In 2010, a foliar and stem-lesion disease that produced moderate to severe defoliation of watermelon was observed in the southern Great Plains. The disease was ultimately determined to be caused by Myrothecium roridum...In 2010, a foliar and stem-lesion disease that produced moderate to severe defoliation of watermelon was observed in the southern Great Plains. The disease was ultimately determined to be caused by Myrothecium roridum. The objective of this study was to compare the susceptibility of the vegetation and fruit of a broad range of commercially important cucurbits to three isolates obtained from these foliar lesions on watermelon. In greenhouse foliar inoculation experiments, cantaloupe, honeydew, cucumber, squash, and watermelon were susceptible to the fungus with cantaloupe and honeydew being the most susceptible and watermelon the most resistant. Furthermore, greenhouse inoculations supported earlier field observations as differential resistance was exhibited among the watermelon cultivars as well as the cucurbit types. All tested cucurbit fruit exhibited interior lesions when inoculated sub-epidermally with M. roridum isolates. However, natural infection of watermelon and pumpkin fruit has never been reported.展开更多
Previously we found that a strain of Myrothecium verrucaria (MV) exhibited bioherbicidal activity against several important weeds, and that some commercial formulations of glyphosate applied with MV resulted in synerg...Previously we found that a strain of Myrothecium verrucaria (MV) exhibited bioherbicidal activity against several important weeds, and that some commercial formulations of glyphosate applied with MV resulted in synergistic interactions that improved weed control efficacy. We also found that MV had bioherbicidal activity against glyphosate-resistant Palmer amaranth. We have also reported that some commercial formulations are inhibitory to MV. Our objectives were to test the effect of unformulated glyphosate (high purity, technical-grade glyphosate) alone and in combination with MV for bioherbicidal activity on glyphosate-susceptible and -resistant Palmer amaranth biotypes under greenhouse conditions and to examine technical-grade glyphosate on the growth of this bioherbicide. High purity glyphosate (without adjuvants/surfactants) was not toxic to MV growth and sporulation at concentrations up to 2.0 mM when grown on agar supplemented with the herbicide. Both biotypes were injured by MV and MV plus glyphosate treatments as early as 19 h after application (3 h after a dew period of 16 h). These injury effects increased and were more evident through the 6-day time course, when after 120 h the MV plus glyphosate treatment had killed all glyphosate-susceptible and -resistant plants. The interaction of glyphosate plus MV was synergistic toward the control of Palmer amaranth. Data strongly suggest that the active ingredient is responsible for the synergy previously found when this bioherbicide was combined with some commercial formulations of glyphosate. Results demonstrated that MV can control both glyphosate-resistant and -susceptible Palmer amaranth seedlings and act synergistically with high-purity glyphosate to provide improved weed control.展开更多
Comparative studies were conducted on mycelial preparations of the bioherbicide, Myrothecium verrucaria (MV) strain IMI 361690 and a recently discovered sector (MV-Sector BSH) of this fungus. The whitish sector was di...Comparative studies were conducted on mycelial preparations of the bioherbicide, Myrothecium verrucaria (MV) strain IMI 361690 and a recently discovered sector (MV-Sector BSH) of this fungus. The whitish sector was discovered, isolated, grown in pure culture on PDA and found to be a stable, non-spore producing mutant when cultured over several months under conditions that cause circadian sporulation during growth of its MV parent. Application of MV and MV-Sector BSH mycelial preparations to intact plants (hemp sesbania and sicklepod) and leaf discs (kudzu and glyphosate-resistant Palmer amaranth) showed that the sector efficacy was generally equal to, or slightly lower than MV. Bioassays of MV and this sector on seed germination and early growth of sicklepod and hemp sesbania seeds demonstrated that hemp sesbania seeds were slightly more sensitive to the fungus than sicklepod seeds and that the sector bioherbicidal activity was slightly less than that of MV. SDS-PAGE protein profiles of cellular