Evaluation of prevalence and incidence of citrus slow decline disease in citrus orchards in district Layyah (original) (raw)
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PATHOGENICITY OF CITRUS NEMATODE (TYLENCHULUS SEMIPENETRANS) ON CITRUS JAMBHIRI
Citrus nematode (Tylenchulus semipenetrans) causes severe damage to citrus. In the present study the relationship between different initial densities of T. semipenetrans and reduction in growth parameters of Citrus jambhiri and nematode infestations was examined in pot experiment under greenhouse conditions using completely randomized design. Seedlings of C. jambhiri were inoculated with T. semipenetrans at the rate of 0, 1,000, 2,000, 4,000 and 8,000 second stage juveniles/pot in the greenhouse. Data were collected on fresh and dry weights of the shoot and root, shoot length, nematode populations in the roots and soil and reproduction factor. All the data were subjected to analysis of variance and means were compared by Duncan's Multiple Range Test at 5%. The relationships between number of galls and growth variables and nematode infestations were determined using regression analysis. It was observed that all the inoculum densities caused reductions in growth parameters and were found directly proportional to the inoculum density. Similarly, a direct relationship was observed between root and soil populations of the nematode and inoculum levels. On the other hand, the nematode build up was the maximum at lower inoculum level and an inverse relationship was observed between reproduction factor and inoculum densities of the nematode.
Advances in Zoology and Botany
The intent of the present study was to investigate the effect of citrus slow decline causing nematode (T. semipenetrans) against different cultivars (kinnow, musambi, shakri, feutrel early and red blood) of citrus in earthen pots (kinnow, musambi, shakri, feutrel and red blood) were filled with formalin sterilized soil. The sterilization of sandy loam soil (72% sand, 17% silt and 8% clay) was accomplished by applying formalin. Diluted formalin (1:320) was poured on the small heap of soil and covered with polythene sheet to stop the fumes completely. Soil treated with water was kept as control. Each treatment was replicated 3 times. Varieties (kinnow, musambi, shakri, feutrel and red blood) were transplanted into these pots. The pots were completely randomized, kept in the glass house and watering was done to avoid drying of soil. After fifteen days, 2000 ± 25 freshly hatched juveniles in 15ml of water were added around the stem of plant of each pot by making holes and then filled with soil to prevent drying. Then they were watered carefully. Over irrigation of the pots was avoided. Experiment was harvested after ninety days. Experiment was repeated twice to confirm the results. The association of inoculated pathogens was confirmed by re-isolation. Survey results showed that maximum T. semipenetrans occurrence was in tehsil Sargodha (90%), Kot Momin (80%), Bhalwal (60%) and minimum prevalence was in sillan wali (50%).
Journal of the Advances in Agricultural Researches, 2020
A survey of plant-parasitic nematodes (PPN) associating citrus trees in Alexandria, El-Behera and Kafr El-Shiekh governorates, northern Egypt was carried-out during 2017-2019 growing seasons. A total of 432 root and rhizosphere soil samples were collected from the surveyed citrus trees. Nematodes were extracted using sieving and Bearmann-pan techniques and, identified to the generic level, based on the morphological characters. Besides, the reaction of mandarine, Citrus deliciosa and lime, C. aurantifolia against the citrus nematode, Tylenchulus semipenetrans, was determined under greenhouse conditions. Results showed that 9 genera of PPN were found in association with the surveyed citrus trees in the three governorates. The citrus nematode, Tylenchulus semipentrans was found to be very common (frequency of occurrence (FO) = 100% in all the surveyed locations, followed by the stubby root nematodes, Trichodorus spp., and the lesion nematodes, Pratylenchus spp. The reaction of the two citrus cultivars; Mandarine, Citrus deliciosa and Lime, Citrus aurantifolia to T. semipenetrans showed that the two cultivars are susceptible to all the tested populations of T. semipentrans with a nematode reproduction factor (RF) was (1.67-2.6).The shoot and root dry weights of these cultivars were reduced as a result of the nematode infection.
