Disinfestation Treatment Research Articles

Numerical studies on the electromagnetic and thermal performances of radio frequency disinfestation treatments for dried apricots

Abstract In recent years, radio frequency (RF) dielectric heating has been increasingly studied as a promising novel disinfestation method for agricultural commodities, especially dried fruit. Three-dimensional multiphysics-based models have been established with a commercial finite element (FE) simulation package (COMSOL Multiphysics) to analyze the RF disinfestation process of dried apricots by defining six sub-domains: the flesh, a thin air layer, pit, air layer, kernel, and Indian meal moth larva located on the apricot surface. Thermo-physical and dielectric properties of the apricot flesh, pit and kernel were measured, respectively, by considering the heterogeneous structures of each individual dried fruit. The models were then experimentally validated by RF heating (27.12 MHz, 6 kW) 0.2 kg dried apricots filled in a rectangular container. The simulated point temperatures matched well with the experimental results both for the dried apricots and larvae, with a smallest average relative percentage error (RPE) of 1.45 %. Spatial distributions of simulated temperatures also indicated good agreement with the available experimental data, indicating that the maximum temperature of insect larvae was 11.3 °C higher than that of the flesh. Model prediction results demonstrated that compared with other physical locations (insect in perfect/partial contact with the flesh), the focusing effect of electric fields caused relatively fast heating rate (10.2 °C min−1) and high average temperature (68 °C) when the insects were located on the fruit surface (in point contact with flesh). Thus, the focusing effect of electric fields within insect body plays an important role in efficacy of RF disinfestation treatment for dried fruit.

An Improved Systems Approach as a Phytosanitary Measure for Thaumatotibia leucotreta (Lepidoptera: Tortricidae) in Export Citrus Fruit From South Africa.

A systems approach was previously developed for mitigating phytosanitary risk of Thaumatotibia leucotreta (Meyrick) in citrus fruit exported from South Africa, as an alternative to a standalone cold disinfestation treatment. The present study first tested the original systems approach by applying it on a semicommercial scale in 10 Nova mandarin orchards. Fruit were inspected at points in the production, packing, and simulated shipping process, to assess performance of the systems approach. Additional data were obtained from 17 Valencia orange orchards and six packinghouses. In the second part of this study, the systems approach was accordingly revised and improved, consisting of three measures: 1) preharvest controls and measurements and postpicking sampling, inspection, and packinghouse procedures; 2) postpacking sampling and inspection; and 3) shipping conditions. The model quantifying the effectiveness of the systems approach was improved by correcting errors in the original version, updating parameter values and adding a component that provides for comparison with the risk mitigation provided by a standalone disinfestation treatment. Consequently, the maximum potential proportion of fruit that may be infested with live T. leucotreta after application of the improved systems approach is no greater than the proportion of fruit that may be infested after application of a Probit 9 efficacy postharvest disinfestation treatment to fruit with a 2% pretreatment infestation. The probability of a mating pair surviving is also determined. The model enables a priori determination of the required threshold levels for any of the three measures, based on quantification of the other two measures.

Studies on the ontogenic radio-sensitivity in Callosobruchus species complex to establish a generic dose of phytosanitary irradiation as a post harvest quarantine treatment for disinfestation of pulses

The effects of gamma radiation were observed on the metamorphosis and reproduction as key target features to be intercepted for disinfestation of the three major pest bruchid species, Callosobruchus maculatus (Fabricius), C. analis (Fabricius) and C. chinensis (Linnaeus) irradiated in the various ontogenic stages. The present study was aimed to determine an efficacious generic dose of phytosanitary irradiation (PI) for bruchid disinfestation in pulses.Callosobruchus chinensis was the most radio-resistant species among the present tested species, and male bruchids were more radio-resistant than the females in this species complex.In this complex of tested bruchid species, the gamma dose required to cause 100% metamorphic disruption in the most radio-resistant pre-imaginal stage (pharate adult) was 20–46% higher than the dose required to induce complete sterility in the most radio-resistant imaginal stage (4–5 day old). The effective dose inducing 99.9% impact (ED99.9) was 105 Gy for sterility induction but ~181 Gy to induce metamorphic disruption in the most radio-resistant pre-imaginal pharate adult in C. chinensis, whereas the most radio-resistant imaginal stage (4–5 day old adult) of this species required 124 Gy for complete sterilization.Based on these results, 160–200 Gy as phytosanitary irradiation dose range was evaluated on a semi-large scale testing on the pigeonpea pulse seeds having mixed infestation of Callosobruchus species complex, which indicated that 200 Gy might be considered as a feasible generic dose of phytosanitary irradiation for bruchid disinfestation in pulses.

