Papers by Edzard van Santen
InTech eBooks, Nov 9, 2016
The use of winter cover crops is an integral component of conservation systems in a corn and cott... more The use of winter cover crops is an integral component of conservation systems in a corn and cotton conservation agriculture rotation. Field experiments were conducted from the autumn of 2003 through cash crop harvest in 2006 at three locations. The treatments were five cover-crop-planting timings each fall and four cover-crop termination timings each spring. Five crimson clover or cereal rye planting timings occurred: on the average first 0 ○ C temperature date, 4 and 2 weeks prior and 4 and 2 weeks after the average 0 ○ C temperature date. Termination dates were 1-4 weeks prior to the average optimum soil temperature date for the establishment of each cash crop. Results showed that biomass production by winter covers decreased with even a week's delay in winter cover-crop seeding and resulted in a corresponding increase in summer annual weed biomass. More than 10 times difference in biomass produced by clover was observed when clover was planted on the earliest date and terminated on the last date compared to late planting and early termination, rye eight times. Correspondingly, weed biomass was 556 kg ha −1 in the treatment with least rye biomass, eight times higher compared to the treatment with greatest rye biomass.
Journal of Equine Veterinary Science, 2017
&NA; A cross‐sectional serological survey was carried out to screen the equine population of ... more &NA; A cross‐sectional serological survey was carried out to screen the equine population of the nonendemic state of Alabama for the presence of detectable antibody titers against Corynebacterium pseudotuberculosis. A second objective was to determine the association of detectable titers with risk factors such as exposure to ruminants or previous travel to endemic states. A total of 342 equine serum samples from 40 Alabama counties were analyzed using the synergistic hemolysis inhibition test (SHI). The prevalence of detectable antibody titers (≥1:8) was 52.5% (95% confidence interval [CI], 47%–57.9%). Titers ≥1:128 were detected in 2.63% (95% CI, 1.2%–4.9%), and titers ≥1:512 were detected in 0.3% (95% CI, 0%–1.6%) of the sampled population. In the final generalized linear model, age (P < .001), breed (P = .023), and contact with cattle (P = .05) were associated with increasing SHI titers. Contact with goats was associated in the initial but not in the final analysis (P = .19). Previous travel was not associated with increasing SHI titer (P = .97). The results demonstrated a high prevalence of low detectable titers and low prevalence of titers ≥ 1:128 in a nonendemic population. Further evaluation of SHI cutoff titers and accuracy is warranted to reduce the risk of a false positive diagnosis. HighlightsAlthough never reported in Alabama, 50% of horses had low detectable synergistic hemolysis inhibition (SHI) titers (1:8 to 1:64) and 2.6% of horses had titers ≥1:128.Increasing SHI titers in horses was associated with contact with ruminants.Further evaluation of cross‐reaction with phospholipase D exotoxin from C. p. biovar ovis is warranted.Additional research regarding the serological diagnosis of pigeon fever is needed.
Lupin, an ancient crop for the new millennium: Proceedings of the 9th International Lupin Conference, Klink/Muritz, Germany, 20-24 June, 1999., 2000
Bulletin of Insectology, Jun 1, 2015
Corynebacterium pseudotuberculosis (Actinomycetales Corynebacteriaceae) infection in horses cause... more Corynebacterium pseudotuberculosis (Actinomycetales Corynebacteriaceae) infection in horses causes three different disease syndromes: external abscesses, infection of internal organs and ulcerative lymphangitis. The exact mechanism of infection in horses remains undetermined, but transmission by insect vectors is suspected. The present study first determined the optimal culture media for inoculation of house flies (Musca domestica L.) (Diptera Muscidae), with C. pseudotuberculosis biovar equi and the time required for fly inoculation. A second experiment determined the duration of bacterial survival on flies. Exposure of house flies to 3 different preparations of blood agar supplemented with dextrose and colonized with C. pseudotuberculosis determined that a 10 minute exposure to the bacteria was enough to inoculate the flies. C. pseudotuberculosis could be recovered for up to 24 hours after house flies were exposed for 30 minutes to a blood agar plate colonized with the bacteria and moistened with 10% dextrose. These findings support the hypothesis that the house fly is a potential vector of pigeon fever and aid in establishing a protocol for a future experimental model to demonstrate the role of house flies as mechanical vectors in C. pseudotuberculosis infection.
