scholarly journals SEASONAL FLUCTUATION OF ASIAN CITRUS PSYLLA POPULATIONS IN THE CITRUS ORCHARDS INFECTED WITH HUANGLONGBING IN SARGODHA, PAKISTAN

2017 ◽  
Vol 29 (1) ◽  
pp. 175
Author(s):  
Yasir Iftikhar ◽  
Imran U. Haq ◽  
Waqas Raza ◽  
Muhammad I. Ullah ◽  
Sajjad Ali ◽  
...  
Keyword(s):  
High Temperature ◽  
Environmental Factors ◽  
Minimum Temperature ◽  
Management Strategy ◽  
Integrated Management ◽  
Seasonal Fluctuation ◽  
Diaphorina Citri ◽  
Citrus Production ◽  
Citrus Orchards ◽  
Citrus Psylla

A study on seasonal fluctuation in Citrus psylla (Diaphorina citri) (CP) population in citrus orchards infected with Huanglongbing was carried out in relation to environmental factors in six tehsils of Sargodha district. The population of citrus psylla was reached to the peak twice in a year. Young flushes favored the build-up in psylla population. Minimum temperature and rainfall had highly significant correlation with build-up in population of citrus psylla in all the six tehsils of Sargodha. Although, high temperature also favored the high population of citrus psylla in two tehsils. August and mid-March to April were the two times when population of citrus psylla reached to the peak. Therefore, an integrated management strategy can be formulated with this study that will not only help in reducing the HLB incidence but also increase in citrus production.

scholarly journals Impact of abiotic factors on build-up of citrus psylla, Diaphorina citri Kuwayama population in Punjab, India

2014 ◽  
Vol 6 (2) ◽  
pp. 371-376 ◽  
Author(s):  
Hijam S. Devi ◽  
D. R. Sharma
Keyword(s):  
Relative Humidity ◽  
Disease Transmission ◽  
Minimum Temperature ◽  
Abiotic Factors ◽  
Winter Season ◽  
Seasonal Abundance ◽  
Maximum Temperature ◽  
Weak Links ◽  
Diaphorina Citri ◽  
Citrus Psylla

Seasonal abundance of citrus psylla (Diaphorina citri) Kuwayama was studied on Kinnow mandarin under Punjab conditions during 2012 and 2013. Population of D. citri was present throughout the year but only adults found surviving during December and February. There was no nymphal population when maximum temperature was > 39°C or < 7°C. Two population peaks of nymphs wer e observed, first in April-May and second in August- September. Thereafter, there was abrupt decline in nymphal population during June and July during both the years when the weather conditions i.e. maximum, minimum temperature (°C), relative humidity (%), rainfall (m m) and sunshine (hrs) ranged from 24.4-44, 22.4-31.8, 25.5-100, 0-108.0 and 0-13.5, respectively. Highest peaks of adult were found during May followed by June. With the decrease in temperature from the end of September, the population of D. citri started to decrease and reached its lowest during winter season. Correlation analysis for both the years indicated that maximum and minimum temperature, sunshine and rainfall were positively correlated with nymphal, adult and mixed population but the effect of rainfall on adult population was non-significant, while relative humidity was negatively correlated. The study is useful to find out the weak links of psyllid populations in relation to abiotic factors and that could be exploited to curb its infestation and disease transmission.

Factors associated with Diaphorina citri immigration into commercial citrus orchards in São Paulo State, Brazil

2020 ◽  
Author(s):  
Fernando P. F. Zorzenon ◽  
Arthur F. Tomaseto ◽  
Matthew P. Daugherty ◽  
João R. S. Lopes ◽  
Marcelo P. Miranda
Keyword(s):  
Sao Paulo ◽  
São Paulo ◽  
Diaphorina Citri ◽  
Factors Associated ◽  
Paulo State ◽  
São Paulo State ◽  
Citrus Orchards

scholarly journals Systemic Infection by Fusarium verticillioides in Maize Plants Grown Under Three Temperature Regimes

