RESEARCHING MAINTENANCE

What's in this stuff?

I have been using a well-known brand of turf fertilizer in the fall on my tall fescue accounts. The turf greened up very well, but every lawn I used it on is getting patch diseases this summer. What's in the fertilizer that causes this? — California (via the Internet)

It's not likely that your fertilizer contains some unique substance that promotes disease. I asked Clemson University's Dr. Bert McCarty about this, and he explained that temperature, nitrogen levels and moisture conditions are typical factors that influence disease incidence. In the dry, hot conditions of your location, frequent irrigations may keep the surface moist a good deal of the time, which favors disease.

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It's also possible that your N rates were on the high side, promoting the lush growth. This also favors disease.

Without additional details, it's impossible to know what other factors may be interacting to produce your disease problems. Practice sound agronomics in all aspects of your management and avoid heavy N applications, particularly in spring or early summer. And realize that even sound management is not going to entirely prevent turfgrass disease outbreaks. It should keep them to a minimum, however.

Worms on the march

What's going on with armyworms lately? They seem to be getting worse. — Via the Internet

The Midwest has experienced more armyworms than they'd like lately. And this year, the Northeast seems to be getting unusually heavy infestations. A variety of climatological factors may be among the explanations for these population swings.

I spoke with University of Nebraska entomologist Dr. Fred Baxendale about armyworms. He pointed out, first of all, that a distinction needs to be made between true armyworms (Pseudaletia unipuncta) and fall armyworms (Spodoptera frugiperda).

Fall armyworms overwinter only in the warmest portions of the southern U.S. (the Gulf states). With succeeding generations, the insects move northward through the season, reaching middle portions of the United States by fall (thus, the name “fall armyworm”). In a typical year, this is late enough that little danger of extensive damage exists to crops or turf. However, Baxendale explains that the unusually mild winters we've had lately may have allowed fall armyworms to survive farther north than typical.

Fall armyworms were especially a problem in the Midwest in 2000. The 2000-2001 winter was relatively harsh in many parts areas, however, so Baxendale does not anticipate a repeat this year. However, he cautions that this can be difficult to predict, and that he has heard anecdotal reports of damage already this year.

Baxendale recommends monitoring infestations by looking for eggs. Fall armyworms lay them in masses on and under various objects, making them relatively easy to spot. If you see them, you can expect a hatch soon and may want to prepare to treat. Turf is relatively easy to treat for armyworms, with several insecticides providing effective control.

The current problems in the Northeast are due to true armyworms and don't appear to be related to the Midwest's infestations. Dr. Pat Vittum, a University of Massachusetts entomologist, says it isn't clear why the infestation is occurring in the Northeast, but speculation centers on stormy weather patterns this spring that may have blown moths farther along or earlier than usual. A dry spell may possibly have made irrigated turf a relatively inviting target, causing proportionately higher levels of damage to turf.

According to Vittum, only one person she's talked to can remember an infestation this heavy, and that occurred in 1937! Fortunately, the outbreaks are not uniformly heavy. They seem to be worse in southeastern Massachusetts, Cape Cod and parts of Rhode Island and Connecticut.

The caterpillars usually do their damage and then move on to more inviting targets. However, attentive visual monitoring will spot the caterpillars while they're small, giving you time for treatment if needed. The web site www.umassturf.org posts frequent updates on the armyworm situation there, as well as monitoring and treatment tips.

What a drag

I have been taught to drag a dirt infield in a circular method, starting at the outfield with the drag overlapping the outfield grass. Some people disagree with me, saying it should be drug back and forth. Which is better? — Via the Internet

Neither. Tom Burns, director of grounds with the Texas Rangers and former board member of the Sports Turf Manager's Association, feels using a particular pattern isn't as useful as varying the pattern each time you drag. For example, Burns says he may drag in a clockwise fashion one time, counterclockwise the next, back and forth another time, etc.

Burns also suggests:

  • Drag from high to low spots (if you have them) to help keep the infield level.

  • Don't use the drag mat any closer than 8 to 12 inches from the edge of the turf, and finish the last strip by hand. This keeps the dirt from building up at the edge of the turf.

  • Take your time! This is especially important while turning because it will prevent the drag mat from slinging dirt where you don't want it, such as onto the turf.

Eric Liskey has a bachelor's degree in ornamental horticulture and a master's degree in botany. He has been licensed for pesticide advising and applications in California and Missouri, and has more than 10 years combined professional experience in landscape installation and maintenance, nursery retailing, pest management and botany.

If you have a question about landscape or turf management, write to “Researching Maintenance,” Grounds Maintenance, P.O. Box 12901, Overland Park, KS 66282-2901, or send you question by e-mail to eliskey@primediabusiness.com.

Questions are selected on the basis of current general interest. Unfortunately, we are unable to guarantee a response to individual letters.

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