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An Instant Classic, Kentucky Bluegrass decline, and a Big Storm

July 19, 2010

The Open Championship concluded over the weekend with first time major champion Louis Oosthuizen running away from the field for the victory. With three of the four majors completed the summer is off and rolling.

The Field Day Classic was held last week at Jewell Golf and Country Club. It was a great day despite the heat with temperatures reaching into the high 90’s and a heat index well over 100. The course was in great shape and the weather didn’t seem to hinder low scoring. Special thanks to Brian Abels and his entire staff for hosting and putting on a great event.







The hot temperatures have also been causing havoc to our cool-season turfgrasses as well. Soil temperatures are now reaching into the low 80’s causing root growth to stop. Research has shown that creeping bentgrass generally loses about three quarters of its root biomass from the end of May to the beginning of June. This natural root decline coupled with the extreme rainfall amounts during the month of June which caused roots to pull back has resulted in turf that is especially sensitive to environmental and fungal stresses.

I have seen Kentucky bluegrass beginning to decline over the last couple of weeks. The pictures below show a low-mow Kentucky bluegrass intermediate rough. After inspecting the area, the decline seemed to be the result of leaf spot/melting out disease. The disease activity was also more prevalent where the turf was under shade part of the day. Notice how the common type Kentucky bluegrass in the primary rough remains largely unaffected. Mowing height also appears to be playing a large role in the disease activity. Leaf spot can be controlled on a curative basis but applications are most effective in the early stages of the disease.









Diseases will continue to wreak havoc on our cool-season grasses the rest of the summer. For those of you with large acres of perennial ryegrass, the prime window for gray leaf spot is right around the corner.

On a side note, Ames and central Iowa had severe storms roll through Saturday night with winds reaching speeds of over 70 mph. While I kind of like severe weather I do not enjoy the cleanup. Waking up Sunday morning it looked like a bomb had went off in the neighborhood with plant debris and trees down everywhere. Luckily the picture below wasn’t from my house but wasn’t too far away. Hopefully the rest of you in central Iowa were able to avoid damage as well.



Unusual September Weeds and Diseases in Iowa

September 24, 2013

With last week’s abnormally warm September weather, several diseases and weeds were discovered around the state of Iowa. Brown patch thrived with night temperatures above 70F⁰ coupled with high humidity. Brown patch is caused by the fungal organism Rhizoctonia solani. Damage affects the leaf blade from the tip down and is usually noticed in grasses which receive high amounts of nitrogen fertilization. Symptoms are straw colored irregularly shaped foliar lesions with a brown boarder. R. Solani can attack most cool-season grasses, but is most commonly noticed on creeping bentgrass greens, tall fescue lawns and Kentucky bluegrass.

Symptoms on bentgrass putting greens appear as a copper/gray-colored “smoke rings” ranging from a few inches to several feet where mycelium can be seen. Figure 1 below was taken last week by Dan Strey at the ISU research station. Figure 2 is from University of Missouri Extension IPM: Identification and management of turfgrass disease - looking at leaf and sheath lesions of brown patch.  


Figure 1: Brown Patch at ISU research station
Figure 2: University of Missouri publication looking at tall fescue foliar syptoms of brown patch


There are many fungicides that provide brown patch control such as Daconil, Banner Maxx, Heritage, and several others. Cultural practices such as reducing nitrogen levels and preventing long periods of wet conditions can reduce disease pressure. With temperatures tapering off over the weekend, hopefully it will be the end to the high temperature summer diseases in Iowa.

Oddly enough, in the middle of September we have also seen crabgrass and goosegrass seedlings germinating at the ISU research farm. Normal crabgrass germination occurs in mid-April to mid-May depending on your location in the state. Crabgrass is easily identified with fine hairs on the leaves and sheaths as well as its distinctive “protruding fingers” seedheads. Crabgrass also has a rolled vernation, while goosegrass has a folder vernation. 

Goosegrass is often mistaken for crabgrass and some people incorrectly refer to it as “silver crabgrass” because if it’s silvery appearance of the lower sheaths.  Goosegrass generally germinates 2-3 weeks later than crabgrass in the spring. The seed stalks of goosegrass also appear somewhat like a zipper with two individual seeds protruding in two directions. In figure 3 and 4 below you will see the side by side comparison from the Scotts grass manual.

