Pub Date : 2023-03-29DOI: 10.1094/php-11-22-0115-br
Paula Andrea Gómez-Zapata, D. Davis, C. Aimé
Pennsylvania is the fourth largest Christmas-tree-producing state in the USA, with annual sales of more than $22 million. During the summers of 2018 and 2019, a rust disease was observed on the leaves of balsam fir, Canaan fir, white fir, and sensitive fern in a Christmas tree crop in PA, USA. The specimens were sent to the Arthur Fungarium at Purdue University for further identification and long-term deposit. Based on morphological characteristics and sequence analysis, the rust species was identified as Uredinopsis osmundae. To our knowledge, this is the first report of Uredinopsis osmundae on balsam fir, Canaan fir, white fir, and sensitive fern in PA.
{"title":"Rust disease caused by Uredinopsis osmundae on balsam fir, Canaan fir, white fir, and sensitive fern reported from Pennsylvania, USA","authors":"Paula Andrea Gómez-Zapata, D. Davis, C. Aimé","doi":"10.1094/php-11-22-0115-br","DOIUrl":"https://doi.org/10.1094/php-11-22-0115-br","url":null,"abstract":"Pennsylvania is the fourth largest Christmas-tree-producing state in the USA, with annual sales of more than $22 million. During the summers of 2018 and 2019, a rust disease was observed on the leaves of balsam fir, Canaan fir, white fir, and sensitive fern in a Christmas tree crop in PA, USA. The specimens were sent to the Arthur Fungarium at Purdue University for further identification and long-term deposit. Based on morphological characteristics and sequence analysis, the rust species was identified as Uredinopsis osmundae. To our knowledge, this is the first report of Uredinopsis osmundae on balsam fir, Canaan fir, white fir, and sensitive fern in PA.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47000153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-23DOI: 10.1094/php-01-23-0002-rv
Chuang Hong
Boxwood blight caused by Calonectria pseudonaviculata and leafminer (Monarthropalpus flavus) are the primary boxwood disease and pest. This review summarizes the latest studies evaluating boxwood cultivars and selections against boxwood blight and/or leafminer in hope to facilitate adoption of identified cultivars with resistance to both, fast tracking the nation onto a more sustainable path towards healthy production and gardening of this iconic landscape plant.
{"title":"Building Health into New Boxwood Crops and Plantings by Making Informed Cultivar Selection","authors":"Chuang Hong","doi":"10.1094/php-01-23-0002-rv","DOIUrl":"https://doi.org/10.1094/php-01-23-0002-rv","url":null,"abstract":"Boxwood blight caused by Calonectria pseudonaviculata and leafminer (Monarthropalpus flavus) are the primary boxwood disease and pest. This review summarizes the latest studies evaluating boxwood cultivars and selections against boxwood blight and/or leafminer in hope to facilitate adoption of identified cultivars with resistance to both, fast tracking the nation onto a more sustainable path towards healthy production and gardening of this iconic landscape plant.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41655099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-23DOI: 10.1094/php-12-22-0123-rs
P. Lujan, S. Dura, Ivette Guzmán, R. Steiner, S. Sanogo
The use of plant-derived secondary metabolites to induce disease resistance in plants has been well documented. In this study, total phenolics and total proanthocyanidins (PAC) were extracted from shell and husk of pecan (Carya illinoinensis) and quantified. Under greenhouse conditions, the extracts were foliarly applied to chile pepper (Capsicum annuum, cultivar NM 6-4) to compare their ability to induce resistance in plants inoculated with a virulent isolate of Phytophthora capsici. Extractions yielded total phenolic contents of 673 ± 28 mg/g and 293 ± 24 mg/g dry weight (DW) for shell and husk and total PAC contents of 1770.10 ± 158.62 mg/g DW and 901.30 ± 22.84 mg/g DW for shell and husk, respectively. Chile plants treated with total phenolic and PAC extracts from pecan husk or shell or 0.1% salicylic acid, a plant defense hormone, remained asymptomatic throughout the study for three weeks, while plants treated with water, which served as a control, died. Both total phenolic and total PAC extracts derived from pecan byproducts can be used within a greenhouse setting as elicitors to induce resistance response in chile pepper against plant pathogens such as P. capsici.
