Pub Date : 2023-10-01DOI: 10.21273/hortsci17313-23
John Ertle, Chieri Kubota
Low evaporative conditions in indoor (vertical) farms reduce mass-flow–driven transport of calcium (Ca), resulting in tipburn of lettuce. Lettuce tipburn symptoms develop along the margins of young leaves and the growing shoot tip, where necrotic tissue forms as a result of Ca deficiency. For indoor farms, lettuce tipburn poses a major economic risk because the crop becomes unmarketable as a result of its appearance. Difference in tipburn sensitivity among cultivars has been thought to be related to differences in growth rate, morphology, or anthocyanin production, whereas most commercial lettuce cultivars have been known to express tipburn symptoms in the indoor farm setting. We created a tipburn-inducing growing condition in walk-in growth chambers that limits plant potential transpiration rate while achieving relatively high growth rates, and examined 10 commercial cultivars selected for tipburn sensitivity. Selected cultivars differ in morphology (butterhead, romaine, and leafy type) and color (red or green; resulting from anthocyanin production). All cultivars expressed visually detectable tipburn symptoms 22 ± 2.6 days after transplanting, and varied tipburn rates of 7% to 41% of all leaves at the time of harvest (28 days after transplanting). Despite cultivar-specific variation, neither lettuce morphology nor anthocyanin content were significantly correlated with the incidence or severity of tipburn. However, cultivars recommended for “indoor” production by seed suppliers had less tipburn severity than those recommended for outdoor or both indoor and outdoor production systems. Although tipburn risk may vary under other environmental conditions, low evaporative conditions in this experiment caused tipburn symptoms in all tested cultivars at varying degrees of severity. Cultivar-specific average yield and tipburn severity were not correlated with the Ca concentrations in the inner leaves, suggesting that the amount of tissue Ca required to prevent tipburn is cultivar specific and not related to yield. Our selected tipburn-inducing condition was found to be effective in comparing tipburn sensitivity of lettuce cultivars for indoor farm settings, and similar fast-growing but low-evaporative conditions should be used to assess cultivars for indoor farm production.
{"title":"Testing Cultivar-specific Tipburn Sensitivity of Lettuce for Indoor Vertical Farms","authors":"John Ertle, Chieri Kubota","doi":"10.21273/hortsci17313-23","DOIUrl":"https://doi.org/10.21273/hortsci17313-23","url":null,"abstract":"Low evaporative conditions in indoor (vertical) farms reduce mass-flow–driven transport of calcium (Ca), resulting in tipburn of lettuce. Lettuce tipburn symptoms develop along the margins of young leaves and the growing shoot tip, where necrotic tissue forms as a result of Ca deficiency. For indoor farms, lettuce tipburn poses a major economic risk because the crop becomes unmarketable as a result of its appearance. Difference in tipburn sensitivity among cultivars has been thought to be related to differences in growth rate, morphology, or anthocyanin production, whereas most commercial lettuce cultivars have been known to express tipburn symptoms in the indoor farm setting. We created a tipburn-inducing growing condition in walk-in growth chambers that limits plant potential transpiration rate while achieving relatively high growth rates, and examined 10 commercial cultivars selected for tipburn sensitivity. Selected cultivars differ in morphology (butterhead, romaine, and leafy type) and color (red or green; resulting from anthocyanin production). All cultivars expressed visually detectable tipburn symptoms 22 ± 2.6 days after transplanting, and varied tipburn rates of 7% to 41% of all leaves at the time of harvest (28 days after transplanting). Despite cultivar-specific variation, neither lettuce morphology nor anthocyanin content were significantly correlated with the incidence or severity of tipburn. However, cultivars recommended for “indoor” production by seed suppliers had less tipburn severity than those recommended for outdoor or both indoor and outdoor production systems. Although tipburn risk may vary under other environmental conditions, low evaporative conditions in this experiment caused tipburn symptoms in all tested cultivars at varying degrees of severity. Cultivar-specific average yield and tipburn severity were not correlated with the Ca concentrations in the inner leaves, suggesting that the amount of tissue Ca required to prevent tipburn is cultivar specific and not related to yield. Our selected tipburn-inducing condition was found to be effective in comparing tipburn sensitivity of lettuce cultivars for indoor farm settings, and similar fast-growing but low-evaporative conditions should be used to assess cultivars for indoor farm production.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135324531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17096-23
D. L. Zakalik, Michael G. Brown, G. Peck
