Plant Disease

This paper deals with the effects of agronomic practices on parasite life cycles, and the design of integrated crop protection strategies. Cropping systems have a large effect on the size of the primary inoculum and its localisation, on the development and spread of epidemics, and on the coordination of the life cycle of cultivated plants and that of their parasites. They can disrupt ecological equilibria, either favouring or disfavouring the pathogens. By combining information concerning the effects of agricultural techniques on diseases and the physiological effects of diseases on growth and crop production, it is now possible to develop new crop management systems, in which the use of non-chemical methods for preventing diseases is a priority. However, the current knowledge need to be completed by studies on other scales, particularly of the effect of cropping systems on the genetics of disease populations integrating more completely the 'long-term' dimension of sustainable agriculture. To cite this article:

Sweet corn, silage and grain crops have been facing the threat of severe corn disease for many years, spreading to various parts of Israel. Over the past few years, we conducted a series of field experiments, with the assistance of Netafim Israel, growers' associations and farmers from the Galilee region. In 2017-2018, this research led to a historic breakthrough: for the first time, 60 years since its discovery, an economically feasible solution was found for late wilt disease of corn in Israel. The successful treatment protocol is based on changing the cultivation method, changing the traditional irrigation method used in most corn growing areas in Israel, and the sophisticated integration of pesticide mixtures in a schedule adapted to key points in the development of the disease. This method can now be widely applied in commercial fields for the protection of sensitive corn varieties.

Late wilt disease in corn is caused by the fungus Harpophora maydis, which is found in the soil and seeds. It penetrates the plant and blocks the water supply to its upper parts. The disease, considered to be the most severe corn disease in our region, was first discovered in Egypt in 1960, where it still persists and causes serious damage. The disease is now reported in 11 countries. In Israel, it has existed for 40 years in the Upper Galilee, especially in the Hula Valley, and in the past decade, has spread to the south of the country. In heavily contaminated fields and in sensitive maize cultivars, the pathogen can cause 100% infection and total yield loss. The disease is characterized by a rapid wilt of the corn plant, which usually occurs two to three weeks before harvesting. In the past, attempts had been made to control the pathogen using different methods, including agricultural (balanced soil fertility and flood fallowing), chemical, biological, physical (solar heating) and plant compounds. Despite the potential of some of these methods, the only means applied in Israel to date to restrict the disease is the use of resistant corn varieties. However, in Egypt and Spain, virulent pathogen strains that threaten resistant maize cultivars have been found.

The research team led by Dr. Ofir Degani from Migal – The Galilee Research Institute and Tel-Hai College, funded and supported by Netafim Israel, the Extension Service of the Israel Ministry of Agriculture and Rural Development, and growers' associations, has recently led to a breakthrough development of historical significance. For the first time, 60 years since the discovery of the late wilt disease, an efficient and economically feasible solution has been found that can be used on a large scale to protect sensitive corn varieties in commercial fields.

This solution, published in December 2018 in the leading scientific journal PloS ONE, saves about 40% of irrigation costs and combines antifungal mixtures with different mechanisms to prevent resistance development. The new application was tested in field trials in 2017-2018 and included the injection to the irrigation system of  the substances Difenoconazole + Azoxystrobin (of which the commercial name is 'Ortiva-Top', manufactured by Syngenta, Basel ,Switzerland, supplied by Adama Makhteshim, Airport City, Israel), at intervals of 15, 30 and 45 days from sowing, or other fungicide mixtures. Savings in the deployment of irrigation lines was acquired by using a dripline for two adjacent rows (a row spacing of 50 cm instead of 96 cm), a row space that maintains the effective concentration of the fungicide in the soil. A recently developed real-time PCR-based molecular detection system showed that following the treatment of 'Ortiva-Top', the amount of pathogen DNA in the host tissue decreased to near zero levels. The successful treatments using 'Ortiva-Top' resulted in a 100% decrease in dehydration symptoms and a 100% increase in crop yield, together with an approximately 40% increase in crop quality (the yield classified as A class that had a cob weight exceeding 250 g). These results were also obtained in an alternative protocol– the replacement of pesticides based on 'Ortiva-Top' in the first application and the application of pesticides harboring a different mechanism of action in the second and third applications. A remote sensing evaluation of the efficacy of the treatments using a quadcopter equipped with a thermal infra-red sensitive camera carried out by Dr. Assaf Chen’s research team (Migal - Galilee Research Institute) supported the results and showed its effectiveness as a research tool for diagnosing infected fields.