Figure 3 and 4: Goosegrass and Crabgrass comparison from Scotts grass manual

Goosegrass is very difficult to control, even with the use of preemergence herbicides. The best postemergence option is a nonselective herbicide such as glyphosate. Optimal crabgrass postemergence control is obtained when applied while the crabgrass is small and actively growing. The use of fenoxyprop, quinclorac, and dithiopyr are the best options.




October 11, 2010

It has been a busy time at turfgrass research this fall. Here are a couple of new things for next year.

The first is a new seeding of 007 Creeping Bentgrass. I often get calls at this time of years asking how late can bentgrass be seeded. We have a 10,000 sq. ft. area that we will be seeding over the next few weeks. The first one quarter of the site was seeded on Oct. 8. We will continue to seed each additional quarter on Oct. 15, Oct. 22, and Oct. 29. We will have this on next years field day and you will be able to see the results in August.

007 Creeping Bentgrass area

The second major trial is a new National Turfgrass Evaluation Program (NTEP) Perennial Ryegrass trial. There are 88 Perennial Rye cultivars in this trial, replicated 3 times. It was seeded on Oct. 1, which is a little late for rye. The wet weather prevented an earlier seeding. The picture below is from Oct. 11. It is amazing how fast perennial rye can establish if conditions are right.

It has been a great fall for Rust (Puccina grminis) on Kentucky bluegrass. The close up shot below was taken on Oct. 11.

Notice how the two clumps of perennial rye in the picture below are not affected and the bluegrass is severely infested with the Rust.



August 5, 2010

The two pictures below are from Tim Christians at Makray golf course in Chicago. It has been very wet there and night temperatures have been high. He is seeing a lot of Brown Patch on greens and Pythium on bluegrass along the fairways. The fairways are bentgrass and they have been treated with phosphites to prevent Pythium. He is reporting a lot of success with phosphites the last two years for Pythium controls. I was a little nervous about relying on phosphites, but I cannot argue with success.

I had some other calls about brown patch earlier in the week. We had a lot of brown patch at the research station in June, but I usually don't expect it in early August. By Thursday, however, we were seeing a lot of brown patch on our bentgrass cultivar trial at the station as well. It must be the saturated conditions.

For some reason we are getting surprisingly little dollar spot at the station this summer. Last year we had plots loaded with dollar spot all summer. This year I had graduate student Derek York start a study on dollar spot. As would be expected, we have almost no dollar spot in the study area. Next year we'll do a study on saturated soil conditions and we'll get a drought.

I can report that our crabgrass work is doing extremely well at the research area this summer.

I have had a lot of questions on water grass lately from homeowners. As many of you know, there is no such thing as water grass. They are generally referring to crabgrass and other annuals that take over in wet weather. There are a lot of people out there who did not put on a preemerge this spring and are interested in the services of a good lawn care company next year.




July 11, 2009


Nick, thought I would send you an update of what's been going on out at the farm in the event you wanted to post something on the blog site.We just finished seeding the new T-1 bentgrass area (July 8)(picture 2). There was approximately 8,000 square feet seeded to T-1 with the surrounding areas seeded to Front Page Kentucky bluegrass. Before the seeding was done 1lb P/1000 sq. ft. was applied using a 11-52-0 fertilizer and 0.5lb K/1000 sq. ft. was applied using potash with an analysis of 0-0-45. Feel free to swing by the research station to view the grow-in progress.

There is also a lot of brown patch present on some of our bentgrass, tall fescue, and bluegrass areas. We have also seen a remarkable amount of red thread, on both tall fescue and perennial rye, that has continued to hang on into early July. Also, last week, on July 2, the second application of herbicides was put out on the crabgrass control study.

Final data on the Tenacity (mesotrione) phytotoxicity study (picture 1) will be taken soon and the third application of fertilizer for the Micropel greens grade fertilizer study is set to go out early next week.The new bentgrass research area at the research station recently recieved its first application of fungicides (Daconil Ultrex (chlorothalonil) and Emerald (boscalid)) on Tuesday June 28.

We are now closely monitoring the amount of dollar spot that has infested the plots to determine the approximate timing of a second application of fungicide.We have also completed replacing close to half of the irrigation heads in the Rainbird section of the research station.

If anyone is interested in seeing any of the research going on at the horticulture research station, feel free to stop by and don't forget that the 2009 All Horticultural Field Day is August 6th.

Nick Dunlap

GCSAA Campus Representative
Turfgrass Management
Iowa State University