Over 3 years (2016–18), tree productivity, biennial bearing, return bloom, and fruit quality were evaluated for seven high-tannin cider apple (Malus ×domestica Borkh.) cultivars. Five treatments were evaluated on each of the seven cultivars: hand-thinned of all fruit (a zero crop load treatment); hand-thinned to crop densities of three, six, or nine fruit/cm2 trunk cross-sectional area (TCSA); or left unthinned. In this paper, we report on the fruit maturity and juice quality properties that were analyzed for the three nonzero crop load treatments and the unthinned control. The effects of crop load on fruit maturity, as measured by starch pattern index and preharvest drop, were cultivar dependent. Crop density (fruit/cm2 TCSA) had a significant effect on all fruit maturity and juice quality variables, although effects were weakest in the “off” year (2017) for the whole planting when initial fruit set was low. As crop density increased, total poly phenols, titratable acidity, soluble solids, and primary amino nitrogen decreased in the juice of all seven cultivars. A partial budget analysis indicated that the reduced costs of nitrogen supplements due to increased primary amino nitrogen concentration alone would not justify cost of chemical or hand-thinning. By extrapolating the spring flowering density in the fourth year to potential fruit yields at harvest, we found that reducing crop load was projected to increase cumulative total polyphenol yields per tree over the long term. For the cultivars in this experiment, a target crop density of nine fruit/cm2 was found to adequately decrease biennial bearing while also not diminishing juice quality for hard cider production. High-tannin cider apple growers should consider juice quality, particularly tannin production, when making crop load management decisions.
{"title":"Fruitlet Thinning Improves Juice Quality in Seven High-tannin Cider Cultivars","authors":"D. L. Zakalik, Michael G. Brown, G. Peck","doi":"10.21273/hortsci17096-23","DOIUrl":"https://doi.org/10.21273/hortsci17096-23","url":null,"abstract":"Over 3 years (2016–18), tree productivity, biennial bearing, return bloom, and fruit quality were evaluated for seven high-tannin cider apple (Malus ×domestica Borkh.) cultivars. Five treatments were evaluated on each of the seven cultivars: hand-thinned of all fruit (a zero crop load treatment); hand-thinned to crop densities of three, six, or nine fruit/cm2 trunk cross-sectional area (TCSA); or left unthinned. In this paper, we report on the fruit maturity and juice quality properties that were analyzed for the three nonzero crop load treatments and the unthinned control. The effects of crop load on fruit maturity, as measured by starch pattern index and preharvest drop, were cultivar dependent. Crop density (fruit/cm2 TCSA) had a significant effect on all fruit maturity and juice quality variables, although effects were weakest in the “off” year (2017) for the whole planting when initial fruit set was low. As crop density increased, total poly phenols, titratable acidity, soluble solids, and primary amino nitrogen decreased in the juice of all seven cultivars. A partial budget analysis indicated that the reduced costs of nitrogen supplements due to increased primary amino nitrogen concentration alone would not justify cost of chemical or hand-thinning. By extrapolating the spring flowering density in the fourth year to potential fruit yields at harvest, we found that reducing crop load was projected to increase cumulative total polyphenol yields per tree over the long term. For the cultivars in this experiment, a target crop density of nine fruit/cm2 was found to adequately decrease biennial bearing while also not diminishing juice quality for hard cider production. High-tannin cider apple growers should consider juice quality, particularly tannin production, when making crop load management decisions.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44051229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17329-23
Ryan N. Contreras
{"title":"‘Emerald Beauty’ and ‘Emerald Sprite’ Cotoneasters","authors":"Ryan N. Contreras","doi":"10.21273/hortsci17329-23","DOIUrl":"https://doi.org/10.21273/hortsci17329-23","url":null,"abstract":"","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47406430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17196-23
P. Devkota, Amy Iezzoni, K. Gasic, Gregory Reighard, Raymond Hammerschmidt
Armillaria root rot (ARR), caused by Armillaria species and Desarmillaria tabescens, is a severe disease that affects stone fruit trees in the United States. One strategy to mitigate the impact of this disease is to develop ARR-resistant rootstocks. However, current techniques to screen Prunus species for resistance to ARR are time-consuming, labor-intensive, and may not fully replicate field conditions. To address these limitations, we developed a new rapid in vitro screening assay, which uses roots of 2-year-old Prunus rootstock genotypes. We screened 12 Prunus genotypes against Armillaria mellea, Armillaria solidipes, and Desarmillaria tabescens in vitro. Freshly excavated root segments were placed next to or on top of fungal cultures. After 21 days, the circumferential percentage and horizontal length of the fungal colonization and the ability of the fungus to enter through root periderm were evaluated. The root tissue surrounding the infection was also evaluated to assess any response reactions against the ARR pathogens. Our results showed that inoculated root tissues displayed signs of fungal infection, and infection and host responses varied among the Prunus genotypes. Host responses similar to those observed in the field, such as compartmentalization of infected tissue with barrier zones, necrophylactic periderm formation, and callus formation on root surfaces, were observed and were more evident in less susceptible genotypes. In conclusion, our newly developed assay, which uses freshly excavated roots from 2-year-old rootstocks, can rapidly screen Prunus genotypes for resistance to ARR.