These results are the fruits of a decade of research (since 2008), in which a fundamental understanding of the pathogen H. maydis and the generation and development of late wilt disease in Israel was established. During this period, new research methods such as sensitive molecular tests (PCR and qPCR) were developed in order to diagnose fungal virulence and in order to detect the pathogen inside the host plant tissue. In addition, a link was found to plant hormones that regulate the development of the pathogen. Complex field trials that were carried out annually over a full growing season (about 80 days) since 2009 led to this important discovery.
However, the work on late wilt disease does not end here. In the past two years, Dr. Degani's research team identified the presence of H. maydis in secondary hosts, such as cotton, watermelon and green foxtail (Setaria viridis), which could support the survival of the pathogen, developed an environmentally friendly biological control method to control the pathogen, and established a new bio-assay for examining soils suspected of being infected with the pathogen. These new findings, which are currently in the process of being prepared for scientific publication, are encouraging the continuation and enhancement of the research.

The plant disease Apple Scab, caused by the ascomycete fungus Venturia inaequalis (Cke.) Wint. (anamorph Spilocea pomi Fr.), is the single most important disease of cultivated apple (Malus domestica Borkh.) worldwide. Severe apple crop losses can result when appropriate control measures are not taken, especially when the spring and early summer seasons are moist and cool. The fungal pathogen has a pronounced low temperature requirement for the initiation of the sexual or pseudothecial stage. In temperate apple growing regions of the world, this temperature requirement is met only after leaf fall, on the orchard floor, where, in winter months, low temperatures trigger the development of pseudothecia. In the spring, overwintered pseudothecia time their production of ascospores to precisely coincide with the emergence of new leaves, thus initiating a new cycle of disease.

Curly top disease is caused by a complex of curtoviruses (family Geminiviridae), and it continues to plague tomato production in California. To better understand the etiology of curly top of tomatoes in California, polymerase chain reaction (PCR)-based methods were developed and used to characterize the curtoviruses involved, and to monitor for these viruses in the beet leafhopper vector, Circulifer tenellus. From 2002 to 2008, 86 processing and fresh market tomato fields in the Central Valley of California were surveyed for the incidence of curly top symptoms. Representative samples with curly top symptoms were collected from the surveyed fields, as well as from another 24 fields. The incidence of curly top symptoms in most fields ranged from trace (<1%) to low (1 to 5%); however, in 2002, 2003, and 2008, some fields had medium (5 to 20%) or high (>20%) incidences. PCR with general and species-specific primers was used to establish that the predominant species associated with...

The relationship between moisture content and carpogenic germination (CG) of Sclerotinia sclerotiorum sclerotia and the dynamics of sclerotial water imbibition were studied in a controlled environment. The study was conducted using laboratory-produced sclerotia from seven S. sclerotiorum isolates. The quantity and rate of water imbibition by three sizes of sclerotia was determined gravimetrically in silty clay, sandy loam, and sandy soils maintained at 100, 75, 50, and 25% of soil saturation and in distilled water. Smaller sclerotia imbibed water at a significantly faster rate (P = 0.05) than larger sclerotia in water and in soil at all saturation percentages. When buried in soil, small, medium, and large sclerotia were fully saturated within 5, 15, and 25 h, respectively, in all three soil types and moisture percentages. The effect of sclerotia moisture content on CG was evaluated on sclerotia maintained at 95 to 100, 70 to 80, 40 to 50, and 20 to 30% of their water saturation capa...

Genetics of resistance in chickpea accession WR-315 to Fusarium wilt was investigated, and a concise set of differentials was developed to identify races of Fusarium oxysporum f. sp. ciceris. A population of 100 F 7 recombinant inbred lines (RILs) from a cross of WR-315 (resistant) and C-104 (susceptible) was used to study genetics of resistance to races 1A, 2, 3, 4, and 5 of F. oxysporum f. sp. ciceris, and a population of 26 F 2 plants from a cross between the same two parents was used to study inheritance of resistance to race 2. Segregations of the RILs for resistance to each of the five races suggest that single genes in WR-315 govern resistance to each of the five races. A 1:3 resistant to susceptible ratio in the F 2 population indicated that resistance in WR-315 to race 2 was governed by a single recessive gene. A race-specific slow disease progress reaction was observed in chickpea line FLIP84-92C(3) to infection by race 2, a phenomenon termed as slow wilting, that is different from previously reported late wilting with respect to latent period, disease progress rate, and final disease rating. Twenty-nine germ plasm lines (27 Cicer arietinum and two C. reticulatum) including previously used differentials were evaluated for their reactions to infection by the five races. Only eight of the 29 germ plasm lines differentiated at least one of the five races based on either resistant or susceptible reactions, whereas the remaining germ plasm lines were either susceptible or resistant to all five races or differentiated them by intermediate reactions. A concise set of eight chickpea lines comprised of four genotypes and four F 7 RILs with vertical resistance was developed as differentials for race identification in F. oxysporum f. sp. ciceris. These differential lines were characterized by early appearance of wilt symptoms, and clear and consistent disease phenotypes based on no wilt or 100% wilt incidence, which offers important improvements over previously available differential sets and provides more precise and unambiguous identification of the races.

