For most turf managers, the worst case scenario is when high temperatures are accompanied by prolonged rain events. Saturated soils heat up increasing turfgrass stress and elevating disease pressure to extraordinary levels. The next worst case scenario is a combination of high temperatures and very low humidity levels. While these make for comfortable conditions for human outdoor activity, these conditions can put tremendous stress on the turf.

For turf managers in the Northeast Region, 2008 is turning out to be a roller coaster ride full of steep climbs, sharp drops, and hairpin turns. Many courses in the New York Metropolitan and southern New England area are now struggling as a result of three days of above 90° temperatures and low levels of humidity. The combination of high air and soil temperatures combined with moisture stress has weakened annual bluegrass populations on greens throughout the region to a point where plenty are teetering on the edge. Under these conditions, the plants are transpiring water far more quickly than their impaired root systems absorb, resulting in large areas of wilt damage. Not surprisingly, Green Section phones have been ringing off the hook.

A number of golf courses also are reporting extraordinarily high nematode populations. We have measured soil temperatures in the 85- 90°F range (upper profile) and heat indexes well above 100° in pocketed environments. Summer patch has become very active on greens and fairways. Throw in prolonged low mowing and poor grass growing environments, and the outcome is predictable: a significant number of annual bluegrass plants are close to meeting their maker.

So what can be done at this late date in the game? Here is a brief checklist of things to consider over the next few weeks:

• Manage water as precisely as you can.
• Make sure everyone thoroughly understands the difference between hand watering and syringing. Remember, syringing involves wetting the leaf tissue and not saturating the soil. The evaporation of water off the leaf provides the short term cooling. If the water cannot evaporate, there will be no cooling.
• Raise the height of cut slightly, switch to smooth rollers or skip mowing altogether if soils are saturated and soft. It is better to be conservative to make it through these difficult weather periods.
• The value of good grass growing environments will become very clear this season. Adequate sun and especially good air circulation produce healthier turf and reduce conditions favorable for summer disease. Ambient air temperatures in pocketed environments will be higher and the turf will struggle. Make note of all the problem areas and do not over look the value of fans to circulate the air if it is not occurring naturally.
• While we have seen some bentgrass under stress in a few areas in the past couple of weeks, the ratio of stressed annual bluegrass to stressed creeping bentgrass is about 10,000 to 1. This is when having more bentgrass pays big dividends.
• If the greens look bad but play fine, think twice before you cultivate them aggressively. There are times when doing less is best especially when the turf is already weak. Traditional spiking and venting with mini tines may be appropriate. Save the aggressive cultivation for the better days ahead.
• Stay focused and go with the programs that you know work. This is not the time for testing exotic tank mixes.

The summer of 08 may be one of those talked about for years to come. Sometimes, you need a little luck to go along with good management to get through these difficult stretches, and do not hesitate to call us if we can be of assistance.

Source: David Oatis, doatis@usga.org , Jim Skorulski, jskorulski@usga.org , and Adam Moeller, amoeller@usga.org