High Disease Intensity Research Articles

Effect of Weather Parameters on Development of Powdery Mildew of Ber (Ziziphus mauritiana) Caused by Oidium erysiphoides

India’s one of the most popular fruits is the ber (Ziziphus mauritiana Lamk.). Ziziphus mauritiana is sometimes referred to as Indian plum or desert apple. Oidium erysiphoides f. sp. Ziziphi, which causes powdery mildew of ber, is more common and a threat in northern states. The white powdery coating on leaves and fruits affects the photosynthesis and growth & development, respectively. This disease results in 50-60% loss in fruit yield and reduces market value of the produce. In the present study, the effect of abiotic environmental elements such as temperature, relative humidity, wind speed, and others were observed and they had a significant impact on the progression of powdery mildew disease. In the study, which was carried out on two ber cultivars viz., Gola and Kaithali, the disease progression on both cultivars showed a significantly negative correlation with maximum (Tmax) and minimum temperature (Tmin) and a significantly positive correlation with morning (RHm) and evening relative humidity (RHe). The favourable weather variables were observed viz., Tmax above 20.3 °C, Tmin around 9.9 °C and RHm was more than 80%. The ber cultivar Gola was more susceptible to disease development than Kaithali, with Gola having the highest disease intensity.

Natural field diagnosis and molecular confirmation of fungal and bacterial watermelon pathogens in Bangladesh: A case study from the Natore and Sylhet districts.

The study investigated watermelon diseases characterized by contrasting climatic conditions in the Sylhet and Natore Districts of Bangladesh. Sylhet experiences lower temperatures and high rainfall, while Natore has higher temperatures and low rainfall. In these survey regions, 40 watermelon fields were selected, and 10 diseases were observed, including 4 fungal, 3 bacterial, 2 water mold, and 1 viral disease. The observed diseases were Anthracnose, Cercospora leaf spot, Fusarium wilt, Gummy stem blight, Downy mildew, Phytophthora fruit rot, Bacterial fruit blotch, Angular leaf spot, Yellow vine, and Watermelon mosaic disease. Molecular analysis was done in the Plant Pathology Lab at Sher-e-Bangla Agricultural University using the specific primers for fungal (ITS1/ITS4) and bacterial (27F/1492R) DNA regions and identified nine pathogen species, excluding the causal organism of the viral disease. The identified pathogens included Colletrotrichum orbiculare, Cercospora citrullina, Fusarium oxysporum, Stagonosporopsis cucurbitacearum, Pseudoperonospora cubensis, Phytophthora capsici, Acidovorax citrulli, Pseudomonas syringae, and Serratia marcescens. The sequencing of the identified pathogens revealed high homology (98.91-99.71%) with known sequences in the GenBank database. Phylogenetic analysis showed six clusters for fungal and water mold pathogen isolates and three for bacterial isolates where the percentages of replicate trees were 100% in all the cases. Among the identified diseases, the highest disease occurrence was caused by Fusarium wilt (47.5%) followed by Gummy stem blight (41.5%) in the Sylhet region and Angular leaf spot (37.5%) followed by Yellow vine (33%) in the Natore area. Fusarium wilt also has a high disease intensity, demonstrating its devastating impact on yield. This study highlights the influence of environmental conditions on disease incidence and underscores the need for tailored management strategies. These findings provide a foundation for developing targeted disease management practices for sustainable watermelon cultivation in Bangladesh.

Evaluation the durable resistance of soybean varieties toward leaf rust caused by Phakopsora pachyrhizi

The main disease of soybean plants is leaf rust caused by the fungus Phakopsora pachyrhizi which can cause a decrease in the yield of up to 60% and has the potential to reduce seed quality. The use of resistant varieties is the main component of rust disease control. The purpose of this research was to determine the resistance level of several soybean varieties to the rust disease caused by Phakopsora pachyrhizi and its effect on the production of each variety. To evaluate the resistance reaction of soybean varieties to rust disease, the IWGSR system was used, as the intensity level of the disease and its effect on the production of each tested soybean variety. The results showed that the Detap 1 variety counted the lowest disease intensity of 22.84% with a susceptible disease reaction and had high productivity, followed by the Agromulyo, Anjasmoro, and Devon 1 varieties which categorized a mildly susceptible disease reaction with a disease intensity of 25.34%, 27.46%, and 28.70% respectively. The Derap 1 and Edamame varieties have a high disease intensity of 35.18% and 29.31% with susceptible disease reactions. The production of the highest number of pods was the Agromulyo variety.