Plant breeders have used disease resistance genes (R genes) to control plant disease since the turn of the century. Molecular cloning of R genes that enable plants to resist a diverse range of pathogens has revealed that the proteins encoded by these genes have several features in common. These findings suggest that plants may have evolved common signal transduction mechanisms for the expression of resistance to a wide range of unrelated pathogens. Characterization of the molecular signals involved in pathogen recognition and of the molecular events that specify the expression of resistance may lead to novel strategies for plant disease control.

Botrytis cinerea isolates from flowers and berries of Vitis vinifera 'Thompson seedless' (grapevine) were characterized in terms of two transposable elements (TEs) Boty and Flipper, random amplified polymorphic DNA (RAPD), infection levels, and resistance to iprodione. The isolates were collected from grapevines under fungicide programs of variable numbers of iprodione applications, and replicated in three Chilean Central Valley locations. Recovery was repeated from clusters collected at four phenological stages. Highest infection levels were found at bloom. Fungicide programs including one iprodione application or a combination of other fungicides were most effective for reducing gray mold symptoms. A total of 457 isolates collected from fungicide programs including only one iprodione application, and the control program, were tested for the presence of TEs. In all locations and during all phenological stages, transposa isolates (containing both TEs) were most common, followed by Boty. Vacuma isolates (containing neither TE) were identified at very low levels in two locations and only in the control treatment, and isolates with only Flipper were not detected at any time or location. Vacuma and Boty isolates were all sensitive to iprodione, while transposa isolates showed a wide range of resistance. Based on response to iprodione, the presence of TEs, and presence of vegetative-incompatibility alleles (Bc-hch), the isolates studied belong to B. cinerea Group II, a phylogenetic species within B. cinerea. Hierarchical analysis of molecular variance and genetic diversity analyses of the RAPD genotypes showed a genetic differentiation linked to location, but it was not related to geographic distance. Moreover, a genetic differentiation related to the phenological stage of grapes was also detected.