Hazard Analysis for Phytophthora Species in Container Nurseries: Three Case Studies

Phytophthora species cause crop losses and reduce the quality of greenhouse and nursery plants. Phytophthora species can also be moved long distances by the plant trade, potentially spreading diseases to new hosts and habitats. Phytosanitary approaches based on quarantines and endpoint inspections have reduced, but not eliminated, the spread of Phytophthora species from nurseries. It is therefore important for plant production facilities to identify potential sources of contamination and to take corrective measures to prevent disease. We applied a systems approach to identify sources of contamination in three container nurseries in Oregon, California, and South Carolina. Surface water sources and recaptured runoff water were contaminated with plant pathogenic species at all three nurseries, but one nursery implemented an effective disinfestation treatment for recycled irrigation water. Other sources of contamination included cull piles and compost that were incorporated into potting media, infested soil and gravel beds, used containers, and plant returns. Management recommendations include preventing contact between containers and contaminated ground, improving drainage, pasteurizing potting media ingredients, steaming used containers, and quarantine and testing of incoming plants for Phytophthora species. These case studies illustrate how recycled irrigation water can contribute to the spread of waterborne pathogens and highlight the need to implement nursery management practices to reduce disease risk.

Decay of Thermal Tolerance in Queensland Fruit Fly Eggs (Bactrocera tryoni, Diptera: Tephritidae) Following Non-Lethal Heat Hardening.

Quarantine disinfestation treatments for Queensland fruit fly (Bactrocera tryoni (Froggatt)) have been developed which use high temperatures to kill preimaginal life stages within fruit prior to export. However, thermal tolerance of individuals can be increased if they are exposed to elevated temperatures before disinfestation treatment. The rate that this thermal conditioning decays after exposure, and the effect of temperature on this decay process, were investigated. Eggs of B. tryoni were exposed to a nonlethal hot water treatment at 38°C for 15 min, 1 or 3 h, then held in air at 25°C for times ranging from 15 min to 12 h, before being exposed to hot water disinfestation at 46°C for various times. From each of these cohorts, the lethal time for 99% mortality (LT99) was calculated. The LT99 of B. tryoni eggs increased with longer conditioning times at 38°C. For each conditioning time, the LT99 decreased with longer delay periods at 25°C prior to disinfestation. The rate of decrease was greatest during the first hour of delay, after which the rate of decrease slowed and tended toward zero. This induction and decay was modeled using a double-exponential equation. These experiments show that thermal conditions prior to disinfestation, and the time delay before the procedure commences, both influence the response of the insect to the disinfestation treatment. These results have implications for the specification of postharvest quarantine treatments, which are usually expressed only in terms of a fruit-center target temperature.

Biological Studies on the Effect of Gamma Radiation and Thermal Treatment on the Angoumois Grain Moth, Sitotroga cerealella (Olivier)

Gamma radiation and heat treatments are considered promising techniques for disinfestation treatments against stored product pests. This study aimed to evaluate the effects of thermal treatment with 40, 50, 70 and 90°C and different doses of gamma radiation from 40 to 350 Gy on Sitotroga cerealella stages. The result demonstrated that the LD50 of gamma-irradiation was 57.7, 61.9 and 74.0 Gy in irradiated eggs, pupae, and larvae, respectively. Concomitantly, the complete mortality (100 %) of heat treatment was recorded at 40°C, while the 90°C caused 100 % mortality to larva and egg stages. The results indicated that the egg stage is highly sensitive to irradiation doses than larvae and pupal stages, while the pupal stage is highly sensitive to the heat treatments than eggs and larval stages. Consequently, treatment with low doses 80 Gy and low heat condition 40°C was more effective than the other combination treatments. The results suggested that 80 Gy & 40°C was an effective treatment to prevent the reproduction of S. cerealella and could use for managing this pest with was the environment.

