Screening of Existing and New Boxwood Cultivars for Disease Resistance and In Vitro Fungicide Screening to Manage Boxwood Dieback Caused by Colletotrichum theobromicola

2021 ◽  
Author(s):  
Harleen Kaur ◽  
Monique DeSouza ◽  
Raghuwinder "Raj" Singh
Keyword(s):  
Active Ingredient ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Management Practices ◽  
Management Strategies ◽  
Host Susceptibility ◽  
Germination Inhibition ◽  
Industry Professionals ◽  
The U.S

Boxwood is one of the most common and widely planted perennial ornamentals in both home gardens and commercial landscapes. Recently reported boxwood dieback, a fungal disease caused by Colletotrichum theobromicola, has been spreading at an alarming rate within the U.S. Boxwood breeders, nursery growers, and landscape professionals have shown great concerns regarding the lack of effective management practices. Therefore, the primary objectives of this study were to devise effective disease management strategies including screening cultivars to determine their susceptibility to boxwood dieback and screening various fungicides to determine their effectiveness in managing the disease. Host range studies were conducted by screening a wide variety of boxwood cultivars under greenhouse conditions. Although, boxwood cultivar ‘Little Missy’ showed much delayed symptom expression as compared to rest of the cultivars but none of the 11 cultivars were found to be resistance to boxwood dieback. In vitro screening of nine fungicides was conducted to determine mycelial growth as well as spore germination inhibition of eight isolates of C. theobromicola collected from eight states in the U.S. Of the nine fungicides, difenoconazole+pydiflumetofen showed maximum mycelial growth and spore germination inhibition at 1 ppm active ingredient followed by fluxapyroxad+pyraclostrobin, and pyraclostrobin+boscalid at 5 ppm active ingredient. Azoxystrobin+benzovindiflupyr significantly inhibited mycelial growth at 1 ppm but reduced spore germination at 10 ppm active ingredient. This study provides the boxwood industry professionals with critical and applied information pertaining to host susceptibility and fungicide efficacy to effectively mitigate boxwood dieback and to reduce its further spread.

scholarly journals Inhibition of Pythium spp. and Suppression of Pythium Blight of Turfgrasses with Phosphonate Fungicides

Plant Disease ◽  
2009 ◽  
Vol 93 (8) ◽  
pp. 809-814 ◽  
Author(s):  
Phillip J. Cook ◽  
Peter J. Landschoot ◽  
Maxim J. Schlossberg
Keyword(s):  
Perennial Ryegrass ◽  
Active Ingredient ◽  
Mycelial Growth ◽  
Phosphorous Acid ◽  
Creeping Bentgrass ◽  
The United States ◽  
Effective Concentration ◽  
Significant Suppression ◽  
Inhibitory Effects

Pythium aphanidermatum and other Pythium spp. cause Pythium blight of turfgrasses in the United States. Phosphonate fungicides suppress Pythium blight when applied preventatively, but efficacy may vary with product, rate and timing of application, and host species. The objectives of this study were to assess the inhibitory effects of phosphorous acid on Pythium spp. in vitro, and determine if active ingredient and formulation of phosphonate fungicides provide similar levels of Pythium blight suppression on perennial ryegrass and creeping bentgrass when applied at equivalent rates of phosphorous acid. Phosphorous acid EC50 values (effective concentration that reduces mycelial growth by 50%) for P. aphanidermatum isolates ranged from 35.6 to 171.8 μg/ml. EC50 values for isolates of six other Pythium spp. were between 38.7 and 220.8 μg/ml. In 2004 and 2005, all phosphonate treatments provided significant suppression of Pythium blight symptoms on creeping bentgrass and perennial ryegrass relative to the untreated control. No differences in percentage of blighted turf occurred among phosphonate treatments when applied at equivalent rates of phosphorous acid in either year of the study, regardless of active ingredient, formulation, or turfgrass species.

scholarly journals Effect of Agrochemicals Used in the Cultivation of Soybean and Irrigated Rice on Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok

2019 ◽  
Vol 11 (17) ◽  
pp. 167
Author(s):  
Vanessa P. Gonçalves ◽  
Cândida R. J. de Farias ◽  
Victoria Moreira-Nunêz ◽  
Renata Moccellin ◽  
Viviana Gaviria-Hernández ◽  
...  
Keyword(s):  
Beauveria Bassiana ◽  
Entomopathogenic Fungi ◽  
Spore Germination ◽  
Metarhizium Anisopliae ◽  
Mycelial Growth ◽  
Potato Dextrose Agar ◽  
Irrigated Rice ◽  
Spray Method ◽  
Fungitoxic Effect

