Articles

Potato virus Y Potyvirus (PVY) is one of the most important aphid transmitted viral pathogen of potato worldwide. PVY affects potato plant (Solanum tuberosum L.), which is an important economic crop. PVY infection with potato viruses usually causing severe economic damage affecting both tubers quality and trade. PVY can degrease the production of certified seed and also crops grown for processing or fresh market. Potato is considered as one of the most economically important solanaceous crops cultivated in different regions that (PVY) has been studied in many parts of the world. Wide host plant range is a characteristic of viruses belonging to the Potyviridae. 495 species in 72 genera of 31 families were reported to be infected by PVY. Under field conditions, potato plants are subjected to attack by many viruses. The most cited virus could affect potato in the world is PVY. It has been long recognized as a threat to potato cultivation. Several studies carried out and reported that PVY is the most important virus infecting potato in different localities. Our review article is showed that PVY are the most frequently detected viruses in potato.

Clarireedia jacksonii sp. nov. Formerly Sclerotinia homoeocarpa F.T. Bennett, the causal agent of dollar spot (DS), is the most destructive pathogen in turfgrass. Symptoms appear as circular patches 10-40 mm in diameter with small tan lesions surrounded by a darker band, sometimes presenting an hour glass appearance. A multi-year study was initiated with the objective of determining the efficacy of biological control agents (BCA) and tank mixes of BCA’s and synthetic fungicides on DS control. Nutrient source was also evaluated to determine any interaction with the BCA’s and tank mixes. in vitro studies evaluated the efficacy of synthetic and BCA’s for C. jacksonii control. Quarter strength potato dextrose agar was amended with ¼, ½ and full labeled rates of various products. Chlorothalonil at all rates provided greatest (> 90%) control of C. jacksonii for study duration. Biological control agents provided best efficacy at ¼ and ½ label rates. Streptomyces griseoviridis provided least efficacy and may have exacerbated formation of C. jacksonii. Preventative field evaluations for synthetic and BCA’s provided different results between two study years. In Year 1, all treatments had < 15% disease severity for the duration of the study. In year 2, disease pressure was extremely elevated. Synthetic program 1, centered on azoxystrobin + propiconazole applications and conventional fertility sources, provided best results with < 5% disease severity for the duration of the study. Reduced synthetic program 1, and synthetic program 2 followed closely with < 10% disease severity. Reduced synthetic programs were based on monthly applications of either chlorothalonil or pyraclostrobin every 30 day, alternated with biofungicide applications. Synthetic program 2 utilized rotation applications of pyraclostrobin and chlorothalonil every 14 days. Organic programs, utilizing only biofungicides and organic fertility sources, provided the least amount of control and exceeded the 15% threshold by the second month of the evaluation period.

The potential of spent compost of oyster mushroom, Pleurotus sajor-caju cultivated on rice (MCR) or wheat straws (MCW) was evaluated against the root-knot nematode, Meloidogyne incognita on tomato plants under field conditions during two successive seasons (2016 and 2017). The field trial was carried out in a clay loam soil naturally infested with M. incognita at a private farm, Kafr El-Sheikh governorate, Egypt. Results revealed that all the tested treatments greatly suppressed final populations (Pf), numbers of galls and egg masses of M. incognita during both seasons as compared to the untreated treatment. The highest percentages of Pf reductions (81.1 - 87%) and (80.2 - 86.2%) were achieved with the chemical nematicide, Vydate® 10 G and treatments of (MCR and MCW) at application rate of 1200 g/m2 in the 1st and 2nd seasons, respectively. Moreover, the fruit yield during both seasons was increased significantly with all the applied treatments, especially treatment of MCW at application rate of 1200 g/m2. Additionally, chemical fruit properties were markedly improved with MCR and MCW treatments. Also, treatments of MCR and MCW achieved the highest percentages of nitrogen and phosphorus contents. Generally, the results indicated that spent compost obtained after cultivation of P. sajor-caju has a nematicidal potential against M. incognita, also improved nutritional status and increased tomato yield.

