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Essay / Management of root and bulb rot affecting some flower bulb production in Egypt
Table of contentsResults and discussionHost rangeLaboratory bulb testingGreenhouse testingResults and discussionIsolation, identification and frequency of fungi associated with infected lilium root and bulb rotSay no to plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”?Get the original essayTwo hundred and thirty-seven fungal isolates belonging to five genera and nine species were recovered from diseased lilium showing symptoms of rot roots and bulbs collected from different fields located in the governorate of Qaluobia. The isolated fungi were identified as Aspergillus niger Tiegh (3 isolates), Fusarium moniliforme J. Sheld (10 isolates), F. oxysporum Schltdl. (100 isolates), F. roseum Beck (20 isolates), F. semitectum Berk (11 isolates), F. solani (Mart.) Sacc. (16 isolates), Pythium spp. (Pringsh.) (45 isolates), Rhizoctonia solani Kühn (30 isolates) and Rhizopus arrizhus Fischer (2 isolates). The data in Table (1) indicate that the most dominant fungi were F. oxysporum (42.14%), followed by Pythium spp. (18.99%), R. solani (12.66%) and F. roseum (8.44%). Meanwhile, Rh. arrizhus recorded less frequency (0.84%). These results are in agreement with those obtained by Hilal et al. (1992); Wright (1998) and Ciampi et al. (2009) who found that 20% of fungi isolated from calla bulbs were Fusarium solani (Mart.) Sacc. and 80% were F. oxysporum Schltdl. In contrast, Mordechai-Sara et al. (2014) reported that leaf chlorosis, wilting, root and bulb rot of lilies grown in commercial greenhouses in Israel are mainly caused by Rhizoctonia AG-A, Pythium oligandrum and Fusarium proliferatum. Additionally, Lakshman et al. (2017) reported that eight fungal isolates were recovered from necrotic roots of Easter lily (Lilium longiflorum cv. Nellie White) and grown in a field in the Pacific Northwest of the United States. The eight fungal isolates identified by sequencing and molecular phylogenetic analyzes based on their ITS rDNA region. Five isolates were identified as Fusarium oxysporum, two as F. tricinctum and one as Rhizoctonia sp. AG-I.Sole fungi, i.e., oxysporum, F. roseum, R. solani and Pythium spp., infecting lilium were determined under greenhouse conditions. Figure (1) shows that F. oxysporum (31.25 and 37.50%, respectively 30 and 60 days after planting), followed by Pythium spp. (18.75 and 37.50%, respectively 30 and 60 days after planting), were the most virulent. F. roseum (18.75 and 25.00%, 30 and 60 days after planting, respectively), followed by R. solani (12.50 and 25.00%, 30 and 60 days after planting, respectively), were the weakest. These results are in agreement with those obtained by Hilal et al. (1992), Schineider et al. (2001), Elewa et al. (2001), Chase (2005), Palmero et al. (2014) and Mordechai-Sara et al. (2014) who reported that artificial inoculation of lily plants with each of R. solani AG-A, P. oligandrum, F. oxysporum and F. proliferatum resulted in chlorosis on lower leaves 7 days after inoculation. Eight weeks later, the symptoms became more severe and accompanied by wilting. Host range Two assays were carried out to test the ability of the tested fungi, namely F. oxysporum, F. roseum, R. solani and Pythium spp. to infect the bulbs of tulips, lilium, iris, calla and freesia either in the laboratory or in the greenhouse on plants grown: Laboratory bulb testsThe ability of the fungi tested to infect the bulbs of tulips, lilium, iris, calla and freesia has summerdetermined under laboratory conditions. The data in Table (2) show that the tested fungi differed in their pathogenic potential to infect the bulbs of the tested plants. F. oxysporum was the most virulent, resulting in disease severity of 83.33, 91.66, 83.33, 25.00, and 83.33%, respectively, for the plants tested. Pythium spp. followed by F. roseum ranked second. R. solani was the weakest fungal pathogen, giving 25, 25, 16.66, 8.33 and 25% disease severity, respectively. Additionally, lillium bulbs were the most susceptible to the pathogens tested, particularly F. oxysporum, with a disease severity of 91.66%. Meanwhile, calla was the least sensitive (Table 2). The high susceptibility of lilium bulbs to infection may be due to the characteristics of its bulbs, which do not have a structure of dry scales (tunic) to protect the bulbs from external factors. Additionally, lillium bulbs have a higher moisture content than other geophytes and they have thicker, succulent scales, which allows pathogens to easily enter cells through the scales (Sirin, 2011). Greenhouse testsUnder greenhouse conditions, the ability of the fungi tested, namely F. oxysporum, F. roseum, R. solani and Pythium spp. it has been determined to infect tulip, lilium, iris, calla and freesia. The data in Table (3) show that the four tested fungi differed in their pathogenic abilities to infect the tested bulbs. F. oxysporum and Pythium spp. were the most aggressive fungi on all bulbs tested, as they gave the highest infection percentages. In contrast, lilium and iris were the most sensitive, while calla bulbs were the least sensitive. These results are in agreement with those obtained by Wright (1998) and Ciampi et al. (2009). Elewa et al. (2001) reported that susceptibility testing of some bulbous ornamental plants to infection by F. oxysporum f. sp. Gladioli revealed that freesia and iris were the most susceptible hosts (100% infection), while lilium and tulip were the weakest hosts. Alternative against a number of pathogens for effective and sustainable management of diseases of several flower bulbs (Lu and Chen, 2005 and Luzzatto-Knaana and Yedidia, 2009). In this study, the effectiveness of two commercial bioformulations and two chemical inducers against root rot of lilium and calla caused by F. oxysporum was estimated by counting the percentage of infected plants 60 days after planting. The data in Table (4) indicate that all treatments tested significantly reduced disease incidence and increased the number of surviving plants compared to the untreated control. The decrease in disease percentages compared to the untreated control ranged from (9.90 to 40.00%) in lilium plants and (15.33 to 66.66%) in calla plants. The increase in number of surviving plants ranged from 16.50 to 66.66% and 10.0 to 40.0% for lilium and calla, respectively. Bio cure-B and followed by Bio cure-F were the best treatments at a significant level, while Chito Care was the least effective. These results are somewhat in agreement with those obtained by Elmer (2006) who reported that benzo (1, 2, 3)-thiadiazole-7-carbothiolic acid (BTH) protected gladiolus (Gladiolus hortulanus) bulbs against attacks of F. oxysporum f. . sp. gladioli. Also, Liu et al. (2008) reported that application of a cell suspension of Bacillus cereus strain C1L as a soil drench 24 h before Botrytis elliptica inoculation reduced disease severity by (40%) in Lilium seedlings. formosanum. Furthermore, Sirin, 2008).