The objective of this work was to evaluate the fungitoxic effect of the agrochemicals used in the cultivation of soybean and irrigated rice on entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae by means of the mycelial growth, sporulation and spore germination. The isolates were inoculated in potato-dextrose-agar (PDA) medium containing the pesticides and exposed to spraying with the products. It was observed that chlorantraniliprole produced the best results regarding and was compatible with the two methods of contact of the product with the fungi. Flubendiamide it’s very toxic to fungi, producing 100% inhibition when incorporated into the medium, when by spraying, the fungus M. anisopliae got mycelial growth. Etofenprox and thiamethoxam changed their toxity classification according to the method of contact with product, was moderately compatible to B. bassiana and compatible to M. anisopliae and spinosad showed more compatibility with M. anisopliae than B. bassiana and was classified as compatible. Among fungicides the tricyclazole was the only compatible with the fungus by the spray method. The results showed that in vitro agrochemicals such as tricyclazole, thiamethoxam, flubendiamide and etofenprox are harmful to fungi. It was found that environmental interference could minimize the effects on organisms, especially when the chemicals are applied by spraying.

scholarly journals Antifungal Activity of Quinofumelin against Fusarium graminearum and Its Inhibitory Effect on DON Biosynthesis

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 348
Author(s):  
Qian Xiu ◽  
Lianyu Bi ◽  
Haorong Xu ◽  
Tao Li ◽  
Zehua Zhou ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Graminearum ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Marker Gene ◽  
Economic Loss ◽  
Inhibitory Effect ◽  
Head Blight ◽  
Excellent Control

Fusarium graminearum, causal agent of Fusarium head blight (FHB), causes a huge economic loss. No information is available on the activity of quinofumelin, a novel quinoline fungicide, against F. graminearum or other phytopathogens. In this study, we used mycelial growth and spore germination inhibition methods to determine the inhibitory effect of quinofumelin against F. graminearum in vitro. The results indicated that quinofumelin excellently inhibited mycelial growth and spore germination of F. graminearum, with the average EC50 values of 0.019±0.007 μg/mL and 0.087 ± 0.024 μg/mL, respectively. In addition, we found that quinofumelin could significantly decrease deoxynivalenol (DON) production and inhibit the expression of DON-related gene TRI5 in F. graminearum. Furthermore, we found that quinofumelin could disrupt the formation of Fusarium toxinsome, a structure for producing DON. Western blot analysis demonstrated that the translation level of TRI1, a marker gene for Fusarium toxinsome, was suppressed by quinofumelin. The protective and curative assays indicated that quinofumelin had an excellent control efficiency against F. graminearum on wheat coleoptiles. Taken together, quinofumelin exhibits not only an excellent antifungal activity on mycelial growth and spore germination, but also could inhibit DON biosynthesis in F. graminearum. The findings provide a novel candidate for controlling FHB caused by F. graminearum.

scholarly journals The effect of fungicides on spore germination, mycelial growth and lesion development of Phlyctema vagabunda (syn: Neofabraea alba) (bull’s eye rot of apples)

2017 ◽  
Vol 70 ◽  
pp. 112-119 ◽  
Author(s):  
P.N. Wood ◽  
B.M. Fisher
Keyword(s):  
Spore Germination ◽  
Mycelial Growth ◽  
Pathogenic Fungus ◽  
Apple Fruit ◽  
Fruit Rot ◽  
Copper Hydroxide ◽  
Lesion Development ◽  
Lime Sulphur ◽  
Bull's Eye

Phlyctema vagabunda (syn: Neofabraea alba) is a plant pathogenic fungus that causes bull’s eye rot on apples and pears. Phlyctema vagabunda fruit infections occur in orchards predominantly pre-harvest, and eventually express as a fruit rot after 4—5 months of cool storage. Twelve fungicides (captan, carbendazim, copper hydroxide, cyprodinil, difenoconazole, dithianon, dodine, isopyrazam, metiram, lime sulphur, sulphur and trifloxystrobin) were tested in vitro for their effects on spore germination and mycelial growth of P. vagabunda. Spore germination was inhibited by metiram, captan, dodine, dithianon, lime sulphur, carbendazim and isopyrazam, in order of effectiveness. Carbendazim, isopyrazam, difenoconazole and cyprodinil, in order of effectiveness, inhibited mycelial growth when used at label rates. Wettable sulphur was ineffective in both assays. On detached apple fruit, carbendazim, cyprodinil, trifloxystrobin and isopyrazam (in order of effectiveness) inhibited lesion development.

