Summer Solstice

Today is the longest day of the year. It marks the official start of summer. As I type this, it is 87 degrees with a heat index of 90. Today's high temperature is expected to be 93. The lowest temperature over the last two days was 69, while the dew point is hovering around the mid-sixties.

It is summer and also time to watch out for turf diseases. The most damaging disease when it is hot and humid is pythium blight (Pythium aphanidermatum.) According to Michigan State University Turf Diseases ID site, pythium first appears as circular reddish brown spots in the turf, ranging in diameter from 1 to 6 in. In the morning dew, infected leaf blades appear water soaked and dark and may feel slimy. When spots are wet with dew, purplish gray or white cottony fungal mycelia can be seen on the outer margins of the spots. Infected grass plants collapse quickly, and when conditions are conducive, spots may coalesce and large areas of turf can be lost in a short period of time (overnight). Pythium blight is a good saprophyte, and survives in the thatch and soil as a water mold until proper conditions occur for it to become pathogenic. As a warm-weather disease of cool season grasses, the disease is most destructive when temperatures are between 85° and 95° F (29.4° - 35° C). When evening temperatures average 68° F or higher, outbreaks will typically first appear in low areas, or poorly drained areas where soil moisture is maintained. Humid periods further favor disease development.


Because of the possibility of this disease, night time watering is on hold until the weather breaks. This will allow me to check the areas to be watered for pythium. We are trying to keep the humidity down as much as possible in the turf canopy in order to keep disease at bay. Also, you may notice us dragging the fairways in the mornings. This is to clear the turf of dew, which can help discourage the dollar spot fungus (Sclerotinia homeocarpa.)


On a totally different note, here are some monarch butterfly caterpillars that I saw on some common milkweed the other day. They are Monarch Butterfly (Danaus plexippus) larvae.

Notice the large hole that has been chewed in the milkweed leaf.

There are several caterpillars on this plant.

Almost

Leslie Park almost made it to triple digit temperatures yesterday but not quite. According to the weather station, we hit 97.3 degrees. Some of the other weather stations around town hit 100, including one in Ypsilanti that recorded 102! We do have the advantage of not being surrounded by pavement and buildings. The low temperature was 76.4 to mark the fourth day the temperature did not drop below 70. It was also the fifth straight day of 90 degrees plus.

We got a nice little surprise this morning, as the temperature when I got in this morning was a comfortable 65. I almost needed a jacket. Almost. Hopefully, this will reset the clock on Pythium development , so we will start watering fairways at night again.

The forecast is still calling for a break from the high temps coming after the weekend. There is also a fair chance for some much needed rain.  We have only gotten 0.51 inches of rain in the month of July. This might seem a little low because of Monday's storms but they seemed to go right around the golf course. While other local communities got up to an inch of rain, we only got 0.01 inches here.

It's not the heat................

It's the humidity. Actually, it's both. As I write this, the weather station says that it is 87 degrees with a heat index of 98. The dew point is 77  and the relative humidity is 72 percent. Did I mention it is 9:18 AM? When I woke up, it was 82.

These conditions are much worse than hot and dry. One of the biggest fears of golf course superintendents is of a Pythium outbreak. Pythium is a fungus, Pythium graminicola and other Pythuim species, that appears suddenly during hot, humid weather. It requires night-time low temperatures of over 68 degrees and more than 10 hours a day of leaf wetness for several consecutive days. The symptoms are greasy, circular spots, 1 to 2 inches in diameter that rapidly enlarge in size. It can also form fluffy white masses of mycelium (the fruiting bodies of a fungus) which can coalesce to form large, irregular patches of dead turf. This mycelium can be transported by vehicles, mowers or water.

Given the speed with which a pythium outbreak can become large patches of dead turf, we have sprayed the greens and tees with a fungicide that will prevent pythium.  We will try to not spray the fairways, given the amount of area that would be involved. Instead, we have cut back on the irrigation on the fairways in order to decrease the humidity in the turf canopy. This may result in some brown areas on the fairways, but will also save us from having to spray a fungicide on 25 acres of turf. This is not only better for the environment, but also helps our budget. 

One of the reasons we can contemplate cutting the irrigation is because of the high humidity. According to our weather station, the evapotranspiration (ET) rate yesterday was 0.14 inches. This is an estimate of the amount of water that the turf will use during a day. To compare, the ET rate on Friday, July 8th was 0.24 inches, even though the high temperature that day was 84 degrees. The relative humidity was down near 32%.

Hopefully, this weather will break soon. WeatherUnderground is forcasting the low temperature on Monday to be 61 degrees. Keep your fingers crossed.

Busy

Happy belated fourth of July!  I have been extremely busy the last couple of weeks (when was the last time I didn't say that?)  My irrigation system has been giving me fits.  We have some sort of problem with the power coming into the station that is causing the computer to shut down the pumps in order to protect them.  For the past month or so, I have been running on one pump.  It only seems to happen when it tries to turn on the second pump.  This is fine, except an irrigation cycle that should take 4 hours takes 8.  If you haven't noticed, we have less darkness than that each night, so I am forced to turn it on earlier than dusk or have it run later than dawn.  Also, when we had that stretch of weather where we had 95 degree days and 30% humidity, my irrigation computer decided it had seen enough and went down.  Not even the blue screen of death, I could not even get it to come on.  To top that all off, I come in last Friday and thanks to George, or resident tee marker/trash/divot guru, I see that we have pythium on our tees.  Pythium is a very nasty fungus that can potentially wipe out turf in a matter of hours.  Luckily, we had a pythium fungicide on the shelf for just such an emergency and the tees are now disease free.

This all comes less than a week before our biggest event of the year, the All-City Golf Championship, which starts this Friday.  I need to get back to work.