{"title":"Rapid In Vitro Screening of Prunus Genotypes for Resistance to Armillaria Root Rot Using Roots of Young Rootstocks","authors":"P. Devkota, Amy Iezzoni, K. Gasic, Gregory Reighard, Raymond Hammerschmidt","doi":"10.21273/hortsci17196-23","DOIUrl":"https://doi.org/10.21273/hortsci17196-23","url":null,"abstract":"Armillaria root rot (ARR), caused by Armillaria species and Desarmillaria tabescens, is a severe disease that affects stone fruit trees in the United States. One strategy to mitigate the impact of this disease is to develop ARR-resistant rootstocks. However, current techniques to screen Prunus species for resistance to ARR are time-consuming, labor-intensive, and may not fully replicate field conditions. To address these limitations, we developed a new rapid in vitro screening assay, which uses roots of 2-year-old Prunus rootstock genotypes. We screened 12 Prunus genotypes against Armillaria mellea, Armillaria solidipes, and Desarmillaria tabescens in vitro. Freshly excavated root segments were placed next to or on top of fungal cultures. After 21 days, the circumferential percentage and horizontal length of the fungal colonization and the ability of the fungus to enter through root periderm were evaluated. The root tissue surrounding the infection was also evaluated to assess any response reactions against the ARR pathogens. Our results showed that inoculated root tissues displayed signs of fungal infection, and infection and host responses varied among the Prunus genotypes. Host responses similar to those observed in the field, such as compartmentalization of infected tissue with barrier zones, necrophylactic periderm formation, and callus formation on root surfaces, were observed and were more evident in less susceptible genotypes. In conclusion, our newly developed assay, which uses freshly excavated roots from 2-year-old rootstocks, can rapidly screen Prunus genotypes for resistance to ARR.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43377509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17241-23
Lamiaa M. Mahmoud, Katherine R. Weber, Tony Trama, G. England, M. Dutt
Citrus greening, or huanglongbing (HLB), caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CaLas), threatens the global citrus industry. Field observations have demonstrated that some citrus cultivars are more tolerant to the CaLas pathogen than others. ‘Parson Brown’ is an early maturing sweet orange variety that has consistently exhibited minimal leaf and fruit drop in the field compared with the ‘Hamlin’ sweet orange under similar conditions. This study aimed to understand performance of the ‘Parson Brown’ cultivar in several locations across the citrus production regions of Florida. Results indicated that the CaLas bacterial titer in both cultivars were similar with the quantitative polymerase chain reaction cycle threshold values ranging between 24.99 and 28.61 in ‘Hamlin’ and between 25.48 and 30.89 in ‘Parson Brown’. Leaves from the ‘Parson Brown’ trees however demonstrated higher chlorophyll content and total phenolic compounds in most of the locations. We also detected higher relative expression of CsPR1 and CsPR2 transcripts in ‘Parson Brown’ leaves in the first sampling period (March) and the fourth period (November). Additionally, Phloem protein 2 transcripts were downregulated in ‘Parson Brown’ leaves compared with ‘Hamlin’ at all locations. The ‘Hamlin’ juice had higher acidity, whereas ‘Parson Brown’ juice demonstrated a higher Brix to acidity ratio and juice color. The oil content in the juice ranged between 0.020% and 0.042%, and there was variation in the oil content between the locations, which could indicate clonal differences. ‘Parson Brown’ juice however contained higher limonin and nomilin content than ‘Hamlin’ juice in most of the locations. Taken together, the current results confirmed the enhanced tolerance of ‘Parson Brown’ trees to HLB when compared with ‘Hamlin’ in all sampled locations.
