Journal of Phytopathology and Pest Management (Al-Azhar University)
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Pathogenic and mating type characterization of an uncommon wilt disease of citrus in Tunisia
Get PDFWilt disease on citrus trees in Tunisia have increased in significance in the northern and center of the country. Trunks and secondary branches of wilted trees were collected and used to isolate the main pathogen and assess pathogenicity on sour orange rootstock. In addition, Mating type (MAT) specific primers were used to assess the mating type of Fusarium oxysporum Schlecht isolates. The distribution of MAT idiomorph may suggest that MAT1-1 is a predominant mating type in the F. oxysporum population. Wilt disease symptoms, recorded at the end of the pathogenicity tests, were associated with reduced plant growth and vigour, with shorter and thinner shoots, and limited number of roots. Principal component analysis (PCA) based on host specificity of isolates (sweet orange and tangerine), geographical origin (CapBon area and Kairouan) and severity index of the isolates showed three groups related to the specific host and origin. The present study has proved essential information on occurrence of mating types of F. oxysporum isolated from citrus
Factors affecting Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) infesting some tomato hybrids throughout summer season in Assiut Governorate, Upper Egypt
Get PDFAn area of about half acre was cultivated with tomato (Lycopersicon esculentum Mill) in 2012 summer season. Obtained data indicated that the infestation began when the plant aged one month. Infestation with T. absoluta reached the maximum number of 50 and 28 larvae per 10 leaves on hybrids of H6 and H7, respectively. The infestation was then decreased gradually until the end of the season. The relative efficiency of the plant age factor was found 25% out of about 90%. Data indicated also that mirid bugs seemed to be responsible for about 14% of the variability of the infestation with T. absoluta larvae. Mirid bugs occupied the second rank of the rating sort. Both hybrids, (H6 and H7) showed similar effect of maximum temperature on larval infestation. Rating sort of co-efficient of determination revealed that the air temperature ranked the fourth factor. However, air temperature was found to be responsible for about 9% and 10% of the variability of larval infestation between the two hybrids H6 and H7, respectively. The maximum relative humidity took the lowest level. The statistical analysis indicated that the coefficient of determination of soil temperature and larvae of T. absoluta infesting H6 and H7 was about 10% and 17%, respectively. Results of the present investigation clearly show that plant age (Rate 1) may be the key factor as it had a small simple correlation despite RH (Rate8) approximately had a similar simple correlation. These reversed evidences, prove that the simple correlation is not enough to determine the potency of an independent factor unless it correlate with other factors. Thus, multi-coefficient analysis is highly recommended in such cases
Management of citrus nematode (Tylenchulus semipenetrans) by certain plant species
Get PDFThe effect of five plant species (Tagetes erecta L., Datura stramonium L., Nerium oleander L., Ipomea palmata L. and Santolina chamaecyparissus L.) on severity of Tylenchulus semipenetrans on citrus rootstocks (Citrus sinensis, C. reticulate grafted on C. aurantium and C. sinensis grafted on C. aurantium) was investigated in greenhouse and laboratory conditions. All plant species reduced the larval population of T. semipenetrans and their effect increase as the period increase. I. palmata gave the highest percentage of reduction when intercropped with C.sinensis and C. reticulate grafted on C. aurantium 20.5 and 25% respectively. N. oleander and D. stramonium came next when intercropped with C. reticulate grafted on C. aurantium 13.5 and 11% respectively, While D. stramonium gave the highest percentage of reduction when intercropped with C. sinensisgrafted on C. aurantium. And T. erecta gave the lowest percentage of reduction when intercropped with the three rootstocks
Field efficiency and selectivity effects of selected insecticides on cotton aphid, Aphis gossypii Glover (Homoptera: Aphididea) and its predators
Get PDFCotton aphid, Aphis gossypii Glover (Homoptera: Aphididae) is a key pest of cotton plants in Egypt. A two-year field study was conducted at Faculty of Agriculture, Assiut University, Egypt, during 2013 and 2014 growing seasons to determined the efficiency of acetamiprid, imidacloprid, thiamethoxam, dinotefuran, pirimicarb and malathion on cotton aphid and selectivity effects of these insecticides on Coccinella undecimpunctata L. and Chrysoperla carnea (Stephens). The results indicated that thiamethoxam, dinotefuran, acetamiprid and imidacloprid proved to be the most effective insecticides in reducing cotton aphid population up to 21 days after treatment throughout both seasons and caused an average reduction percentage ranged from 73.58 to 96.42%%, whereas pirimicarb and malathion showed the lowest reduction with an average ranged 38.08 to 66.68 % at different exposure dates during 2013 and 2014 seasons. In addition, the selectivity effects of acetamiprid, imidacloprid, pirimicarb and malathion