roots on the dead one) for rodent damage. If it is a fungus the fungicide will only protect new leaves. We do not think the wood chips are a problem and if it is anthracnose no other plants should be affected. You haven't said what the water situation has been or how long the first plants leaves have been missing.

  • Rake up and destroy fallen leaves before the first snowfall to eliminate locations where pathogens can survive to re-infect the plant the following growing season.
  • Do not overcrowd plants — use size at maturity as a spacing guide when planting.
  • Prune trees or shrubs to increase light penetration and improve air circulation throughout the canopy.
  • Wet conditions promote disease, so avoid or redirect lawn and landscape sprinklers that wet the lower canopy of the tree.
  • Reduce stress to your tree:
  1. Water your tree throughout the growing season so that the top 6 to 8" of the soil is moist, especially during dry summer periods. Soil should be allowed to dry before watering again.
  2. Maintain a 3 to 4" deep layer of mulch around your tree. Do not mound the mulch around the trunk of the tree but lay a flat layer with at least a 2 inch space between the mulch and stem to allow for air movement. Annually reapply mulch and inspect to ensure levels are maintained.
  • Do not fertilize trees and shrubs suffering from leaf spot diseases, unless it is recommended by a soil test to correct a nutrient deficiency.
  • Fungicides are not necessary unless a tree has been completely defoliated several years in a row.
  • Fungicides are protective and need to be applied before symptoms appear on the leaves. Proper timing of fungicide applications can vary depending on the biology of the disease.