Early and late leafspot diseases are major constraints in peanut production, causing up to 70% yield losses in combined occurrences. Phenotyping has focused mainly on disease incidence and severity with little attention on disease progression and component traits that determine overall resistance. This study distinguished resistant and susceptible genotypes based on disease progression and components of resistance. Ten peanut genotypes were evaluated under natural leafspot pressure at Nyankpala, Ghana, over two cropping seasons. The set included six genotypes derived from crosses between BC3F6 interspecific introgression lines and Spanish peanut genotypes and four released varieties. Disease incidence, severity, lesion number and diameter, and percentage of necrotic area were recorded to compute area under disease progress curve (AUDPC) and residence indices. Results revealed that leafspot disease progressed steadily among susceptible peanut genotypes as compared with the resistant genotypes. Susceptible genotypes exhibited higher lesion number, lesion diameter, and percentage necrotic area, which showed strong positive correlations with AUDPC-ELS, AUDPC-LLS, and AUDPC-DI. L076J had the highest resistance based on components of resistance index, whereas Nkatiesari had the highest level of resistance based on the disease progression index (DPI). Integrating both components into an overall resistance index (ORI) classified Nkatiesari and Sarinut-1 as resistant; L076J, L027B, and L010A1 as moderately resistant; L030, L046, and L104B as susceptible; and Sarinut-2 and Chinese as highly susceptible. These resistant genotypes provide valuable sources for leafspot management and peanut improvement in sub-Saharan Africa.

Abstract Leafspot disease causes up to 70% yield losses in peanut production areas across the globe. One way to curb this menace is to use leafspot resistant peanut ( Arachis hypogaea L.) varieties. In breeding for disease resistance, quantitative characterization of disease dynamics, including initial inoculum ( y 0 ) and apparent infection rate ( r ), is essential for improving disease assessment, resistance evaluation, and the development of future decision‐support systems in agriculture. This study evaluated the performance of commonly used nonlinear models for characterizing leafspot disease incidence (DI) and severity in peanut genotypes. Field‐based time‐series data on leafspot DI, early leafspot (ELS) severity, and late leafspot (LLS) severity were collected on 10 peanut genotypes over two growing seasons. Disease progress was analyzed using both linearized and nonlinear forms of the Gompertz, logistic, monomolecular, and exponential models. Model‐derived parameters revealed clear genotypic differences: resistant genotypes (Nkatiesari, Sarinut‐1) exhibited low y 0 and r , moderately resistant genotypes (L010A1, L027B, L076J) showed intermediate dynamics, and susceptible genotypes (L030, L046, L104B, Chinese, Sarinut‐2) displayed rapid epidemic amplification. The Gompertz and exponential models generally provided the best fit for DI and ELS severity, whereas LLS severity exhibited greater interannual variability, with logistic and monomolecular models performing best in different years. These findings provide a comparative modeling framework to support the quantitative evaluation of crop disease dynamics and highlight the value of nonlinear disease progress models for agricultural disease assessment and resistance evaluation.

A high incidence of brown leaf spot disease was observed on rice foliage during field visits, with no management strategy employed by farmers. To confirm the aetiology for the future development of a management strategy, isolation and identification of the associated fungal pathogen was carried out morphologically and confirmed molecularly through amplification and sequencing of the ITS region. Pathogenicity test on the rice variety 'AGRA' was performed to confirm Koch's postulates. The pathogen was morphologically identified to belong to the genus Bipolaris. A molecular analysis based on the sequencing dataset placed the isolates in the same clade as Bipolaris oryzae. The current results should guide plant protectionists in developing sustainable management strategies to curtail the spread of the disease in the country.