Chemical control of prune leaf rust (Tranzschelia dextrose agar (APDA) amended with 5, discolor f. sp. domesticae) in California. Plant Disease 70: 307-309. 10, or 15 .tg a.i./ml of WS or mancozeb. The fungicides and the acid (2.5 ml of The effects of wettable sulfur (WS), mancozeb, and timing of mancozeb applications in controlling 25% lactic acid per liter) were added to prune rust (Tranzschelia discolor f. sp. domesticae) of French prunes were evaluated. In an the medium after autoclaving the agar, experimental plot of prunes, unsprayed trees had 44% and WS-and mancozeb-sprayed trees had 21 and urediniospore germination was and < 1% rusted leaves, respectively. In vitro urediniospore germination on acidified potatorecorded after 22-24 hr of incubation at dextrose agar amended with5, 10, or 15pga.i./mlofWS ormancozeb was reduced ll,33,and38% 18 C. Data were analyzed by a two-way with WS and 97, 97, and 97% with mancozeb. Results of three mancozeb sprays (in June, July, and August 1983) proved that the last application alone was sufficient for controlling prune rust. Factorinalysis fuvaice (ANO a). Sprayed trees had fewer infected leaves and also fewer rust pustules per leaf. On unsprayed trees, Factors included fungicide tested and most of the infected leaves had > 16 pustules per leaf. In a commercial prune orchard already rate of fungicide. infected by rust, two mancozeb sprays (in July and August) protected the sprayed trees for 3 mo 1983 Experiments. To determine the from further rust infections, whereas 100% of the leaves on unsprayed trees were infected, appropriate number and timing of mancozeb applications, prune trees at the Davis campus plot were sprayed with Prune leaf rust, caused by the fungus rust, prune trees (Prunus domestica L.) in mancozeb at a concentration of 5,378 g Tranzschelia discolor (Fuckel) Tranzschel the experimental plot of the Department a.i./ha on the following schedule: one & Litvinov f. sp. domesticae (1), is widely of Plant Pathology at University of spray (20 June), one spray (27 July), one distributed in California and may be a California, Davis, were sprayed with a spray (19 August), two sprays (20 June serious problem in certain years (2,4,8). handgun sprayer on 15 August, 23 and 27 July), two sprays (20 June and 19 During early stages of infection, September, and 19 October of 1981 and August), two sprays (27 July and 19 symptoms of the disease are distinct, 1982. The dosages used were 20,167 and August), and three sprays (20 June, 27 angular, yellow-orange lesions on the top 5,378 g a.i./ha for WS and mancozeb, July, and 19 August). The test plot was a surfaces of leaves that correspond to light respectively. The experimental layout completely randomized block design with brown to reddish pustules on the lower was a completely randomized block design six single-tree replicates in each treatment. surfaces (6). These are the uredinia (sori) with eight single-tree replicates. Evalu-Disease incidence was evaluated 3 wk of the fungus that produce urediniospores ation of disease incidence was made dur-after the appearance of first rust during summer and teliospores later ing the first week in November (about 3 symptoms, using 100 leaves collected at during summer and fall. wk after the incidence of first rust symprandom from each tree. Symptoms were When extensive, the disease causes toms) by collecting randomly 400 leaves classified into four disease severity premature defoliation of the prune trees per tree (100 leaves per tree quadrant). categories according to the number of (6-8). Defoliation not only creates Urediniospore germination tests. pustules per leaf, as shown in Table I. difficulties in mechanical harvest opera-Because urediniospores are the infective ANOVA and mean calculations were tions (3) but also reduces the vigor of the stage of the fungus (6,8), to explain conducted with the Statistical Analysis trees. To avoid early defoliation of the results obtained in the field, we tested the Program (SAS) (5) and mean comparisons trees, chemical control of the disease is effects of WS and mancozeb on with orthogonal contrasts. required. Wettable sulfur (WS) is the only urediniospore germination. Uredinio-To evaluate the efficacy of mancozeb fungicide registered in the United States spores from rust pustules on leaves were when the disease was already present, an

During spring 2009, lavender plants (Lavandula stoechas L.) showing a bright yellow mosaic of calico type and light stunting were observed in a commercial nursery in Liguria Province in northern Italy. Of 300 plants inspected, ~2% were symptomatic. Preliminary observations of leaf sap with the transmission electron microscope revealed bacilliform virus-like particles in three symptomatic plants, whereas no virus-like particles were observed in asymptomatic plants. The same symptomatic plants were tested by double-antibody sandwich-ELISA with polyclonal antisera against Cucumber mosaic virus, Potato virus Y, Tobacco mosaic virus, and Alfalfa mosaic virus (AMV). All three plants reacted positively against AMV antibodies, but not the other antibodies. A crude sap extract obtained from a single symptomatic plant, hereafter referred to as the Lst isolate, was prepared by macerating 1 g of fresh leaves in 4 ml of sodium phosphate 0.03 M, containing 0.2% sodium diethyldithiocarbamate, 75 m...

Aim: The aim was to assess the incidence, severity and symptoms of the leaf blight of taro. Methodology: A survey of 50 taro fields was conducted during the major cropping season of 2015 in 11 districts of the semi deciduous forest zone of Ghana. Disease incidence and severity were calculated and samples collected. Isolation, morphological identification and Koch's postulate of the associated pathogen was carried out at the Plant Pathology Laboratory of the CSIR-Crops Research Institute, Kumasi, Ghana. Results: Phytophthora colocasiae Raciborski, was identified as the causal pathogen of the leaf Original Research Article Adomako et al.; AJEA, 11(4): 1-7, 2016; Article no.AJEA.23806 2 blight disease attacking taro. The study revealed a high incidence and severity of the disease across all locations surveyed. Incidence ranged from 30% in the East Akim District to 92.5% in the Tano South district whilst severity ranged from 6.5% to 86.5% in the East Akim and Tano North districts respectively. Disease incidence and severity was significantly different (P < 0.05) across the districts surveyed. Symptoms of the disease included multiple circular spots on the leave surface, white mycelia on lesion surface; shot holes on affected parts and water soak beneath the developed spots. Conclusion: The current study revealed a high incidence and severity of the disease in the surveyed districts and has laid the foundation for extensive studies on the epidemiology of the disease in Ghana and the need to develop management strategies to reduce its impact.

