June has felt more like July or August with record breaking high temperatures and more than twenty days over ninety degrees. Rainfall has been tough to come by as well. The average precipitation for the month of June is 4.50”, which we are currently under by 3.10”. The abundance of bright, sunny days and lack of rainy, cloudy weather has allowed for less grass disease pressure than what we usually face during June. Yet it has greatly increased the irrigation demands from the grass on all areas of the golf course. The combination of meager natural rainfall, low humidity breezy days in conjunction with hot temperatures have created some of the most extreme evapotranspiration (ET) I have witnessed in my career.
The greens, tees and fairways have remained healthy so far this June. Similar to our efforts on the greens, on days when highs in the 90s are predicted we have to irrigate fairways extensively during the overnight and early morning hours to prevent wilt stress and resultant thinning of the bentgrass during the intense afternoon heat. Even with an early morning irrigation cycle on the fairways we still often have to run brief, 3 to 5 minute irrigation cycles during the heat of the afternoon to cool off wilting fairways. We have found over the last 2 years that this afternoon cooling of the bentgrass greatly helps retain the density of the turf during the warmer months. The tees are also in good health. The worst areas on the course from a turfgrass health standpoint are the weak Poa annua patches that have discolored and thinned in the collars and approaches. As the Poa annua weakens the creeping bentgrass will begin “creeping” over the Poa annua and fill in nicely.
Irrigating the golf course is one of the biggest challenges we face during the summer months. Our goal is to evenly replace the moisture lost from the previous day and prevent isolated dry spots while maintaining desirable playing condition for the golfers. If localized dry spots remain dry for an extended period of time the soil becomes hydrophobic and water and nutrients become unavailable for the plant to absorb causing the grass to thin and eventually die. Generally, dry areas start forming on the south facing edges of the fairways. This is where irrigation coverage is poor and tree roots out compete grass plants for moisture.
We have a single row irrigation system, meaning our irrigation heads are located in the center of the fairways and throw water outward in a 90’ radius. Naturally, the turf around the irrigation heads receives more water than out towards the edges of the fairway, making the centers of the fairway softer than the edges. In order to dry down the areas around the irrigation head, the irrigation head must be turned off. Turning off the irrigation head eliminates water coverage in the entire 90’ radius. While the centers of the fairways have more than adequate amounts of moisture the edges become under watered and localized dry spots start forming quickly. In our best efforts we try to offset the poor coverage with supplemental hand watering, micro sprinklers, and utilize wetting agents.