Plant Disease ◽  
2008 ◽  
Vol 92 (12) ◽  
pp. 1695-1700 ◽  
Author(s):  
A. Murillo-Williams ◽  
G. P. Munkvold
Keyword(s):  
High Temperature ◽  
Environmental Factors ◽  
Fusarium Verticillioides ◽  
Systemic Infection ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Kernel Infection ◽  
Temperature Regimes ◽  
Maize Plants ◽  
Systemic Development

Fusarium verticillioides causes seedling decay, stalk rot, ear rot, and mycotoxin contamination (primarily fumonisins) in maize. Systemic infection of maize plants by F. verticillioides can lead to kernel infection, but the frequency of this phenomenon has varied widely among experiments. Variation in the incidence of systemic infection has been attributed to environmental factors. In order to better understand the influence of environment, we investigated the effect of temperature on systemic development of F. verticillioides during vegetative and reproductive stages of plant development. Maize seeds were inoculated with a green fluorescent protein-expressing strain of F. verticillioides, and grown in growth chambers under three different temperature regimes. In the vegetative-stage and reproductive-stage experiments, plants were evaluated at tasseling (VT stage), and at physiological maturity (R6 stage), respectively. Independently of the temperature treatment, F. verticillioides was reisolated from nearly 100% of belowground plant tissues. Frequency of reisolation of the inoculated strain declined acropetally in aboveground internodes at all temperature regimes. At VT, the high-temperature treatment had the highest systemic development of F. verticillioides in aboveground tissues. At R6, incidence of systemic infection was greater at both the high- and low-temperature regimes than at the average-temperature regime. F. verticillioides was isolated from higher internodes in plants at R6, compared to stage VT. The seed-inoculated strain was recovered from kernels of mature plants, although incidence of kernel infection did not differ significantly among treatments. During the vegetative growth stages, temperature had a significant effect on systemic development of F. verticillioides in stalks. At R6, the fungus reached higher internodes in the high-temperature treatment, but temperature did not have an effect on the incidence of kernels (either symptomatic or asymptomatic) or ear peduncles infected with the inoculated strain. These results support the role of high temperatures in promoting systemic infection of maize by F. verticillioides, but plant-to-seed transmission may be limited by other environmental factors that interact with temperature during the reproductive stages.

Testing Integrated Management Strategies for Tall Buttercup (Ranunculus acris) in Irrigated Hayfield Meadows

2015 ◽  
Vol 8 (4) ◽  
pp. 385-392
Author(s):  
Hally K. Strevey ◽  
Jane M. Mangold
Keyword(s):  
Management Strategy ◽  
Integrated Management ◽  
Management Strategies ◽  
Forage Production ◽  
Canadian Province ◽  
Herbicide Treatments ◽  
Production Research ◽  
Second Year ◽  
Ranunculus Acris ◽  
Plot Design

AbstractTall buttercup is an invasive forb that has been reported in all but eight states and one Canadian province. The species has been of concern in Montana where it has invaded over 8,300 ha, and it has been particularly problematic in irrigated hayfield meadows that are used for forage production. This study sought to develop an integrated management strategy to control tall buttercup while maintaining forage production. Research was conducted over 2 yr at flood-irrigated and subirrigated hayfield meadows near Twin Bridges, MT. Treatments were randomly applied in a split-plot design with four replications at both sites. Herbicide treatments occurred at the whole-plot level: nonsprayed, aminopyralid (172 g ai ha−1), aminocyclopyrachlor + chlorsulfuron (83 g ai ha−1+ 33 g ai ha−1), and dicamba (981 g ai ha−1). Split plots consisted of mowing and fertilization (28 kg N ha−1). All herbicides provided up to 2 yr of tall buttercup control at both sites. In the second year, aminocyclopyrachlor + chlorsulfuron and aminopyralid reduced tall buttercup by 93% and 96%, respectively, for the subirrigated and flood-irrigated sites. At the subirrigated site, mowing reduced tall buttercup by 71%, and fertilization reduced it by 57%. Forage decreased following aminocyclopyrachlor + chlorsulfuron treatments. The integration of herbicide, mowing, and fertilization did not improve tall buttercup control.

