Rain in the summer can be the worst management nightmare for bentgrass greens in the South. What do you need to change in your management program to deal with these rains?

The mat layer in bentgrass greens can quickly become a gel-like consistency if:

• The organic matter percentage is too high.
• The mat layer has not been sufficiently aerated.
• The greens cannot dry out and the mat layer seals off the surface

If any of the above exists, the pore spaces are blocked and soil moisture content quickly increases. The result is an increase in temperature, a decrease in oxygen, and the rapid die back of roots. Algae formation sets in as the turf thins.

To correct this problem, pencil tine venting (¼" solid tines) is a must, and sometimes has to be done every one to two weeks if summer rains are persistent. The Hydroject is used in this scenario as well. Under severe stress, ¼" side eject tines are excellent for this venting, followed by blowing off the cores and rolling to push the 'shoulders' of the tine holes flush with the green surface. Rolling is needed when solid tines are used as well.

¼ inch solid tines for 'venting' the mat layer during summer stress

Fungicide rotation is the other critical part of the management scheme. Koban fungicide still proves to be an important part of bentgrass summer stress management, especially in high rainfall and humidity. The four ounce rate should be applied with three gallons of water per 1000 sq. ft. as a soil drench in a four week rotation. Remember, this treatment is applied early in the morning and showered in with ⅛" water to get it off the leaf surface. Follow up in one week with Insignia for a proven rotation as the best control program for Pythium root dysfunction. Signature/Fore is the other combination spray that has shown in research to be a foundation in summer fungicide management. It should be part of everyone's rotation.

If Pythium root dysfunction is diagnosed, you should implement the following:

1. Mow when the grass is as dry as possible.
2. Use solid tine rollers versus grooved rollers.
3. Make sure you have adequate foliar nutrition - especially nitrogen as nutrients are flushed in greater rain fall and often overlooked.
4. Raise the cutting height to at least 0.135" if you are below that level.

These steps are proven measures for bentgrass management during summer stress, especially when rainfall and humidity are higher than normal. Weigh them carefully as part of your bentgrass management program.

If overseeding transition has been a problem this year I refer you to John Foy's June 28^th Florida regional update as he has an excellent discussion of the same problem. (http://www.usga.org/turf/regional_updates/regional_reports/florida/06-28-2007.html)

Need agronomic assistance this summer? Want to help your course survive the summer and get ready for fall? Planning any reconstruction? Don't hesitate to contact our office at (972) 662-1138 or via e-mail at budwhite@usga.org for further information.