Phytosanitary Treatment Research Articles

Impact of Natural Phytosanitary Product Residuals on Yeast Fermentation Performance and Wine Composition

Although phytosanitary treatments are necessary to protect grapes from parasitic diseases, consumers are increasingly concerned about the use of synthetic phytosanitary products and their possible residues in wine. Pre-harvest phytosanitary treatments are often inevitable, and consequently downtime is required to avoid possible residues on the grapes. Instead, natural phytosanitary products, such as essential oil (EO)-based products, can be applied close to the harvest without specific restrictions, with results that are not only technically convenient but also more attractive for the consumers. Because of the high antimicrobial activity of EO products, in the present study we evaluated the effect of different residual amounts of two new EO-based phytosanitary products on the alcoholic fermentation and the chemical composition of the final fermented products. In particular, two EO-based new formulations, exploitable in organic viticulture management, were evaluated. Increasing concentrations of each formulation were tested during laboratory scale fermentations and in comparison with synthetic and natural commercial phytosanitary products. Growth and fermentation kinetics of a commercial yeast strain of Saccharomyces cerevisiae and the chemical and sensory profiles of the final products were evaluated. Both new formulations showed no significant impact on the growth and fermentation kinetic of S. cerevisiae at any of the concentrations tested. In all trials, alcoholic fermentation was completed in 15 days. Instead, a different chemical composition of the final products was observed. Therefore, these new products might represent an interesting alternative tool to the conventional phytosanitary treatments, being applicable close to the harvest without negative impacts on the kinetics of alcoholic fermentation and also being more acceptable to wine consumers.

The Impact of Agricultural Inputs and Environmental Factors on Potato Yields and Traits

Potato, a component of global food security and economic stability, is cultivated extensively worldwide due to its adaptability to diverse climates and soil types. Ongoing research and technological advancements, including the use of unconventional products destined to fight the most harmful pathogens, are essential for enhancing productivity and resilience in potato farming. The current study aimed to identify the most appropriate fertilizers and phytosanitary treatments in order to attain optimal potato yields, dry matter, and starch contents, under climate-specific environments. The experiment was conducted in the northwest of Romania in 2023. The research was organized as a trifactorial experiment with the factors variety, fertilization, and phytosanitary treatment. XLSTAT (2022.2.1v.) was utilized for data processing. Mineral fertilization combined with conventional phytosanitary treatment led to the highest average yields in both potato varieties. Also, a combination of organic fertilization and treatment with 4% A. cepa extracts led to notable results, which suggests the possibility of successfully using these inputs in organic agriculture. The study shows the importance of selecting appropriate agricultural inputs to optimize potato yields, achieve specific levels of dry matter and starch content in a specific area, and promote sustainability.

Approach to Validate ISPM-15 Compliance for Commercial Treatment Certification of Dielectric Standard Heating of Bulk Solid Wood Packing Materials using Radio Frequency

Abstract To substantially reduce the risk of alien invasive species moving to new geographic areas, phytosanitary treatment of wood packaging materials (WPM) in compliance with the International Standard of Phytosanitary Measures No. 15 (ISPM-15) is required by trading partners. Approved treatments include conventional heating, methyl bromide and sulfuryl fluoride fumigation, and dielectric heating (DH). The DH standard was officially adopted in 2013 but has not been practiced commercially due primarily to insufficient operational validation at commercial scale. In 2022, we converted our 50-kW radio frequency (RF) unit with a 1,200-board foot capacity from an oscillator electromagnetic field power generator to a solid-state power supply, which allows for selective power input adjustments during treatment; we also switched from a five-plate to a three-plate winged electrode system to improve heating uniformity. Each loading cycle can treat sufficient material to build ∼94 standard Grocery Manufacturers Association pallets. Our research team characterized the dielectric heating pattern and options for monitoring wood temperatures over a wide-ranging test matrix of WPM that varied by wood species, dimension, moisture content, and loading configuration. We found that this upgraded RF system markedly reduced treatment times and improved heating uniformity, allowing us to develop methods that can be used to verify compliance with ISPM-15 for improved technology transfer to industry. We also discuss the operational cost of RF treatment and make general cost comparisons to conventional heat treatment for WPM.

Phytosanitary irradiation as an effective treatment for Drosophila suzukii.