scholarly journals A Survey for ‘Candidatus Liberibacter’ Species in South Africa Confirms the Presence of Only ‘Ca. L. africanus’ in Commercial Citrus

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 244-249 ◽  
Author(s):  
G. Pietersen ◽  
E. Arrebola ◽  
J. H. J. Breytenbach ◽  
L. Korsten ◽  
H. F. le Roux ◽  
...  
Keyword(s):  
South Africa ◽  
Western Cape ◽  
Chain Reaction ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Orchards ◽  
Polymerase Chain ◽  
Serious Disease ◽  
Production Areas ◽  
Representative Samples

Greening disease of citrus is a serious disease known in South Africa since the late 1920s. In South Africa, it is associated with infection by ‘Candidatus Liberibacter africanus’, a heat sensitive, phloem-limited, noncultured alpha-proteobacterium. Huanglongbing (HLB), a similar, but more devastating disease that was described initially from China but which now occurs in several citrus producing countries, is associated with a different Liberibacter species, ‘Ca. L. asiaticus’. A ‘Ca. L. africanus’ subspecies, ‘Ca. L. africanus subsp. capensis’, has been found only in South Africa infecting an indigenous Rutaceous species, Calodendrum capense (Cape Chestnut), in the Western Cape in 1995. The discovery of a new Liberibacter species in Brazil, ‘Ca. L. americanus’, and the spread of ‘Ca. L. asiaticus’ to a number of additional countries over the last few years prompted us to assess whether only ‘Ca. L. africanus’ is present in commercial citrus orchards in South Africa. Samples displaying greening or similar symptoms were collected from 249 citrus trees from 57 orchards distributed throughout the greening affected citrus production areas of South Africa. Multiplex polymerase chain reaction (PCR) was performed on DNA extracts to detect the known citrus Liberibacters. Amplicons were obtained from 197 samples. None of the samples yielded a 1,027-bp amplicon indicative of ‘Ca. L. americanus’ infection. The amplicons of 84 samples were sequenced, and all were identical to the cognate ‘Ca. L. africanus’ Nelspruit sequence in GenBank. No instance of ‘Ca. L. asiaticus’ or ‘Ca. L. africanus subsp. capensis’ sequence was found. Geographically representative samples that tested negative for Liberibacter also tested negative for phytoplasmas based on real-time PCR results. Based on the results of this survey, it is concluded that to date only ‘Ca. L. africanus’ is associated with citrus greening in commercial citrus in South Africa.

scholarly journals An Evaluation of the Use of Calcium, Potassium and Silicon for the Management of Diaphorina citri Populations in Tahiti Lime Trees

2018 ◽  
Vol 46 (2) ◽  
pp. 546-552 ◽  
Author(s):  
Augusto RAMÍREZ-GODOY ◽  
Ginna PUENTES-PÉREZ ◽  
Hermann RESTREPO-DÍAZ
Keyword(s):  
Integrated Management ◽  
Similar Efficacy ◽  
Potassium Nitrate ◽  
Mineral Nutrients ◽  
Management Program ◽  
Diaphorina Citri ◽  
Soil Fertilization ◽  
Number Of Individuals ◽  
Absolute Control ◽  
Alternative Control Methods