{"title":"A Comparative Study between ‘Parson Brown’ and ‘Hamlin’ Sweet Oranges Growing under Endemic Huanglongbing Conditions in Florida","authors":"Lamiaa M. Mahmoud, Katherine R. Weber, Tony Trama, G. England, M. Dutt","doi":"10.21273/hortsci17241-23","DOIUrl":"https://doi.org/10.21273/hortsci17241-23","url":null,"abstract":"Citrus greening, or huanglongbing (HLB), caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CaLas), threatens the global citrus industry. Field observations have demonstrated that some citrus cultivars are more tolerant to the CaLas pathogen than others. ‘Parson Brown’ is an early maturing sweet orange variety that has consistently exhibited minimal leaf and fruit drop in the field compared with the ‘Hamlin’ sweet orange under similar conditions. This study aimed to understand performance of the ‘Parson Brown’ cultivar in several locations across the citrus production regions of Florida. Results indicated that the CaLas bacterial titer in both cultivars were similar with the quantitative polymerase chain reaction cycle threshold values ranging between 24.99 and 28.61 in ‘Hamlin’ and between 25.48 and 30.89 in ‘Parson Brown’. Leaves from the ‘Parson Brown’ trees however demonstrated higher chlorophyll content and total phenolic compounds in most of the locations. We also detected higher relative expression of CsPR1 and CsPR2 transcripts in ‘Parson Brown’ leaves in the first sampling period (March) and the fourth period (November). Additionally, Phloem protein 2 transcripts were downregulated in ‘Parson Brown’ leaves compared with ‘Hamlin’ at all locations. The ‘Hamlin’ juice had higher acidity, whereas ‘Parson Brown’ juice demonstrated a higher Brix to acidity ratio and juice color. The oil content in the juice ranged between 0.020% and 0.042%, and there was variation in the oil content between the locations, which could indicate clonal differences. ‘Parson Brown’ juice however contained higher limonin and nomilin content than ‘Hamlin’ juice in most of the locations. Taken together, the current results confirmed the enhanced tolerance of ‘Parson Brown’ trees to HLB when compared with ‘Hamlin’ in all sampled locations.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45733879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17302-23
An-Na Wu, Yu-Sen Chang, Chun-Wei Wu
{"title":"‘Taoyuan No. 3-Spring Red’ and ‘Taoyuan No. 4-Red Glory’, the New Cultivars of Cherry Blossom in Subtropical Area","authors":"An-Na Wu, Yu-Sen Chang, Chun-Wei Wu","doi":"10.21273/hortsci17302-23","DOIUrl":"https://doi.org/10.21273/hortsci17302-23","url":null,"abstract":"","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135274132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17291-23
Raymond A. Cloyd, Nathan J. Herrick
The citrus mealybug, Planococcus citri , is an insect pest of greenhouse-grown horticultural crops. Citrus mealybug causes plant damage when feeding on plant leaves, stems, flowers, and fruits, resulting in a substantial economic loss. Insecticides are applied to manage citrus mealybug populations in greenhouse production systems. Anecdotal information suggests that mixing entomopathogenic fungal-based insecticides with insect growth regulators may be effective for managing citrus mealybug populations under greenhouse conditions. Consequently, we conducted two experiments in a research greenhouse at Kansas State University (Manhattan, KS, USA) in 2023. The experiments were designed to determine the efficacy of three commercially available entomopathogenic fungal-based insecticides [ Beauveria bassiana Strain GHA (BotaniGard ® ), B. bassiana strain PPRI 5339 (Velifer™) and Isaria fumosorosea Apopka Strain 97 (Ancora ® )] when mixed with three insect growth regulators [azadirachtin (Azatin ® O), novaluron (Pedestal ® ), and pyriproxyfen (Distance ® )] on citrus mealybug feeding on coleus, Solenostemon scutellarioides , plants. The entomopathogenic fungal-based insecticides alone or when mixed with the insect growth regulators were not effective in managing citrus mealybug populations, with <20% mortality during each experiment. In addition, all coleus plants treated with the entomopathogenic fungal-based insecticides had a white, powdery residue on the leaves. Our study demonstrates that entomopathogenic fungal-based insecticides, even when mixed with insect growth regulators, are not effective in managing citrus mealybug populations in greenhouses, which is likely because the environmental conditions (temperature and relative humidity) are not optimal for conidial germination and hyphal infection to occur. Therefore, entomopathogenic fungal-based insecticides have limited use for managing insect pests in greenhouse production systems.