Biosynthetic genes are responsible for antibiotic production by rhizobacterial antagonists.Detection of antibiotic biosynthetic genes of an antagonist is therefore important for the identification of genes and antibiotics responsible for disease suppression.The study was carried out to detect the antibiotic producing genes of eight rhizobacteria responsible for fungal disease suppression.Eight yam (Dioscorea sp.) rhizobacterial isolates which were found to possess antifungal properties against several plant pathogenic fungi and identified as Bacillus species were tested for the presence of genes for biosynthesis of antifungal lipopeptides; bacillomycin D, iturin A, surfactin, fengycin, and aminopolyols, zwettemycin A as possible antibiotic tools for biocontrol using specific primers.The detection of bacillomycin D gene by PCR amplification, gene sequencing, and BLAST analysis, was achieved through the use of the primer pair, BACC1-F/BACC1-R, capable of detecting 875-bp region, iturin A through the use of ITUD1-F/ITUD1-R primer pairs, capable of detecting 647-bp region while primer pair SUR3-F/SUR3-R, capable of detecting 441-bp region was also used for the detection of surfactin.Three separate primer pairs were used for fengycin viz.FEND1-F/FEND1-R, FENA1-F/FENA1-R, and FENB2-F/FENB2-R, capable of detecting 964-bp region corresponding to fengycin D, fengycin A and fengycin B respectively.Zwettermycin A was detected through the use of ZWET-F2/ZWET-R1 primer pairs, capable of detecting 1-kb region.The outcome of the study shows that all the eight rhizobacteria possessed biosynthetic genes for the production of bacillomycin D, iturin A, and surfactin, however, neither the three types of fengycin nor the zwettermycin A were detected.Sequenced data of these antibiotics have been deposited with GenBank and the following accession numbers assigned to bacillomycin D (MW263002-MW263009), iturin A (MW263010-MW263017), and surfactin (MW263018-MW263025).All the eight rhizobacteria tested were found to possess three out of the five biosynthetic genes namely bacillomycin D, iturin A and surfactin.The detection of these biosynthetic genes confirms and justify why these rhizobacteria are potential biocontrol agents of plant pathogens.

Mychorrizae are indigenous soil fungi that are found associated symbiotically with plant root system. They promote growth of the root system by protecting the plant from pathogen attack, acting directly or indirectly as biocontrol agents and offering plant resistance. These group of rhizosphere fungi also benefit from various biosynthetic substances produced by the root of the plant (root exudates). In this chapter, attempt is being made to present a balanced account of the various roles these fungi play in plant protection. This will give our cherish readers the opportunity to appreciate the mycorrhizal fungi as potential biocontrol agents or bioprotectants of soilborne plant pathogens.

This Edited Volume Current and Emerging Challenges in the Diseases of Trees is a collection of reviewed and relevant research chapters, offering a comprehensive overview of recent developments in the field of Life Sciences. The book comprises single chapters authored by various researchers and edited by an expert active in the Agricultural and Biological Sciences research area. All chapters are complete in themselves but united under a common research study topic. This publication aims at providing a thorough overview of the latest research efforts by international authors on Agricultural and Biological Sciences and open new possible research paths for further novel developments.

The issue of food security has gained global significance in both political and social discourse due to a projected worldwide population increase by 2050. A major hindrance to achieving food security is the negative effects of insect pests. Insect pests competes with humans at the highest level for agricultural resources and it is estimated that their activities accounts for between 30–40% losses in food crops globally. For decades, numerous policies aimed at ameliorating the impact of insect pests on crops have been implemented. Prominent among these is the development and use of pesticides. Notwithstanding its effectiveness, this strategy is bereft with serious limitations such as poisoning, environmental pollution and insect pest developing resistance to pesticides. A sure way to defeat the food production challenges in a sustainable manner is to explore the use of new engineering techniques to develop superior crop varieties that are high-yielding, environmentally sustainable, cost-effective to produce and resistant to insect pests. Conventional breeding techniques to achieve this may be limited by time and space, hence the need for modern tools for the development of transgenic crops that are resistant to insects attack; these techniques hasten the process of insect pest control strategies in crop husbandry. The adoption of transgenic plants could reduce the usage of pesticides with broad-spectrum effect, in order to reduce the damages they cause. Since its introduction, transgenic plants have been a main tool for managing several insect pests of economic importance successfully. The adoption of such plants will reduce pesticides use. Despite its benefits, there is limited acceptance of transgenic plants globally. Notwithstanding this, the prospects of integrating transgenic plants in crop production to manage the negative effects of insect pests look promising as the demand for safe food and public involvement in evaluating such materials increases.