{"title":"Comparison of Proanthocyanidin and Phenolic Rich Extracts Derived from Pecan Shell and Husk as Elicitors of Induced Resistance against Phytophthora capsici on Chile Pepper","authors":"P. Lujan, S. Dura, Ivette Guzmán, R. Steiner, S. Sanogo","doi":"10.1094/php-12-22-0123-rs","DOIUrl":"https://doi.org/10.1094/php-12-22-0123-rs","url":null,"abstract":"The use of plant-derived secondary metabolites to induce disease resistance in plants has been well documented. In this study, total phenolics and total proanthocyanidins (PAC) were extracted from shell and husk of pecan (Carya illinoinensis) and quantified. Under greenhouse conditions, the extracts were foliarly applied to chile pepper (Capsicum annuum, cultivar NM 6-4) to compare their ability to induce resistance in plants inoculated with a virulent isolate of Phytophthora capsici. Extractions yielded total phenolic contents of 673 ± 28 mg/g and 293 ± 24 mg/g dry weight (DW) for shell and husk and total PAC contents of 1770.10 ± 158.62 mg/g DW and 901.30 ± 22.84 mg/g DW for shell and husk, respectively. Chile plants treated with total phenolic and PAC extracts from pecan husk or shell or 0.1% salicylic acid, a plant defense hormone, remained asymptomatic throughout the study for three weeks, while plants treated with water, which served as a control, died. Both total phenolic and total PAC extracts derived from pecan byproducts can be used within a greenhouse setting as elicitors to induce resistance response in chile pepper against plant pathogens such as P. capsici.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42037382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-22DOI: 10.1094/php-10-22-0112-rs
F. Rotondo, Nitika Khatri, A. Testen, S. Miller
Bacterial canker of tomato, caused by the systemic bacterial phytopathogen Clavibacter michiganensis, can result in significant economic losses in hydroponic tomato production systems. Lacking effective bactericides, the disease is managed primarily by clean seed procedures, sanitation and quarantine. Plant extracts have been shown to display antimicrobial activity and/or induce plant resistance to disease. We tested the efficacy of AOMMA-Agro, an Organic Materials Review Institute (OMRI)-listed proprietary blend of plant extracts, in suppressing bacterial canker and improving yield and shelf life in hydroponic tomato trials over two years. Experiments were conducted in a greenhouse with ‘Campari’ tomatoes transplanted into coconut coir blocks and grown under hydroponic conditions. Plants were trellised, pruned and harvested according to commercial standards. AOMMA-Agro was applied weekly or biweekly as a foliar spray and inoculated with C. michiganensis. Plants treated with water and inoculated or not inoculated served as controls. Disease severity was relatively low in both years, however disease progress was significantly lower for plants inoculated and treated bi-weekly, but not weekly, with AOMMA-Agro than non-treated, non-inoculated plants in one of two trials. Similar results were observed in C. michiganensis incidence determined using qPCR. Marketable yield was 29% and 44% higher from inoculated plants treated bi-weekly with AOMMA-Agro than from non-treated, non-inoculated plants in the two experiments. These results support the use of AOMMA-Agro as a potential option for bacterial canker management and yield enhancement in hydroponic tomato greenhouse production systems.
{"title":"Evaluation of a proprietary plant extract to suppress bacterial canker and improve yield in hydroponic tomatoes","authors":"F. Rotondo, Nitika Khatri, A. Testen, S. Miller","doi":"10.1094/php-10-22-0112-rs","DOIUrl":"https://doi.org/10.1094/php-10-22-0112-rs","url":null,"abstract":"Bacterial canker of tomato, caused by the systemic bacterial phytopathogen Clavibacter michiganensis, can result in significant economic losses in hydroponic tomato production systems. Lacking effective bactericides, the disease is managed primarily by clean seed procedures, sanitation and quarantine. Plant extracts have been shown to display antimicrobial activity and/or induce plant resistance to disease. We tested the efficacy of AOMMA-Agro, an Organic Materials Review Institute (OMRI)-listed proprietary blend of plant extracts, in suppressing bacterial canker and improving yield and shelf life in hydroponic tomato trials over two years. Experiments were conducted in a greenhouse with ‘Campari’ tomatoes transplanted into coconut coir blocks and grown under hydroponic conditions. Plants were trellised, pruned and harvested according to commercial standards. AOMMA-Agro was applied weekly or biweekly as a foliar spray and inoculated with C. michiganensis. Plants treated with water and inoculated or not inoculated served as controls. Disease severity was relatively low in both years, however disease progress was significantly lower for plants inoculated and treated bi-weekly, but not weekly, with AOMMA-Agro than non-treated, non-inoculated plants in one of two trials. Similar results were observed in C. michiganensis incidence determined using qPCR. Marketable yield was 29% and 44% higher from inoculated plants treated bi-weekly with AOMMA-Agro than from non-treated, non-inoculated plants in the two experiments. These results support the use of AOMMA-Agro as a potential option for bacterial canker management and yield enhancement in hydroponic tomato greenhouse production systems.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42483380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-21DOI: 10.1094/php-09-22-0085-rs