Drosophila suzukii is a pest native to Southeast Asia that causes significant economic losses to soft fruit crops. Phytosanitary irradiation is a promising treatment for D. suzukii hosts; yet an internationally recognized irradiation protocol is lacking. To fulfil specific requirements for proposing an irradiation treatment for D. suzukii, naturally infested blueberries and cherries containing a total of 37,489 late pupae were irradiated with a maximum absorbed dose of 80Gy. Infested hosts containing a total of 9578 late pupae were considered unirradiated controls. Prevention of egg laying by females that emerged from treated pupae was considered the treatment endpoint. The fecundity and egg viability of females that emerged from treated pupae mated with their siblings were evaluated using blueberries. While females from unirradiated pupae laid a total of 43,142 eggs, no egg was laid by females that emerged from irradiated pupae. In addition, 1-day-old adults were irradiated with nominal doses of 20 and 72Gy to evaluate whether egg laying could be prevented in flies emerging before the irradiation treatment. Females irradiated with 72Gy laid eggs that did not hatch. Our findings suggest the minimum absorbed dose of 80Gy as a phytosanitary irradiation treatment against D. suzukii and may support its inclusion as a treatment option in the annex of the International Standard for Phytosanitary Measures 28 (ISPM 28).

Bio-based coatings containing mycosporine-like amino acids (MAA) to control sunscald abiotic stress in orange fruit (Citrus sinensis L)

Oranges are susceptible to many abiotic stresses, and the fruit is particularly susceptible to sunscald, a physiological disorder caused by excessive solar radiation. Sunscald is commonly controlled by spraying the fruits with calcium hydroxide and/or kaolin, but this procedure is not always effective due to rain and the application of phytosanitary treatments. Since mycosporine-like amino acids (MAAs), produced by many marine organisms, protect them against ultraviolet radiation UV-A and UV-B, these compounds could be incorporated into bio-based emulsions to control sunscald in oranges. Therefore, increasing concentrations of the commercial product Helioguard™ 365 (0 %, 1 %, 2 %, and 4 % - v/v), a source of MAAs, were incorporated into lipid-based emulsions. The emulsions were applied during the final stage of development of ‘Hamlin’, ‘Pera-rio’, and ‘Valencia’ oranges at 21-day intervals. Spraying with 5 % (w/v) calcium hydroxide served as the positive control treatment, while untreated fruits served as the negative control. Incorporating MAA into the emulsion did not demonstrate effective control of sunburn compared to the positive control treatment with calcium hydroxide, as all fruits exhibited varying degrees of sunscald, ranging from low to high severity. Regarding physicochemical parameters, as well as oxidative metabolism, except for color parameters, soluble solids content, ascorbic acid, and overall biochemical parameters, there was no difference among treatments for any of the evaluated orange cultivars. The activities of ascorbate peroxidase (APX) and superoxide dismutase (SOD) did not show consistent with efficient antioxidant potential capable of significantly reducing the malondialdehyde (MDA) content. Despite using MAA at the evaluated concentrations and experiencing severe climatic interference in 2020, efficient control of sunscald in oranges was not achieved. Further research is needed to identify more effective alternatives and gain a better understanding of how climate affects oxidative aspects.

Internal Disorders of Mango Fruit and Their Management-Physiology, Biochemistry, and Role of Mineral Nutrients.

Mango (Mangifera indica L.) is a popular fruit grown in tropical and subtropical regions. Mango has a distinctive aroma, flavour, and nutritional properties. Annual global mango production is >50 million tonnes. Major producers of mango include India, Bangladesh, China, Mexico, Pakistan, Indonesia, Brazil, Thailand, and the Philippines, and it is shipped worldwide. Harvested mango fruit are highly perishable, with a short shelf life. Physiological disorders are among the major factors limiting their postharvest quality and shelf life, including when fruit need phytosanitary treatments, such as hot water treatment, vapour heat treatment, and irradiation. This review focuses on problematic physiological disorders of mango flesh, including physiology and biochemistry. It considers factors contributing to the development and/or exacerbation of internal disorders. Improved production practices, including pruning, nutrient application, and irrigation, along with monitoring and managing environmental conditions (viz., temperature, humidity, and vapour pressure deficit), can potentially maintain fruit robustness to better tolerate otherwise stressful postharvest operations. As demand for mangoes on international markets is compromised by internal quality, robust fruit is crucial to maintaining existing and gaining new domestic and export consumer markets. Considering mango quality, a dynamic system, a more holistic approach encompassing pre-, at-, and post-harvest conditions as a continuum is needed to determine fruit predisposition and subsequent management of internal disorders.