reduced the population of C. undecimpunctata with an average ranged from 78.05 to 96.43% and were classified as harmful. Thiamethoxam reduced the population with an average ranged from 68.72 to 69.20% and was classified as moderately harmful. Dinotefuran showed a slightly harmful effect to C. undecimpunctata with an average reduction 44.3 and 41.81% during 2013 and 2014 seasons. On the other hand, acetamiprid and dinotefuran caused a significant reduction in the population of C. carnea with an average ranged from 28.28 to 56.52% and were classified as harmless. Thiamethoxam and imidacloprid reduced the population with an average ranged from 55.53 and 64.39% and were classified as moderately harmful. By contrast, malathion and pirimicarb showed the highest reduction in the population with an average ranged from 67.15 to 96.57% and were classified as harmful during both seasons. These results suggested that, the selection of a suitable insecticide in an IPM program to control the cotton aphid not only depends on its efficiency against the aphid but also its toxicity to natural enemies (predators and parasitoids) and its persistence
Effect of certain commercial compounds in controlling root-knot nematodes infected potato plants
Get PDFTo examine the effect of certain commercial compounds against root-knot nematode (Meloidogyne incognita) which infect potato plants (Solanum tuberosum L. var. sponta). Two experiments were carried out under laboratory and field conditions during 2012 and 2013 seasons. Eight nematicides were used as treatments i.e., Mocap, Super control, Dento, Nematex, Vertimyl, Oxamyle, Bionematone, and Bioxy+. The successful treatments were chosen due to their effectiveness on percentage reduction in nematode populations, maximize plant production. The chosen treatments applied in soil naturally infected with nematode in the experimental field in Nubaria, Behira Governorate, North Egypt. Results exhibited significantly reduction in all nematode developmental stages in plant and soil, ex. number of egg masses, galls and nematodes in 250 cm3 soil with all chemical compounds. The consequence of vegetative growth parameters and yield were increased significantly with tested treatments compared with control. Moreover, results of laboratory experiments recorded that 87 to 98% inhibition for egg-masses hatching and 85 to 98% mortality for juveniles, respectively, with 90% for the lethal concentration of Bioxy+, Oxamyl and Vertimyl
Susceptibility of certain wheat varieties to the infestation by Rhyzopertha dominica (F.) and Tribolium confusum (du Val)
Get PDFEight Egyptian flour wheat varieties were assessed in order to determine their appropriate level of susceptibility to Rhyzopertha dominica (F.) and Tribolium confusum (du Val). Free choice test for attraction insect adults was used in the first experiment at time interval ranged from 0.125 to 5 days post infestation. At days, results showed that the lowest attracted numbers of R. dominica adults were 5.00 and the highest ones were 22.67 for SAKL8 and SIDS1 varieties, respectively. The varieties can be arranged descendently according to the attracted numbers of R. dominica as follow: SAKL8, SAKL1, BACANORA, DEBEIRA, , GIZA168, GIZA164, SIDS6 and SIDS1. The descending order results were obtained for T. confusum could be the similar. Statistical analysis demoed significant differences between the numbers of the eight varieties. In the second experiment, the numbers of F1 and the duration of offspring of each stage were determined. Based on the Dobie Index (D.I.) for R. dominica, SAKL8, DEBEIRA, BACANORA and SAKL1 were found to be resistant varieties. While the SIDS1 and SIDS6 varieties have a moderate resistant. In the case of T. confusum all varieties showed a degree of resistance, except SAKL8 and SIDS1showed a moderate resistant. The BACANORA cultivar showed the lowest D.I. value in the two tested insect species. The obtained results can give a better understanding to the stored-grain managers regarding to the prospective differences in wheat susceptibility to R. dominica and T. confusum infestation
Toxicity of Basil (Ocimum basilicum L.) and Rosemary (Rosmarinus officinali L.) extracts on Tribolum confusum (DuVal) (Coleoptera:Teneberionidae)
Get PDFThis study was conducted to monitor the effect of two-plant extracts viz. leaves of Ocimum basilicum L. and Rosmarinus officinalis L. on the last larval and adult stages of Tribolum confusum (DuVal). Bioassay was made using the ethanol as a solvent for both plants to find out the median lethal concentration (LC50). Results showed that the last larval instar was more highly susceptible to both plant extracts than the adult stages. The LC50 of R. officinali were 113.15 and 135.18, whereas the LC50 of O. basilicum extract were 148.38 and 218.78 ppm for the last larval and adult stages after 24 hours exposure respectively. The highest mortality percentages were 78% and 72% for R. officinali and 74%, 66% for O. basilicum against T. confusum last larval instar and adult stages, respectively, after 24 hours exposure at 250 ppm. The application of these botanicals extracts might be promising in protecting the stored grains against coleopteran pests
Molluscicidal effect of biogenic silica and botanical pesticides for the control of Achatina fulica (giant African land snail) and Laevicaulis alte (garden slug)
