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Dollar Spot diagnosis and questions.

Posted by shawnann zn 6 ky (My Page) on
Sat, Jul 11, 09 at 10:35

So the coop ext sent a diagnosis of Dollar spot and also told us not to fertilize in the summer (we used scotts turfbuilder w/ summergaurd) only fall. How can this be treated with organics? Do we need to wait till fall? Leave it alone? DH read that a possible cause is low nitrogen...true? The coop said that our recent rainy and humid weather probably contributed.

We also mow at a higher height (we read about this last year to crowd out weeds). The grass is fescue mix and is not even a year old.

They also said they attached a publication about it, but it wasn't in there.
Thanks for all your help, we really appreciate it!

My Garden Blog

Follow-Up Postings:

RE: Dollar Spot diagnosis and questions.


Symptoms: Infection by dollar spot fungus (Sclerotinia homeocarp) appears as tan or straw-colored spots ranging in size from a quarter to that of a silver dollar sunken in the turf. Occasionally, small cottony strings of the fungus can be seen growing from the diseased leaf blades. Dollar Spot occurs throughout the growing period, and is most active during moist, warm days and cool nights. As the disease progresses, individual spots may join to destroy large patches of lawn. It occurs widely on golf greens, but may also be a severe problem on lawns growing under dry soil conditions. Damage is usually more severe if there is a deficiency of nitrogen. Disease fungi are spread from one area to another by water, wind, mowers, other equipment or shoes.

Control: Practices that promote healthy lawns help to reduce the occurrence of dollar spot. Mow lawns at the recommended maximum height. Try not to remove more than 1/3 of the leaf surface in any one mowing, and if possible, wash the mower between cuttings with a 10% bleach solution. Remove excess thatch and aerate compacted soils. Improve drainage by top-dressing with organic matter, such as compost or well-aged animal manure. Keep lawns well watered, but avoid sprinkling in the late afternoon or evening. Do not over water. In the meantime, apply a slow-release organic fertilizer high in nitrogen; applying liquid seaweed and chelated iron is also helpful. Don't overfertilize, since this can result in an increase of other turf grass diseases, such as brown patch. Avoid night watering or other irrigation practices that allow the leaves to remain wet for long periods. Over seed in fall with resistant cultivars. Dollar spot is rarely serious enough on home lawns to require fungicide treatments.

RE: Dollar Spot diagnosis and questions.

Contrary to what you hear from the people that are selling fertilizers your turf does not need to be fertilized 4 or more times per year. What that turf needs is about 2 pounds of Nitrogen per 1,000 square feet per year and that cna be applied in the fall, in mid to late October, even up to the end of November is the weather stays fairly moderate. Mulch mowing, putting the grass clippings right back where they came from, will supply 1/2 of that Nitrogen need so all you need is a good organic soil food that will supply the rest.
Most often I see grass diseases in turf that is feed synthetic fertilizers on a schedule as reccommended by someone that sells the fertilizers, not as guided by a good, reliable soil test.

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