Incorporating statistical strategy into image analysis to estimate effects of steam and allyl isocyanate on weed control.

Weeds are the major limitation to efficient crop production, and effective weed management is necessary to prevent yield losses due to crop-weed competition. Assessments of the relative efficacy of weed control treatments by traditional counting methods is labor intensive and expensive. More efficient methods are needed for weed control assessments. There is extensive literature on advanced techniques of image analysis for weed recognition, identification, classification, and leaf area, but there is limited information on statistical methods for hypothesis testing when data are obtained by image analysis (RGB decimal code). A traditional multiple comparison test, such as the Dunnett-Tukey-Kramer (DTK) test, is not an optimal statistical strategy for the image analysis because it does not fully utilize information contained in RGB decimal code. In this article, a bootstrap method and a Poisson model are considered to incorporate RGB decimal codes and pixels for comparing multiple treatments on weed control. These statistical methods can also estimate interpretable parameters such as the relative proportion of weed coverage and weed densities. The simulation studies showed that the bootstrap method and the Poisson model are more powerful than the DTK test for a fixed significance level. Using these statistical methods, three soil disinfestation treatments, steam, allyl-isothiocyanate (AITC), and control, were compared. Steam was found to be significantly more effective than AITC, a difference which could not be detected by the DTK test. Our study demonstrates that an appropriate statistical method can leverage statistical power even with a simple RGB index.

Impact of microwave disinfestation treatments on the bacterial communities of no‐till agricultural soils

AbstractGrowing herbicide resistance has encouraged the development of new technologies for weed control. Microwave (MW) heating of soil before sowing has been shown to reduce weed establishment in no‐till farming systems and substantially increases crop productivity. However, the effect of this technology on the soil microbial community in general, and on beneficial soil microbes such as ammonia oxidizers in particular, warrants further study. In order to check the effect of MW soil disinfestation treatments on the soil biota, indigenous soil microcosms were treated under a horn antenna of the MW prototype for three distinct durations. Immediately after heating (T0) and 28 days after heating (T28) the soil was collected at two penetration depths (0–5 and 5–10 cm) of MW energy to determine the bacterial community responses based on 16S rRNA amplicon sequencing and the total abundances of bacteria and ammonia oxidisers with qPCR. Although total bacteria and ammonia oxidizer abundances exhibited no response to the MW treatments, bacterial community composition differed according to the treatment durations. Community responses clustered into two categories: no effect at low heating intensities (0 and 30 s, 17–45°C) and strong effect at high heating intensities (60 and 90 s, 65–78°C). For the latter group, community richness did not recover to its pre‐heating levels within the 4 weeks studied. Immediately after high heating intensity treatments, the relative abundance of Firmicutes increased and that of Proteobacteria decreased significantly regardless of penetration depth. The relative abundances of beneficial soil microbes (Micromonosporaceae, Kaistobacter and Bacillus) were significantly higher as soils recovered from high heating intensities compared with untreated soils at T28. Our findings suggest that although pre‐sowing MW treatments alter the soil microbial community, beneficial soil microbes exhibit faster recovery.Highlights High heating intensities reduced bacterial community richness that did not recover to pre‐heating condition. Heat resistant bacterial taxa survived high heating intensities < 28 days after heating regardless of penetration depth. High‐intensity heating did not induce a negative impact on the abundance of ammonia‐oxidizing bacteria and archaea. Relative abundances of dormant heat‐resistant beneficial taxa exhibited recovery after 28 d.

Molecular mechanisms involved in postharvest chilling tolerance of pomegranate fruit.