E. Pfeufer, William B. Barlow, Bob Pearce
Phytophthora-induced plant diseases are most effectively managed using an integrated strategy that includes host resistance, best cultural practices, and fungicide applications. Black shank, caused by Phytophthora nicotianae, is the most significant soilborne disease affecting tobacco, and extensive breeding for resistance has resulted in an array of varieties with a spectrum of black shank resistance. Estimates of plant survival are the most common measurement in tobacco black shank trials, however, survival may not be the most accurate indicator of yield for varieties with robust resistance. Through the presented analyses, at-harvest green yield estimates are shown to be more closely associated with cured tobacco yields than survival counts, irrespective of black shank resistance status. However, green yield may only be considered a standalone yield predictor for low resistance varieties, with other factors likely contributing to cured yield of moderate and high resistance varieties. This prevents development of a unified (variety-nonspecific) cured yield model, which would be useful not only for tobacco scientists, but also commercial growers in planning labor activities and the industry at-large in managing cured tobacco inventory. More broadly, this suggests that research in other Phytophthora pathosystems may benefit from yield estimates in addition to survival counts in resistant variety evaluations.
{"title":"Green yield as a potential predictor of cured burley tobacco yield in a Phytophthora nicotianae-infested field over four seasons","authors":"E. Pfeufer, William B. Barlow, Bob Pearce","doi":"10.1094/php-09-22-0085-rs","DOIUrl":"https://doi.org/10.1094/php-09-22-0085-rs","url":null,"abstract":"Phytophthora-induced plant diseases are most effectively managed using an integrated strategy that includes host resistance, best cultural practices, and fungicide applications. Black shank, caused by Phytophthora nicotianae, is the most significant soilborne disease affecting tobacco, and extensive breeding for resistance has resulted in an array of varieties with a spectrum of black shank resistance. Estimates of plant survival are the most common measurement in tobacco black shank trials, however, survival may not be the most accurate indicator of yield for varieties with robust resistance. Through the presented analyses, at-harvest green yield estimates are shown to be more closely associated with cured tobacco yields than survival counts, irrespective of black shank resistance status. However, green yield may only be considered a standalone yield predictor for low resistance varieties, with other factors likely contributing to cured yield of moderate and high resistance varieties. This prevents development of a unified (variety-nonspecific) cured yield model, which would be useful not only for tobacco scientists, but also commercial growers in planning labor activities and the industry at-large in managing cured tobacco inventory. More broadly, this suggests that research in other Phytophthora pathosystems may benefit from yield estimates in addition to survival counts in resistant variety evaluations.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46673967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-14DOI: 10.1094/php-10-22-0097-rs
Ateet Maharjan, Jobelle Bruno, S. Osti, I. Barphagha, J. Ham
Sheath blight (ShB), caused by Rhizoctonia solani, is one of the economically important rice diseases in Louisiana and other rice-growing regions. Fungicides are used to manage ShB but such chemical methods are not economically or ecologically sustainable. To develop new biological control agents for the management of ShB, bacteria isolated from rice plants in the field were initially screened in the laboratory based on their antagonistic activities against R. solani through plate assays that exhibit growth inhibition of the fungal pathogen. Efficacy of three selected strains of Bacillus spp. (RAB14R, REB711, and RRB985) in suppression of ShB was further evaluated under the greenhouse and field conditions. In field trials conducted in 2017 and 2018, foliar spray of Bacillus sp. REB711 significantly reduced the development of ShB compared to the non-treated control, although it was less effective than the azoxystrobin fungicide Quadris®. In greenhouse tests, Bacillus sp. REB711 significantly reduced ShB development (disease severity and lesion length) through seed treatment, while the other two strains of Bacillus spp. did not. The observed efficacy of Bacillus sp. REB711 could result from competition, antibiosis, and/or induction of plant defense system, and suggests that this bacterial strain could be used a potential biological agent for managing ShB by itself or in combination with fungicides to reduce the risk of fungicide resistance.