Crops grown in the Macon Ridge region of northeast Louisiana are very responsive to irrigation. I... more Crops grown in the Macon Ridge region of northeast Louisiana are very responsive to irrigation. In dry years, it is extremely difficult to maintain adequate soil mois ture on the Macon Ridge soils because of a shallow root zone. Additionally, when several irrigations are required, high salt accumulation occurs in the root zone because of poor quality irrigation water. An experiment was con ducted in 2001 on a Gigger silt loam at the Macon Ridge Research Station near Winnsboro, LA to evaluate the influence of irrigation, cover crop, N rate, and plant population on corn grain yield, soil moisture, and total soil salts. Data suggest that a mulch-forming cover crop such as cereal rye that persists through most of the growing season can improve soil moisture conditions and enhance yield. Further findings suggest that potential salt problems may be alleviated somewhat by the use of a cover crop.
Journal of Production Agriculture, Jul 1, 1997
Although they may not be a producer's principal vegetable crop, collards often are a valuable rot... more Although they may not be a producer's principal vegetable crop, collards often are a valuable rotation or double crop. Efficient application of N to produce maximum economic yield is desirable. The objective of this work was to examine the effect of N rate and timing on yield and N concentration of open-pollinated and hybrid collards. Although the benefits of N fertilization for vegetable crop production have long been known, the effect of split applications of N on collard yield has not been examined fully. Additionally, cole (broccoli, cabbage, turnip greens, collards) crop yield responses to N were often found to increase with increasing rates of N, and maximum yields were often observed at the highest rates of applied N. When extremely high rates of N (>300 lb N/acre) were applied, a lack of yield response and inefficient use of N was discovered. The experiment was initiated in the fall of 1993 in northern Alabama on a Hartsell fine sandy loam. The experiment consisted of four replicates of an unfertilized check plus 12 N treatments. Nitrogen treatments consisted of four N rates: 60, 120, 180, or 240 lb N/acre, applied as 100% preplant or in split applications. Split applications were applied either half preplant and half 4 wk after transplanting, or one-third preplant, one-third 2 wk after transplanting, and one-third 4 wk after transplanting. Collards were planted in the fall and spring for 2 yr, resulting in four harvests. Collected data included fiesh weight, whole plant total N concentration, and plant population at harvest. Did split applications of N fertilizer increase collard yield? Split applications of N fertilizer increased collard yield over yields obtained when all the N fertilizer was applied preplant. Splitting N fertilizer application into three-and two-way applications both increased collard yield over 100% preplant treatments. There was no fhther yield advantage when N was split into three vs. two applications. At what N rate was collard yield maximized? Collard yields were maximized at rates between 222 Ib N/acre and 250 lb N/acre. These values are much larger than currently recommended (1 20 lb N/acre), but are similar to those found in other cole crop fertility research. Maximum profit was also obtained near these same rates of N application. Full scientific article from which this summary was written begins on page 438 of this issue.
Lupin, an ancient crop for the new millennium: Proceedings of the 9th International Lupin Conference, Klink/Muritz, Germany, 20-24 June, 1999., 2000
Lupin, an ancient crop for the new millennium: Proceedings of the 9th International Lupin Conference, Klink/Muritz, Germany, 20-24 June, 1999., 2000
Nematropica, Dec 1, 2013
The reniform nematode, Rotylenchulus reniformis, infests over 300 plant species worldwide and ove... more The reniform nematode, Rotylenchulus reniformis, infests over 300 plant species worldwide and over the last two decades it has emerged as a major cotton pest in the southeastern United States. Nine locations in Alabama and one location in Mississippi were selected for study of R. reniformis. Thirteen morphometric measurements were made on 20 male and 20 female nematodes from each population. The sex and location interaction was significant (P < 0.005) for all traits except total body length (P = 0.29) and the derived ratio trait a (body length / maximum body width, P = 0.06). Canonical discriminant analysis effectively separated the 10 sampling locations into three distinct groups; among them, Group 1 and 3 were distinct with an intermediate group (Group 2) differentiating in the middle. Furthermore, both female and male R. reniformis based on the morphometrics measured here adhered to this metrics-based grouping. Belle Mina (Limestone County, AL), Huxford (Escambia County, AL), and Mississippi State University, MSU (Oktibbeha County, MS) locations were separated from the remaining seven locations based on the large positive CAN1 centroid means. Eight out of 13 traits had high phenotypic correlations (r > 0.80) with CAN 1 for both sexes. Anal width and length of the hyaline portion of the tail measurement accounted for a significant amount (r > 80%) of the variation in total and sex-based canonical structure. Occurrence of the three non-overlapping morphometric groups in cotton-growing fields in close proximity (250 mile radius) suggests a greater biological variation in this species than expected. Cotton cultivars with differential resistance and soil types are among the major factors to be tested for further delineating the causes of morphometric variation in R. reniformis.