extracts of MV and the sector and their respective culture supernatants showed several differences with respect to quantity and number of certain protein bands. Overall results showed that the isolate was a non-spore producing mutant with phytotoxicity to several weeds (including weeds tolerant or resistant to glyphosate), and that the phytotoxic effects were generally equivalent to those caused by MV treatment. Results of this first report of a non-sporulating MV mutant that suggest additional studies on protein analysis, and an extended weed host range under greenhouse and field conditions are needed in order to further evaluate its possible bioherbicidal potential.展开更多
The fungus Myrothecium verrucaria (Alb. & Schwein.) (MV), originally isolated from diseased sicklepod (Senna obtusifolia L.), has bioherbicial activity against kudzu and several other weeds when applied with low c...The fungus Myrothecium verrucaria (Alb. & Schwein.) (MV), originally isolated from diseased sicklepod (Senna obtusifolia L.), has bioherbicial activity against kudzu and several other weeds when applied with low concentrations of the surfactant Silwet L-77. To more fully understand the initial events of MV infection or disease progression, and to improve knowledge related to its mechanism of action, the effects of MV and its product (roridin A) on kudzu seedlings were examined at the ultrastructural level. Ultrastructural analysis of MV effects on kudzu seedlings revealed a rapid (~1 h after treatment) detachment of the protoplast from the cell wall and plasmodesmata appeared to be broken off and retained in the wall. These symptoms occurred well in advance of the appearance of any fungal growth structures. Some fungal growth was observed after severe tissue degeneration (24 to 48 h after treatment), but this occurred primarily at the extra-cellular location with respect to the kudzu tissues. Kudzu seedlings treated with roridin A, a trichothecene produced by the fungus, exhibited some symptoms similar to those induced by the fungus applied in spore formulations with surfactant. The overall results are the first to report the ultrastructural effects of this bioherbicide on plants and suggest that penetration of a phytotoxic substance(s) in the fungal formulation was facilitated by the surfactant, and that roridin A exerts phytotoxicity toward kudzu.展开更多
Kudzu is an exotic invasive weed in the southeastern U.S. that is difficult to control with current commercial herbicides. Some success for its control has been achieved using a bioherbicidal agent, Myrothecium verruc...Kudzu is an exotic invasive weed in the southeastern U.S. that is difficult to control with current commercial herbicides. Some success for its control has been achieved using a bioherbicidal agent, Myrothecium verrucaria (MV). Spore and mycelial formulations of MV were tested alone and in combination with glyphosate for control of kudzu (Pueraria lobata) under greenhouse and field conditions in naturally-infested areas. In greenhouse and field experiments, kudzu control increased as the concentration of spores or mycelia increased. Glyphosate alone provided 10%, 35%, 50% and 60% control in field experiments at 0.25, 0.50, 0.75 and 1.0X rates, respectively and MV alone spores provided 15%, 50%, 65% and 85% control at 0.25, 0.50, 0.75 and 1.0X rates, respectively. However, when MV spores were combined with glyphosate, significantly higher control occurred than that caused by either component alone. Similar levels of control were observed for MV mycelial formulations applied alone or with glyphosate at equivalent concentrations of the fungus. The rate of disease progression was more rapid and severe at all fungal spore or mycelial formulations and herbicide rates when these propagules were applied in combination with glyphosate. In field tests, 24 h after application, only 20% of kudzu plants were severely damaged by MV alone (0.25X), whereas 80% were severely diseased when MV spores and glyphosate were mixed and applied at 0.25X rates each. A similar trend occurred with the MV mycelial formulation applied at these rates. Synergist interactions on kudzu control were observed, especially when lower levels of MV (spores or mycelia) and glyphosate were combined and applied to kudzu in the greenhouse or in the field. These results suggest that it may be possible to incorporate glyphosate to improve the bioherbicidal control potential and reduce herbicide and inoculum requirements of M. verrucaria spores or mycelium for controlling kudzu.展开更多