Response of cucumber cultivars to target spot based on epidemiological components of the disease monocycle

AbstractCorynespora cassiicola is the causal agent of target spot of several cultivated species, among which cucumber is highlighted for frequent reports of yield losses under greenhouse conditions. Given the difficulties managing this disease due to the lack of information about the resistance of cucumber cultivars, the aim of the present study was to evaluate the response of ten cucumber cultivars to C. cassiicola based on epidemiological components of the disease in a greenhouse. Symptoms of target spot were apparent in all cucumber cultivars from the second day of inoculation of C. cassiicola, demonstrating the short incubation period of the disease and the susceptibility of the crop. The components latent period, number of lesions, lesion diameter, disease severity, number of sporulating lesions, number of spores per affected leaf area and number of spores per sporulating lesion varied according to the cucumber cultivar. The monomolecular model showed the best fit to the number of target spot lesions during the ten days of evaluation, showing differences between cultivars for initial inoculum and disease progression rate parameters. Multivariate analysis with the epidemiological components combined identified three groups of cultivars: one group that was less affected by the disease, represented by Safira and Diplomata cultivars; a second group showing intermediate behaviour, including Valent, Eureka, Taiko, Yamarashi and Darlington cvs., and a third group that was most susceptible to the pathogen and was represented by Soldier, Vulcano and Exocet cvs. Safira and Diplomata cultivars showed low level of susceptibility to target spot and can be recommended for areas with high disease intensity.

Combining ability of superior cacao clones for assembling high productivity and disease resistant cocoa

This research aimed to determine the potentiality of P1 and P2 as parents to produce superior strains of hybrid cacao by estimating general combining ability (GCA) and specific combining ability from crossed diallel among high yielding parents which are resistant to P. palmivora. The study was conducted at the Experimental Farm Sumber Asin, Malang, East Java, from 2010 to 2018. The research was arranged in Randomized Block Design (RBD) consisted of 10 hybrids and 5 parents so that the treatment used 15 genotypes. Each treatment consisted of 12 plants in triplicates. Resistance test on parents and F1 showed that all crossed combination strains were infected by pod rot disease (P. palmivora) with various intensity. The highest disease intensity was a strain combination of DR 1 x ICS 13 and the lowest one was ICS 13 and SCa 6. All crossed combination strains in the field had not shown symptoms of any pest infection. Cacao clones that have low GCA value based on the disease intensity were TSH 858, ICCRI 3 and SCa 6. These clones have the potential to be used in the assembly of disease-resistant and high-yielding cocoa hybrids in the future.

Abstract 108: Work of Breathing Scale to Assess Need of Intubation in Covid-19 Pneumonia

COVID-19 pneumonia presents in most patients with significant hypoxemia but without substantial impairment of lung compliance that would increase the work of breathing (WOB) to levels requiring invasive mechanical ventilation. Thus, the ability to assess the WOB independent of the oxygen needs could help guide management and possibly avoid intubation. We previously developed and implemented in our ICU a WOB scale based on respiratory physiology ranging from 1 to 7 by assigning points to the respiratory rate level and the use of respiratory accessory muscles. We analyzed the use of our WOB scale in 10 patients admitted to our ICU with severe COVID-19 pneumonia. All patients had radiographic evidence of extensive lung disease with significant hypoxemia and multiple risk factors associated with poor outcome. Hypoxemia was successfully managed using high-flow nasal cannula. The WOB level was measured every 4 hours. The maximum WOB was 4.3 ± 0.9, contributed primarily by the respiratory rate with a score of 3.6 ± 0.5 but with infrequent use of respiratory accessory muscles. All 10 patients survived without need of intubation. For comparison, three other patients who needed intubation had a maximal work of breathing within the preceding 24 hours of 5.3 ± 1.2 with a respiratory rate score of 3.7 ± 0.6, as in non-intubated patients, but with more often use of respiratory accessory muscles. Our data suggest that patients with COVID-19 pneumonia can be supported for extended periods using HFNC despite tachypnea provided there is only infrequent use of respiratory accessory muscles, corresponding to a WOB scale ≤ 4, prompting closer assessment for possible intubation when WOB > 4. This approach would be especially advantageous under conditions of high disease intensity when avoidance of intubation is likely to result in a better outcome.