Mango is one of the frequently cultivated seasonal fruit crops in several tropical and subtropical regions. It is consumed as whole fruits apart from serving as raw materials for most industries that are into mineral production. Mango production is, however, constrained by diseases, pests, and poor post-harvest handling of fruits. Anthracnose disease, caused by Colletotrichum gloeosporioides Penz and Sacc, is one of the most important yields limiting constraint in mango production across the globe. The disease occurs in both the field and post-harvesting. In the field, it affects aboveground parts, such as the stem, branches, leaves, flowers, and fruits. Anthracnose disease reduces the shelve life and marketability of mango fruit. In Ghana, anthracnose disease is responsible for about 30% yield/fruit loss. Most farmers do not control it, although some have resorted to the application of various fungicides not registered for mango anthracnose disease management in Ghana. This chapter will highlight on the importance of the disease on the mango industry in Ghana, control strategies currently employed thereby reducing the over-reliance on chemical control option and propose ways to minimize the effect of the disease in the country.

Aflatoxin contamination poses serious health concerns to consumers of peanut and peanut products. This study aimed at investigating the response of peanuts to Aspergillus flavus infection and aflatoxin accumulation. Isolates of A. flavus were characterised either as aflatoxigenic or non-aflatoxigenic using multiple cultural techniques. The selected isolates were used in an in vitro seed colonisation (IVSC) experiment on two A. flavus-resistant and susceptible peanut genotypes. Disease incidence, severity, and aflatoxin accumulation were measured. Genotypes differed significantly (p < 0.001) in terms of the incidence and severity of aflatoxigenic and non-aflatoxigenic A. flavus infection with the non-aflatoxigenic isolate having significantly higher incidence and severity values. There was no accumulation of aflatoxins in peanut genotypes inoculated with non-aflatoxigenic isolate, indicating its potential as a biocontrol agent. Inoculations with the aflatoxigenic isolate resulted in the accumulation of aflatoxin B1 and G1 in all the peanut genotypes. Aflatoxin B2 was not detected in ICGV–03401 (resistant genotype), while it was present and higher in Manipinta (susceptible genotype) than L027B (resistant genotype). ICGV–03401 can resist fungal infection and aflatoxin accumulation than L027B and Manipinta. Non-aflatoxigenic isolate detected in this study could further be investigated as a biocontrol agent.

Host plant resistance in sweet potato, under a long-term management approach, is one of the most effective, economical, and environmentally benign management approaches for sweet potato virus diseases (SPVD). In the current study, different sweet potato genotypes were evaluated for resistance to the SPDV and also with higher yield potential under field conditions. The experiment was conducted from July – November 2018 at the University for Development Studies (UDS) experimental field. Thirty-two sweet potato genotypes, including five, already released varieties (also served as checks) were used. The genotypes (treatments) were arranged in a Randomized Complete Block Design (RCBD) with three plications. The results showed that three of the checks (Apomuden, Bohye, Tu-Purple) and PG17207-N1, PG17257-N1, PG17305-and N had significantly higher virus susceptibility levels as compared to the remaining genotypes. Thirteen (13) genotypes showed no visible symptom of the virus, fifteen (15) genotypes were moderately resistant to the disease whiles the remaining four (4) were slightly susceptible to the disease. The results further revealed that PG17584-N1, PG17257-N1 and PG17149-N2 produced the highest root yield while the least was observed for PG17205-N. PG17584-N1, PG17257-N1. Furthermore, PG17149-N2 combines higher root yield with resistance to the SPVD. They can therefore be used as resistant sources for further breeding interventions.