Phytosanitary cold treatment of cherry tomatoes infested with Bactrocera dorsalis, Zeugodacus cucurbitae, and Zeugodacus tau (Diptera: Tephritidae).

Fruit flies attack numerous crops, including cherry tomatoes (Solanum lycopersicum var. cerasiforme). The potential presence of the immature stages of fruit fly species inside tomatoes during export hinders their international market access. Therefore, phytosanitary treatment must be performed before export to prevent fruit fly species from entering countries where they are not naturally found. We developed a phytosanitary cold disinfestation treatment protocol to eliminate oriental fruit fly (Bactrocera dorsalis Hendel), melon fly (Zeugodacus cucurbitae Coquillett), and pumpkin fruit fly (Zeugodacus tau Walker) concealed inside cherry tomatoes without causing critical damage to the fruit. We determined that the third instar of Z. cucurbitae exhibited the highest cold tolerance among the various development stages of the three fruit fly species. Thus, we performed a small-scale disinfestation test on Z. cucurbitae in two cultivars of tomato. We achieved complete disinfestation after 15 days of cold treatment at 1°C-1.5°C. The confirmatory test revealed the elimination of more than 80,000 treated third instar of Z. cucurbitae in each tomato variety. The developed phytosanitary cold treatment allows the tomatoes to retain their commercial value. This study provides a standard phytosanitary cold treatment protocol for cherry tomatoes, ensuring the disinfestation of fruit flies before their export to international markets.

Comparing the biological effectiveness of low energy 100 kV and high energy 5 MeV X-rays against Oriental fruit fly (Diptera: Tephritidae).

Radioisotope irradiators (using cesium-137 or cobalt-60) are used as sources of ionizing radiation to control quarantine or phytosanitary insect pests in internationally traded fresh commodities and to sterilize insects used in sterile insect release programs. There are institutional initiatives to replace isotopic irradiators (producing γ-rays) with lower-energy X-ray machines due to concerns about radiological terrorism and increasingly stringent regulations on the movement of radioisotopes. Questions remain about whether the biological effects of low-energy X-rays are comparable to those of γ-rays since differences in energy levels and dose rates of X-rays may have different efficacies. We compared adult emergence, flight ability, and adult survival in the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritdae), after irradiation of third instar larvae with 100 kV or 5 MeV (5,000 kV) X-rays at 20 and 40 Gy in replicated studies. At 20 Gy, the adult emergence rate was significantly lower after irradiation with 100 kV compared to 5 MeV X-rays, suggesting higher efficacy at the lower energy level. In a follow-up study using 100 kV X-rays, applying 20 Gy using a slow dose rate (0.24 Gy min-1) resulted in significantly higher adult emergence than did a fast dose rate (3.3 Gy min-1), suggesting lower efficacy. Although our study suggests higher efficacy of low energy 100 kV X-rays, there is uncertainty in measuring the dose from an X-ray tube operating at 100 kV using an ionization chamber; we discuss how this uncertainty may change the interpretation of the results. Using a 100 kV X-ray irradiator to develop a phytosanitary treatment may underestimate the dose required for insect control using commercial high-energy γ-ray or X-ray systems.

Phytosanitary Cold Treatment of the Spotted Wing Drosophila (Diptera: Drosophilidae) in Postharvest ‘Red Globe’ Grapes