{"title":"Are Entomopathogenic Fungal-based Insecticides and Insect Growth Regulator Mixtures Effective Against the Citrus Mealybug, Planococcus citri (Hemiptera: Pseudococcidae), Feeding on Coleus, Solenostemon scutellarioides, Plants under Greenhouse Conditions?","authors":"Raymond A. Cloyd, Nathan J. Herrick","doi":"10.21273/hortsci17291-23","DOIUrl":"https://doi.org/10.21273/hortsci17291-23","url":null,"abstract":"The citrus mealybug, Planococcus citri , is an insect pest of greenhouse-grown horticultural crops. Citrus mealybug causes plant damage when feeding on plant leaves, stems, flowers, and fruits, resulting in a substantial economic loss. Insecticides are applied to manage citrus mealybug populations in greenhouse production systems. Anecdotal information suggests that mixing entomopathogenic fungal-based insecticides with insect growth regulators may be effective for managing citrus mealybug populations under greenhouse conditions. Consequently, we conducted two experiments in a research greenhouse at Kansas State University (Manhattan, KS, USA) in 2023. The experiments were designed to determine the efficacy of three commercially available entomopathogenic fungal-based insecticides [ Beauveria bassiana Strain GHA (BotaniGard ® ), B. bassiana strain PPRI 5339 (Velifer™) and Isaria fumosorosea Apopka Strain 97 (Ancora ® )] when mixed with three insect growth regulators [azadirachtin (Azatin ® O), novaluron (Pedestal ® ), and pyriproxyfen (Distance ® )] on citrus mealybug feeding on coleus, Solenostemon scutellarioides , plants. The entomopathogenic fungal-based insecticides alone or when mixed with the insect growth regulators were not effective in managing citrus mealybug populations, with <20% mortality during each experiment. In addition, all coleus plants treated with the entomopathogenic fungal-based insecticides had a white, powdery residue on the leaves. Our study demonstrates that entomopathogenic fungal-based insecticides, even when mixed with insect growth regulators, are not effective in managing citrus mealybug populations in greenhouses, which is likely because the environmental conditions (temperature and relative humidity) are not optimal for conidial germination and hyphal infection to occur. Therefore, entomopathogenic fungal-based insecticides have limited use for managing insect pests in greenhouse production systems.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135275170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17321-23
Emma Volk, Katie Jennings, Steven F. Fennimore, Mark Hoffmann
Allyl isothiocyanate (AITC) is a colorless aliphatic oil that naturally occurs in many plants of the cabbage and mustard family (Brassicaceae). It has antimicrobial activity and is used as pesticide for a variety of applications. However, AITC as a soil disinfectant has exhibited inconsistent weed and pathogen control, mainly because of its higher viscosity and low vapor pressure (5 mmHg at 25 °C). Steam, however, effectively controls soil-borne pathogens if soil temperatures of 65 °C or more are reached for a minimum duration of 30 minutes. We hypothesized that steam applications targeting lower temperatures, when combined with soil-injected AITC, will provide sufficient weed and pathogen control. We further hypothesized that the combination of AITC and steam will lead to higher strawberry yields compared with either of the components on their own. Two strawberry ( Fragaria × ananassa cv. Camarosa) trials were conducted during two consecutive seasons (2020–21 and 2021–22). The trials were conducted at the Central Crops Research Station in Clayton, NC, USA, and the Horticulture Research Station in Castle Hayne, NC, USA. Eight treatments and a nontreated control were established in a randomized complete block design (four replicates each). The treatments were Pic-Clor 60, AITC, AITC followed by 60 minutes of steam injection, AITC followed by 30 minutes of steam injection, AITC followed by 10 minutes of steam injection, 60 minutes of steam injection, 30 minutes of steam injection, and 10 minutes of steam injection. Soilborne pathogen control efficacy was assessed using wet Pythium sp. plating assays. Weed control was assessed through weed seed/tuber germination assays. Our results showed that combining ATIC with steam did not reduce weed or pathogen levels or improve yield when compared with AITC alone or Pic-Clor 60. Moreover, treatment comprising steam alone did not provide sufficient control. However, AITC alone controlled weeds and pathogens as effectively as Pic-Clor 60 during both years and both locations of the study. These results showed that AITC alone could be a potential alternative soil disinfectant for Eastern North Carolina strawberry production.