Management of pearl millet blast through fungicides and biocontrol agents

The in vivo experiment was conducted at Agricultural Research Station, Vizianagaram against pearl millet blast revealed that all the treatments showed significant reduction in blast disease incidence in pearl millet. Among all the treatments T3i.e., foliar application of Pseudomonas fluorescens at 20 DAS and Trifloxystrob in + Tebuconazole at 35 DAS was found effective with least disease intensity of blast (14.1%), highest grain (26.0 q/ha) and fodder yield (60.9 q/ha). While the highest disease intensity (94.8) was noticed in the treatment T6i.e., control with lowest grain (9.3 q/ha) and fodder yiled (26.3 q/ha). The highest cost benefit ratio (2.5) was obtained in treatment T3.

Distribution of maize lethal necrosis epidemics and its association with cropping systems and cultural practices in Ethiopia

Four hundred thirteen fields in five major maize growing regions of Ethiopia were surveyed to determine the prevalence, intensity and distribution of maize lethal necrosis (MLN) disease, and its associations with different maize cropping systems and cultural practices. The disease was most prevalent in South Nation, Nationality and Peoples (SNNP) region with 66.67% prevalence followed by Oromia region that had a prevalence of 65.62%. Similarly, MLN disease intensity and distribution varied among the regions surveyed, cropping systems and cultural practices used by the farmers. The associations of MLN disease intensity with independent variables were analyzed using logistic regression. Region, altitude, cropping season, cropping system, variety, insect vector, planting month and cropping year were significantly associated with high disease intensity of MLN in a multiple variable model. SNNP, Oromia and Benishangul-Gumuz regions, maize cultivated at altitudes of 900–1600 and 1700–2000 m.a.s.l, mono-cropping, presence of insect vectors, medium and high weed density and the 2015, 2016 and 2017 cropping years had a significant association with MLN disease epidemics. This study indicated that MLN disease is a major maize production constraint in Ethiopia. The findings suggested that planting maize at the beginning of the main rainy season, proper weed management and crop rotation practices can minimize the negative impact of the MLN disease until resistant maize genotypes are developed and distributed to the farmers.

The resistance of upland rice doubled haploid lines to blast diseases and brown planthopper

The objective of this study was to determine the resistance of doubled haploid lines of upland rice to leaf blast race 033, 073, 133, 173 and brown planthopper biotype 1, 2 and 3. The experiments were conducted in the Muara greenhouse, Indonesia Center for Rice Research (ICRR), Bogor-West Java Province. All experiments were conducted in the span of October 2017 to April 2018. The materials used in the research were 14 upland rice doubled haploid lines, 2 check varieties namely Inpago 10 and Limboto. Testing the resistance of doubled haploid rice of upland rice to blast disease was coupled with differential varieties i.e Asahan as blast-resistant check variety and Kencana Bali as blast susceptible check variety, while to brown planthopper with differential varieties i.e TN1, Pelita, IR26, IR42, PTB 33 and Rathu Heenati. The experimental design was a randomized complete block design with three replications. Resistance study of doubled haploid lines to leaf blast showed that ST7 and Limboto were resistant to race 033 while ST4, ST7, ST9, ST10, ST12, and Limboto were resistant to race 073. Meanwhile, ST4, ST9, ST10, ST11, ST12, Limboto and Inpago 10 were resistant to race 173. Four doubled haploid lines were moderately resistant to race 133 i.e. ST6, ST12, ST4, and ST14. The highest disease intensity was found in race 133 (52.2%) followed by race 033 (35.9%), race 173 (30.4%) and the lowest in race 073 (28.1%). Based on IRRI method of evaluation, two doubled haploid lines of upland rice i.e. ST1 and ST3 were moderately resistant to the biotypes of brown planthopper.