The shelf-life of a bioherbicide product is an important factor with regard to its commercial potential. The bioherbicidal efficacy of freshly fermented Myrothecium verrucaria (strain IMI 368023) (MV) mycelia formulat...The shelf-life of a bioherbicide product is an important factor with regard to its commercial potential. The bioherbicidal efficacy of freshly fermented Myrothecium verrucaria (strain IMI 368023) (MV) mycelia formulations and MV mycelia preparations that had been freeze-dried and then stored at -20°C for 8 years was compared. Two concentrations of each formulation (1.0x and 0.5x) were tested, utilizing bioassays on seedlings of the weed, hemp sesbania (Sesbania exaltata) under greenhouse conditions or in darkness utilizing hydroponically grown seedlings. Freeze drying of freshly prepared MV mycelium produced a light, brownish-colored powder. Efficacy tests of this reconstituted 8-year-old dried material showed that some bioherbicidal activity was lost during long-term storage, i.e., ~20% and ~60% seedling dry weight reduction at the 1.0x and 0.5x rate, respectively. Although plant mortality was greater in the fresh mycelial preparations treatments versus the freeze-dried and stored samples at all time points in the time-course, the stored material still caused >80% mortality, 15 days after treatment. Comparative disease progression ratings also showed a similar trend. Overall results show that freeze-drying MV is a useful method to reduce the bulk and cumbersomeness of storing heavy liquid fermentation product, while retaining bioherbicidal activity. These findings increase the utility of this bioherbicide and offer the potential to use the dried material in soil treatments or in a more concentrated form than attainable via the fermented product.展开更多
A mycelial formulation of the bioherbicidal fungus Myrothecium verrucaria (Alb. & Schwein.) Ditmar: Fr. (MV) was tested alone and in combination with a commercially available glyphosate [N-(phosphonomethyl)glycine...A mycelial formulation of the bioherbicidal fungus Myrothecium verrucaria (Alb. & Schwein.) Ditmar: Fr. (MV) was tested alone and in combination with a commercially available glyphosate [N-(phosphonomethyl)glycine] (GLY) product for controlling the invasive vines, redvine [Brunnichia ovata (Walt.) Shinners], and trumpet creeper [Campsis radicans (L.) Seem. ex Bureau] in field experiments conducted near Stoneville, MS. Several application timing regimens were evaluated (Fall, Spring, Fall + Spring, and Spring + Fall). We found that a Fall + Spring application of MV + GLY controlled redvine and trumpet creeper by 95%, 12 days after the second treatment, through a synergistic interaction of the fungus and glyphosate. Disease symptomatology was characterized by rapid necrosis of leaf and stem tissues, with mortality occurring within 72 h. Neither glyphosate alone, nor MV alone, effectively controlled either weed species under any application timing regimen. No visual disease or herbicide damage occurred on glyphosate-resistant soybean plants in the treated test plots. These results suggest that some formulations of glyphosate, mixed with the bioherbicide MV, can effectively control redvine and trumpet creeper, two of the most troublesome weeds in the row crops of the Mississippi Delta region in the mid-southern U.S.展开更多
文摘In 2010, a foliar and stem-lesion disease that produced moderate to severe defoliation of watermelon was observed in the southern Great Plains. The disease was ultimately determined to be caused by Myrothecium roridum. The objective of this study was to compare the susceptibility of the vegetation and fruit of a broad range of commercially important cucurbits to three isolates obtained from these foliar lesions on watermelon. In greenhouse foliar inoculation experiments, cantaloupe, honeydew, cucumber, squash, and watermelon were susceptible to the fungus with cantaloupe and honeydew being the most susceptible and watermelon the most resistant. Furthermore, greenhouse inoculations supported earlier field observations as differential resistance was exhibited among the watermelon cultivars as well as the cucurbit types. All tested cucurbit fruit exhibited interior lesions when inoculated sub-epidermally with M. roridum isolates. However, natural infection of watermelon and pumpkin fruit has never been reported.