{"title":"Preplant Application of Allyl Isothiocyanate Controls Weeds and Pathogens in Eastern North Carolina Strawberry (Fragaria ×ananassa cv. Camarosa) with and without Addition of Soil-applied Steam","authors":"Emma Volk, Katie Jennings, Steven F. Fennimore, Mark Hoffmann","doi":"10.21273/hortsci17321-23","DOIUrl":"https://doi.org/10.21273/hortsci17321-23","url":null,"abstract":"Allyl isothiocyanate (AITC) is a colorless aliphatic oil that naturally occurs in many plants of the cabbage and mustard family (Brassicaceae). It has antimicrobial activity and is used as pesticide for a variety of applications. However, AITC as a soil disinfectant has exhibited inconsistent weed and pathogen control, mainly because of its higher viscosity and low vapor pressure (5 mmHg at 25 °C). Steam, however, effectively controls soil-borne pathogens if soil temperatures of 65 °C or more are reached for a minimum duration of 30 minutes. We hypothesized that steam applications targeting lower temperatures, when combined with soil-injected AITC, will provide sufficient weed and pathogen control. We further hypothesized that the combination of AITC and steam will lead to higher strawberry yields compared with either of the components on their own. Two strawberry ( Fragaria × ananassa cv. Camarosa) trials were conducted during two consecutive seasons (2020–21 and 2021–22). The trials were conducted at the Central Crops Research Station in Clayton, NC, USA, and the Horticulture Research Station in Castle Hayne, NC, USA. Eight treatments and a nontreated control were established in a randomized complete block design (four replicates each). The treatments were Pic-Clor 60, AITC, AITC followed by 60 minutes of steam injection, AITC followed by 30 minutes of steam injection, AITC followed by 10 minutes of steam injection, 60 minutes of steam injection, 30 minutes of steam injection, and 10 minutes of steam injection. Soilborne pathogen control efficacy was assessed using wet Pythium sp. plating assays. Weed control was assessed through weed seed/tuber germination assays. Our results showed that combining ATIC with steam did not reduce weed or pathogen levels or improve yield when compared with AITC alone or Pic-Clor 60. Moreover, treatment comprising steam alone did not provide sufficient control. However, AITC alone controlled weeds and pathogens as effectively as Pic-Clor 60 during both years and both locations of the study. These results showed that AITC alone could be a potential alternative soil disinfectant for Eastern North Carolina strawberry production.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135275173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.21273/hortsci17158-23
Kenneth W. Pierce, Michael P. Nattrass
Cover crops are defined as crops grown primarily for agroecosystem improvement rather than for market or sale. The use of cover crops to decrease the negative effects of weeds and improve soil and ecosystem health is increasing, but unanticipated allelopathic responses to those cover crops by subsequent crops is sometimes a problem. Allelopathy is broadly defined as the biochemical interactions between all types of plants, including microorganisms. Because allelopathic effects include both inhibitory and stimulatory responses and may be species- and cultivar-specific, a method of rapidly screening donor and recipient crops for allelopathic interactions is needed. The objective of this research was to evaluate a growth chamber bioassay for rapidly screening spinach (Spinacia oleracea L.) cultivars for allelopathic interactions with an aqueous extract from fresh whole-plant tissue of sorghum-sudangrass [Sorghum bicolor (L.) Moench; SSG] cultivars. The bioassay exposed the seed of 10 spinach cultivars to the aqueous extract of three cultivars of SSG during the imbibition and germination processes and evaluated the consequent root and stem development. Compared with the control, the extract from all three SSG cultivars decreased the root length of all spinach cultivars. A subsequent field screen where spinach cultivars were planted into decomposing SSG residue resulted in a similar pattern of growth suppression. These results demonstrate that the growth chamber bioassay is suitable for predicting allelopathic interactions between cultivars of SSG and cultivars of spinach and can be used by growers for making cultivar selection decisions when spinach follows SSG in a cropping sequence. This rapid-screening growth chamber bioassay protocol eliminates many of the environmental and other challenges frequently associated with field trials and may be adaptable for predicting allelopathic interactions among other cover crops, weeds, and subsequent market crops.