{"title":"Biological control efficacy of Bacillus sp. REB711 on sheath blight of rice","authors":"Ateet Maharjan, Jobelle Bruno, S. Osti, I. Barphagha, J. Ham","doi":"10.1094/php-10-22-0097-rs","DOIUrl":"https://doi.org/10.1094/php-10-22-0097-rs","url":null,"abstract":"Sheath blight (ShB), caused by Rhizoctonia solani, is one of the economically important rice diseases in Louisiana and other rice-growing regions. Fungicides are used to manage ShB but such chemical methods are not economically or ecologically sustainable. To develop new biological control agents for the management of ShB, bacteria isolated from rice plants in the field were initially screened in the laboratory based on their antagonistic activities against R. solani through plate assays that exhibit growth inhibition of the fungal pathogen. Efficacy of three selected strains of Bacillus spp. (RAB14R, REB711, and RRB985) in suppression of ShB was further evaluated under the greenhouse and field conditions. In field trials conducted in 2017 and 2018, foliar spray of Bacillus sp. REB711 significantly reduced the development of ShB compared to the non-treated control, although it was less effective than the azoxystrobin fungicide Quadris®. In greenhouse tests, Bacillus sp. REB711 significantly reduced ShB development (disease severity and lesion length) through seed treatment, while the other two strains of Bacillus spp. did not. The observed efficacy of Bacillus sp. REB711 could result from competition, antibiosis, and/or induction of plant defense system, and suggests that this bacterial strain could be used a potential biological agent for managing ShB by itself or in combination with fungicides to reduce the risk of fungicide resistance.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48328771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-07DOI: 10.1094/php-07-22-0063-rs
A. Ajitomi, Mohanmad Ashik Iqbal Khan, Thi Nhai Nguyen, Thi Oanh Nguyen, Y. Fukuta
Rice ( Oryza sativa L.) is a major crop, and blast ( Pyricularia oryzae Cavara) has been the most serious disease in Japan. Ninety-seven rice blast isolates were collected from the Ryukyu Archipelago, including Okinawa Main Island (OK) and Yaeyama Islands (YA), in Japan's southern region. The pathogenicities of blast isolates were clarified by an inoculation test based on the resistance reaction patterns to differential varieties (DVs) and a susceptible control, Lijiangxintuanheigu (LTH). Virulent isolates occurred with high frequencies to LTH and DVs for Pish, Pia, Pii, Pi3, Pik-s, and Pi19(t). The DVs for Pib, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Pi9(t), Piz, Piz-5, Piz-t, Pita-2 (two lines), Pil2(t), and Pi20(t) had low frequencies, and those for Pit, Pi5(t), and Pita (two lines) had intermediate frequencies. These isolates were classified into two groups (I and II) based on the reaction patterns to DVs by cluster analysis. The virulence of the blast isolates from cluster II against DVs for Pit, Pi5(t), Pita (two lines), and Pi20(t) was much greater than that of those in cluster I. Cluster I blast isolates were distributed dominantly in OK, and those of cluster II were in YA. This is the first report on the distribution of blast races in the Ryukyu Archipelago in Japan. This information will be useful for developing sustainable protection systems and rice breeding against blast disease.