文摘Previously we found that a strain of Myrothecium verrucaria (MV) exhibited bioherbicidal activity against several important weeds, and that some commercial formulations of glyphosate applied with MV resulted in synergistic interactions that improved weed control efficacy. We also found that MV had bioherbicidal activity against glyphosate-resistant Palmer amaranth. We have also reported that some commercial formulations are inhibitory to MV. Our objectives were to test the effect of unformulated glyphosate (high purity, technical-grade glyphosate) alone and in combination with MV for bioherbicidal activity on glyphosate-susceptible and -resistant Palmer amaranth biotypes under greenhouse conditions and to examine technical-grade glyphosate on the growth of this bioherbicide. High purity glyphosate (without adjuvants/surfactants) was not toxic to MV growth and sporulation at concentrations up to 2.0 mM when grown on agar supplemented with the herbicide. Both biotypes were injured by MV and MV plus glyphosate treatments as early as 19 h after application (3 h after a dew period of 16 h). These injury effects increased and were more evident through the 6-day time course, when after 120 h the MV plus glyphosate treatment had killed all glyphosate-susceptible and -resistant plants. The interaction of glyphosate plus MV was synergistic toward the control of Palmer amaranth. Data strongly suggest that the active ingredient is responsible for the synergy previously found when this bioherbicide was combined with some commercial formulations of glyphosate. Results demonstrated that MV can control both glyphosate-resistant and -susceptible Palmer amaranth seedlings and act synergistically with high-purity glyphosate to provide improved weed control.
文摘Comparative studies were conducted on mycelial preparations of the bioherbicide, Myrothecium verrucaria (MV) strain IMI 361690 and a recently discovered sector (MV-Sector BSH) of this fungus. The whitish sector was discovered, isolated, grown in pure culture on PDA and found to be a stable, non-spore producing mutant when cultured over several months under conditions that cause circadian sporulation during growth of its MV parent. Application of MV and MV-Sector BSH mycelial preparations to intact plants (hemp sesbania and sicklepod) and leaf discs (kudzu and glyphosate-resistant Palmer amaranth) showed that the sector efficacy was generally equal to, or slightly lower than MV. Bioassays of MV and this sector on seed germination and early growth of sicklepod and hemp sesbania seeds demonstrated that hemp sesbania seeds were slightly more sensitive to the fungus than sicklepod seeds and that the sector bioherbicidal activity was slightly less than that of MV. SDS-PAGE protein profiles of cellular extracts of MV and the sector and their respective culture supernatants showed several differences with respect to quantity and number of certain protein bands. Overall results showed that the isolate was a non-spore producing mutant with phytotoxicity to several weeds (including weeds tolerant or resistant to glyphosate), and that the phytotoxic effects were generally equivalent to those caused by MV treatment. Results of this first report of a non-sporulating MV mutant that suggest additional studies on protein analysis, and an extended weed host range under greenhouse and field conditions are needed in order to further evaluate its possible bioherbicidal potential.
文摘The fungus Myrothecium verrucaria (Alb. & Schwein.) (MV), originally isolated from diseased sicklepod (Senna obtusifolia L.), has bioherbicial activity against kudzu and several other weeds when applied with low concentrations of the surfactant Silwet L-77. To more fully understand the initial events of MV infection or disease progression, and to improve knowledge related to its mechanism of action, the effects of MV and its product (roridin A) on kudzu seedlings were examined at the ultrastructural level. Ultrastructural analysis of MV effects on kudzu seedlings revealed a rapid (~1 h after treatment) detachment of the protoplast from the cell wall and plasmodesmata appeared to be broken off and retained in the wall. These symptoms occurred well in advance of the appearance of any fungal growth structures. Some fungal growth was observed after severe tissue degeneration (24 to 48 h after treatment), but this occurred primarily at the extra-cellular location with respect to the kudzu tissues. Kudzu seedlings treated with roridin A, a trichothecene produced by the fungus, exhibited some symptoms similar to those induced by the fungus applied in spore formulations with surfactant. The overall results are the first to report the ultrastructural effects of this bioherbicide on plants and suggest that penetration of a phytotoxic substance(s) in the fungal formulation was facilitated by the surfactant, and that roridin A exerts phytotoxicity toward kudzu.