The spotted wing drosophila, Drosophila suzukii (Matsumura), is currently distributed in the main soft-skinned fruits production areas in China and 59 other countries, presenting a significant threat to importing nations. Optimal phytosanitary treatments, including fumigation, irradiation, and cold treatment, have been developed to prevent the international movement of this invasive fly. To determine the most cold-tolerant stage and facilitate the development of the technical schedules requested by the Technical Panel on Phytosanitary Treatment (TPPT), cold treatments of D. suzukii immature stages in ‘Red Globe’ grapes were conducted. Dose–mortality data at 0 °C and 2 °C from repeated trials were subjected to analysis of covariance, linear regression, and probit analysis. Results identified 3 d old pupae as the most cold-tolerant stage, followed by 1 d old pupae, 4 d old larvae, and 6 h old eggs with similar tolerance. The 2 d old larvae were the most sensitive stage. In subsequent confirmatory tests, 3 d old pupae were subjected to cold treatment at 0 °C for 9 and 10 days, and at 2 °C for 10 and 12 days, based on the probit estimation of the probit-9 value. No adult emergence occurred in the confirmatory tests except for one deformed adult from a 2 °C 10 d treatment. Therefore, the recommended treatment schedule requires fruit temperatures below 0.00 °C (or 1.62 °C) for no less than 10 (or 12) continuous days, with treatment efficacy not less than 99.9960% (or 99.9955%) at a 95% confidence level, respectively. These schedules are intended for submission to TPPT for the development of phytosanitary treatment standards.

INFLUENCE OF TECHNOLOGICAL FACTORS ON QUALITY AND SOME YIELD ELEMENTS OF ANDRADA WINTER WHEAT VARIETY, CULTIVATED IN TRANSLILVANIA PLAIN CONDITIONS

For evaluating the influence of tillage system, fertilization and phytosanitary treatment on wheat seed quality, an experiment was conducted at Research and Development Station for Agriculture (RDSA) Turda. Seeds of Andrada winter wheat variety were analysed for: Ash [%], G, Gluten [%], HlWeight [kg/hl], L [mm], Moisture [%], P [mm], P/L, Protein [%], Protein_DM [%], W [Jx10E-4], Zeleny [ml]. Generally, quality was influenced by fertilization and phytosanitary treatment, small variation depending on tillage system being identified. In the no-tillage version, when the mineral fertilizer N134P48K48 and when seed treatment and two foliar treatments were applied maximum values wwre obtained for: prorein content (11.69%), gluten content (22.4%), Zeleny index (33 ml). In terms of hectoliter weight, the highest value of 77.75 kg/hl was obtained in the classical crop system, when fertilization with complex fertilizer N88P48K48 together with seed treatment and one foliar treatment were applied. In terms of yield elements, the negative relationship between quality and yield is highlighted, namely if in the „no tillage system” good results for quality were obtained, in classic system, high values for plant height, numebr of grains/spike, grain weight/spike and for spike lenght compared to „minimum” or „no tillage” were identified.

Adoption and Impact of Fungus-Resistant Grape Varieties within German Viticulture: A Comprehensive Mixed-Methods Study with Producers

The reduction of phytosanitary treatments in viticulture is widely demanded by policymakers and consumers. An important solution is the use of resistant grapes, which can cut plant protection applications by up to 80%. Although this is a significant improvement, viticulture is mainly carried out with traditional grapes. Therefore, the aim of this paper is to identify the factors that encourage the cultivation of fungus-resistant grape varieties (FRGV), as well as the challenges and opportunities in marketing. Our study used an exploratory sequential mixed-methods model design. In the first step, data were collected through 48 in-depth interviews and analyzed. Based on the qualitative results, a survey of 422 producers was conducted. The quantitative research results were segmented by company size and production type to provide a deeper understanding. The main drivers for cultivation are the ecological benefits resulting from the reduction of pesticide use, with organic producers particularly motivated by sustainability goals. Smaller producers are driven by the opportunity to introduce a new wine style, whereas larger producers are more cautious and focus on cost savings. The cultivation of resistant grape varieties is restricted by a large number of varieties, lack of experience, and unfavorable characteristics from initial generations of resistant grapes. A low level of grape variety prominence and customer awareness, as well as unattractive variety names, negatively affect producer acceptance. To facilitate higher market acceptance, it is important to offer attractive grape varieties, directly communicate them to consumers, and provide information about the sustainable effects.

