What is Leaf Spot Fungus?

Leaf spot fungus occurs in warm weather. It typically affects plants, but it also occurs in home lawns and golf courses. It causes spotted-looking leaves and wilted grass.

So, before your yard falls victim to it, let’s find out what causes leaf spot fungus and how you can prevent it. 

Leaf Spot Fungus On Plants

Spotted leaves occur when fungal spores in the air find a warm, wet, plant surface to cling to. As soon as that microscopic spore gets comfortable in its new home, sporulation (the fungal method of reproduction) occurs and the tiny brown fungal leaf spot begins to grow.

What Does Leaf Spot Fungus Look Like?

If you’re seeing brown or black spots on the leaves of your plant or the blades of your grass, you have an infection. 

leaf-spot-fungusSymptoms of bacterial leaf spot may include black-edged lesions, brown spots with yellow halos, or just light and dark areas on the foliage. 

The spots will vary in size and will be seen on the leaf surface. Spots are irregular and measure between 3/16 and ½ inch (0.5 to 1.5 cm.) wide

What Types of Plants Are Affected?

It can affect many different types of plants. In Michigan these include:

  • Astilbe
  • Chrysanthemum
  • Delphinium
  • Echinacea
  • Heuchera
  • Hypericum
  • Rudbeckia

Bacteria on the plant surface are easily spread by splashing rain and irrigation to nearby plants.

How To Eliminate It From A Plant

The good news is that your plants won’t die from leaf spot fungus.Most trees tolerate leaf spots with little or no apparent damage. But you can help keep them disease-free in the future. You can do things like

  1. Remove infected leaves and dead twigs
  2. Keep foliage dry
  3. Keep plants healthy
  4. Use fungicides if needed
  5. Replace the plant

Avoiding overhead watering can also help keep plant diseases (particularly leaf spot fungus) from spreading. Watering from overhead simulates rain.

Leaf Spot Fungus On Grass

Unfortunately, leaf spot pathogens can spread from your infected plants to your lawn. But leaf spot on grass generally develops in cool, cloudy, and wet conditions.

Symptoms appear as small dark purple to black spots on grass (leaf) blades. The spots will eventually get bigger with centers fading to tan, often with a yellow halo.  The term “cigarette burn” is often used to describe the appearance of the spots. If these cool, cloudy, and wet conditions persist for a long time, leaf spot may cause grass blades to turn yellow as the lesions restrict the movement of food and water up the grass blades.

The disease is confined to leaf blades in the early stages, but sheaths, roots, and crowns can become infected during hot, humid weather. Close mowing can aggravate disease outbreaks by increasing stress on plants and allowing spores greater access to crowns and roots.

It Can Lead To Melting Out

Remember that leaf spot makes turf look sick, but does little permanent damage. However, it sets the stage for the more serious melting-out phase of the disease. Leaf spot and melting out actually are different diseases with similar symptoms and pathogen characteristics. 

They both attack Kentucky bluegrass, perennial ryegrass, and tall fescue, and appear to cause the most damage to golf course roughs, sports turf, and residential lawns. Both pathogens can affect all parts of the plant (leaves, shoots, and roots). 

The major apparent difference between the two is that the melting-out pathogen is active during cool, wet weather, while the leaf spot pathogen infects during the heat of the summer.

How We Can Help

The way you water, feed and mow your lawn makes a huge difference in the fight against lawn diseases.

So, whether it’s the (fallen) leaves from the trees or the grass down below, Safari Tree can help you take care of your entire yard. Typically, it’s only a matter of time before a problem that starts in the treetops ends up affecting your turf. 

Safari Tree offers a year-round healthcare program for trees and shrubs. It’s perfectly designed for Michigan’s four-season climate.