The soybean cyst nematode, Heterodera glycines, is the most economically important pathogen of soybean in Missouri. Knowledge of the nematode's distribution and ability to adapt to resistant varieties is important for determining crop losses and establishing research priorities. No previous surveys of Missouri have provided reliable population density and phenotypic diversity data; therefore, we conducted a random survey to obtain both. Two samples from each of 200 fields were collected; 392 samples were processed for extractions of cysts and eggs. Two hundred and forty seven (63%) of the samples had detectable cyst nematode populations, which ranged from 15 to 149,700 eggs per 250 cm3 of soil. The lowest average population densities were observed in the east-central region of Missouri (2,260 eggs per 250 cm3 of soil), and the highest were observed in the northeast (9,238 eggs per 250 cm3 of soil), but among the eight regions sampled, mean population densities did not differ significantly. These population densities were potentially responsible for losses worth over $58 million in 1999 in Missouri. Race tests were conducted on populations from 183 samples. In order of frequency, races 3, 1, and 2 accounted for 86% of H. glycines populations. Nearly 60% of the populations were virulent (able to produce females) on plant introduction (PI) 88788, which is the source of resistance for most H. glycines-resistant cultivars. More than a third of the populations were virulent on cv. Peking, another common resistance source. Very few populations were virulent on PI 90763 or PI 437654, suggesting that these sources of resistance should be exploited more frequently.

In the past decade, increased attention has been placed on biological control of plant-parasitic nematodes using various fungi and bacteria. The objectives of this study were to evaluate the potential of 662 plant growth-promoting rhizobacteria (PGPR) strains for mortality to Meloidogyne incognita J2 in vitro and for nematode management in greenhouse, microplot, and field trials. Results indicated that the mortality of M. incognita J2 by the PGPR strains ranged from 0 to 100% with an average of 39%. Among the PGPR strains examined, 212 of 662 strains (or 33%) caused significantly greater mortality percent of M. incognita J2 than the untreated control. Bacillus was the major genus initiating a greater mortality percentage when compared with the other genera. In subsequent trials, B. velezensis strain Bve2 reduced M. incognita eggs per gram of cotton root in the greenhouse trials at 45 days after planting (DAP) similarly to the commercial standards Abamectin and Clothianidin plus B. firmus I-1582. Bacillus mojavensis strain Bmo3, B. velezensis strain Bve2, B. subtilis subsp. subtilis strain Bsssu3, and the Mixture 2 (Abamectin + Bve2 + B. altitudinis strain Bal13) suppressed M. incognita eggs per gram of root in the microplot at 45 DAP. Bacillus velezensis strains Bve2 and Bve12 also increased seed-cotton yield in the microplot and field trials. Overall, results indicate that B. velezensis strains Bve2 and Bve12, B. mojavensis strain Bmo3, and Mixture 2 have potential to reduce M. incognita population density and to enhance growth of cotton when applied as in-furrow sprays at planting.

Over the past decade, we have seen an increasing market for biopesticides and an increase in number of microbial control studies directed towards plant‐parasitic nematodes. This literature survey provides an overview of research on biological control of two economically important plant‐parasitic nematodes, Meloidogyne incognita (Kofoid & White) Chitwood (southern root‐knot nematode) and Heterodera glycines Ichinohe (soybean cyst nematode) using spore‐forming plant growth‐promoting rhizobacteria (PGPR). In this review, the current biological control strategies for the management of those cotton and soybean nematodes, the mechanism of using BacillusPGPR for biological control of plant‐parasitic nematode including induced systemic resistance and antagonism and the future of biological control agents on management of plant‐parasitic nematodes are covered.

The tactic of choice for managing soybean cyst nematode (SCN) in infested fields is the use of resistant cultivars. Because expression of SCN resistance is dependent on the occurrence and frequencies of genes for virulence in SCN populations, labeling of SCN-resistant cultivars can be difficult and, occasionally, highly misleading, leading to unanticipated yield losses. The authors' objective was to offer a set of standards for assessing and labeling SCN-resistant cultivars that would allow farmers to make direct comparisons of cultivars. Accepted for publication 15 March 2009. Published 13 May 2009.

Data were collected 2006 through 2008 from 527 soil samples to determine the current effectiveness of PI 88788 and other sources of Heterodera glycines resistance in three geographically separated areas of soybean production: Tennessee and Indiana/Illinois, USA, and Ontario, Canada. In Tennessee where PI 88788 source of resistance has been used since 1978, 93% of field populations reproduced on PI 88788 (≥10% of susceptible cultivar), and no HG Type 0 populations were found. In Indiana and Illinois, where resistance was used since the mid-1980s, from 56 to 88% of the populations reproduced on PI 88788 (≥10%). PI 548402 (Peking), PI 90763, and PI 437654 had low reproduction (≤10%) unlike Tennessee where 78% of the populations reproduced on PI 548402 (≥10%) and 93% reproduced on PI 90763 (≥10%). In Ontario, where cultivars with PI 88788 resistance were used after 1989, PI 88788 in 73% of the field populations had ≤10% reproduction. But 15% of Ontario populations reproduced on PI 548402 (≥10%) and 6% reproduced on PI 90763 (≥10%), two sources of resistance not generally present in commercial cultivars grown in Ontario. Accepted for publication 9 March 2010. Published 26 April 2010.