The nematicidal efficacy of abamectin, boron, chitosan, hydrogen peroxide, Bacillus thuringiensis and oxamyl 24% SL against citrus nematode, Tylenchulus semipenetrans were examined on Valencia orange trees under field condition for two successive seasons (2017 and 2018). The experiment was conducted in a Valencia orange orchard infested with citrus nematode at Nubaria, El-Behera governorate, Egypt. The obtained results showed that all the tested treatments reduced nematode final population ((Pf) and reproduction factor (Rf) compared with that obtained from the untreated trees. The highest percentages of Pf reductions (74.5-83.4 %) and (70%-82%) were recorded with oxamyl, boron, abamectin, chitosan and H2O2 in the 1st and the 2nd tested seasons, respectively. Whereas, B. thuringiensis had the least nematode Pf reduction with 60.7 and 55.8% in the 1st and 2nd seasons, respectively. Additionally, all treatments significantly improved orange yield (30.9-83.2% increase), physical fruit parameters and orange juice properties. The highest orange yield increase (83.2%) was recorded with boron treatment followed by oxamyl (70.3%). Also, boron increased total soluble solids (TSS) by 13.6%, volume of orange juice (36.4%) and vitamin C (19.7%) and decreased juice acidity (A) by (16.7%). It is concluded that abamectin, boron and the other tested compounds have potential as non-chemical control strategy tools in managing the citrus nematode. These bioagents reduced the amount of traditional chemical nematicides and are considered to be environmentally safe.

Physicochemical and pharmacological studies indicated that Filicium decipiens seeds contained various specialized metabolites, including saponins. The aim of this work is to reveal the nephrotoxicity of FDS, a saponin isolated from Filicium decipiens seeds on male Wistar rats histopathological and biochemical parameters. Rats were submitted to oral ingestion of FDS (6.0 mg/kg) and crude extract (120.0 mg/kg) and were observed high levels of urea and creatinine in blood analyses of all animals followed by an acute renal failure by glomerular retraction. In the present study, FDS and crude extract when administered in Wistar rats induced an increase of serum levels of Urea and Creatinine, biochemical markers of kidney function. Table 1 shows Urea concentration at Test group with FDS (54.3 ± 1.80 mg/ml) and Test group with crude extract (49.7 ± 2.00 mg/ml), were 47% and 34.7% higher, respectively, when compared to control group (36.9 ± 2.00 mg/ml), and Creatinine at the test group with FDS (2.1 ± 0.03 mg/ml) and test group with crude extract (1.6 ± 0.09 mg/ml) presented a value 3.5 and 2.8 times higher, respectively, than control (0.6 ± 0.08 mg/ml). Based on these results, our data demonstrate a significant effect in renal function of rats treated with F. decipiens saponin.

The use of enzyme linked immunosorbent assay (ELISA) for the detection of plant viruses is well documented. It proved to be a very valuable detection tools for the plant viruses. The efficiency of the ELISA technique was for practical purpose independent of the ratio of antibodies to antigen. This avoids the necessity of making specific enzyme conjugates for each antigen to be tested and eliminates the extreme specificity, thus allowing for quantitative evaluation of strain relationships. The advantages of indirect ELISA are sample. It needs only to be macerated and added to the plate. The crude antiserum could be used, although it should be cross absorbed before to prevent spurious host reaction. Single commercially available second antibody conjugate is utilized, thus eliminating the problems of preparing and storing many different conjugated antisera. Blotting technique has become widely used for specific identification of nucleic acid and proteins. This dot assay was modified to detect protein by spotting the antigen on a nitrocellulose membrane and incubating the membrane in test antibody followed by incubation in peroxidase-conjugated second antibody to the first antibody, and by development in 4-chloro-1-naphthol. The above procedure termed dot blot immunobinding assay (DBIA). The technique of tissue blotting on nitrocellulose membrane was described for detection of plant viruses in infected plants. Tissue blots were made by pressing with a firm and gentile force, the freshly cut tissue surface on nitrocellulose membranes. The possibility of using both sides of the nitrocellulose membrane (NCM) by tissue blot immuno assay (TBIA) for the detection plant viruses. In an effort to reduce the cost of virus assays, different types of regular paper were evaluated as possible replacements for the commonly used nitrocellulose membrane (NCM) as the solid phase in the tissue-blot immunoassay (TBIA) were used. Comparisons between different serological methods were demonstrated by many investigators Dot immunobinding was eight times more sensitive for detection of PVX and four times more sensitive for detection of PVS and PVY than DAS-ELISA.