The early and late leaf spot disease (ELS and LLS) caused by the Cercospora arachidicola and Cercosporidium personatum is one of the most important economic diseases in groundnut production. The effect of the disease can lead to up to 70% yield loss under severe conditions. Even though there are an array of management approaches in curbing the menace of the disease, these seem not to be enough to completely control the disease. It is therefore important to develop additional and more improved strategies via the implementation of sustainable approaches. Around the globe, several researches have been conducted on this topic, with most of them leading to prosperous and dynamic outcomes that could lead to a lasting solution to the disease, and hence improving farmers' income. It is therefore important to know what work has been done in order to identify gaps that needs to be filled. The objective of this review is to discuss recent research findings on the management of the leaf spot disease on groundnut. This will include cultural control, chemical control, the use of antagonistic organisms, and host plant resistance. These areas unabatedly continue to be an active research area, and current information on their efficacy will continuously be available. In this review, we have discussed some of the mechanisms involved and also suggested some ways to maximize the outcomes for further interventions.

Ghana’s agricultural economy is largely dominated by the crop subsector with much focus on the production of tree, arable and vegetable crops. Nevertheless, Phytophthora spp. are major threat to the production of these crops contributing significantly to yield reduction. In this review, the main focus will be to look at the threats the pathogen poses to production, economic importance of Phytophthora diseases, highlights some Phytophthora diseases with limited research in the country but have the potential of affecting crop production, management options and the prospect of developing and deploying biological control strategies considered environmentally friendlier and devoid of human health risks to reduce the effect of this pathogen on crop production as well as reducing the dependency on chemical control option.

Rhizobacteria have huge potential for biocontrol activity against many plant pathogens. Isolation and identification are therefore crucial to understand their microbial diversity and ecological importance. The study sought to identify eight yam (Dioscorea sp.) rhizobacterial isolates found to be inhibitory in a previous study to several fungal pathogens, using polyphasic approach (morphological, biochemical, and molecular approaches). Morphological and biochemical characterizations were carried out at the Noguchi Memorial Institute for Medical Research (NMIMR), Legon-Accra, Ghana while the Molecular characterization was done at Functional Biosciences Inc., Wisconsin, USA. Morphological and biochemical characters determined were texture, consistency, the morphology of cell growth on nutrient agar, citrate utilization, catalase reaction, Gram reaction, and endospore formation. Molecular identification was achieved through the amplification and sequencing of the 16SrRNA and gyrB regions of the eight rhizobacterial genomic DNA followed by BLAST analysis. Sequencing data were also deposited at GenBank to obtain accession numbers for the rhizobacteria. All the eight bacterial isolates were shown to possess rod-shaped bacilli cells, Gram-positive, and were endospore producers. The amplification of the 16SrRNA and the gyrB regions of the bacterial DNA and subsequent BLAST of these two regions revealed that they were all members of the Bacillus subtilis group at percentage similarity between 99-100%. Four out of the eight isolates were, Bacillus subtilis, three were B. amyloliquefaciens and the last, B. velezensis. Sequence data of both the 16SrRNA and gyrB deposited at the GenBank provided GenBank accession numbers for nucleotide sequence of 16SrRNA as GenBank MT535846-MT535853 and gyrB as GenBank MT908225-MT908232 respectively. This is the first attempt to identify these rhizobacteria, which have huge potential as fungal antagonists of many plant pathogens in Ghana.

Groundnut is a very important legume that is recognized worldwide for its benefits. It is grown in over 100 countries. The nutritional benefits such as its provision of important vitamins cannot be overemphasized. However, the production, marketing and consumption of groundnut is threatened by mycotoxins with aflatoxin being the major. Aflatoxin is produced by a difficult to control, complex pathogen, spergillus species that contaminate groundnut with this mycotoxin both in the field and during storage especially Aspergillus flavus which is the most common in nature. The response of moisture, temperature and even soil type all influence the proliferation of this pathogen and its subsequent aflatoxin contamination. In view of the many health challenges that this mycotoxin poses to humans and animal, various control measures involving biological, use of resistant groundnut genotypes, chemical strategies and physical separation have been proposed to be a remedy to this global issue. Keywords: Mycotoxin, Aflatoxin, Aspergillus flavus, Health hazards, Groundnut.