scholarly journals In vitro inhibition of Fusarium solani by Trichoderma harzianum and biofertilizer

2021 ◽  
Vol 10 (3) ◽  
pp. e5210312994
Author(s):  
Paula Fernanda de Azevedo ◽  
Ana Carolina de Almeida ◽  
Rodrigo Domiciano Marques ◽  
Christiane Luciana da Costa ◽  
Anderson Roberto Benedetti ◽  
...  
Keyword(s):  
Trichoderma Harzianum ◽  
Spore Germination ◽  
Fusarium Solani ◽  
Mycelial Growth ◽  
Culture Media ◽  
Antagonistic Activity ◽  
Dual Culture ◽  
Sporulation Rate ◽  
Biological Fertilizer

Cassava root rot causes significant production losses. Difficulties of management, along with the lack of chemical fungicides officially registered by the Ministry of Agriculture, Livestock and Supply (MAPA), require alternative control methods. This study investigated the in vitro antagonistic activity of Trichoderma harzianum as well as a biological fertilizer MICROGEO® on Fusarium solani. The phytophatogenic strains of F. solani, called F1 and F2 were isolated from rotted cassava tubers and T. harzianum, strain ESALQ 1306, from a biological fungicide. Continuous liquid composting of bovine ruminal content, water and MICROGEO® produced the biological fertilizer. Dual culture method was used at the bioassay with T. harzianum. Sterilized (St) and unsterilized (USt) biological fertilizer were tested in different concentrations (% v/v) diluted in the culture media. Colony diameters were measured daily in order to establish the mycelial growth velocity index, inhibition percentage, aside from the sporulation rate and spore germination percentage. The mycelial growth of F. solani isolates was interrupted after hyphae encounter with T. harzianum, due to the occurrence of mycoparasitism, but without influence on the sporulation rate. Sterilized biological fertilizer induced no biocontrol, whereas the unsterilized product (concentration 2.5%) inhibited approximately 64% and 85% of the mycelial growth of isolates F1 and F2, respectively. Moreover, spore germination declined with increasing concentration. In conclusion, T. harzianum and the unsterilized biofertilizer showed in vitro antagonistic activity on F. solani.

scholarly journals (E)-2-Hexenal Can Stimulate Botrytis cinerea Growth in vitro and on Strawberries in vivo during Storage

1998 ◽  
Vol 123 (5) ◽  
pp. 875-881 ◽  
Author(s):  
Elazar Fallik ◽  
Douglas D. Archbold ◽  
Thomas R. Hamilton-Kemp ◽  
Ann M. Clements ◽  
Randy W. Collins ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Spore Germination ◽  
Mode Of Action ◽  
Mycelial Growth ◽  
Titratable Acidity ◽  
Soluble Solids ◽  
In Vivo Studies ◽  
High Concentration

Some plant-derived natural volatile compounds exhibit antifungal properties and may offer an opportunity to control the causes of postharvest spoilage without affecting quality of, or leaving a residue on, fresh produce. The natural wound volatile (E)-2-hexenal has exhibited significant antifungal activity in earlier studies, but effects on spore germination and mycelial growth have not been separated, nor has the inhibitory mode of action been determined. To determine the efficacy of (E)-2-hexenal for control of Botrytis cinerea Pers. ex Fr. spore germination and mycelial growth, and to examine the mode of action, in vitro and in vivo studies were performed. Under in vitro bioassay conditions, spore germination was more sensitive to the compound than was mycelial growth. Vapor from 10.3 μmol of (E)-2-hexenal in a 120-mL petri dish completely inhibited spore germination. However, 85.6 μmol of (E)-2-hexenal was required to completely inhibit mycelial growth. Lower concentrations of the compound (5.4 and 10.3 μmol) significantly stimulated mycelial growth, especially when the volatile was added 2 days following inoculation. Mycelial growth did not occur as long as the vapor-phase concentration was 0.48 μmol·L-1 or greater. Light microscopy analysis indicated that a high concentration of volatile compound dehydrated fungal hyphae and disrupted their cell walls and membranes. Exposure of B. cinerea-inoculated and non-inoculated strawberry (Fragaria ×ananassa Duch.) fruit in 1.1-L low-density polyethylene film-wrapped containers to vapor of (E)-2-hexenal at 85.6 or 856 μmol (10 or 100 mL, respectively) per container for durations of 1, 4, or 7 days during 7 days of storage at 2 °C promoted the incidence of B. cinerea during subsequent shelf storage at 20 to 22 °C. Loss of fruit fresh mass and fruit firmness during storage at 22 °C was increased by (E)-2-hexenal treatment, but fruit total soluble solids, pH, titratable acidity, and color (L, C, and H values) were not affected. Thus, maintenance of a high vapor-phasel level of (E)-hexenal, perhaps >0.48 μmol·L-1, may be necessary to inhibit mycelial growth and avoid enhancing postharvest mold problems, while significantly higher levels may be necessary to completely eliminate the pathogen.