Goosegrass (Eleusine indica L. Gaertn.) is a troublesome weed in turfgrass systems throughout the world. The development of herbicide resistant ecotypes has occurred to multiple modes of action. Goosegrass is a prolific seed producer (~50,000 per plant), fast growing and diverse weed. Such growing attributes make it essential to have a better understanding of the genetic diversity of various ecotypes. The objectives of this study were to determine if morphologically distinct goosegrass ecotypes collected in Florida were phenotypically distinct and genetically different. Phenotypically, the goosegrass ecotypes can be classified as follows; dwarf, intermediate 1 (int_I), intermediate 2 (int_II) and wild. The dwarf had the least seedheads followed by the wild ecotype; 5 and 17 respectively, while int_I and int_II had highest number of seedheads; 22 and 34 respectively. The dwarf ecotype had lowest height of 6 cm and the wild ecotype had highest height of 36 cm. Dwarf and int_II ecotypes had shortest internode length of 0.2 cm and 1 cm, respectively, while the wild ecotype had longest internode length of 7 cm. The dwarf ecotype had lowest number of racemes per plant of 1, while the wild ecotype had highest number of racemes per plant of 7. Total biomass was lowest for the dwarf and int_II ecotype; 0.7 g and 1.5 g, respectively, and total biomass was highest for the wild ecotype at 5 g. Gene sequencing of two rice (Oryza) gene sequences (accession AP014964 (gene A) and AP014965 (gene B)) and subsequent phylogenetic analysis suggest the ecotypes are genetically different. Three single nucleotide polymorphisms (SNP) of interest were discovered indicating allelic differences between ecotypes.

Cowpea plants naturally infected with cowpea mosaic comovirus (CPMV) showed different mosaic, mottle, dwarfing, and vain clearing symptoms. Diseased plants were ollected from certain locations of Alexandria and El-Beheira governorates during the growing seasons from 2011 to 2012. CPMV was detected in infected sap at 8 to 24 days after inoculation by DBIA, indirect ELISA and tissue blot immunoassay (TBIA). Chlorotic local lesions were observed on Chenopodium amaranticolor in infectivity test. By using indirect ELISA and DBIA, CPMV were detected in infected plant sap of serial dilutions up to 1: 400. The incidence of CPMV in 21 day old cowpea seedlings grown from infected seeds was determined by ELISA and positive detection of virus antigen reached 65%. Nitrocellulose membrane and canson paper could be used as solid carriers in TBIA and DBIA for detection of CPMV in infected plant tissues. Results revealed that both faces of nitrocellulose membrane and canson paper could be used as solid carriers in TBIA for detection of CPMV in infected plant tissues. According to reverse transcription polymerase chain reaction (RT-PCR) assay of CPMV infected plant; the amplified product was approximately 800bp of partial coat protein gene. The nucleotide sequences accession number were LN606585 and LN606586. The phylogenetic tree was generated using sequences of CPMV isolates with the other CPMV records from GenBank.

Abamectin and emamectin are members of avermectin family which categorized as very effective but in the same time are toxic naturally. Most of products in this family are utilized as pharmaceuticals in both humans & animals and for crop protection. Despite avermectins are having complex chemical structures, but they are produced via synthesis in large scales for commercial use. Plant parasitic nematodes (PPNs) cause severe damages in all parts of their host plants, in addition to yield losses. The available strategies to control PPN include use of insecticides/nematicides but these have proved detrimental to environment and human health. Therefore, this scenario gave an opportunity for the utilization of avermectins (abamectin and emamectin) to control plant parasitic nematodes because of their chemical and biological properties, as well as relative safety. Avermectins have short half-lives and their residues can be eliminated easily through different food processing methods. Both abamectin and emamectin were very effective nematicides which proved capability of reducing PPNs significantly in various crops.

Standardized method of seed treatment is of prime importance in the production of groundnut. The study was to carry out control trial using bark extract (aqueous and ethanol) and oil (seed) of mahogany (Khaya senegalensis) on seven (7) isolated fungi from two groundnut varieties (peruvian and valencia). The result shows that both mahogany bark and seed extracts are capable of inhibiting mycelial growth of all the isolates. There was no significant variation between the aqueous and ethanol bark extracts in-vitro, however the in-vivo test shows a significant difference between the aqueous and the ethanol bark extract in which the ethanol extract reduced growth of the pathogens more than the aqueous. For all the pathogens except Rhizopus stolonifer there was no growth between 50% to 100% concentration of the Khaya senegalensis oil in-vitro, however in-vivo control at 50% produced scanty to moderate growth for all the pathogens except Rhizopus stolonifer on peruvian, while there was full coverage on the seeds of valencia variety with Aspergillus niger and Rhizopus stolonifer having total coverage though Pseudaiiescheria boydii and Cylindrocarpon lichenicola were effectively inhibited and showed no growth at the 50% and 100%. Further research to focus on the quantifying the chemical constituents and formulation are suggested.