NDSU Extension Service - Ramsey County

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May 5, 2014 Horticulture Column

Gardening in Your Yard!!

What a great weekend, we could do away with the rain and cold however, we got many spring jobs completed to include the annual lawn cleanup.  For the first time, ever, I hired someone to go our spring cleanup and even though it cost my yard looks really nice today.  The crew even cleaned our water garden area so except for some minor details the pond should be ready for water in another couple of weeks.  While the lawn service was blowing , cleaning and mowing up the debris I was busy trimming trees.  I had one crab apple tree that has been needing trimming for many years and it finally got a hair cut.  The tree looks quite different but I am writing this article to tell you that tree trimming should be done earlier in the season.  The buds were starting to break on this crab tree and trimming should be accomplished before that period.  This tree is getting quite old so if I do some damage I can replace but by doing this trimming I will be able to keep you posted the “why we should or the why we should not”. 

Driving around the community you cannot but help notice all of the dead spots in the lawns this spring.  These spots can be from many different sources but the first culprit to look at is white grubs.  Check your lawn and if can grab the dead lawn and slightly lift the grass it is very likely white grub damage.  The grubs chew off the roots causing the grass to die and have no root structure.  Another cause could be Nicrotic ring disease.  This is caused by a fungal infection which is caused by stressed grass from the previous year, soil compaction and/or too much thatch from the previous year.  A good aeration will help the area but grass will likely need to be seeded to establish the area back to good health.  I have included an article about what I just talked about to include some fungicides that could be used to help alleviate the problem.

  In a lawn where patch disease is diagnosed, aerating in the both the spring and the fall may be necessary for a couple of years. In addition, low nitrogen applications (even in the spring, to minimize fast, lush growth) will help decrease a favorable disease climate. This means using a balanced fertilizer such as 9-3-6 instead of a 29-3-4 formulation for example.

The other important cultural control measure is to water two to three times a week in the heat of the day while the weather is hot (greater than about 85 degrees). This ensures that the grass is not drought stressed since the thatch layer tends to dry out quickly. It is beneficial to cut the grass no shorter than three to three and a half inches in the heat of the summer to shade the crowns and reduce stress.

Dead patches will need to be re-seeded and using a Fusarium-resistant variety is recommended. Because this is a disease of the roots and crown, getting fungicide to the area where the pathogen was active has proven somewhat challenging, Biller says. Several fungicides are labeled for use against this disease including fenarimol (Twosome Flowable, Rubigan, Patchwork), propiconizole (Banner Maxx), muclobutanil (Golden Eagle, Eagle) thiophanate methyl (Cavalier), and the newest chemistry, azoxystrobin (Heritage). Azoxystrobin has given very good results in studies of fungicide efficacy for this disease. In lawns with extensive disease symptoms or high value turf, use of a fungicide should be integrated into the disease management strategy. In most home lawns, cultural practices are usually sufficient.

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