Weed emergence and seedbank after three years of repetitive shallow cultivation in a muck soil field

Frequent cultivation is often used to control weeds in crops such as lettuce. The efficacy of this technique on weed populations has been evaluated, but the effect on weed emergence and seedbanks is less documented. Studies in mineral soil indicate that soil disturbance can increase both weed emergence and seed persistence depending on where seeds are redistributed in the soil profile. Evaluations done in muck soil are scarce. This study evaluated the effect of two and four repetitive shallow (3.4 to 7.1 cm deep) cultivations on weed emergence and the weed seedbank in muck soil. Cultivation treatments (0, 2 and 4 cultivations using a inter-row rototiller) were done in lettuce plots from 2017 to 2019. Weed density was evaluated by species before each cultivation date and after crop harvest. Viable seedbanks were evaluated by collecting soil samples before and after each growing season and placing them in greenhouse flats. Statistical analyses were based on mixed models. Results showed that shallow cultivation modified the emergence patterns of weeds but did not reduce total emergence during the subsequent years or viable seedbanks. After two seasons without seed inputs, total emergence was reduced by 46.6% and the seedbank was reduced by 31.7% regardless of the cultivation treatment. However, the seedbank of the very abundant common purslane (<i>Portulaca oleracea</i>) remained high.

Risk Identification of Heavy Rain-induced Muck soil Landslide

Based on Monte Carlo method, this paper calculates landslide probability of muck soil slopes under different rainfall time, rainfall intensity, soil permeability coefficient and slope angle, thus obtaining the probability samples of muck soil landslides. On this basis, logistic regression method of nonlinear classification is used for data fitting and analysis, thus establishing nonlinear function . Function expression is derived by data fitting, and a landslide probability evaluation model is constructed. Based on analysis of engineering examples, the error between this method and the numerical calculation results is within 10%, and the evaluation results are reasonable. It provides theoretical support for rapid identification of muck soil landslide risk under heavy rain conditions.

Survival and Behavior of Melanotus communis (Coleoptera: Elateridae) in Florida Sugarcane Soils

Wireworms (Coleoptera: Elateridae) are major economic pests of Florida sugarcane (Saccharum spp. hybrid). The corn wireworm, Melanotus communis (Gyllenhal), is the most important wireworm pest of Florida sugarcane occurring in both sandy and muck soils. The objective of this study was to determine survivability, preference, and dispersal of wireworms in sandy and muck soils. There was no significant difference in starved wireworm survival between the soils after 2 mo. However, the starved wireworms gained more weight in muck soil than in sand. Wireworms dispersed at similar rates toward oat baits in both soil types. Interestingly, in free choice tests wireworms showed a high preference to reside in muck versus sandy soil, which corresponds to the greater wireworm weight change found in muck versus sandy soil. The high preference for muck and greater weight gain in muck found in this study partially explains why M. communis is more abundant in muck soils than in sandy soils in Florida sugarcane.

Anaerobic Soil Disinfestation Reduces Viability of Sclerotinia sclerotiorum and S. minor Sclerotia and Root-Knot Nematodes in Muck Soils

Experiments were conducted to evaluate potential functional and mechanistic differences in the suppression of Sclerotinia sclerotiorum and S. minor and root-knot nematodes in muck soils by anaerobic soil disinfestation (ASD) using different carbon source amendments. Volatile compounds produced during ASD in muck soil amended with molasses, wheat bran, or mustard greens at 20.2 Mg/ha or a 2% ethanol solution significantly reduced the mycelial growth and number of sclerotia produced by both Sclerotinia spp. compared with the anaerobic control. In amended soils, acetic and butyric acids were detected in concentrations that reduced the viability of sclerotia of both pathogens. Higher concentrations of carbon dioxide were observed in ASD-treated soils, regardless of the amendment, than in the nonamended anaerobic control. Only amendment with wheat bran did not increase the production of methane gas during ASD compared with the controls. Meloidogyne hapla survival was completely suppressed in soils treated with ASD regardless of carbon source. Field trials were conducted in Ohio muck soil to assess survival of sclerotia of both Sclerotinia spp. The viability of sclerotia of both Sclerotinia spp. was significantly reduced in soil subjected to ASD amended with wheat bran (20.2 Mg/ha), molasses (10.1 Mg/ha), or wheat bran (20.2 Mg/ha) plus molasses (10.1 Mg/ha) compared with the controls. A consistent negative correlation between soil reduction and viability of sclerotia of both pathogens was observed. Wheat bran and molasses are both widely available amendments that can be used as ASD carbon sources for the management of soilborne pathogens in muck soils.