Screening, selection and real-time qPCR validation for phytoplasma resistance in sesame (Sesamum indicum L.)

Phyllody is one of the most destructive diseases of sesame and causes serious yield losses worldwide. The present research was conducted to identify phyllody resistant genotypes in sesame. A total of 542 sesame genotypes were screened for the disease resistance in the field using a disease incidence scale of 1–5 in the year 2012. Three hundred four genotypes showing high disease intensity were eliminated under artificially infected field conditions. In the year 2013, only 30 out of 238 accessions were determined as potential resistant genotypes based on the disease incidence scale. These selected genotypes were further evaluated for confirmation of the resistance in greenhouse conditions using the phytoplasma-infected vector insects under choice and no-choice conditions. Furthermore, real-time qPCR was employed for detection and quantification of phytoplasmas to select true resistant genotypes. The sesame accessions ACS38 and ACS102 were identified as resistant to the disease after evaluation in field, greenhouse and qPCR assays. This work is one of the most comprehensive studies to select genotypes resistant to the diseases caused by phytoplasmas.

KETAHANAN VARIETAS PADI LOKAL MENTIK WANGI TERHADAP PENYAKIT BLAS

Mentik Wangi, one of the local rice varieties, is highly favored by rice farmers in Central Java. Marketers and consumers highly accept Mentik Wangi with its elliptical seeds because it has delicious taste and aroma. Besides having delicious taste, the variety is resistant to blast disease in various locations, whether planted in lowland or upland. In endemic blast disease areas, Mentik Wangi variety showed resistance to blast disease with low disease intensity, although the other varieties in these places showed quite high disease intensity. Rice blast disease is a disease that damages the rice not only on dry land, but also on rainfed and irrigation lands. At a high level of disease intensity, blast disease can cause yield losses of up to 100%. Planting resistant rice variety to prevent damage due to blast disease is one of the methods to blast disease control which is effective, inexpensive, and safe for the environment. However, control of blast disease with one component such as planting resistant rice is estimated to be ineffective in the long term, because the pathogen causes the blast disease to be able to adapt to the rice variety to form a new race that is more virulent. A rice variety that is originally resistant will gradually become susceptible to the new pathogen race. When the rice varieties which are resistant to blast disease is controlled by a single gene (monogenic resistant), the resistance of these varieties within 2-4 planting seasons will be broken by a new pathogenic race. Mentik Wangi that shows resistance to blast disease in various rice planting regions is expected to have some of the resistance genes, so that it can be used as a durable resistant variety. Keywords: Rice, Mentik Wangi, resistance, blast

Susceptible Phase of Chili Pepper Due to Yellow Leaf Curl Begomovirus Infection

One of factors that affect the severity of plant diseases caused by virus is the time of Begomovirus infection. There is a tendency that the younger the plants are infected, the greater the damage caused by the Begomovirus infection will be. This study aimed to reveal the exact time of Begomovirus infection for the purpose of resistance plant selection and to determine the onset of Begomovirus infection which resulted in the most devastating damage to the plant. The study was conducted in a factorial randomized completely block design with two factors. The first factor was 5 chili pepper genotypes and the second factor was the infection at three phases of the plant with no infection as a control treatment. The results showed that the screening for resistant and susceptible Begomovirus infection on pepper genotypes was very effective when it was done during cotyledon phase/two leaf using individual transmission method. Genotype UNIBC GTS1 was the most susceptible to infection of Begomovirus because it had the highest disease intensity, the fastest incubation period, small plant dry weight and fruit weight per plant. In contrast, genotype IPBC 12 was the most resistant genotypes. It had lower disease intensity and long incubation period. However, despite this resistant characteristic, the weight of fruit per plant of IPBC 12 genotype was not significantly different from the susceptible genotype. Genotype IPBC 14, despite having high disease intensity, could produce the highest fruit weight per plant compared to other genotypes. The infection of Begomovirus on susceptible genotype UNIB C GTS1 at various phases of the plant growth led to the pepper fruit become shorter, lower plant dry weight, smaller numbers of fruits and fruit weight per plant. While the resistant genotypes IPBC 12 had low dry weight when infected by Begomovirus in the phase of cotyledon.