A molecular method to assess viability of Phytophthora in infected wood following heat treatment

International trade in wood products is an important component of the global economy. However, wood and wood products may have pests associated with them that could be introduced into importing countries, posing phytosanitary risks, and leading to the implementation of regulatory restrictions that affect wood trade. The application of heat to kill wood-associated pests has been a successful phytosanitary method to reduce their spread. To evaluate the efficacy of wood heat treatment to kill fungal and fungus-like pathogens, the method of choice has been to grow organisms in cultures for subsequent identification. However, some plant pathogens can be difficult or impossible to grow in axenic cultures and a molecular method can still be useful for assessing pathogen viability after heat-treatment. RNA is a single stranded molecule that is responsible for the transcription of genes. Since it becomes rapidly unstable after cell death, it provides a measure of viability. We therefore designed and tested RNA-based molecular diagnostic assays targeting essential genes and assessed their presence after heat treatment in wood colonized by four Phytophthora species of phytosanitary concern (P. xmultiformis, P. cinnamomi, P. lateralis and P. ramorum) through reverse transcription and real-time polymerase chain reaction (RT-qPCR). Our assays differentiate between genomic and mRNA as the TaqMan probes span exon-intron junctions. We validated these RT-qPCR assays to assess heat treatment efficacy of Phytophthora-inoculated wood. These assays can be very useful tools to assess effectiveness of current and emerging phytosanitary wood treatments.

UNRAVELING THE USE OF PESTICIDES IN THE NORTHWEST AND SOUTHWEST MESOREGIONS OF RIO GRANDE DO SUL: A COMPRE-HENSIVE ANALYSIS OF MARKET CHARACTERISTICS AND DYNAMICS

Pesticides have the function of protecting agricultural crops through phytosanitary treatments, helping increase productivity to feed an ever-growing population. They exist in a globally competitive market, where pesticide companies, resellers, and agricultural cooperatives are responsible for the sales and distribution to the final consumer, in this case the farmer. In this context, this research aims to characterize the agricultural pesticide sector and the agricultural marketing system in the Northwest and Southwest Mesoregions of the State of Rio Grande do Sul, Brazil. This research consisted of a bibliographic research followed by a field survey of 40 companies, including owners and pesticides resale managers (32) and agricultural cooperatives (8). The results show a marketing system aimed at Rio Grande do Sul conducted mainly through the sale of supplier companies to resellers and agricultural cooperatives, which resell them to the farmer. The tendency of the agricultural pesticides market is to stabilize, even with the decline of the sector in Brazil in successive years, with a current resumption of growth, much of it driven by national and multinational supplier companies that invest in countries like Brazil.

Impact of Fruit Maturity on Internal Disorders in Vapor Heat Treated Mango Cv. ‘B74’

UN Sustainable Development Goal 12 (SDG 12) aims to reduce food losses in production and postharvest stages within supply chains. Identifying and addressing contributors to such losses is crucial to their reduction and to overall supply chain sustainability. Internal disorders (IDs) often contribute to postharvest losses and waste of highly perishable fruits like mangoes. Understanding and addressing influencers of susceptibility is limited but essential. Factors potentially associated with the expression of IDs in ‘B74’ mango commercial supply chains were investigated. Over three fruiting seasons (2020/21, 2021/22, and 2022/23), 43 export supply chains in Australia were monitored from two major production regions, the Northern Territory and North Queensland. Prior to export, the mangoes were subject to a mandatory phytosanitary vapor heat treatment (VHT) in which they were heated with saturated water vapor to a core temperature 46 °C maintained for 15 min and were then assessed for IDs at the end of their shelf life. The predominant IDs observed in the ‘B74’ fruit were flesh cavity with white patches (FCWP) and flesh browning (FB). VHT-induced FCWP, but not FB. Harvest maturity was identified as a predisposing factor. FB was generally positively correlated and FCWP was typically negatively correlated with fruit maturity at harvest. Relatively more-mature fruit was prone to FB irrespective of VHT, and relatively less-mature fruit was susceptible to FCWP post-VHT. Therefore, selective harvesting and/or sorting for optimum maturity after harvest can be practiced minimizing the incidence and severity of these two IDs in ‘B74’ fruit. Thus, dry matter (DM) sorting can contribute to postharvest loss reduction and the general sustainability of mango supply chains.