Get PDFThe molluscicidal effect of silica synthesized from rice husk ash (RHA) on snails (Achatina fulica Bowdich) and slugs (Laevicaulis alte Férussac) was assessed under laboratory conditions. The silica particles derived from RHA were also coated with leaf extracts (botanical pesticides): Azadirachta indica A. Juss, Pongamia pinnata (L.), Nicotiana tabacum (L.), and Calotropis procera (L.). The silica coated with plant extracts and the uncoated silica were applied to the molluscs in dust or slurry form. Inactivation, mortality, and body fluid loss in A. fulica and L. alte were observed over 24 h and recorded. The body fluid losses were 25%–42% for snails and 37%–62% for slugs that had been dusted with silica. During the experiment it was also noted that as the concentration of silica increased (0.15, 0.20, and 0.25 g), the time required for inactivation and mortality was reduced. The dust application was more effective than the slurry. The lower concentration of silica in the slurry (0.05 and 0.10 g) did not have any significant effect on A. fulica or L. alte. For A. fulica the biopesticide-coated silica particles were more effective when coated with neem, followed by tobacco and karanj; for L. alte, the particles were most effective when coated with tobacco, followed by neem and karanj. The plant extract (liquid as well as dry powder) without silica showed no molluscicidal effect on A. fulica and L. alte, except for some temporary inactivation, particularly with tobacco extract. The application of common salt, a practice often used by farmers, was also tested. It was observed that the effects of common salt on A. fulica and L. alte were less significant than those of silica coated with botanical pesticides.Â
Effect of extreme low and high temperatures on the almond moth, Ephestia cautella (Walker) (Lepidoptera: Pyralidae)
Get PDFhe different immature stages of the almond moth, Ephestia cautella (Walker) were exposed to low temperature of -5ºC for different exposure times. Exposure of eggs to 240 to 360 minutes is sufficient to achieve 100% mortality for this stage. Exposed early larval instar to -5ºC for 180 minutes is sufficient to achieve 100% mortality. Exposure of the late larval instars to 300 and/or 360 minutes is effective to achieve a complete mortality for the late larval instars of the pest. The calculated LT50 and LT95 were 113.73 and 208.64 minutes. Exposure of pupae to 300 minutes or more is effective to get a complete mortality for the pupal stage. High temperatures of 45º, 50º, 55º and 60ºC were tested against egg, late larval instars and pupal stages of E. cautella. Mortality tended to be increased with the increasing of temperature and exposure time. Exposure time for more than one hour at 45ºC, 15 minutes at 50ºC and 10 minutes at 55ºC were more effective and led to more than 95% mortality for the egg stage of E. cautella. Exposure of the late larval instars for more than 97.22, 72.17, 17.65 minutes at 45, 50 and 55ºC is sufficient to achieve more than 95% mortality for the late larval instars as indicated by LT95 values. Exposing the pupae to 25 minutes at high temperatures of 50ºC and to 15 minutes at 55ºC is an effective to get complete mortality for the pupal stage. Thus exposure times for more than 90 minutes at high temperature of 45ºC; 33 minutes at 50ºC and/or 11.67 minutes at 55ºC were more effective to achieve more than 95% mortality of the pupal stage of E. cautella.Â
Management of root rot and wilt diseases of date palm offshoots using certain biological control agents and its effect on growth parameters in the New Valley Governorate, Egypt
Get PDFRoot Rot and wilt diseases were observed on different date palm offshoots in nurseries and new orchards in New Valley Governorate, Egypt. Pathogenicity tests showed that Fusarium oxysporum, F. solani and F. moniliforme were the causal agents of root rot and wilt diseases on date palm offshoots (cv. Saidy). In addition, the isolates of the three Fusarium spp. differed in their pathogenic capabilities. The effect of Bacillus subtilis (BSM1), B. megaterium (BMM5), B. cereus (BCM8), Trichoderma viride (TVM2), T. harzianum (THM4) as bioagents against root rot/wilt disease complex of date palm offshoots under natural infection in nursery cultivated in two location (Al-Kharga and El-Dakhla) and also, on growth of the tested pathogenic fungi under laboratory were evaluated. Under laboratory conditions, all the tested bioagents inhibited the growth of the pathogenic fungi with different percentages. Bacillus megaterium and B. subtilis showed the highest percentage of fungal growth inhibition, while T. harzianum gave the lowest ones. At the field level, the application of bioagents significantly reduced the disease severity compared with untreated offshoots (control) in both locations. Bacillus megaterium and T. viride showed the highest protection against fungal causal agents, while B. cereus and T. harzianum gave the lowest ones in this respect. Moreover, the bioagents significantly improved the growth parameters of offshoots viz. plant height, number of leaves plant-1, leaflet number leaf-1, and leaf thickness. Bacillus megaterium and T. viride recorded the highest values of all growth parameters in El-Kharga and El-Dakhla locations, while B. cereus and T. harzianum gave the lowest ones.Â