Liming with dolomite reduces the efficacy of the biocontrol fungus Trichoderma koningiopsis against cabbage clubroot

<p><span>Cabbage clubroot<em> </em>is a major constraint for the pro</span><span lang="EN-US">duction of cruciferous species. This research aimed to explore the effect of <em>Trichoderma koningiopsis </em>(as the wettable powder formulated product Tricotec®) and dolomite on the disease and crop growth of cabbage. This study was carried out in a field with a prolonged history of clubroot incidence. The trial was set up in a randomized complete block design with five repetitions. The following treatments were applied: 0) absolute control; 1 and 2) liming with dolomite at 1.0 and 2.1 t ha<sup>-1</sup>; 3) Tricotec® at 200 g ha<sup>-1</sup>; 4) combination of treatments 1 and 3; 5) combination of treatments 3 and 4. The treatment with just Tricotec® applications gave the lowest disease incidence and severity and the heaviest plant dry weight. Joint applications of Tricotec® and dolomite at 2.1 t ha<sup>-1</sup> reduced the crop growth variables and had the highest disease intensity. The <em>Trichoderma</em> concentration in the soil was increased by a factor of 10 in the plots that received just Tricotec®, but not in the limed plots. These results showed that <em>T. koningiopsis,</em> in a Tricotec® formulation, is a promising candidate for the control of cabbage clubroot and that its biological activity is affected by dolomite when applied jointly at 2.1 t ha<sup>-1</sup>.</span></p>

Characterization of the transcriptome and temperature-induced differential gene expression in QPX, the thraustochytrid parasite of hard clams.

BackgroundThe hard clam or northern quahog, Mercenaria mercenaria, is one of the most valuable seafood products in the United States representing the first marine resource in some Northeastern states. Severe episodes of hard clam mortality have been consistently associated with infections caused by a thraustochytrid parasite called Quahog Parasite Unknown (QPX). QPX is considered as a cold/temperate water organism since the disease occurs only in the coastal waters of the northwestern Atlantic Ocean from Maritime Canada to Virginia. High disease development at cold temperatures was also confirmed in laboratory studies and is thought to be caused predominantly by immunosuppression of the clam host even though the effect of temperature on QPX virulence has not been fully investigated. In this study, the QPX transcriptome was sequenced using Roche 454 technology to better characterize this microbe and initiate research on the molecular basis of QPX virulence towards hard clams.ResultsClose to 18,000 transcriptomic sequences were generated and functionally annotated. Results revealed a wide array of QPX putative virulence factors including a variety of peptidases, antioxidant enzymes, and proteins involved in extracellular mucus production and other secretory proteins potentially involved in interactions with the clam host. Furthermore, a 15 K oligonucleotide array was constructed and used to investigate the effect of temperature on QPX fitness and virulence factors. Results identified a set of QPX molecular chaperones that could explain its adaptation to cold temperatures. Finally, several virulence-related factors were up-regulated at low temperature providing molecular targets for further investigations of increased QPX pathogenicity in cold water conditions.ConclusionsThis is one of the first studies to characterize the transcriptome of a parasitic labyrinthulid, offering new insights into the molecular bases of the pathogenicity of members of this group. Results from the oligoarray study demonstrated the ability of QPX to cope with a wide range of environmental temperatures, including those considered to be suboptimal for clam immunity (low temperature) providing a mechanistic scenario for disease distribution in the field and for high disease prevalence and intensity at low temperature. These results will serve as basis for studies aimed at a better characterization of specific putative virulence factors.