Complex Habitats Boost Predator Co-Occurrence, Enhancing Pest Control in Sweet Pepper Greenhouses

Sweet pepper is a crop that benefits from phytosanitary treatments with low environmental impact, especially the successful control of pests through the introduction of biological control agents in greenhouses. However, predators that naturally occur in these surroundings often enter greenhouses. The precise roles of these natural predators and their interactions with the introduced predatory insects and mites are often unknown. This study investigated the relationships between Nesidiocoris tenuis, which is naturally present, and Amblyseius swirskii and Orius laevigatus, which are two species of generalist predators released for the control of multiple pests. This study was conducted for two years on 13 commercial sweet pepper crops in various types of greenhouses (tunnels and traditional greenhouses) in Sicily. The environmental complexity value (ECV) for each site was estimated based on 18 points detected around the site according to the different habitats that occurred at each coordinate. The results showed that the occurrence of N. tenuis in greenhouses, independently of their typology (tunnel or traditional greenhouse), was mainly promoted by the greater diversification of habitats immediately surrounding the pepper crops (in a circular area with a diameter of 500 mt), with an increase in its density during the crop season. Moreover, N. tenuis–O. laevigatus’s co-occurrence in flowers suggested that they were not impacted by each other’s presence and that their co-occurrence had a significant effect on pest reduction, although their co-occurrence was density-dependent. As an intraguild predator, N. tenuis competed with O. laevigatus for Frankliniella occidentalis when many predators were present. In addition, N. tenuis also competed with A. swirskii when they both occurred in flowers at a higher density. This study highlights the importance of pepper plant flowers in promoting a higher occurrence of juvenile forms of N. tenuis within flowers. Amblyseius swirskii colonized the plants in 3 weeks, distributing itself almost uniformly over the leaves with a clear control action against not only Bemisia tabaci but also F. occidentalis when present on the flowers. Thus, this concurrent analysis of several commercial pepper sites within the same production area suggests that, even with similar pest control plans, the diverse variability in the presence of natural enemies must be considered when selecting control strategies for pepper crop pests and that N. tenuis, favored by complex surrounding habitats, contributes actively to pest reduction.

Hot Water Treatment as a Quarantine Measure for Controlling Pratylenchus penetrans Cobb in Syngonium podophyllum Schott and Perilla frutescens Britton

Syngonium podophyllum Schott plants are increasingly being imported in Korea due to their ability to purify indoor air. Root lesion nematodes, Pratylenchus spp., are the most frequently occurring nematodes associated with S. podophyllum, leading to the disposal of plants or their return to the country of origin, due to inadequate phytosanitary treatments. We evaluated the effectiveness of hot water treatment in controlling Pratylenchus penetrans Cobb, present in S. podophyllum and Perilla frutescens Britton. The mortality rate (LT99%: the time at which 99% lethality is achieved) of P. penetrans at 44 to 52 °C water and treatment-caused plant damage were evaluated in vitro and in vivo. The in vitro test showed the LT99 at 44, 46, 48, 50, and 52 °C was 119.1, 27.0, 14.70, 1.40, and 0.48 min, respectively. The LT99 of hot water treatment on the nematodes infecting both plants was 18.4 to 1.7 min at 46 to 50 °C. S. podophyllum was undamaged at 30 days after treatment with 49 and 51 °C water for 30 min. This study demonstrates that hot water treatment is a potential phytosanitary disinfection method for Pratylenchus spp. infecting foliage plants, which can accelerate their trade by reducing incidents of disposal or return to the country of origin.

Phenology of Apple Cultivars with Different Chilling Requirements

Under mild climate conditions where chilling requirements are not met, the different phenological stages tend to extend and vary according to the year and chilling intensity. Knowledge on the phenological stages becomes important for the management of some cultural practices such as fruit thinning and phytosanitary treatments. The phenology of ‘Condesa’, ‘Imperatriz’, ‘Fred Hough’, ‘Gala’, ‘Fuji Suprema’ and ‘Baronesa’ apple cultivars with different chilling requirements was studied for a period of 20 years. The method employed made it possible to analyze the evolution of the different phenological stages, allowing the chronological determination of their development. The results suggest adaptability of the different cultivars in the same region, highlighting the influence of environmental factors. The duration of the different phenological stages varied according to the chilling requirements of each cultivar, being directly influenced by climatic factors.