Tomato plants can be infected by several diseases, among them, the early blight disease, caused by the necro-trophic fungus Alternaria solani is very dangerous. Plant growth promoting rhizobacteria (PGPR) are enhanced the plant growth and suppress plant diseases. The current study was conducted in a pot experiment to investigate the bio-efficacy antagonistic bacterial isolates as either individual or combination against tomato early blight disease. Disease severity and protection percent, morphological indicators as well as yield characters were recorded. In vitro antagonistic activity assay of PGPR against A. solani was estimated. Metabolic indicators of resistance in plant as response to induction of systemic resistance (ISR) were recorded. Our results indicated that, PGPR isolates were reduced the percent disease severity by 13.0 % and recorded highly protection percent by 84.3 %. The beneficial effects of the used elicitors were extended to increase not only the morphological characters (shoot lengths, root lengths and leaflet number/plant) but also the yield characters. All tested elicitors caused the marked significant increases in the photosynthetic pigments. PGPR isolates were exhibited the most potent effect in terms of the contents of chlorophyll a, b and the total chlorophyll (a + b) followed by plants treated with A. xylosoxidans (A3), B. subtilis (B1) and L. fusiformis (L2) in the infected plants, compared to the non-treated infected control. PGPR isolates were increased total phenol (56.15 mg/100 g dry wt.), free proline (1.435 mg/g dry wt.), total protein (1.198 mg/g dry wt.) and the activities of peroxidase (0.705 μg/100 g fresh wt.) and polyphenol oxidase (1.281 μg/100 g fresh wt.). All the tested treatments resulted in increasing the contents of indole acetic acid (IAA), Abscisic Acid (ABA), Salicylic Acid (SA), and Jasmonic acid (JA) compared with those of the infected plants. PGPR isolates' antifungal activity may be attributed to cell wall disruption of A. solani and the normal conidial development inhibition. Therefore, due to these outstanding properties of PGPR isolates as plant growth promoters and antifungal activity, this study could give insights for solving serious agricultural challenges and particularly in the treatment of A. solani invasion across the tomato plants.

Sesame (Sesamum indicum L.) is one of the oldest oil seed crops known, and its use probably goes back to 2130 BC (WEISS 1983). Almost 100% of the world's sesame area is found in the developing countries (ASHRI 1998). In Egypt, sesame is grown in many governorates, where it is ranked as the first among the cultivated oil crops in Ismailia Governorate (ANONYMOUS 2005). Wherever sesame is grown it is liable to be attacked by at least eight economically important fungal diseases (KOLTE 1985) and by 65 species of insects at different stages of its growth (AHUJA & BKHETIA 1995), causing considerable yield losses. Fusarium wilt disease (FOS), caused by Fusarium oxysporum f.sp. sesami, is a serious disease in Egypt that limits production of sesame. It was reported for the first time from North America in 1950 (ARMSTRONG & ARMSTRONG 1950). In our Zone, there is considerable variability of the sesame germplasm in reaction toward Fusarium (EL-BRAMAWY 1997, 2003; EL-SHAZLY et al. 1999; EL-BRAMAWY et al. 2001; AMMAR et al. 2004). The pathogen survives as chlamydospores in the soil, and due to its soilborne nature, practically no field control is available

Lima beans are an important crop in Delaware and the Mid-Atlantic Region. In the summer of 2000, five commercial cultivars (3-28, 184-85, C-elite Sel, Butter Bean, and Jackson Wonder) of lima bean in Delaware, Maryland, and New Jersey were observed with white, appressed mycelia on infected pods that appeared distinctly different from signs of downy mildew infection caused by Phytophthora phaseoli. Isolations were made by placing diseased pods between layers of rye media (1). A fungus that produced white mycelia with sporangia was consistently isolated. All Phytophthora isolates from the infected pods were heterothallic, grew at 35°C, had as much as 100 µm long pedicles on varying shapes of caducous sporangia with tapering base and >2 papillae, and were identified as P. capsici (2). Initially, three surface-disinfected pods from cv. Early Thorogreen plants grown in the greenhouse were floated on 20 ml of sterile water in a petri dish, and each was inoculated with a disk of P. capsici. This was repeated for nine isolates obtained from lima bean. After incubation for 7 days at room temperature, all 27 pods were infected, and P. capsici was reisolated from all the pods. A pathogenicity test was performed on the same cultivars from which the original field isolates were collected. Three seedlings and two plants with mature pods were inoculated with a sporangial suspension of each of the nine isolates and placed in a dew chamber for 5 days at 20 to 25°C and 100% relative humidity. White mycelial growth was observed on seedlings and mature pods. One inoculated plant developed brown-to-black stem lesions with white mycelia. All pods on the mature plants showed appressed, white mycelia identical to that observed in the commercial lima bean fields. P. capsici was consistently reisolated from all inoculated plants. In 2000, most infected pods in infested fields were observed low in the plant canopy or touching the soil. However, in 2001, infected pods were mostly in the lower and mid-portion of the plants observed in baby lima bean fields in Kent County, DE.

