Earthworms

After a very dry summer, the cool wet weather that we experienced in late September and October allowed the turf throughout the golf course to recover from the extended drought.  Much of the summer I was approached by golfers concerned about the brown appearance of the fairways and rough.  I explained that the turf was exhibiting signs of stress, but there was little risk of permanent damage.  Sure enough, shortly after the rains came the turf returned to a consistent emerald green.
And then a few of the fairways seemed to turn brown again.  This time the problem was that there was too much moisture, and the earthworms were thriving.  Their castings would be crushed by mowers and golf carts, and would leave brown pock marks of mud on the surface. 
I was asked if there were any chemicals that I could use to control the worms, and my answer was always no.  While there are chemicals that can offer temporary relief from worm castings, there are no products that are labeled for this application.  Therefore using these products to control worms is illegal. 
One of the most important things to consider with this issue is the fact that earthworms are signs of a healthy soil, and offer many benefits to the turf system.  They help breakdown organic matter in the soil and convert it to available nutrients for the plants, and their burrow act a channels for water and air movement in the soil.
I have experimented with a fertilizer that aggravates worms and brings them to the surface, but it is very expensive and it must be applied just before a heavy rain event.  If the weather does not cooperate it can be a very costly failure.  The second issue with this strategy is handing the worms that are driven to the surface.  I have seen superintendents refer to the process as "dealing with the carnage".  I am willing to try the product again in the spring if people feel strongly enough about eliminating the mess from the worms. 


Click here to read a USGA research article about controlling earthworms.