Cold storage of pomegranates is essential for prolonging postharvest storage and for the implementation of cold-quarantine insect disinfestation treatments required for international trading. However, pomegranates are chilling sensitive; they may develop chilling injuries upon exposure to unfavorable low temperatures. In this mini-review, we summarize molecular data obtained from three different RNA Seq transcriptome analyses of responses of pomegranate fruits to cold storage. These experiments included comparisons among the transcriptomic responses following a 2-week exposure to 1 °C in three different model systems: 1) unconditioned chilling-sensitive fruits versus relatively chilling-tolerant low-temperature-conditioned fruits; 2) chilling-sensitive early harvested fruits versus relatively chilling-tolerant late-harvested ones; and 3) chilling-sensitive 'Ganesh' variety versus the relatively chilling-tolerant 'Wonderful' variety. Comparisons among differentially expressed transcripts that were exclusively and significantly up-regulated in the relatively chilling-tolerant fruits in all three model systems enabled identification of 573 common chilling tolerance-associated genes in pomegranates. Functional categorization and classification of the differentially expressed transcripts revealed several regulatory, metabolic, and stress-adaptation pathways that were uniquely activated in response to cold storage in relatively chilling-tolerant fruits. More specifically, we identified common up-regulation of transcripts involved in activation of jasmonic acid and ethylene hormone biosynthesis and signaling, stress-related transcription factors, calcium and MAPK signaling, starch degradation and galactinol and raffinose biosynthesis, phenol biosynthesis, lipid metabolism, and heat-shock proteins. We hypothesized these pathways to be involved in imparting chilling tolerance to pomegranate fruits. © 2019 Society of Chemical Industry.

Hot water immersion as a disinfestation treatment for grapevine root cuttings against genetically diverse grape phylloxera Daktulosphaira vitifoliae Fitch

Background and Aims Grape phylloxera, Daktulosphaira vitifoliae Fitch, is an important biosecurity pest in Australia. As part of a management strategy, movement of grapevine cuttings, rootlings and propagation material must comply with the National Phylloxera Management Protocols which recommend a hot water treatment. This study validated the effectiveness of the protocol against genetically diverse phylloxera strains and developmental stages. Methods and Results Excised roots of Vitis vinifera L. infested with first instars of phylloxera G1, G4, G7, G19, G20 and G30 genetic strains, and eggs, intermediates and adult stages of G4 were immersed in water for 5 and 30 min at 22, 40, 45, 50 and 54°C. Treatments of 45°C for 30 min and >50°C for a minimum of 5 min resulted in 100% mortality of first instars across all six genetic strains as well as eggs, intermediates and adults of phylloxera G4 strain. Insects survived at 22 and 40°C when immersed for 5 and 30 min and 45°C for 5 min and subsequently developed into egg laying adults. Conclusions Hot water immersion for grapevine root material, as currently recommended in the National Phylloxera Management Protocols is effective for disinfestation of genetically diverse phylloxera and developmental stages. A lower temperature treatment of 45°C for 30 min was 100% effective across diverse strains and developmental stages. Significance of the Study Immersion duration and water temperature are important considerations for effective disinfestation of grapevine material against genetically diverse phylloxera strains and different developmental stages.

A comparison of postharvest quality of breadfruit (<i>Artocarpus altilis</i>) after disinfestation with hot air or hot water treatments

Breadfruit from Samoa potentially host the Pacific fruit fly (Bactrocera xanthodes) and so their export to New Zealand requires a disinfestation treatment. Heat treatments by air (HAT) or water (HWT) are common fruit-fly disinfestation treatments for tropical crops. Two breadfruit cultivars – Puou and Ma’afala – were subjected to three heat treatments, HAT-1 (minimum 47.2oC for 20 min at core), HAT-2 (49.0oC for 100 min at core) and HWT (47.2oC for 20 min at core), and an untreated control was also included. Fruit were stored for one week at 15oC followed by three days at 25oC. Disorders observed were heat damage to the skin (blackening) and increased decay on the body and stem-end. Heat damage was at an acceptably low level following HAT-1 but was unacceptable following HAT-2 or HWT. Initial results suggest that a HAT can be tolerated, but the effect of ramp rate and the potential of using a two-step HWT system should be examined.