Evaluation of Local Common Bean (Phaseolus vulgaris L.) Genotypes for Resistance to Fungal Diseases in the Bimodal-rainfall Forest Zone of Cameroon

The general objective of the present study was to evaluate the susceptibility to fungal diseases of some bean collections in the bimodal rainfall forest zone of Cameroon. To this end, 12 bean collections from Foumbot were grown at the University of Yaoundé I in a completely randomized block design without phytosanitary treatments. Symptoms identified on the leaves of diseased plants were used to characterize the fungal agents in the laboratory using an identification key. Incidence and severity were assessed, as well as the number of pods and seeds in plants under fungal pressure. Following the evolution of symptoms, all collections showed fungal disease attacks at different rates. Macroscopic and microscopic laboratory observations identified Sclerotinia sclerotiorum, Uromices appendiculatus and Fusarium solani as the fungal agents responsible for these symptoms. The incidence of disease caused by F. solani was lower in the NJBPRNV (16.67%) and NJBV (22.22%) collections, as was severity (3.33% and 4.44%). On the other hand, the LGRTE (47.06%) and GGRBE (44.44%) LGRV (43.75%) collections showed high incidences of disease caused by S. sclerotiorum, U. appendiculatus and F. solani respectively. Considering the number of seeds, the KPGPV (403.2 seeds) and KPGPTV (350.4 seeds) collections recorded the highest number of seeds, compared with the GGRBE (15.93 seeds); LGRTE (23.87 seeds); GGRBTE (25.53 seeds); LGRV (42.4 seeds) and GGRTE (52.2 seeds) collections. However, the NJBPRNV collection requires special attention in varietal creation, given its greater resistance to the fungal diseases identified.

Assessing the Tolerance of Cocoa (Theobroma cacao L.) Progenies to the Black Pod Disease Caused by Phytophthora megakarya Bras. and Griff.

The cocoa (Theobroma cacao L.) is a cash crop of great economic importance to some cocoa-growing countries. However, diseases and pests, including black pod disease caused by Phytophthora megakarya, can cause yield losses of up to 100% if no phytosanitary treatment is applied. Thus, the aim of the present study is to evaluate the tolerance of five cocoa hybrids developed by IRAD (PA107*SNK614, IMC67*SNK109, SCA12*SNK16, IMC67*SNK64 and T79/501*SNK64) against black pod disease in relation to the parent clones. Mature pods (approximately 5 months old) were harvested and used to assess black pod tolerance using the Iwaro Detached Pod Test (DPT-SM). Means were separated using the general linear model (GLM) and ranked using the Student Newman-Keuls multiple comparison test (SNK). ANOVA showed a significant difference at P=0.01 on tolerance between hybrids and P=0.001 on tolerance between hybrids and clonal groups. 40% of the hybrids tested were more tolerant than all the clonal groups. The IMC clonal group was the most tolerant of the six clonal groups tested and ranked third overall between hybrids and clonal groups tested. Although the tolerance score varied between hybrids of clones PA107*SNK614 was the most tolerant (0.79) and T75/501*SNK 64 being least tolerant (2.00), all of these hybrids of clones possesses real potential to the tolerant to the black pod disease.

Perception of Environmental Risks of Phytosanitary Products in the Market Gardening in Douvar Municipality of Mokolo (Far North Region of Cameroon)

Peri-urban market gardening plays an important role in the supply of fresh vegetables in the town of Mokolo (Far North, Cameroon) and its surroundings. This activity is concentrated around the dam supplying drinking water to the Mokolo city. To fight against pests and increase their yield, market gardeners’ resort to pesticides, with the risks they often ignore. The objective of this study is to assess the perception of risks and effects linked to the use of plant protection products on human health and the environment in particular. The study was made through a survey and was carried out among 88 market gardeners using survey sheets. The results obtained show that in the locality of Douvar, market gardening is more practiced by young people under 35 years old. They also use plant protection products which are dangerous for human health and the environment. Market gardeners use 13 different types of pesticides with a dominance of insecticides (60.92%). The survey also showed that 100% of farmers agree that the use of pesticides leads to good yields and also eradicated insects and disease. However, the decision to carry out phytosanitary treatments and the timing of treatment are often conditioned by the availability of the product and the presence of the attack. The majority of market gardeners (83%) are not educated and therefore do not have a good knowledge on the application rates and the frequencies of treatment of crops.