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Pub Date : 2023-10-01DOI: 10.21273/hortsci17118-23
Gabriel Campbell-Martínez, Mack Thetford, Debbie Miller, Sandra Wilson, Celina Gómez
Sandhill milkweed [ Asclepias humistrata (Walter)] is important for monarch butterfly [ Danaus plexippus (L.)] conservation efforts, yet precise cultivation practices are largely not available. We tested the effects of three fertilizer rates and four substrate types and four container types on the performance of sandhill milkweed during greenhouse production. Seedlings fertilized with a high (0.90 g per 48-cell container) controlled-release fertilizer rate of 15N–3.9P–10.0K (15–9–12 Osmocote ® Plus) had reduced performance compared with low and medium fertilizer rates (0.34 and 0.56 g per 48-cell container, respectively). Seedlings grown in large containers (∼175 mL including standard 32-cell liners and tall tree-tubes) outperformed seedlings grown in small containers (∼100 mL including standard 48-cell liners and short tree tubes). A transplant ready plant can be produced for spring within 16 weeks when seeds are sown in early January. Although sandhill milkweed seedlings can be grown under various fertilizer rates and in various containers and substrates, seedlings grown in tall tree tubes in a peat-based mix (Sunshine Mix) outperformed a nursery standard substrate and two wood fiber substrates. We recommend growing plants in a peat-based substrate within tall tree tube containers and applying a medium fertilizer rate.
沙丘乳草对帝王蝶(Danaus plexippus, L.)的保护工作很重要，但精确的栽培方法在很大程度上是不可用的。试验了三种施肥水平、四种基质类型和四种容器类型对沙山乳草温室生产性能的影响。施用15N-3.9P-10.0K (15-9-12 Osmocote®Plus)高控释肥料量(0.90 g / 48细胞容器)的幼苗，与低和中施肥量(分别为0.34 g / 48细胞容器和0.56 g / 48细胞容器)相比，表现较差。在大容器(~ 175 mL，包括标准32细胞衬垫和高树管)中生长的幼苗优于在小容器(~ 100 mL，包括标准48细胞衬垫和短树管)中生长的幼苗。在1月初播种时，16周内就可以生产出适合春季移植的植株。虽然沙丘乳草幼苗可以在不同的肥料用量和不同的容器和基质中生长，但在泥炭基混合物(阳光混合物)中生长的幼苗比苗圃标准基质和两种木纤维基质表现更好。我们建议在高大的树管容器中种植植物，并施用中等肥料。
{"title":"Effect of Fertilizer Rate, Substrate, and Container Type on Greenhouse Production of Sandhill Milkweed","authors":"Gabriel Campbell-Martínez, Mack Thetford, Debbie Miller, Sandra Wilson, Celina Gómez","doi":"10.21273/hortsci17118-23","DOIUrl":"https://doi.org/10.21273/hortsci17118-23","url":null,"abstract":"Sandhill milkweed [ Asclepias humistrata (Walter)] is important for monarch butterfly [ Danaus plexippus (L.)] conservation efforts, yet precise cultivation practices are largely not available. We tested the effects of three fertilizer rates and four substrate types and four container types on the performance of sandhill milkweed during greenhouse production. Seedlings fertilized with a high (0.90 g per 48-cell container) controlled-release fertilizer rate of 15N–3.9P–10.0K (15–9–12 Osmocote ® Plus) had reduced performance compared with low and medium fertilizer rates (0.34 and 0.56 g per 48-cell container, respectively). Seedlings grown in large containers (∼175 mL including standard 32-cell liners and tall tree-tubes) outperformed seedlings grown in small containers (∼100 mL including standard 48-cell liners and short tree tubes). A transplant ready plant can be produced for spring within 16 weeks when seeds are sown in early January. Although sandhill milkweed seedlings can be grown under various fertilizer rates and in various containers and substrates, seedlings grown in tall tree tubes in a peat-based mix (Sunshine Mix) outperformed a nursery standard substrate and two wood fiber substrates. We recommend growing plants in a peat-based substrate within tall tree tube containers and applying a medium fertilizer rate.","PeriodicalId":13140,"journal":{"name":"Hortscience","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135275174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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