Effect of gamma radiation as a post-harvest disinfestation treatment against life stages of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae)

Purpose: Gamma radiation is mainly used for disinfesting insect pests as an alternative for harmful fumigants. The specific dose of radiation is known to affect different developmental stages of insect pests. The study was conducted to determine the effective irradiation doses for inhibition of developmental stages and adult longevity of the coffee berry borer, Hypothenemus hampei (Ferrari).Materials and methods: Irradiation was carried with the following doses: five levels between 0.01 and 0.16 kGy for eggs, seven levels between 0.10 and 2.00 kGy for larva and prepupa, six levels between 0.10 and 1.60 kGy for pupa and ten levels between 0.10 and 3.20 kGy for adults.Results: Egg development was completely arrested at 0.160 kGy. A dose of 2.00 kGy caused 100% mortality in the first and second instar larva and 98.99% mortality in prepupa. The dose of 1.60 kGy prevented adult eclosion from the irradiated pupa. The adult mortality was 100% at 3.20 kGy.Conclusion: A dose of 3.20 kGy could successfully provide complete security from all developmental stages of H. hampei and prevent yield loss in green coffee as well as the spread of the pest.

Thermal distribution analysis of rice weevil disinfestation using microwave heating treatment

This paper presents an analysis of a microwave heating thermal distribution in the rice weevil disinfestation treatment. The sample of rice and rice weevil has been heated by microwave and the infrared thermal camera has been used to capture the heating distribution. The analysis of the rice and the rice weevil condition due to electromagnetic energy exposure is presented. There are three stages of the microwave heating has been taken in the analysis i.e. 10, 20, 30 seconds exposure period at 100W of energy. Found that the treatment of rice weevil disinfestation using microwave energy is promising in the future, but needs a lot of improvement to be studied. The beauty of using microwave energy for rice weevil disinfestation is not only the rice weevil can be killed, but even its eggs or larvae inside the rice kernel will be killed before it hatches.

Dielectric properties characterization of the rice and rice weevil for microwave heating treatment

This paper presents the dielectric properties characterization of the rice and rice weevil for microwave heating disinfestation treatment application. Infestations of insects in stored grain have become a major threat to food supply globally. It contributes to damage to the stored grain and had caused economic losses. The current method to control the infestation which is by using chemical fumigation could give harm to human health and cause environmental pollution. The ability of microwave energy to kill the insects using dielectric heating technique has a high potential as an alternative method to control the infestation of the insect. Knowledge of dielectric properties of the insects is important to understand the interactions of the insect with electromagnetic fields. Hence, this paper presents the evaluation of the dielectric constant, and dielectric loss factor, of the insects and grain using open- ended coaxial probe method. The dielectric properties of the rice weevil, <em>S. Oryzae </em>and rice are measured using an open-ended dielectric probe. Found that the dielectric constant, loss factor and loss tangent for both samples are inversely proportional to the frequency. Knowledge of the moisture content and temperature of the insects and rice is very important to characterize the dielectric properties for future development of microwave heating disinfestation treatment effectively.

Irradiation for Quarantine Control of Coffee Berry Borer, Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae) in Coffee and a Proposed Generic Dose for Snout Beetles (Coleoptera: Curculionoidea).

Coffee berry borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), is the most serious insect pest of coffee worldwide. Green coffee used in blending and roasting is traded between countries and may be subjected to fumigation for disinfestation of CBB. For example, green coffee shipped to Hawaii from the U.S. mainland must be treated with methyl bromide. Irradiation is an alternative disinfestation treatment option. Dose-response tests were conducted with adult beetles to identify a sterilizing dose, followed by large-scale confirmatory tests with adults infesting coffee berries at 100 Gy (measured doses 84–102 Gy). In total, 6,598 adult CBBs naturally infesting dried coffee berries were irradiated at 100 Gy and produced no viable offspring, whereas 1,033 unirradiated controls produced 327 eggs, 411 larvae, and 58 pupae at 3 wk post treatment. This is the first study to develop a postharvest irradiation treatment for a scolytine bark beetle and supports other studies suggesting 150 Gy is sufficient to prevent reproduction in snout beetles in the superfamily Curculionoidea.