文摘Kudzu is an exotic invasive weed in the southeastern U.S. that is difficult to control with current commercial herbicides. Some success for its control has been achieved using a bioherbicidal agent, Myrothecium verrucaria (MV). Spore and mycelial formulations of MV were tested alone and in combination with glyphosate for control of kudzu (Pueraria lobata) under greenhouse and field conditions in naturally-infested areas. In greenhouse and field experiments, kudzu control increased as the concentration of spores or mycelia increased. Glyphosate alone provided 10%, 35%, 50% and 60% control in field experiments at 0.25, 0.50, 0.75 and 1.0X rates, respectively and MV alone spores provided 15%, 50%, 65% and 85% control at 0.25, 0.50, 0.75 and 1.0X rates, respectively. However, when MV spores were combined with glyphosate, significantly higher control occurred than that caused by either component alone. Similar levels of control were observed for MV mycelial formulations applied alone or with glyphosate at equivalent concentrations of the fungus. The rate of disease progression was more rapid and severe at all fungal spore or mycelial formulations and herbicide rates when these propagules were applied in combination with glyphosate. In field tests, 24 h after application, only 20% of kudzu plants were severely damaged by MV alone (0.25X), whereas 80% were severely diseased when MV spores and glyphosate were mixed and applied at 0.25X rates each. A similar trend occurred with the MV mycelial formulation applied at these rates. Synergist interactions on kudzu control were observed, especially when lower levels of MV (spores or mycelia) and glyphosate were combined and applied to kudzu in the greenhouse or in the field. These results suggest that it may be possible to incorporate glyphosate to improve the bioherbicidal control potential and reduce herbicide and inoculum requirements of M. verrucaria spores or mycelium for controlling kudzu.
文摘The shelf-life of a bioherbicide product is an important factor with regard to its commercial potential. The bioherbicidal efficacy of freshly fermented Myrothecium verrucaria (strain IMI 368023) (MV) mycelia formulations and MV mycelia preparations that had been freeze-dried and then stored at -20°C for 8 years was compared. Two concentrations of each formulation (1.0x and 0.5x) were tested, utilizing bioassays on seedlings of the weed, hemp sesbania (Sesbania exaltata) under greenhouse conditions or in darkness utilizing hydroponically grown seedlings. Freeze drying of freshly prepared MV mycelium produced a light, brownish-colored powder. Efficacy tests of this reconstituted 8-year-old dried material showed that some bioherbicidal activity was lost during long-term storage, i.e., ~20% and ~60% seedling dry weight reduction at the 1.0x and 0.5x rate, respectively. Although plant mortality was greater in the fresh mycelial preparations treatments versus the freeze-dried and stored samples at all time points in the time-course, the stored material still caused >80% mortality, 15 days after treatment. Comparative disease progression ratings also showed a similar trend. Overall results show that freeze-drying MV is a useful method to reduce the bulk and cumbersomeness of storing heavy liquid fermentation product, while retaining bioherbicidal activity. These findings increase the utility of this bioherbicide and offer the potential to use the dried material in soil treatments or in a more concentrated form than attainable via the fermented product.
文摘A mycelial formulation of the bioherbicidal fungus Myrothecium verrucaria (Alb. & Schwein.) Ditmar: Fr. (MV) was tested alone and in combination with a commercially available glyphosate [N-(phosphonomethyl)glycine] (GLY) product for controlling the invasive vines, redvine [Brunnichia ovata (Walt.) Shinners], and trumpet creeper [Campsis radicans (L.) Seem. ex Bureau] in field experiments conducted near Stoneville, MS. Several application timing regimens were evaluated (Fall, Spring, Fall + Spring, and Spring + Fall). We found that a Fall + Spring application of MV + GLY controlled redvine and trumpet creeper by 95%, 12 days after the second treatment, through a synergistic interaction of the fungus and glyphosate. Disease symptomatology was characterized by rapid necrosis of leaf and stem tissues, with mortality occurring within 72 h. Neither glyphosate alone, nor MV alone, effectively controlled either weed species under any application timing regimen. No visual disease or herbicide damage occurred on glyphosate-resistant soybean plants in the treated test plots. These results suggest that some formulations of glyphosate, mixed with the bioherbicide MV, can effectively control redvine and trumpet creeper, two of the most troublesome weeds in the row crops of the Mississippi Delta region in the mid-southern U.S.
