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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #197705
Title: TROPICAL SPIDERWORT AS A HOST FOR NEMATODES AND DISEASES

Author
item Davis, Richard
item BRENNEMAN, T - UNIV OF GA, TIFTON,GA
item Webster, Theodore

Submitted to: American Peanut Research and Education Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2006
Publication Date: 7/11/2006
Citation: Davis, R.F., Brenneman, T.B., Webster, T.M. 2006. Tropical spiderwort as a host for nematodes and diseases [abstract]. In: Proceedings of the American Peanut Research and Education Society Annual Meeting, July 11-14, 2006, Savannah, GA. 38:86.

Interpretive Summary:

Technical Abstract: Nematodes are the most damaging pathogens of cotton, and one of the most important pathogens of peanut. Crop rotations utilizing cotton, peanut, and corn can be used to manage the southern root-knot (Meloidogyne incognita), peanut root-knot (M. arenaria), and reniform (Rotylenchulus reniformis) nematodes, though weeds can support reproduction and reduce the effectiveness of rotation as a management tool. This study documents 1) the relative host status of tropical spiderwort for M. incognita, M. arenaria, and R. reniformis, and 2) the host status of tropical spiderwort for the fungal pathogens Sclerotium rolfsii and Cylindrocladium parasiticum. A reproductive factor (RF) was calculated for each nematode as the final population level divided by the initial population level (Pf/Pi). Galling was estimated on a 0 to 10 scale for the Meloidogyne species. Data from two trials with M. incognita were statistically similar, so the data was combined into a single analysis. Data from trials with M. arenaria also were combined, but data from trials with R. reniformis could not be combined. Meloidogyne incognita reproduced well on C. benghalensis, leading to a mean gall rating of 3.1 and a mean RF of 15.5 on C. benghalensi. Meloidogyne arenaria also reproduced well on C. benghalensis, with a mean gall rating of 2.1 and a mean RF of 7.2. In the first trial with R. reniformis, the RF was 2.4 on C. benghalensis and 1.4 on cotton. In the second trial, the RF was 3.6 on C. benghalensis and 13.5 on cotton. The severity of symptoms caused by Sclerotium rolfsii was estimated on a 0 to 10 scale. In the first trial, peanut had a mean disease severity rating of 4.0 and C. benghalensis had a mean rating of 1.4, and the fungus could be seen growing on 40% of the C. benghalensis plants. In the second trial, peanut had a mean disease severity rating of 10.0 and C. benghalensis had a mean rating of 5.0, but the fungus could be seen growing on all of the C. benghalensis plants. The trials with Cylindrocladium parasiticum were inconclusive due to low infection rates, but the fungus appears to be weakly pathogenic to C. benghalensis. In conclusion, it appears that C. benghalensis is a sufficiently good host for some of the primary nematode and fungal pathogens of major crops in the southeastern US that its presence at high plant population densities can greatly reduce the pathogen-suppressive effects of crop rotation.