{"title":"Pathogenicity of Rice Blast (Pyricularia oryzae) Isolates from the Ryukyu Archipelago, Okinawa, in Southern Japan","authors":"A. Ajitomi, Mohanmad Ashik Iqbal Khan, Thi Nhai Nguyen, Thi Oanh Nguyen, Y. Fukuta","doi":"10.1094/php-07-22-0063-rs","DOIUrl":"https://doi.org/10.1094/php-07-22-0063-rs","url":null,"abstract":"Rice ( Oryza sativa L.) is a major crop, and blast ( Pyricularia oryzae Cavara) has been the most serious disease in Japan. Ninety-seven rice blast isolates were collected from the Ryukyu Archipelago, including Okinawa Main Island (OK) and Yaeyama Islands (YA), in Japan's southern region. The pathogenicities of blast isolates were clarified by an inoculation test based on the resistance reaction patterns to differential varieties (DVs) and a susceptible control, Lijiangxintuanheigu (LTH). Virulent isolates occurred with high frequencies to LTH and DVs for Pish, Pia, Pii, Pi3, Pik-s, and Pi19(t). The DVs for Pib, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Pi9(t), Piz, Piz-5, Piz-t, Pita-2 (two lines), Pil2(t), and Pi20(t) had low frequencies, and those for Pit, Pi5(t), and Pita (two lines) had intermediate frequencies. These isolates were classified into two groups (I and II) based on the reaction patterns to DVs by cluster analysis. The virulence of the blast isolates from cluster II against DVs for Pit, Pi5(t), Pita (two lines), and Pi20(t) was much greater than that of those in cluster I. Cluster I blast isolates were distributed dominantly in OK, and those of cluster II were in YA. This is the first report on the distribution of blast races in the Ryukyu Archipelago in Japan. This information will be useful for developing sustainable protection systems and rice breeding against blast disease.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44346208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-06DOI: 10.1094/php-01-23-0010-sc
Liza DeGenring, Anissa Poleatewich
Modern greenhouse crop production utilizes soilless substrates that range from inorganic substrates (Oasis foam and rockwool) to blends of organic substrates (sphagnum peat moss, coconut-fiber, bark mulch, wood chips, and wood products). Additionally, greenhouse growers utilize beneficial microorganisms in the form of commercial biopesticides to reduce disease. Few research studies have examined the effect of propagation substrate on the efficacy of commercial biopesticides under greenhouse production conditions. The objective of this study was to evaluate the effect of propagation substrates on commercially available microbial biopesticides (Rootshield WP, Cease, and Regalia) applied in propagation and at transplant for management of Pythium root rot. In this study, cucumber and calibrachoa were used as model crops. Over both cropping systems, plants propagated in Oasis foam had lower root rot compared to plants propagated in coconut coir. Across all biopesticide treatments, cucumber plants propagated in Oasis foam had 52% less root rot compared to plants propagated in coconut coir. In both infested and non-infested calibrachoa plants, plants propagated in Oasis foam had 45% to 67% less disease and plants propagated in peat had 25% to 40% less disease compared to plants propagated in coconut coir. There was no effect of biopesticide on Pythium root rot severity except for a reduction seen in calibrachoa plants propagated in coconut coir and treated with Rootshield WP. This research suggests that propagation substrate is important for root disease management.
{"title":"The effect of propagation substrate on Pythium root rot severity and the efficacy of biopesticides","authors":"Liza DeGenring, Anissa Poleatewich","doi":"10.1094/php-01-23-0010-sc","DOIUrl":"https://doi.org/10.1094/php-01-23-0010-sc","url":null,"abstract":"Modern greenhouse crop production utilizes soilless substrates that range from inorganic substrates (Oasis foam and rockwool) to blends of organic substrates (sphagnum peat moss, coconut-fiber, bark mulch, wood chips, and wood products). Additionally, greenhouse growers utilize beneficial microorganisms in the form of commercial biopesticides to reduce disease. Few research studies have examined the effect of propagation substrate on the efficacy of commercial biopesticides under greenhouse production conditions. The objective of this study was to evaluate the effect of propagation substrates on commercially available microbial biopesticides (Rootshield WP, Cease, and Regalia) applied in propagation and at transplant for management of Pythium root rot. In this study, cucumber and calibrachoa were used as model crops. Over both cropping systems, plants propagated in Oasis foam had lower root rot compared to plants propagated in coconut coir. Across all biopesticide treatments, cucumber plants propagated in Oasis foam had 52% less root rot compared to plants propagated in coconut coir. In both infested and non-infested calibrachoa plants, plants propagated in Oasis foam had 45% to 67% less disease and plants propagated in peat had 25% to 40% less disease compared to plants propagated in coconut coir. There was no effect of biopesticide on Pythium root rot severity except for a reduction seen in calibrachoa plants propagated in coconut coir and treated with Rootshield WP. This research suggests that propagation substrate is important for root disease management.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47363699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-06DOI: 10.1094/php-08-22-0078-rs
A. I. Zuniga, Nan-Yi Wang, N. Peres
Nursery transplants have been reported as one of the major sources of Botrytis cinerea primary inoculum causing Botrytis fruit rot (BFR) of strawberry in Florida. In this study, we evaluated the efficacy of heat treatment to reduce Botrytis spp. on strawberry transplants. In laboratory experiments, conidia and sclerotia of four isolates with different fungicide resistance phenotypes were exposed to 44, 48, 52, and 56°C for 1, 5, 10, 30, 60 (1 h), 120 (2 h), and 240 (4 h) min. Conidial germination was completely inhibited after exposure for 5 min at 48°C or higher temperatures, or after 30 min at 44°C. Sclerotial germination varied for different isolates but in general required higher exposure times and temperature for inhibition. Based on a previous protocol developed to target Xanthomonas fragariae, strawberry transplants were treated at 44°C for 2 or 4 h with or without a pre-heat step of 37°C for 1 h and a cooling step of 1 h. After exposure to the heat treatments, detached leaf assays showed the treatments significantly reduced pathogen incidence on leaves. Treatments at 44°C for 4 h, with or without pre-heat, significantly reduced Botrytis spp. incidence by 95.3 to 100% on non-inoculated and 88.9 to 100% on inoculated transplants. In field trials, early fruit production was not affected by the heat treatments. Our results suggest that heat treatment could reduce the inoculum load of Botrytis spp. on strawberry transplants and potentially help improving the efficacy of fungicides to control the disease in production fields.
