We are finishing up our nematode survey for 2006 and following is a summary of the results:
• We processed a total of 163 samples from 26 golf courses across Indiana, Illinois, and northern Kentucky.
• Ring nematodes were most common, found in 97% of the samples and 49% of the samples had counts higher than the published threshold (Table 1).
• Stunt nematodes were the second most common being found in 47% of the samples and 28% of the samples tested higher than published threshold (Table 1).
• Likely nematode symptoms were seen on only two or three of the sampled golf courses. However, cause and effect relationships are extremely difficult to detect with nematodes. Stress from heat, drought, localized dry spots, cultivation, low mowing, compaction, take-all patch, summer patch, natural decline of Poa annua, and other factors complicate diagnosis of nematode symptoms. Additionally, microclimates within golf courses and sometimes even within greens further complicates confirming nematode damage.
What’s next?
As long as funding can be secured, we hope to further evaluate nematode populations on local greens and in the greenhouse. Seasonal patterns, spatial variability, clarification of thresholds, understanding complicating factors, and potential management strategies are just a few of the areas we are considering.
We’d like to especially thank Oscar Miles for his generous financial and conceptual contribution in ideas and to this study.
Jamal Faghihi and Virginia Ferris, Purdue Nematology
Zac Reicher, Turfgrass Extension Specialist
| Table 1. Summary of the 163 nematode samples collected from 26 golf courses across Indiana, Illinois, and northern Kentucky in 2006. | ||||||
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| Samples with counts | Samples with counts | |||||
| Thresholda | above threshold | below threshold | Range | |||
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| Nematodes/ | # | % | # | % | Nematodes/ | |
| 100 cc soil | 100 cc soil | |||||
| Ring | 300 | 80 | 49% | 83 | 51% | 0-3450 |
| Stunt | 100 | 45 | 28% | 118 | 72% | 0-3450 |
| Lance | 76 | 7 | 4% | 146 | 90% | 0-270 |
| Rootknot | b | 4 | 2% | 159 | 98% | 0-450 |
| Spiral | 300 | 3 | 2% | 160 | 98% | 0-570 |
| Lesion | 51 | 0 | 0% | 163 | 100% | 0 |
| Dagger | 51 | 0 | 0% | 163 | 100% | 0-30 |
| Needle | 501 | 0 | 0% | 163 | 100% | 0 |
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| a Thresholds are from Nematode Parasites of Turfgrass, publication RPD No. 1108, from the Univ. of Illinois http://web.aces.uiuc.edu/vista/pdf_pubs/1108.pdf | ||||||
| b No threshold listed in Nematode Parasites of Turfgrass, publication RPD No. 1108, from the Univ. of Illinois http://web.aces.uiuc.edu/vista/pdf_pubs/1108.pdf | ||||||