Dry heat as a disinfestation treatment against genetically diverse strains of grape phylloxera

Background and Aims Grape phylloxera, Daktulosphaira vitifoliae (Fitch), causes damage to ungrafted European grapevine, Vitis vinifera L. worldwide. In Australia, 83 phylloxera genetic strains exist in distinct zones and the primary management strategy is quarantine. While moving viticultural machinery, particularly harvesters from a phylloxera infested zone, dry heat treatment at 40 and 45°C for 75 and 120 min, respectively, is recommended. Methods and Results First instars of six root-feeding phylloxera, G1, G4, G7, G19, G20 and G30, were subjected to dry heat treatment at 22, 35, 40 and 45°C for 75, 90 and 120 min. For G20 and G30, first instars were subjected to 40°C for 135 min in a separate treatment. Across the six phylloxera genetic strains, no phylloxera survived treatment at 45°C for 75 min. First instars of G1, G4, G7, G19 phylloxera did not survive treatment at 40°C for 120 min. For G20 and G30 phylloxera, however, 100% mortality at 40°C was achieved only when time of treatment was increased to 135 min. The development of surviving phylloxera on excised V. vinifera cv. Chardonnay roots was influenced by the temperature of the dry heat treatment. Conclusions Results validated the effectiveness of dry heat disinfestation protocol of 45°C for 75 min across diverse phylloxera genetic strains. The alternative protocol of 40°C for 120 min was not effective across all phylloxera strains and a duration of 135 min is recommended. Significance of the Study This study highlights the relative sensitivity of genetically diverse phylloxera to heat treatment and duration of exposure.

Using antimicrobials as a food safety measure during phytosanitary treatments in mangoes

Prevention of plant-borne pest infestation necessitates use of phytosanitary procedures, as in the case of U.S.-imported mangoes. Supplementation of hydrothermal disinfestation and/or post-process cooling waters with chemical sanitizers could provide mango packers with antimicrobial interventions reduce or prevent microbial pathogen transmission on mangoes. The current study determined: i) the effectiveness of chlorine (CL) or lactic acid (LA) addition to water used for hydrothermal and cooling treatments to reduce Salmonella survival on mangoes during disinfestation treatment, and; ii) Salmonella internalization into stem scars following hydrothermal and cooling treatments in sanitizer-supplemented water. Salmonella survival during post-treatment storage and effects of treatments on mango color and firmness were also determined. A 2.0 log-cycle reduction was obtained on stem scars subjected to hydrothermal treatment; reductions of 2.2 and 1.3 log-cycles were obtained on stem scars with LA and OCl− treatment, respectively. An additional 1.0 log-cycle reduction during cooling was observed for OCl−-treated mangos; Salmonella were not detected (<2.0 log CFU/10 cm2) on LA-treated mangos. On hydrothermal-treated rinds, a 0.5 log cycle reduction was obtained for control fruit; a reduction of 1.7 log cycles was obtained for both LA- and OCl−-treated fruit. Internalized Salmonella were detected in stem scar tissues obtained following hydrothermal treatment and cooling by enrichment, and survived storage at 10 °C for 12 days. In general, there were no differences in the reduction of Salmonella between CL and LA, although in two occasions CL was less effective. However, mango color was compromised by use of LA. Chlorine use both in hot and cool dips is recommended for minimizing Salmonella transmission on mango surfaces.