To understand the relationship between natural physicochemical properties of soil and abundance of citrus root nematode (Tylenchulus semipenetrans), a survey was conducted during 2009-2010 in some 37 citrus orchards, in Kohgilouyeh va Boyerahmad Province, Iran. Distribution of the citrus nematode was determined by collecting random samples from the soil and citrus plant roots, extracting and enumerating the number of second stage juveniles, males/100 g of soil and females/5 g of root. The relationships between nematode population, and the factors of: organic matter content, Nitrogen (N), Phosphorus (P), Potassium (K), organic carbon, Calcium Carbonate, soil texture, Electrical Conductivity (EC) and pH were determined. Increase in nematode population density was observed by increasing soil saturation percentage (up to 43%), and by an increase in soil silt, sand, P, K and organic carbon, but by an increase in soil salinity, Calcium Carbonate, total Nitrogen and the amount of clay in soil, the nematode population decreased. Maximum nematode population density was recorded in a loamy soil texture. The most suitable soil pH for nematode activity was found almost seven while either an increase or decrease in soil pH, resulted in a decrease in nematode population. The number of second stage juveniles ranged from 58 to 2,730/100 g of soil while females were present by 11 to 331 individuals/g of root respectively. About 62% of the studied orchards were infested with T. semipenetrans.
Control of citrus nematode, Tylenchulus semipenetrans in Nagpur Mandarin Orchard
Indian journal of nematology, 2004
A field trial for the control of the citrus nematode, Tylenchulus semipenetrans in a ten year old Nagpur mandarin orchard on rough lemon rootstock showed that the application of carbofuran 3G and phorate 10G, each at 1, 3 and 5kg a.i/ha reduced the nematode (Tylenchulus semipenetrans) populations in soil and on roots significantly within one month of nematicide application. The repeated application of the nematicides after one year kept the namatode populations significantly lower as compared to non-repeated and check treatments. Increase in canopy volume was also significant in treatments where carbofuran and phorate were applied at 5kg a.i/ha during first year and in repeated treatments during second year. In second year, the fiuit yield was increased by 32.4 and 29.7% over check in the repeated treatments where carbofuran and phorate were applied each at 5 kg a.i/ha.
2011
This study aimed to determine resistance level of some citrus cultivars to the citrus nematode (Tylenchulus semipenetrans Cobb). Number of T. semipenetrans female penetrated per cm root not significantly different on all citrus cultivar. Number T. semipenetrans female per cm root on all citrus cultivar was < 1 nematode per cm root. This fact showed that Citrus jambhiri, C. reticulate, C. aurantium, C. nobilis, C. medica, C. macrocarpa, and C. hystryx ABC showed resistant reaction on T. Semipenetrans.
Pakistan Journal of Zoology, 2019
The study of the population dynamics of citrus nematode (Tylenchulus semipenetrans) in a production area is required for the assessment of damaging potential of the nematode to citrus, identification of key factors that influence population densities, and to devise effective management strategies. In the present study, seasonal fluctuations in the population densities of T. semipenetrans were studied in two citrus orchards naturally infested with citrus nematode during the year 2014. The effect of soil temperature was also evaluated on the populations of the nematode. The nematode populations differed significantly at both the soil depths. The populations were significantly higher at a depth of 30 cm as compared to 45 cm throughout the year at both the orchards. Similarly, females per gram of roots also followed the same pattern. The number of nematodes in the soil and females in the roots were the higher during the months of April to June and August-September showing two peaks throughout the year. The regression analysis between temperature and number of nematodes in the soil and females in the roots showed highly significant results at both the orchards. A direct relationship was observed between nematode population and temperature. Maximum nematode and female populations were observed at a temperature ranging between 26°C to 29°C at a soil depth of 30 cm. On the other hand, minimum populations were recorded at a temperature range of 9°C to 12°C. Similar trends were observed at the soil depth of 45 cm. It is concluded from the present study that the management of nematode including application of nematicides should be started in the spring season, just prior to the first root flush, to protect the new roots from nematode infection.
Non-chemical based management of Tylenchulus semipenetrans, a major threat to the citrus industry
World Journal of Biology and Biotechnology, 2020
There is a vast variety of microbes available in soil performing diverse functions for plants including root colonization for protection against pathogens and nutrient acquisition. In the present study, efficacy of rhizospheric microbial strains and plant extracts were evaluated against citrus nematode for their nematicidal activity. Three different concentrations of plant extracts were evaluated in vitro, results depicts that 10% solution of Tagetes erecta (root) has given 46% the highest percentage mortality at 48hrs followed by Tagetes erecta (leaf) and Datura stramonium killed 41% and 37% nematodes respectively, similarly for 20% of plant extract in distilled water, the highest mortality rate was recorded for T. erecta (root) 68% followed by D. stramonium 47% and Acacia nilotica 44% at 48hrs of application. While using a higher concentration 30% of SS. the percentage mortality elevated multifold i.e. Marigold root has killed maximum 76% nematodes followed by Marigold leaves and...