Ramularia collo-cygni is the biotic factor responsible for the disease
Ramularia leaf spot (RLS) of barley (Hordeum vulgare). Despite
having been described over 100 years ago and being considered a minor
disease in some countries, the fungus is attracting interest in the
scientific community as a result of the increasing number of recorded
economically damaging disease epidemics. New reports of disease
spread and fungal identification using molecular diagnostics have
helped redefine RLS as a global disease. This review describes recent
developments in our understanding of the biology and epidemiology of
the fungus, outlines advances made in the field of the genetics of both
the fungus and host, and summarizes the control strategies currently
available.

Maize is a staple food crop which plays a great role in food security in Ethiopia. It is affected by many diseases which reduces yield. Mycotoxin contamination of maize grain (Zea Mays L.) is a global threat to safety both for human food and animal feed. Mycotoxins are secondary metabolites produced by fungi, which may be toxic or have other debilitating effects on living organisms. The major control methods are use of relative resistant or tolerant varieties mean that varieties with tight husk coverage, harvest on the time, proper storage and good crop management. An experiment conducted on experimental field of Jinka Agricultural Research Center to evaluate 12 improved maize varieties and one local check using Randomized Complete Block Design with three replications. The objective of the study was to select maize variety /varieties resistant/tolerant to ear rot. The variety BH660 and BH540 was highly resistant compare to the other tested varieties with the incidence of 19.00% and 14.66% and a grain yield of 3.70kg/plot and 3.79kg/plot respectively. The varieties BH543, Melkassa7 and BH661 were susceptible with the incidence of 64.00%, 50.13%, and 64.33% and their grain yields were of 3.37kg/plot,2.62kg/plot and 3.62kg/plot respectively. On the other hand BHQPY545 and local check were susceptible to ear rot but their yields were 4.05kg/plot and 3.84kg/plot respectively. This indicates that the local check and BHQPY545 were able to tolerate high disease pressure. Therefore, the variety BHQPY545 is recommended for mid land maize production areas of South Omo zone.

The main theme of the book is sustainable disease management in a European context. Some of the questions addressed are: How does society benefit from plant pathology research? How can new molecular approaches solve relevant problems in disease management? What other fields can we exploit in plant pathology research? What challenges are associated with free trade across the new borders? How can we contribute to solving problems of developing countries? How does plant pathology contribute to food quality and safety? How does globalisation/internationalisation affect teaching and extension in plant pathology?

. Control of postharvest blue and green molds of oranges by hot water, sodium carbonate, and sodium bicarbonate. Plant Dis. 85:371-376. Control of citrus blue mold, caused by Penicillium italicum, was evaluated on artificially inoculated oranges immersed in water at up to 75°C for 150 s; in 2 to 4% sodium carbonate (wt/vol) at 20 or 45°C for 60 or 150 s; or in 1 to 4% sodium bicarbonate at room temperature for 150 s, followed by storage at 20°C for 7 days. Hot water controlled blue mold at 50 to 55°C, temperatures near those that injured fruit, and its effectiveness declined after 14 days of storage. Sodium carbonate and sodium bicarbonate were superior to hot water. Temperature of sodium carbonate solutions influenced effectiveness more than concentration or immersion period. Sodium carbonate applied for 150 s at 45°C at 3 or 4% reduced decay more than 90%. Sodium bicarbonate applied at room temperature at 2 to 4% reduced blue mold by more than 50%, while 1% was ineffective. In another set of experiments, treatments of sodium bicarbonate at room temperature, sodium carbonate at 45°C, and hot water at 45°C reduced blue mold incidence on artificially inoculated oranges to 6, 14, and 27%, respectively, after 3 weeks of storage at 3°C. These treatments reduced green mold incidence to 6, 1, and 12%, respectively, while incidence among controls of both molds was about 100%. When reexamined 5 weeks later, the effectiveness of all, particularly hot water, declined. In conclusion, efficacy of hot water, sodium carbonate, and sodium bicarbonate treatments against blue mold compared to that against green mold was similar after storage at 20°C but proved inferior during long-term cold storage.

