A low-input sustainable agricultural system for the production of staked, fresh-market field tomatoes (Lycopersicon esculentum Mill.) is described. The system uses winter annual cover crops to fix N, recycle leftover nutrients, produce biomass, and prevent soil erosion throughout the winter and spring. Yields of tomato plants grown in hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and rye (Secale cereale L.) plus hairy vetch mulches were higher than those grown in the conventional black polyethylene (BP) mulch system in 2 of 3 years. Fruit were heavier with the plant mulches than with BP mulch. Eight weeks after transplanting, N levels in tomato leaves were higher with plant than with BP mulch, although the plant mulch plots received only 50% of the N applied to the BP plots. The cover crops had no effect on populations of five phytoparasitic nematode species.

Fungi were isolated from soybean cyst nematode (SCN, Heterodera glycines) eggs collected in China, and 253 fungal isolates were assayed for production of compounds active against SCN and root-knot nematode (RKN, Meloidogyne incognita). Fungal isolates were grown for 3 and 7 days in potato dextrose broth (PDB), the culture broths were sterile-ltered to remove fungal biomass, and the ltrates were placed into 24-well plates to test for effects on egg hatch and juvenile motility. Meloidogyne incognita egg hatch ranged from 2 to 121% of hatch in PDB controls and H. glycines hatch from 15 to 224%. Activities of ltrates harvested after 3 and 7 days were signi cantly correlated. Only four isolates produced ltrates that signi cantly inhibited juvenile motility of SCN, RKN or both nematodes. This study identi ed fungal isolates capable of producing compounds active against these nematodes, and demonstrated that there was a low correlation in activity against SCN and RKN. The active fungal isolates are candidates for studies on identi cation of potential nematicides.

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A single compound with sex pheromone activity was isolated from the female soybean cyst nematode,Heterodera glycines, by a sequence of four high-performance liquid chromatographic steps and identified as vanillic acid by a combination of ultraviolet spectroscopy and chromatography. The structure was confirmed by gas chromatography-mass spectrometry. Both attractancy and coiling behavior in male soybean cyst nematode were elicited by authentic vanillic acid.

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Soil bacterial communities have significant influence on soilborne plant pathogens and, thus, crop health. The present study focuses on ribotyping soil bacterial communities in different peanut-cropping sequences in Alabama. The objective was to identify changes in microbial assemblages in response to cropping sequences that can play a role in managing soilborne plant pathogens in peanut. Four peanut-cropping sequences were sampled at the Wiregrass Research Station, Headland, AL in 2006 and 2007, including continuous peanut, 4 years of bahiagrass followed by peanut, peanut-cotton, and peanut-corn-cotton. Soil sampling was done at early and mid-season and at harvest. Bacterial community structure was assessed using ribosomal intergenic spacer analysis (RISA) combined with 16S rRNA cloning and sequencing. RISA results indicated >70% dissimilarities among different cropping sequences. However, 90% similarities were noticed among replicated plots of the same cropping sequences. Cropping sequences and time of soil sampling had considerable effect on soil microbial community structure. Bahiagrass rotation with peanut was found to have the highest bacterial diversity, as indicated by a high Shannon Weaver Diversity index. Overall, higher bacterial diversity was observed with bahiagrass and corn rotations compared with continuous peanut. The bacterial divisions Proteobacteria, Acidobacteria, Firmicutes, Bacteroidetes, and Actinomycetes were the predominant bacterial phyla found in all peanut-cropping sequences. The Proteobacteria taxa in these soils were negatively correlated with the abundance of members of division Firmicutes but, conversely, had a significant positive correlation with Gemmatimonadetes taxa. The prevalence of the division Actinomycetes was negatively correlated with the relative abundance of members of division Verrucomicrobia. These results indicate complex interactions among soil bacteria that are important contributors to crop health.

The spore appendages of Clostridium taeniosporum NI were removed from the spores by sonic treatment and were isolated by using discontinuous sucrose gradients. The amino acid composition of the appendages, which are elaborations of the spore coat, was similar to but not identical with the amino acid composition of the coats. Approximately 80% of the appendage dry weight was composed of 17 common amino acids, whereas 68% of the spore coat dry weight was amino acids. Mole ratios of the amino acids differed between the appendages and spore coats. The appendages contained neither diaminopimelic acid nor hydroxyproline. Glucosamine was an abundant constituent but muramic acid was absent. Approximately 10% of appendage dry weight consisted of three sugars, one of which was glucose. Phosphorus content was high and dipicolinic acid was absent. Appendage fine structure was not affected by common buffers, dilute acids and bases, hydrogen bond-breaking agents, certain proteolytic enzymes, or lysozyme.Some anaerobic bacteria of the genus Clostridium produce spores with prominent protuberances or appendages. Current knowledge of bacterial spore appendages has been summarized in a recent review (8). In no case have spore appendages been isolated and characterized chemically. This paper describes procedures for removal and isolation of the spore appendages of one organism, Clostridium taeniosporum NI (5), and presents a partial chemical characterization of these structures. Preliminary accounts of portions of this work have been made previously (D. P. Yolton and L. J. Rode, Bacteriol. Proc., p. 23, 1969; Diane P. Yolton, M.A. Thesis, Univ. of Texas at Austin, 1969). MATERIALS AND METHODSOrganism. C. taeniosporum NI, also designated as Clostridium sp. NI, produces spores with appendages which have been characterized morphologically (5, 10). A culture has been deposited in the collection of Louis DS. Smith, Anaerobe Laboratory, Virginia Polytechnic Institute and State University, Blacksburg, Va.Growth and sporulation. Growth and sporulation of the organism was on Brain Heart Infusion medium, pH 7.4, supplemented with 0.5% sodium thioglycolate and 2% agar (10), all from Difco. Petri dishes were surface-inoculated and incubated at 30 C in desiccators over wet oats to provide the anaerobic environment. Sporulation was abundant in 7 days. Spore harvest and cleaning. Spores were washed 4 to 6 times with cold demineralized water and centrifuged at 3,000 x g to remove vegetative cells and cell debris. Concentrated suspensions of washed spores were treated for 30 sec with a Bronson sonifier model W185D to disperse clumps and then were layered on discontinuous sucrose gradients. The gradients contained 50 ml of 40% sucrose, 40 ml of 20% sucrose, 25 ml of 10% sucrose, and 20 to 25 ml of spore suspension and were centrifuged 15 to 20 min at 4 C and 810 x g. The spores either pelleted or suspended in the 40% layer, whereas vegetative cells, germinated spores, and cell debris were suspended in the 10 and 20% layers. The fractions containing r...

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