{"title":"Heat Treatment as a Possible Means to Reduce Botrytis Inoculum on Strawberry Transplants","authors":"A. I. Zuniga, Nan-Yi Wang, N. Peres","doi":"10.1094/php-08-22-0078-rs","DOIUrl":"https://doi.org/10.1094/php-08-22-0078-rs","url":null,"abstract":"Nursery transplants have been reported as one of the major sources of Botrytis cinerea primary inoculum causing Botrytis fruit rot (BFR) of strawberry in Florida. In this study, we evaluated the efficacy of heat treatment to reduce Botrytis spp. on strawberry transplants. In laboratory experiments, conidia and sclerotia of four isolates with different fungicide resistance phenotypes were exposed to 44, 48, 52, and 56°C for 1, 5, 10, 30, 60 (1 h), 120 (2 h), and 240 (4 h) min. Conidial germination was completely inhibited after exposure for 5 min at 48°C or higher temperatures, or after 30 min at 44°C. Sclerotial germination varied for different isolates but in general required higher exposure times and temperature for inhibition. Based on a previous protocol developed to target Xanthomonas fragariae, strawberry transplants were treated at 44°C for 2 or 4 h with or without a pre-heat step of 37°C for 1 h and a cooling step of 1 h. After exposure to the heat treatments, detached leaf assays showed the treatments significantly reduced pathogen incidence on leaves. Treatments at 44°C for 4 h, with or without pre-heat, significantly reduced Botrytis spp. incidence by 95.3 to 100% on non-inoculated and 88.9 to 100% on inoculated transplants. In field trials, early fruit production was not affected by the heat treatments. Our results suggest that heat treatment could reduce the inoculum load of Botrytis spp. on strawberry transplants and potentially help improving the efficacy of fungicides to control the disease in production fields.","PeriodicalId":20251,"journal":{"name":"Plant Health Progress","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2023-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46526702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-20DOI: 10.1094/php-12-22-0127-br
J. Oliver, K. Lewis, M. Aktaruzzaman, Md Emran Ali
Pseudocercospora leaf spot is frequently observed in blackberry production in the southeastern U.S. To manage the impacts of leaf spot diseases, blackberry growers in the southeastern U.S. typically rely on the application single-site fungicides including the quinone outside inhibitors (QoI) (FRAC 11) pyraclostrobin and azoxystrobin. In recent years, despite the regular application of chemical fungicides to manage leaf spots, blackberry growers and extension personnel in Georgia have noticed relatively poor control of these diseases. To investigate potential control failures due to fungicide resistance development, Pseudocercospora were isolated from symptomatic leaves collected from blackberry (Rubus fruticosus) in five commercial fields in southeastern Georgia. Using a mycelial growth inhibition assay, isolates were screened for resistance to pyraclostrobin. Among the 13 isolates tested, 12 were determined to be resistant to the fungicide. Subsequent sequencing of the cytochrome b gene indicated the presence of the G143A mutation in all fungicide-resistant isolates. The identification of fungicide resistance in 12 of 13 isolates and 4 of 5 examined commercial blackberry sites in Georgia suggests that resistance to this fungicide may be prevalent among Pseudocercospora on blackberry in Georgia and that future fungicide resistance monitoring efforts in Georgia blackberry plantings may be warranted. This represents the first report of QoI fungicide resistance in Pseudocercospora spp. from blackberry.
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