The efficacy of biofumigation with Brassica carinata pellets (BioFence) to control vegetative and reproductive structures of Phytophthora cinnamomi was investigated in vitro at different doses and temperatures. Biofumigation was effective in inhibiting mycelial growth (culture diameter) and chlamydospore and zoospore germination, and was lethal at 24 mg of pellet per plate (approximately 0.4 mg/liter). The 50% effective concentration values showed that efficacy of B. carinata pellets in inhibiting or killing the vegetative and reproductive structures of P. cinnamomi was maximum at 15°C and decreased as temperature rose to 25°C. However, the fungicide effect was independent of the temperature. In vivo biofumigation of Quercus cerris seedlings with BioFence confirmed efficacy by reducing the inoculum density (CFU/g) of P. cinnamomi, thus protecting the host from root infection. The use of BioFence provides an alternative to synthetic pesticides to control P. cinnamomi within disease m...

Abstract: Wilt is an important disease of brinjal crop causing significant reduction in yield. In present study, the pathogenic fungus was isolated from infected plant parts and identified based on morphological and cultural characters as Fusarium solani f. sp. melongenae. ...

Aberrant phenotypes of cauliflower were detected throughout the cultivation period and in any variety type. The rate of these phenotypes in the field has recently increased. We reported previously on the first part of our results which showed that (1) the rate of aberrant plants varied with genotype and cultivation area, (2) the aberrant phenotypes can evolve or reverse to normality during the plant cycle and (3) the capacity to express a variant phenotype can be transmitted to the progeny. An epigenetic hypothesis has been proposed to explain the determinism of the phenomenon. Further investigation on the ''aberrant'' character focussed on the flow cytometric estimation of ploidy levels and on the parallel observation of meiosis. Only a fraction of aberrant plants did show aneuploidy and various ploïdy levels were found for the same phenotype. Indeed, aneuploidy could not be related to the aberrant phenotype although it could probably be a consequence of the aberration phenomenon. HPLC analysis of global DNA methylation rates showed that DNA hypermethylation occurred in plants which exhibited an evolution of their phenotype during vegetative cycle. The epigenetic origin of aberrant phenotypes in cauliflower is discussed with reference to epigenetic diseases described in human beings.

The role of initial inoculum (yo), rate (r) of pathogen or disease development (infection), and period of time (t) that the pathogen and host populations interact during the cropping period is revisited in modeling plant disease epidemics. The importance of quantitative informations and the relationship between initial inoculum and the rate of disease development represent key elements for identification of the most useful disease models to be used. For effective Integrated Disease Management of monocyclic or polycyclic epidemics, temporal population growth models of plant disease epidemics (monomolecular, exponential, logistic and Gompertz population models) are presented. Sanitation and disease management principles (exclusion, avoidance, eradication, protection, resistance and therapy) are described. Finally, the integration of IPM practices, at the disease components level, with Lieberg’s Law of the Minimum is discussed.

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The use of deep learning models to identify lessions on cotton leaves on the basis of images of the crop in the field is proposed in this article. Its cultivation in tropical regions has made it the target of a wide spectrum of agricultural pests and diseases, and efficient solutions are required. Moreover, the symptoms of the main pests and diseases cannot be differentiated in the initial stages, and the correct identification of a lesion can be difficult for the producer. To help resolve the problem, the present research provides a solution based on deep learning in the screening of cotton leaves which makes it possible to monitor the health of the cotton crop and make better decisions for its management. For this approach, Automatic classifier CNN will be used for classification based on learning with some training samples of that two categories. Finally the simulated result shows that used network classifier provides minimum error during training and better accuracy in classification.

Since the introduction and subsequent naturalisation of five species of Berberis into New Zealand, two species, B. glaucocarpa and B. darwinii have become aggressive invaders of both agricultural and native ecosystems throughout many regions. Both are now targets for a biological control program. A survey for pathogens to be used as potential classical or inundative biocontrol agents was initiated on weed infestations in New Zealand. Five species of primary plant pathogens were found to be associated with systemic leaf, flower and/or fruit disease symptoms, Colletotrichum gloeosporioides, C. acutatum, Pestalotiopsis sp., Phomopsis sp., and Sclerotinia sclerotiorum. The aecial stage of a barberry rust, Puccinia graminis, was recorded from the flowers of B. glaucocarpa, which is a new host record for New Zealand.

... Francis P. Wong and Wayne F. Wilcox, Department of Plant Pathology, Cornell University, New York Agricultural Experiment Station, Geneva, NY 14456 Plasmopara viticola (Berk. &amp;amp;amp; Curt.) Berl. &amp;amp;amp; Toni., the causal agent of grape-vine downy mildew, is a highly destructive ...