Bahasa Indonesia

Budok caused by Synchytrium pogostemonis is the important and destructive disease on patchouli plant (Pogostemon cablin). Chemical control must be done in incidence with high disease intensity and prediction of outbreak. The experiment was done using benomyl (Benlate 50 WP) and cuprous oxide (Kocide 77WP) 0.1%, 0.2% and mixture of both ( 1 g cuprous oxide and 1 g L-1 benomyl). Patchouli plant was sprayed eight times with one week interval. Harvesting was done two weeks after the end of spraying. Residue analysis of Cu was done with AAS and benomyl residue with HPLC. The result showed that 0.1% benomyl significantly reduced the disease intensity. The other treatments showed lower result. Harvested patchouli plants treated with 0.1% benomyl showed higher yield compare with 0.2% benomyl and cuprous oxyde. Cu residue in dried leaves was between 460 ppm and 950 ppm. Residue of benomyl was 54–100 ppb. Diseased seedling still can be used after spraying by benomyl four times with 2 weeks interval.

Rust resistance in Arabic Coffee cultivars in northern Paraná

The objective of the study was to evaluate the resistance to rust in coffee cultivars developed by research institutes of Brazil in Parana state. Resistance to the local leaf rust races was assessed in high disease intensity field conditions at Londrina and Congonhinhas in 2009 and 2010.The cultivars were developed by the EPAMIG/UFV, IAPAR, IAC and MAPA/Procafe. The resistant standard 'IAPAR 59' and the susceptible standards Catuai Vermelho IAC 144' and 'Bourbon Amarelo' were used. A randomized block design with three replications and plots with 10 plants was used. A scale from 1 to 5 based on the rust intensity was used to evaluate the resistance. The Catigua MG 1, Catigua MG 2, IAPAR 59, IPR 98, IPR 104, Palma II, Paraiso H-419-10-6-2-5-1, Paraiso H-419-10-6-2-10-1, Paraiso H-419-10-6-2-12-1, Pau Brasil MG 1 and Sacramento MG 1 cultivars presented complete resistance to rust at Londrina and Congonhinhas. The cultivars derived from the Catucai germplasm were susceptible or showed different levels of partial resistance. Partial resistance to the rust was observed in several coffees derived from Hibrido de Timor. 'Acaua' and 'Obata IAC 1669-20' presented complete resistance at Londrina, but at Congonhinhas, they were partially resistant, indicating that different rust races have occurred at these two locations.

Spatiotemporal patterns of pandemic influenza-related deaths in Allied naval forces during 1918

This paper draws on the mortality records of the French, US and UK Royal navies to reconstruct the spatiotemporal evolution of the 1918–1919 influenza pandemic in global Allied naval forces. For a total of 7658 deaths attributed to respiratory diseases (French and US navies) and all diseases (UK Royal Navy) at 514 locations worldwide, techniques of spatial point pattern analysis were used to generate weekly maps of global mortality intensity in 1918. The map sequence for the main period of pandemic mortality, mid-August to mid-November 1918, revealed a near-simultaneous development of mutiple foci of high disease intensity in three distant locations (Europe, North America, West Africa). Given the relatively slow speed of naval ships in convoy at this time (<12 knots), our findings suggest that the pandemic influenza virus was circulating on three continents at the observed onset of the main mortality wave.

Incidence and severity of coffee leaf rust and other coffee pests and diseases in Rwanda

Coffee Leaf Rust (CLR) caused by Hemileia vastatrix Berk. and Br. has a worldwide distribution and causes enormous yield losses. A survey was conducted in Rwanda to evaluate incidence and severity of CLR and other coffee pests and diseases and to determine how the crop management contributes to CLR severity. A stratified random sample of 307 coffee farms was visited and the prevalence, incidence and severity were recorded. Results showed that all provinces were affected by CLR with the highest severity in Eastern province where the incidence was up to 100%. High altitudes were associated with low disease severity with a negative correlation of - 0.71. Coffee berry disease (CBD) was a minor disease but with a potential to become an epidemic in the future. Coffee leaf miner, Antestia bugs and Coffee stem borer were recorded but were managed below economic injury levels. All commercial cultivars were susceptible to CLR and most management practices such as mulching, pruning and fertilizer application were associated with lower levels of CLR severity except intercropping which resulted in higher disease intensity. Implications of this survey in relation to CLR management in Rwanda are discussed in this study. Key words: Coffee, diseases, incidence, severity, management, Rwanda.

