Wednesday, 14 September 2011

How Turfgrass Pests Can Be Your Most Powerful Pesticide

For years we as turfgrass managers have been taught to make preventative pesticide applications. The logic behind this was that if you could prevent the problem you would in turn have to use less chemicals to control the pest. In some cases this is true. There are some pests out there that you just don't want to get. In the case of cool season turfgrass fungal diseases during the summer I think that you can afford to skip the preventatives and here's why.

Dollar spot is a fungus that can wreak havoc
on poorly maintained putting greens.
When we get sick it is often for a reason. You get a cold because you forgot to wash your hands or touched something that was infected. You get heart problems because you smoked for 20 years and had a poor diet and ate deep fried everything for lunch. You get diabetes because you ate too much sugars when you were young. Out turf is exactly the same. When it gets sick there is often a reason why. There are many things that can kill our grass but where I'm from (West Coast of Canada) our main threat to the health of our turfgrass comes from fungi.

Each fungal disease has a very specific range of environmental conditions that it requires to thrive. These conditions often aren't conductive to the growth of healthy turf. Shade, moisture or drought stress, compaction, lack of air in the soil, excess or lack of fertility, and otherwise unhealthy turf lead to disease. In the summer we have almost total control over all of these conditions.

If we are making preventative fungicide applications we aren't seeing the active disease. The poor growing conditions are still there but we are covering up our poor management with fungicides. This active disease tells us a lot about what our turf is experiencing.

Yellow patch usually doesn't harm the turf
but it can tell you what could be done better!
At first sign of Dollar spot I know that my greens are probably dry and that I should irrigate in the middle of the night to knock off the dew. When I see Anthracnose I know that my greens are over-watered or under-fertilized. Who needs fancy dancy electronic tools when you have fungi?

We need to change the way we think about pests on turfgrass. I see the disease on my turf as my most valuable tool for maintaining healthy turfgrass. By spraying preventatives I am basically throwing away my most valuable tool as a turf manager.

When I use less chemicals on my greens I have less surprises. Covering up the poor conditions of your turfgrass with chemicals will only make the infection worse and more severe when the chemicals wear off. If you have no chemicals on your turf the initial infection will be less sever because the environmental conditions on your turf don't change that rapidly. Compaction slowly builds, drought doesn't happen overnight, irrigation systems don't over-water, trees don't decide to shade your turf on a whim, thatch doesn't appear in a week, layering in your soil happens over years, etc.

Early sign of Fusarium on putting greens. This
particular infection took a month to cause
significant damage that would warrant a
corrective fugicide application
Now sometimes you will be hit with a particular disease and the only option would be to spray some pesticides. This usually happens when we cannot control the environment especially during the winter months.

Here's my challenge to everyone. Let the disease and pests on your course tell you what's wrong. Don't kill them, use them to make your grass better!