The development and application of pesticides such as insecticides, fungicides, herbicides/weedicides, rodenticides, nematicides and other registered and unregistered materials for pests’ control during crop production, have come with their accompanied risks of contamination in the environment. Failure by applicators in following safety protocols associated with pesticide application, handling, storage and disposal leads to contamination and poisoning of water sources, nearby food and feed materials, beneficial animals, applicators themselves and other farm workers. This review considered dangers associated with pesticides contaminations and poisonings, events that lead to pesticides contaminations, common symptoms and disorders of pesticides poisonings, types and classes of pesticides, groups that are vulnerable to pesticides contaminations and poisonings. It also focused on some best alternative measure to employ in order to curb hazards associated with pesticides use. To achieve this, there is a need for proper implementation, strengthen of government’s pesticides regulatory bodies and enforcement of related regulations. Stakeholder fora and intensification of education on pesticides use, handling, storage and disposal for dealers, distributors and the users are required. Also, the production and release of detoxifying agents into industrial drainage systems, water sources that can potentially be contaminated as well as into farmlands and the environment, is necessary to ensure effective management and reductions in the incidences of pesticides contaminations. It is thus, necessary to enforce the much needed precautions and alternative measures required to mitigate global and local cases of pesticide hazards.

Potato plays an important role in food systems and its usefulness cannot be downplayed. However, the production and output of potato have been threatened by Rhizoctonia disease, caused by Rhizoctonia solani. Evidence of the negative effects of this fungal disease of potato is enormous in major potato growing zones in the world, particularly in temperate regions. R. solani produces some phytotoxins, which are detrimental to plants. It poses phytotoxic effects on the potato plants, inducing symptoms on the aerial parts and in extreme cases, on the roots as well. This review presents the overviews on Rhizoctonia disease of potato, disease cycle and its epidemiology. Data on the mycotoxins and various phytotoxins from R. solani and their respective chemical structures are included. It provides information on the mode of actions of the various phytotoxins produced by the R. solani. It also provides detailed information on the different recommended methods for the treatment of potato Rhizoctonia disease. The review seeks to make available, information about the Rhizoctonia disease and its respective pathogen, as a guide to farmers engaged in potato production, for the control of the disease and reduction of yield

Groundnut (Arachis hypogaea L.) is a leguminous crop with high economic and nutritional value. However, increased production is hampered by Cercospora leaf spot (CLS) caused by Cercospora arachidicola and Cercosporidium personatum. Studies were conducted in vitro and in vivo to evaluate the efficacy of aqueous extracts of desert date seed (DDSE), neem seed (NSE), jatropha seed (JSE) and tobacco leaf (TLE) for the management of CLS. The antifungal activities of 25, 50, 75 and 100 g/l concentrations of each of the plant extracts was assessed in vitro on potato dextrose agar using the food poison technique. The field study was a factorial experiment consisting of 18 treatments laid in a Randomised Complete Block Design with four replications over two cropping seasons. The in vitro results revealed that all the botanicals at 100 g/l recorded the highest inhibition percentages. DDSE at 100 g/l significantly (P < 0.001) inhibited the highest mycelia growths compared to other levels of plant extracts used with inhibition percentages of 90.33 and 84.96% in C. arachidicola and C. personatum, respectively. Three out of the four aqueous extracts (DDSE, NSE and JSE) at 100 g/l significantly (P < 0.05) lowered disease incidence, severity and defoliation in the field and increased yield. Pod yield was significantly (P < 0.05) higher in plants treated with JSE, NSE, DDSE and Topsin-M, compared to those treated with TLE and the negative control plants. For most of the parameters, DDSE produced similar results as Topsin-M followed by NSE and JSE. Farmers can adopt DDSE, NSE and JSE as alternatives to fungicides leading to minimal effect on the environment since they are biodegradable. Key words: Cercospora leaf spot, plant extracts, groundnut, incidence, severity, aqueous.