The recent appearance of the disease known as huanglongbing (HLB) in Colombia has caused the demand for alternative control methods for Diaphorina citri (i.e., the disease vector). Specifically, the use of nutrients, such as calcium (Ca), potassium (K) and silicon (Si), may provide some degree of plant defense against herbivory. One set of experiments (in the form of two separate experiments) was conducted on two different farms in the municipality of Jerusalén to study the effects of foliar and soil applications of nutrients (Ca, K and Si) on controlling the population dynamics of Diaphorina citri. Tahiti lime trees were treated as follows: i) untreated trees (absolute control); ii) clothianidin at a dose of 50 g active ingredient per hectare (chemical control); iii) Ca, K and Si foliar applications (at doses of 3 mL, 3 g and 2 mL of the commercial compound used per liter of H2O, respectively); and iv) soil application of potassium nitrate and potassium silicate (1 kg of commercial fertilizer per tree). Foliar sprays were carried out at 0 and 4 weeks after treatment (WAT) began; meanwhile, soil fertilization occurred at the beginning of the trial (i.e., 0 WAT). The results showed that differences were observed only in adults at 7 WAT, and the foliar calcium and silicon applications resulted in the lowest number of individuals (i.e., 1.13 per flush) compared with untreated trees (i.e., 3.13 per flush). The foliar clothianidin, Ca, Si and K sprays also affected the total number of nymphs. Additionally, Tahiti lime trees treated with either silicon or insecticide had fewer eggs than did trees in the other treatments. The use of these mineral nutrients showed a similar efficacy when compared to clothianidin, indicating that these mineral nutrients can enhance plant resistance. These observations suggest that foliar applications of K, Ca and Si could be considered as complementary tools within an integrated management program for D. citri in Colombia.

EFFECT OF ENVIRONMENT ON BROMOBUTYL RUBBER–STEEL ADHESION

2019 ◽  
Vol 93 (2) ◽  
pp. 429-444 ◽  
Author(s):  
Essi Sarlin ◽  
Ari Rosling ◽  
Mari Honkanen ◽  
Mari Lindgren ◽  
Mira Juutilainen ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
High Temperature ◽  
Relative Humidity ◽  
Environmental Factors ◽  
Adhesive Layer ◽  
Metal Structure ◽  
Adhesive System ◽  
Metal Interface ◽  
Weakest Link ◽  
Industry Sectors

ABSTRACT Optimizing the maintenance cycles of rubber-lined components is of great importance. Especially for the industry sectors operating under demanding conditions, challenges in the lifetime evaluation of rubber linings may cause apparent premature failures. Thus, understanding the effect of environmental factors on the performance and durability of rubber linings, as well as on the weakest links of the structure in certain environments, is essential. The performances of bromobutyl rubber and rubber–steel interfaces after exposure to different environments, namely, high temperature (95 °C), moisture (95% relative humidity and immersion), and sulfuric acid (solution with 75 g/L of acid) were investigated. The weakest link of the rubber–metal structure and, consequently, the location of the fracture were mostly within the adhesive layer or at the primer–metal interface. However, the most degraded component of the adhesive system depends on the aging environments.

scholarly journals Screen Mesh Size for Exclusion of Diaphorina citri (Hemiptera: Liviidae) in Citrus Production

2020 ◽  
Vol 113 (4) ◽  
pp. 2026-2030
Author(s):  
Timothy A Ebert ◽  
Laura Waldo ◽  
Daniel Stanton ◽  
Arnold W Schumann
Keyword(s):  
Tree Mortality ◽  
Mesh Size ◽  
Diaphorina Citri ◽  
Short Side ◽  
Vector Management ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Pass Through ◽  
Individual Trees

Abstract Huanglongbing is a citrus disease that reduces yield, crop quality, and eventually causes tree mortality. The putative causal agent, Candidatus Liberibacter asiaticus (Rhizobiales: Rhizobiaceae), is vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama. Disease management is largely through vector control, but the insect is developing pesticide resistance. A nonchemical approach to vector management is to grow citrus under screen cages either as bags over individual trees or enclosures spanning many acres. The enclosing screen reduces wind, alters temperature relative to ambient, and excludes a variety of pests that are too large to pass through the screen. Here we evaluated the potential of six screens to exclude D. citri. We conclude that screens with rectangular openings need to limit the short side to no more than 384.3 µm with a SD of 36.9 µm (40 mesh) to prevent psyllids from passing through the screen. The long side can be at least 833 µm, but the efficacy of screens exceeding this value should be tested before using in the field.

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