Anaerobic Soil Disinfestation to Manage Soilborne Diseases in Muck Soil Vegetable Production Systems

Anaerobic soil disinfestation (ASD) was evaluated as a tool for managing the root-knot nematode Meloidogyne hapla in lettuce (Lactuca sativa) and clubroot disease, caused by Plasmodiophora brassicae, in mustard greens (Brassica juncea) produced on Ohio muck soils in Huron and Stark Counties. In two consecutive years of field trials, wheat bran (20.2 Mg ha−1), molasses (10.1 Mg ha−1), and wheat bran (20.2 Mg ha−1) plus molasses (10.1 Mg ha−1) were assessed as ASD carbon sources and compared with nonamended controls. Data were collected from plants grown in the field and from plants grown in field-treated soils in growth chamber-based post-ASD bioassays. Anaerobic conditions developed in ASD-treated soils in both trial years, as indicated by polyvinyl chloride pipes painted with an iron oxide paint. Soil pH did not decrease during ASD at the Huron County site of the mustard greens clubroot trials in either trial year but soil pH decreased significantly during ASD in Stark County soils treated with ASD with either wheat bran or wheat bran plus molasses compared with control soils in both trial years. Impacts of ASD on plant biomass were inconsistent in direct field measurements; however, significantly higher biomasses were observed in lettuce and mustard greens grown in bioassay soils collected from plots treated with ASD with wheat bran-based amendments compared with plants grown in soils from control plots. Based on direct field measurements and bioassays, the use of ASD with any carbon source led to significant reductions in root-knot nematode galling on lettuce compared with controls. Reductions in clubroot severity in mustard greens following ASD were less consistent; however, significant reductions in clubroot severity were observed in the field in one trial year and in both years of bioassays. The results of these studies indicate that ASD is a promising tool for managing soilborne diseases in muck soil vegetable production systems.

Safety of Bicyclopyrone on Several Vegetable Crops and Efficacy of Weed Control

Weed control in vegetable production is especially challenging, because few registered herbicides simultaneously offer excellent crop tolerance and broad-spectrum weed control. We report here the response of several vegetables and weeds to 37.5 and 50 g ai ha−1 of the new herbicide bicyclopyrone (BCP). Vegetable crops showed good tolerance to BCP PRE and post-directed (POST-DIR) in high organic matter content muck soil. POST BCP severely injured all crops. Soil type and the rate of BCP PRE significantly affected response of vegetable crops, and variety of onion was significant. POST BCP controlled hairy galinsoga and small common purslane plants (>80% injury). Hairy galinsoga was not controlled by BCP PRE application in muck soil but was controlled in a 2:3 (vol/vol) blend of Wooster silt loam and a commercial potting mix. Common purslane was slightly injured in the muck soil and was well controlled in the soil and potting mix blend by PRE BCP. The herbicide did not control prostrate pigweed in either soil type or at any growth stage.

Irrigation Water Sources and Time Intervals as Variables on the Presence of Campylobacter spp. and Listeria monocytogenes on Romaine Lettuce Grown in Muck Soil

ABSTRACT Irrigation water has been identified as a possible source of vegetable contamination by foodborne pathogens. Risk management for pathogens such as Campylobacter spp. and Listeria monocytogenes in fields can be influenced by the source of the irrigation water and the time interval between last irrigation and harvest. Plots of romaine lettuce were irrigated with manure-contaminated water or aerated pond water 21, 7, or 3 days prior to harvesting, and water and muck soil samples were collected at each irrigation treatment. Lettuce samples were collected at the end of the trials. The samples were tested for the presence of Campylobacter spp. and L. monocytogenes. Campylobacter coli was isolated from 33% of hog manure samples (n = 9) and from 11% of the contaminated water samples (n = 27), but no lettuce samples were positive (n = 288). L. monocytogenes was not found in manure, and only one sample of manure-contaminated irrigation water (n = 27) and one lettuce sample (n = 288) were positive. No Campylobacter or L. monocytogenes was recovered from the soil samples (n = 288). Because of the low incidence of pathogens, it was not possible to link the contamination of either soil or lettuce with the type of irrigation water. Nevertheless, experimental field trials mimicking real conditions provide new insights into the survival of two significant foodborne pathogens on romaine lettuce.