7/2/2013 - By Michael Kroian

Red Leaf Spot – “All of a sudden it's all over the place” is what I’m hearing throughout my region. We’re all familiar with Red Leaf Spot, but here is some of what I’ve experienced over the years.

Red Leaf Spot Facts

• It really seems to like the older wide bladed bent’s (Penncross, Penneagle) and colonials.
• It is usually more noticeable on the higher cut turf, but will run on the greens as well.
• It will make things look really bad and will kill turf, especially soon after someone does anything physical to the turf that may damage it and/or open wounds.
• It loves wet conditions, with Spring time temperatures.

Combo applications have always seemed to work the best.  DMI’s (even the new ones) by themselves are very slow to react.  The fastest working applications (for me) have always been a combo of 26GT + 3336 or 26GT + Compass (Interface).  Either way 26 GT (Curalan as well) is a great base partner for this problem. Unfortunately, by itself, it’s good but never seems to really shake things out all the way and the conditions will linger (and even flare back up).

We’re looking at a forecast of constant showers and rain, which complicate things a bit. There are a couple of options.

• Applying a Headway (type) of application is one recommendation.  Instead of watering in the spray, allow mother nature to take care of it if your forecast cooperates. In addition, if we lay it on top (even for a while), we should get some good A.I. into the plant before the rest gets showered down.
• Strobies are also very good on the Red Leaf Spot and when combined with the DMI’s they can be very effective.  The other reason I will be considering this particular combo is because, even though the temperatures will be cool this week, when you have excessive moisture and the temp’s rise, Summer Patch will activate itself and become one of the next problems the turf will face.

So, even though I may like the first products I mentioned the best, after taking Mother Nature into consideration, I will probably go in the later direction.  This kind of recommendation should be looked at as trying to maximize a spray to take care of one immediate problem and help transition to what most likely will be the next concern Mother Nature is setting us up for.

Be careful not to mistake this outbreak as physiological problem (like what you see when bent goes into dormancy).  Trust me, it may look that way, but most likely it is this form of Leaf Spot and it can’t be left untreated,  especially with this week’s conditions coming up.

For more information on this, take a look at this article from NC State. (http://www.turffiles.ncsu.edu/diseases/Red_Leaf_Spot.aspx)

By Michael Kroian, Harrell's turf sales representative serving the Northeastern US.