Agricultural drones are one of the important innovations for increasing productivity of the crops in Indian agriculture field. The monitoring of the crops and the need for spraying pesticides and fertilizers at the correct moment and at the exact location of plants is an important parameter to increase the productivity of the crops. Unmanned Aerial Vehicle (UAV) can be used in agricultural sectors which will reduce the time and the hazardous effects that can cause due to the spraying of pesticides and fertilizers. This paper reviews briefly the implementation of UAVs for crop monitoring and pesticide spraying.

Deep Learning becomes the most accurate and precise paradigms for the detection of plant disease. Leaves of Infected crops are collected and labelled according to the disease. Processing of image is performed along with pixel-wise operations to enhance the image information. It is followed with feature extraction, segmentation and the classification of patterns of captured leaves in order to identify plant leaf diseases. Four classifier labels are used as Bacterial Spot, Yellow Leaf Curl Virus, Late Blight and Healthy Leaf. The features extracted are fit into the neural network with 20 epochs. Several artificial neural network architectures are implemented with the best performance of 98.59% accuracy in determining the plant disease. This was a great success, demonstrating the feasibility of this approach in the field of Plant Disease Diagnosis and high crop yielding.

Potato (Solanum tuberosum L.) belongs to family Solanaceae of order Solanales. Potato is one of the unique crop grown in the country having high productivity and supplementing food needs. Potato is rich in carbohydrates, proteins, phosphorus, calcium, vitamin C and vitamin A. The vegetable basket is incomplete without this king of vegetables, a sustaining force and a culinary delight. The power of potato is known for
sustaining million of lives by providing nutritious food in the time of war and hunger and also used as staple food in several countries of the world. The world annual production of potato during 2013 was 453.44 million tonnes covering an area of 19.92 million hectare with the productivity of 22.8 tonnes per hectare. Indian contribution to the world’s
production was 45.34 million tonnes from 1.99 million hectare area with average productivity of 22.8 tonnes per hectare (Anonymous, 2013).The high production potential per unit area, high nutritional value and great taste make potato one of the most important food crops in the world.

A new tospovirus isolated from naturally infected tomato plants grown in Nakhon Pathom province (Thailand) was characterized. Infected plants showed symptoms consisting of necrotic spots, necrotic ringspots and stem necrosis. This virus was detected using general antibodies that could recognize watermelon silver mottle virus (WSMoV), capsicum chlorosis virus (CaCV) and melon yellow spot virus (MYSV). However, it did not react with specific monoclonal antibodies (MAbs) to WSMoV and CaCV or a specific MAb to MYSV. The complete nucleotide sequences of S and M RNAs of the virus were determined. They were 3,023 and 4,716 nucleotides in length, respectively, and contained two ORFs in an ambisense arrangement. Sequence analysis indicated that amino acid sequence of the N protein shared 58.2%, 56.0% and 51.8% identity with those of CaCV, WSMoV and MYSV, respectively. The virus was experimentally transmitted by Thrips palmi and Ceratothripoides claratris. Based on our results, we conclude that this tospovirus isolate should be considered a member of a new species. The name tomato necrotic ringspot virus (TNRV) is proposed for this tospovirus.

Bemisia tabaci is an extremely polyphagous pest that causes direct damage and can act as a vector of viral plant diseases. The activity of natural enemies can be exploited by employing proper conservation and augmentation techniques. In addition to use of extant fauna, importation of parasitoids belonging to the genera Encarsia and/or Eretmocerus and of various predators has been successfully employed in greenhouses and out of doors. Biological control practice in greenhouses differs greatly in warmer climates, where interchanges of the pest and its enemies with the outdoor environment are possible, than in cold countries where the crop is more isolated. Recent successes in the biological control of Trialeurodes vaporariorum and B. tabaci in greenhouses and out of doors lead the way to a better understanding of the types of studies necessary for implementing future programs. Although certain natural enemy species have proven effective components in B. tabaci control, there are still unexplored, potentially valuable species in many areas of the world. This paper reviews the identity and biological attributes of known natural enemies, summarizes the studies conducted on them during the last decade, reviews current efforts in biological control of B. tabaci in greenhouse and field crops, and highlights research gaps and directions deserving further development. r Recent evidence suggests that B. tabaci represents a species complex with numerous biotypes and two described cryptic species. The binomial B. tabaci here is used in the broadest sense to include all members of the species complex unless a more specific designation is indicated.