Suppression of Common Scab of Potato Caused by Streptomyces turgidiscabies Using Lopsided Oat Green Manure.

Field experiments were conducted to determine the effect of green manure as fallow on common scab of potato caused by Streptomyces turgidiscabies. Significantly fewer diseased tubers were harvested from soil incorporated with lopsided oat or woolly pod vetch compared with those from oat and continuous potato cultivation in a planter experiment. Each field experiment consisted of lopsided oat cultivated during the spring and summer prior to the potato planting. Comparisons were also made with several other treatments, including cultivation of woolly pod vetch, oat, soybean, sugar beet, and potato ('Yukirasya', which is resistant to potato common potato scab) and soil application of Ferosand (Fe, mainly FeSO4, to decrease the soil pH). In field experiments conducted during 1999-2000, treatment with lopsided oat followed by lopsided oat or woolly pod vetch was significantly more effective at suppressing the disease severity than oat and continuous potato cultivation (P < 0.001). An increase in the marketable tuber ratio was also more significant than for oat and continuous potato cultivation (P < 0.001). In field experiments conducted during 2000-01, lopsided oat cultivation alone and with the application of Ferosand (1.8 t/ha) or resistant potato cultivar treatment were significantly more effective at suppressing the disease severity and incidence than sugar beet cultivation (P < 0.001), even under high disease intensity in the field. However, potato yield had a tendency to reduce after lopsided oat treatment with an application of Ferosand (1.8 t/ha) compared with lopsided oat alone or the application of Ferosand at 600 kg/ha, due to low pH conditions. In field experiments conducted during 2001-02, the lowest severity and incidence of common scab of potato were observed in soil treated with lopsided oat than with other treatments (P < 0.05 and P < 0.001, respectively). These findings suggest that lopsided oat used as fallow green manure can reduce the severity of common scab and increase potato yield.

Multiple Treatment Meta-Analysis of Products Evaluated for Control of Fire Blight in the Eastern United States

The aim of this analysis was to estimate the effect sizes and consistency of products evaluated for fire blight control in the eastern United States over the last decade. Because only 3% of the 69 studies published from 2000 to 2008 explicitly presented a measure of within-study variability, a method for estimating the least significant difference (LSD) and, hence the sampling variance, for studies with at least two significant mean separations in the presented mean multiple comparisons was developed. Lin's concordance analysis indicated that the estimated LSD was an accurate predictor of the actual LSD based on 35 studies in a calibration evaluation (ρ(c) = 0.997). Separate multi-treatment random-effects meta-analyses were performed for three control categories: antibiotics, biological control, and plant defense-activating products and mean log response ratios relative to the nontreated controls ([Formula: see text]) were computed for each treatment and then back-transformed to obtain the mean percent disease control. None of the products evaluated performed as well as streptomycin, the standard product for fire blight control, for which the mean disease control was 68.6%. As a group, experimental antibiotics provided the best fire blight control with mean effect sizes ranging from 59.7 to 61.7%. Among the biological controls, the best control was noted for treatments combining the antibiotic streptomycin with a product based on Pantoea agglomerans (55.0% mean disease reduction) or Bacillus subtilis (53.9%). Mean disease control was 31.9, 25.7, and 22.6%, respectively, for products based on B. subtilis, Pantoea agglomerans, and Pseudomonas fluorescens without an antibiotic, suggesting that the higher efficacy of the combination treatments was due to the antibiotic. Among the plant defense-activating products, prohexadione calcium had the highest and most consistent effect size (50.7% control), while other products provided modest mean disease control of between 6.1 and 25.8%. Percent control values were significantly moderated by study location and cultivar used in the study, and were smaller, but more variable, when products were tested under high disease intensity compared with low disease intensity. Results indicate that wide-scale use of biological control and plant defense-activating products in the eastern United States is likely to remain low.