scholarly journals Fungitoxicity of the Pyroligneous Extract in the Development in vitro of Colletotrichum gloeosporioides

2020 ◽  
Vol 8 (4) ◽  
pp. 82
Author(s):  
Cleverson Rodrigues ◽  
João Aguilar Massaroto ◽  
Grace Queiroz David ◽  
Dilânia Lopes de Matos ◽  
Walmor Moya Peres ◽  
...  
Keyword(s):  
Spore Germination ◽  
Mycelial Growth ◽  
Colletotrichum Gloeosporioides ◽  
Tectona Grandis ◽  
Growth Speed ◽  
Randomized Design ◽  
Agar Media ◽  
Completely Randomized Design ◽  
Development In Vitro

Products derived from renewable sources have been studied for their use in agriculture enabling increments in the production of agricultural culture, such as in the case of the pyroligneous extract. The research aimed at evaluating the fungitoxic potential of the pyroligneous extract of teak (Tectona grandis L.) on mycelial growth, sporulation and spore germination of Colletotrichum gloeosporioides. The experiment was conducted in completely randomized design with five treatments and four replications. Five doses of pyroligneous extract were tested (0, 25, 50, 100, 150 mL L-1) following the pour-plate methodology in 10 mL of potato dextrose agar media and kept in the incubating room maintained at 25 ± 2 °C in a 12 hour-photoperiod for eight days. Mycelial growth variables (cm), mycelial index growth speed, growth inhibition (%), sporulation inhibition (%) and spore germination (%) were evaluated. There was a reduction for the mycelial growth as well as for the rate of mycelial growth, sporulation inhibition and spore germination as the doses were increased. The percentage inhibition of mycelial growth was 56 % for the highest dose (150 mL L-1). Pyroligneous extract of teak has a direct fungitoxic action on growth, sporulation and germination in vitro of the fungus C. gloeosporioides.

scholarly journals Evaluation of Fungicides and Management Strategies against Cercospora Leaf Spot of Olive Caused by Pseudocercospora cladosporioides

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 271
Author(s):  
Joaquín Romero ◽  
Arantxa Ávila ◽  
Carlos Agustí-Brisach ◽  
Luis F. Roca ◽  
Antonio Trapero
Keyword(s):  
Leaf Spot ◽  
Mycelial Growth ◽  
Management Strategies ◽  
Conidial Germination ◽  
Field Conditions ◽  
Cercospora Leaf Spot ◽  
Wide Range ◽  
Traditional Strategy ◽  
Mediterranean Conditions

Cercospora leaf spot of olive (CLSO), caused by Pseudocercospora cladosporioides, is one of the most important foliar diseases of olives worldwide. This study aimed to evaluate the effect of a wide range of fungicides on mycelial growth and conidial germination of P. cladosporioides in vitro, and to evaluate the effect of several fungicides, application timings and management strategies (conservative and risky) to control CLSO under field conditions. Of the studied fungicides, strobilurin compounds and benomyl were the most effective active ingredients, followed by folpet, captan and maneb, in inhibiting mycelial growth and conidial germination. The pyraclostrobin + boscalid treatment was effective under field conditions, even without the application of supplementary copper. Treatments conducted in October or March were more effective than those conducted in May. Management strategies based on the author’s experience reduced copper applications up to 32.0% and 50.0% (conservative and risky strategy, respectively) in comparison to the reduction with the traditional strategy, without increasing CLSO incidence. This work provides useful information about effective formulations against CLSO and a reduction in unnecessary fungicide applications in an effort to implement IPM in olive orchards under Mediterranean conditions.

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