Soil erosion is a major threat to the resource soil. The objective of this 8 yr-field study was t... more Soil erosion is a major threat to the resource soil. The objective of this 8 yr-field study was to compare different tillage systems with respect to runoff, soil loss, nutrient, and pesticide transport. Three different tillage systems were compared: 1) conventional tillage (CT), 2) conser vation tillage with cover crop (CS), and 3) no-till with cover crop (NT). No significant differences in total runoff during growing season were measured between the three tillage practices. Overall average annual soil loss ranged from 0.82 to 3.13 tons acre-1 , with the highest amount for conventionally tilled plots and the lowest for no-till plots. Nutrient losses from April to October were 8.4 lbs acre-1 yr-1 for CT, 5.4 lbs acre-1 yr-1 for CS, and 2.7 lbs acre-1 yr-1 for NT. Corresponding values for phosphorus were 4.1, 1.9, and 1.0 lbs acre-1 yr-1. Conservation tillage and no-till management were able to reduce pesticide losses between 23 and 99 %.
PubMed, Jun 1, 2004
The impact of 10 Fusarium species in concomitant association with Rotylenchulus reniformis on cot... more The impact of 10 Fusarium species in concomitant association with Rotylenchulus reniformis on cotton seedling disease was examined under greenhouse conditions. In experiment 1, fungal treatments consisted of Fusarium chlamydosporum, F. equiseti, F. lateritium, F. moniliforme, F. oxysporum, F. oxysporum f.sp. vasinfectum, F. proliferatum, F. semitectum, F. solani, and F. sporotrichioides; Rhizoctonia solani; and Thielaviopsis basicola. The experimental design was a 2 x 14 factorial consisting of the presence or absence of R. reniformis and the 12 fungal treatments plus two controls in autoclaved field soil. In experiment 2, the same fungal and nematode treatments were examined in autoclaved or non-autoclaved soil. This experimental design was a 2 x 2 x 14 factorial consisting of field or autoclaved soil, presence or absence of R. reniformis, and the 12 fungal treatments plus two controls. In both tests, Fusarium oxysporum f. sp. vasinfectum, F. solani, R. solani, and T. basicola consistently displayed extensive root and hypocotyl necrosis that was more severe (P </= 0.05) in the presence of R. reniformis. Soil treatment (autoclaved vs. non-autoclaved) influenced the impact of the Fusarium species on cotton seedling disease, with disease being more severe in the autoclaved soil. Rotylenchulus reniformis reproduction on cotton seedlings was greater in field soil compared to autoclaved soil (P </= 0.05). This study suggests the importance of Fusarium species and R. reniformis in cotton seedling disease.
Changes in agricultural land use, tillage systems, and conservation programs have resulted in a m... more Changes in agricultural land use, tillage systems, and conservation programs have resulted in a meaningful saving of soil resources for Mississippi over the past twenty-five years. Approximately 5,000 acres of crop land has been taken out of production since 1977. Over two thousand acres have gone into the Conservation Reserve Program (CRP) since 1985. It is doubtful that any of these acres will ever return to cropland produc tion. Tillage operations for major field crops have gone from 10 passes across the field before planting in 1977 to less than 2 passes across the field today. Average soil erosion for the state dropped from 5.2 tons per acre in 1982 to 3.7 tons per acre in 1997. Attitudes of producers concerning practices using reduced tillage or no-tillage has moved from the extreme, where intensive tillage was practiced in 1977, to a moderate approach today, where conservation tillage is an acceptable practice for farming.
PubMed, Dec 1, 2010
Rotylenchulus reniformis is the most damaging nematode pathogen of cotton in Alabama. It is easil... more Rotylenchulus reniformis is the most damaging nematode pathogen of cotton in Alabama. It is easily introduced into cotton fields via contaminated equipment and, when present, is difficult and costly to control. A trial to monitor the natural migration of R. reniformis from an initial point of origin was established in 2007 and studied over two growing seasons in both irrigated and non-irrigated no-till cotton production systems. Vermiform females, juveniles and males reached a horizontal distance of 200 cm from the initial inoculation point, and a depth of 91 cm in the first season in both systems. Irrigation had no effect on the migration of vermiform females and juveniles, but males migrated faster in the irrigated trial than in the non-irrigated trial. Population density increased steadily in the irrigated trial during both years, exceeding the economic threshold of 1,000 per 150 cm(3), but was highly correlated with rainfall in the non-irrigated trial. The average speed of migration ranged from 0- to 3.3-cm per day over 150 days. R. reniformis was able to establish in both the irrigated and non-irrigated trials in one season and to increase population density significantly.
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Papers by Edzard van Santen