Efficacy of steam and hot water disinfestation treatments against genetically diverse strains of grape phylloxeraDaktulosphaira vitifoliaeFitch (Hemiptera: Phylloxeridae) on viticulture equipment and machinery

Background and Aims In Australia, hot water immersion and steam application are recommended disinfestation strategies for harvesting bins, vineyard machinery and vehicles against grape phylloxera, Daktulosphaira vitifoliae Fitch. This study validated the effectiveness of these two strategies against genetically diverse phylloxera strains. Methods and Results The first instars of six phylloxera genetic strains, G1, G4, G7, G19, G20 and G30, were subjected to steam projected from 8 and 24 cm, and from 92 cm for G1 only, for 10, 20 and 30 s. All steam treatments achieved 100% mortality across the six genetic strains. The efficacy of hot water treatment (HWT) against phylloxera was investigated by immersing first instars in a water bath set at 22, 40, 45, 50, 60 and 70°C for 60 and 120 s. Treatments of 50°C and above for a minimum of 60 s resulted in 100% mortality across the six genetic strains. Survival was observed at 40 and 45°C, and first instars subsequently established feeding sites, developed into adults and reproduced on excised grapevine roots. Conclusions Steam application and HWT, as currently recommended in the Australian National Phylloxera Management Protocol, are effective for disinfestation of diverse phylloxera strains. Significance of the Study This study has validated, for the first time, the efficacy of steam application and HWT against phylloxera first instars and highlights the potential to lower the recommendations for treatment duration and water temperature disinfestation while still achieving 100% mortality.

A Soil Probe System to Evaluate Weed Seed Survival in Soil Disinfestation Trials

Weed seed viability is an important parameter to assess the efficacy of soil disinfestation methods like fumigation and steam. In field experiments, seed samples are commonly placed in permeable bags and buried at several depths in soil before the application of soil disinfestation treatments. The seed samples are recovered several days to weeks after treatment and then seed viability is determined in the laboratory. The process of sample installation and recovery is time consuming and may expose personnel to hazardous conditions such as heat or fumigants. Described is a custom soil probe system, developed to simplify installation and recovery of weed seeds from soil. Each soil probe is capable of holding weed seed samples at three different depths up to 30 cm. The following hypothesis was tested: viability of weed seeds is similarly affected by soil disinfestation treatments whether the seeds were contained in the soil probe system or seed bag assays. Two different soil disinfestation trials were conducted: (1) a repeated micro-plot study (USDA Salinas, 1 m-2), using steam as a soil disinfestation treatment and (2) a field study in a commercial strawberry field with 1,3-dicloropropene plus chloropicrin (Pic-Clor 60) as soil disinfestation method. In both studies, seed viability of burning nettle, common knotweed, and common purslane (tetrazolium assay) and germination rates of yellow nutsedge tubers were assessed. Results indicate that the soil probe system can be used as an alternative to the seed bag assay to assess weed control efficacy of described soil disinfestation methods.

Exotic pulse beetles intercepted in imported legume germplasm

Quarantine examination of 13,29,901 imported seed samples of various crops during 1999- 2014 revealed presence of exotic bruchids commonly called seed or pulse beetles in 2,819 samples which were detected by X-ray radiography. Thirteen exotic bruchid species viz., Acanthoscelides desmanthi in Desmanths spp. from Colombia, A. obtectus in Phaseolus vulgaris from Argentina, Colombia Mexico, Peru; Bruchidius atrolineatus in Vigna unguiculata from Nigeria; Bruchus affinis in Vicia faba from Afghanistan; B. dentipes in Vicia spp. from Afghanistan, ICARDA (Syria) and Syria; B. ervi in Lens spp. from Afghanistan, Chile, Cyprus, Ethiopia, Germany, Greece, ICARDA (Syria), Iran, Iraq, Italy, Jordan, Lebanon, Mexico, Morocco, Russian Federation, Syria and Turkey; B. nubilis in V. faba from Ukraine; B. rufimanus in V. faba from Afghanistan, Canada, Spain and Syria; B. signaticornis in L. culinaris from ICARDA (Syria); B. tristis in Lathyrus odoratus from ICARDA (Syria); B. tristiculus in V. narborensis from Portugal; Callosobruchus rhodesianus in Vigna unguiculata from Nigeria and C. subinnotatus in V. subterranea from Ghana were intercepted. Many of the pulse beetles were intercepted repeatedly from the same/ different source(s) year after year. All the infested samples were salvaged using suitable disinfestation treatments. None of the intercepted beetles are yet reported from India, and are therefore, of high quarantine significance.